Traumatic Injuries of the Foot and Ankle

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1-1-2021

Traumatic Injuries of the Foot and Ankle Traumatic Injuries of the Foot and Ankle

Alexander D. Grushky

Sharon J. Im

Scott D. Steenburg

Suzanne Chong

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Traumatic Injuries of the Foot and AnkleAlexander D. Grushky, MD,*, Sharon J. Im, MD,†, Scott D. Steenburg, MD, FASER,z andSuzanne Chong, MD, MS, FASERx

Introduction

The pathologies involving the foot and ankle in the emer-gency setting are widely ranging and vary from traumatic

fractures to soft tissue/joint infection. The ankle is the mostfrequently injured major weight-bearing joint in the body,with lateral ankle sprains representing the most commoninjury in the musculoskeletal system.1,2 Fractures of theankle and foot account for 9% and 10% of all fractures,respectively1,3; a review of the National Trauma Data Bankbetween 2007 and 2011 revealed 280,933 fracture-disloca-tions of the foot and/or ankle4 and a population-based studyfound an incidence of 168.7/100,000/year, with lateral mal-leolus fractures representing 55% of fractures.5 Commoncauses of injury range from trauma, eg, motor vehicle acci-dents and sports injury, to osteoporosis.6

In addition to the physical and emotional effects of aninjury, there are also significant financial implications, withankle sprains costing an average of $318-$914 per sprain.7

In a review of calcaneal fractures sustained by industrialworkers, the average total cost and time from injury to returnto work was estimated for operative and nonoperative frac-tures. The nonoperative subset averaged 18 weeks untilreturn to work, with an average cost of $14,230, while the

operative subset averaged 69 weeks until return to work,with an average cost of injury of $65,384.8

Timely recognition of these injuries allows for early treat-ment and minimizes the risk of complications related todelayed or missed diagnosis. Knowledge of mechanism andpatterns of injury can aid in the detection of subtle or unsus-pected injuries that impact management.

Imaging TechniqueThe recommended initial imaging evaluation of patients withsuspected acute traumatic injuries to the foot and ankle con-sists of standard 3 view radiographs (Reference 2 ACR-Appropriateness Criteria: Acute Trauma to Ankle, and Foot).Standard radiographic evaluation of the foot consists of ante-rior-posterior (AP), lateral, and oblique views. The lateralview of the foot allows evaluation of the talocalcaneal relation(Bohler’s angle, Critical angle of Gissane).1 For the ankle, thestandard views are AP, lateral, and mortise. The ankle mor-tise view allows for evaluation of the tibial plafond and tibio-talar congruence. Accurate and thorough descriptions offractures are important to guide appropriate management;Tables 1 and 2 outline descriptors of fractures and associatedfindings, respectively.

Additional views of the foot and ankle can be helpful forelucidating injuries. Weight-bearing views of the foot arerequired if there is suspicion for injury to the Lisfranc liga-ment complex, as nonweight-bearing views may miss orunderestimate injury.9 Ankle stress views can be employedto better detect medial clear space widening due to deltoidligamentous injury in the setting of distal fibular fracture.Stress can be applied via manual external rotation; however,this results in additional radiation exposure to the personapplying the stress and can cause discomfort to the patient.Gravity stress views, with the patient in lateral decubitusposition, a wedge under the calf of the injured side, andviews obtained with 10⁰-15⁰ internal rotation, have beenshown to be as effective in detecting medial clear space wid-ening in the setting of an isolated fibular fracture and are bet-ter tolerated by patients.1,10-13

Abbreviations: ATFL, Anterior Talofibular Ligament; PTFL, PosteriorTalofibular Ligament; CFL, Calcaneofibular Ligament; AITFL, AnteriorInferior Tibiofibular Ligament; PITFL, Posterior Inferior TibiofibularLigament; TTFL, Transverse Tibiofibular Ligament; IOL, InterosseousLigament; IOM, Interosseous Membrane; MCS, Medial Clear Space;TCS, Tibiofibular Clear Space; TFO, Tibiofibular Overlap; aTFD,Anterior Talofibular Distance

*Division of Emergency Radiology, Department of Radiology, University ofMichigan, Ann Arbor, MI.

yDepartment of Sports Medicine, Henry Ford Hospital, Detroit, MI.zDepartment of Radiology and Imaging Sciences, Indiana University School

of Medicine and Indiana University Health, Indianapolis, IN.xEmergency Radiology Division, Department of Radiology and Imaging

Sciences, Indiana University School of Medicine and Indiana UniversityHealth, Indianapolis, IN.

Conflicts of Interest: None.Address reprint requests to Alexander D. Grushky, MD, Division of

Emergency Radiology, Department of Radiology, University ofMichigan, Taubman Center, TC B1-132K, 1500 E. Medical CenterDrive, Ann Arbor, MI 48109. E-mail: [email protected]

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Computed tomography (CT) is superior to radiography fordepicting the severity of comminution, intra-articular exten-sion, displacement and angulation of fractures. In the acutesetting, CT is reserved for patients in whom clinical suspicionfor fracture persists despite normal radiographs or for preop-erative planning.1 CT has been shown to be superior toradiographs for the evaluation of distal tibiofibular syndes-motic injury,14 and allows for better detection and descrip-tion of fractures involving the Tillaux-Chaput tubercle andposterior malleolus.15 In the setting of a Lisfranc injury, CTis often required to fully characterize and identify all frac-tures.1 For cases of suspected musculoskeletal infection, CTperformed with intravenous iodinated contrast is useful toevaluate for extent of infection, given its ability to depictcross-sectional and compartmental anatomy.17 While therole of dual-energy CT in the musculoskeletal system haslargely been reserved for detection of urate deposits inpatients with gout, there is increasing evidence supportingthe use of dual-energy CT for metal artifact reduction anddetection of bone marrow edema.16,17

Magnetic resonance imaging (MRI) is superior to CT for theevaluation of soft tissue structures, can detect marrow edema,and is more sensitive and specific than nuclear medicine scin-tigraphy for the evaluation of infection.1 MRI can depict purelyligamentous injury and allows for detailed assessment of theextent of soft tissue infection and injury given its inherentlyhigh contrast and good spatial resolution.1 However, MRI isless widely available, particularly after hours in the emergentsetting, and is a more expensive examination.18,19

Adjunctive modalities used in the evaluation of foot andankle emergencies include sonography, nuclear medicine,and joint aspiration. Ultrasonography can detect ligamentousand tendinous injuries but is not widely available, particu-larly after-hours in emergent settings, because it requiressonographers and physicians with sufficient expertise inmusculoskeletal ultrasound.20 Sonography is also useful toevaluate for superficially located soft tissue fluid collectionssuch as abscess and hematoma and to evaluate for vascularabnormalities such as deep venous thrombosis.19,21 Nuclear

medicine has almost no role in characterizing acute foot andankle traumatic injuries but can be useful to evaluate forstress fractures and to distinguish between cellulitis vs septicarthritis. Joint aspiration remains the gold standard for con-firming joint infection.1

AnkleAnatomyThe ankle is comprised of the distal tibia, fibula, and talus,while the ankle joint is formed by the tibiotalar, distal tibio-fibular, and talofibular articulations. The tibiotalar and talo-fibular articulations together are considered the “true” anklejoint and are referred to as the talocrural joint. The lateralmalleolus is the distal extension of the fibula, and the medialmalleolus is the distal extension of the tibia. The fibular inci-sion (“incisura fibula” or “peroneal groove”) is located alongthe lateral aspect of the distal tibia and represents the articu-lating face of the tibia at the distal tibiofibular joint. Whileusually concave with 1-7.5 mm of depth, the fibular incisionvaries widely between individuals, with some demonstratinga convex appearance, which may increase the risk of malre-duction in the setting of ankle fractures.22 The tibiotalar andtalofibular joints are responsible for motion in the sagittalplane, with 23⁰-48⁰ plantarflexion and 10⁰-23⁰ dorsiflexion.9

The ligaments of the ankle can be grouped into 3 ligamen-tous complexes: lateral collateral, medial collateral, and syn-desmotic. The lateral collateral ligament complex (Fig. 1)includes the anterior and posterior talofibular (ATFL/PTFL)and calcaneofibular (CFL) ligaments. The ATFL functions toresist inversion, anterior translation, and internal rotation.The CFL acts as a stabilizer against inversion forces and pro-vides stability to the talocrural and subtalar joints. The PTFL

Table 1 Important Descriptors of Osseous Fractures1

Site of fracture and extent of involvementAlignment of fracture fragments (overriding, displacement)Direction of fracture line (transverse, oblique)Special or associated features (comminution, dislocation)Special type of fracture (Maisonneuve, Lisfranc)Open vs closedInvolvement of growth plates in the pediatric population

Table 2 Indirect Signs of Osseous Injury1

Soft tissue swelling, obliteration of adjacent fat stripesPeriosteal/endosteal reactionJoint effusion (+/- intracapsular fat-fluid level)Double cortical lineCortical bucklingMetaphyseal corner irregularity

Figure 1 Lateral ankle ligaments. Sagittal projection of the lateralaspect of the ankle reveals the major ligaments of the lateral liga-mentous complex. Note the calcaneofibular ligament passes beneaththe peroneal tendons, and traverses both the talofibular and subtalarjoints. The superior and inferior peroneal retinaculum (not labeled)are seen superior and inferior to the CFL.

48 A.D. Grushky et al.


has an important stabilizing role in dorsiflexion, but in thesetting of an intact ATFL and CFL, acts primarily in a supple-mentary capacity.9,23

The primary medial collateral ligament (Fig. 2) is the del-toid ligament, which functions primarily to prevent lateraltalar translation, and is made of deep and superficial compo-nents. The deep deltoid ligament prevents lateral talar shiftand rotation, and the superficial deltoid ligament functionsmore in the prevention of talar tilt due to a valgus force.1,9,24

The integrity of the deltoid ligament is evaluated on radio-graphs by measuring the medial clear space between themedial talar border and lateral border of the medial malleo-lus. Gibson et al24 evaluated uninjured ankles using externalrotation stress views and found that no normal ankles had amedial clear space (MCS) >5 mm on stress. In ankles withan MCS between 4 and 5 mm, a concurrent lateral shift of>2 mm would suggest instability. While the sample size ofthis study was small (15 patients), it does suggest the use ofan MCS >5 mm on stress views as a cutoff for instability.The syndesmotic ligament complex (Fig. 3) is a complex

articulation of the distal tibiofibular joint, consisting of theanterior and posterior inferior tibiofibular ligaments (AITFL/PITFL), transverse tibiofibular ligament (TTFL), interosseousligament (IOL), and interosseous membrane (IOM). The syn-desmosis provides stability against lateral talar translation,and also allows for the transfer of axial compressive forcesfrom the tibia to fibula in a weight-bearing position. There isa small amount of normal physiologic movement at the syn-desmosis with approximately 2 degrees of fibular rotation/external rotation and 2 mm displacement of the fibula rela-tive to the tibia.1,9,22,25-27 The radiographic evaluation of thesyndesmosis includes measuring the tibiofibular clear space(TCS), tibiofibular overlap (TFO), and MCS. Recommendednormal measurements are presented in Table 3 and Figure 4,

Figure 2 Medial ankle ligaments. Sagittal projection of the medialaspect of the foot. The multiple bands of the deltoid ligament canbe seen extending from the distal tibia to the talus, navicular, andcalcaneus. Also shown are the calcaneonavicular components of theSpring ligament, as well as the medial talocalcaneal ligament.

Figure 3 Posterior ankle ligaments. Frontal projection of the poste-rior ankle, with the posterior ligaments displayed. The TTFL runsalong the distal aspect of the PITFL, and can be difficult to distin-guish as a separate entity. The interosseous ligament (not shown)connects the distal tibia and fibula near the fibula incisura, and canbe difficult to distinguish from the superior fibers of the PITFL.

Table 3 Normal Radiographic Measurements of the AnkleJoint24,28,29,35,36,39

Measurement Value

Tibiofibular overlap - >6 mm on AP view- >1 mm on mortise view

Tibiofibular clear space - <6 mm on both AP and mortise- Most reliable

Medial clear space - Less than or equal to superiorclear space

- <5 mm on stress view- 4-5 mm WITH >2 mm lateralshift on stress suggests injury

- >4 mm AND >1 mm vs SCSsuggests injury

Talocrural angle - 72-86⁰Fibular fracture gap(lateral view)

- >1-2 mm can suggest MCSinstability

Anterior tibiofibulardistance*

- <2 mm

Posterior tibiofibulardistance*

- <4 mm

Tibiofibular distance† - <2 mm

Please note that there is considerable variation in these measure-ments between individuals, and that there is some controversyregarding the cutoff values above. The tibiofibular overlap, tibio-fibular clear space, and medial clear space are measured onradiographs and are useful in detecting syndesmotic and deltoidligament injury. The fibular gap is a measurement of the anterior-posterior widening of a distal fibular fracture and can suggestmedial clear space instability. The talocrural angle is helpful inthe detection of fibular shortening. The anterior tibiofibular dis-tance, posterior tibiofibular distance, and tibiofibular distanceare useful in the detection of syndesmotic injury.

*Measured 9-12 mm above plafond on axial CT.†Measured at the plafond on axial CT.

“Traumatic Injuries of the Foot and Ankle” 49


with the caveat that normal anatomic variation exists,10,21,24

including no tibiofibular overlap.A separate set of CT-based measurements for the syn-

desmosis can be used. Elgafy et al28 measured the dis-tance between the anterior tibial tubercle and nearestfibular margin and determined a normal limit of <2 mm,and the distance between the medial fibula and nearestpoint on the lateral border of the posterior tibial tubercle,with a normal cutoff of <4 mm. Measurements weremade 9-12 mm above the tibial plafond in axial CTimages. Ahn et al29 measured the narrowest distance ofthe syndesmosis at the level of the plafond and foundhigh diagnostic accuracy of syndesmotic injury whenusing a cutoff of 2 mm.Although a more in-depth discussion of the muscles

and tendons of the ankle is beyond the scope of this arti-cle, the Achilles tendon deserves mention as Achillesinjury is commonly encountered in the emergent setting.The Achilles tendon is the largest tendon in the body,connecting the gastrocnemius-soleus complex to theinsertion on the posterior calcaneus. The primary role isto plantarflex the foot, and during the act of running,plantar forces can reach up to 10£ body weight. TheAchilles tendon is unique in that it lacks a true tendonsheath, instead containing a paratenon, or thin layer of

fibrous tissue. The paratenon provides blood supply tothe Achilles tendon, particularly anteriorly. The Achillesalso gets blood supply from the soleus proximally andcalcaneus distally. However, this arrangement results in a“watershed” area of relatively scarce blood supply approx-imately 2-6 cm from the calcaneal insertion and predis-poses to injury.30

Ankle FracturesAnkle fractures are commonly encountered in the emergentsetting, representing 9% of fractures and are second only tothe proximal femur as the most common fracture of the lowerlimb.3 Fractures may result from high energy (motor vehiclecollisions, fall) or lower energy (twisting) injuries, with lowerenergy injuries having a better prognosis. Important featuresto describe in ankle fractures include the presence and levelof the fibular fracture, the presence and orientation of anymedial malleolar fracture, and the presence and size of anyposterior malleolar fracture. Subtle fibular fractures may bebest seen on lateral radiographs, which may be the only pro-jection to show displacement in the sagittal plane.9

The determination of whether an ankle fracture is stable orunstable guides management, as unstable fractures are almostuniversally managed operatively. Some authors suggest using

Figure 4 Normal measurements of the ankle. (a) AP view of the ankle with the tibiofibular clear space (double arrow)and tibiofibular overlap (single arrow). (b) Mortise view of the ankle with the tibiofibular clear space (A), superior clearspace (B), and medial clear space (C).



a “ring” analogy, whereby the bones and ligaments of theankle form a contiguous ring—1 break is stable, but 2 ormore breaks in the chain indicate instability. For example,bimalleolar or trimalleolar fractures are considered unstableand usually require open reduction and internal fixation. Inthe setting of an isolated distal fibular fracture and absence ofa medial malleolar fracture, deltoid ligament injury can act asa medial malleolar fracture equivalent, thus rendering theankle unstable and indicating the need for surgery.9 As such,it is important to identify signs of instability radiographicallyto help aid in management.

Distal Fibular FractureThere are several different classification systems used for dis-tal fibular fractures, the most common being the Danis-Weber and Lauge-Hansen systems. Both systems aim to dis-tinguish stable from unstable injuries. The Danis-Weber clas-sification relates the level of fibular fracture to thesyndesmosis with Weber A being inferior to the syndesmosis,Weber B at the level of the syndesmosis, and Weber C abovethe syndesmosis (Figs. 5 and 6). The Danis-Weber systemcenters on the importance of the lateral syndesmotic ligamentcomplex to ankle congruence and stability by incorporating

Figure 5 Danis-Weber classification of fibular fractures. Frontal projection of the Danis-Weber, or Weber, classification.This is based on the location of the fibular fracture relative to the ankle joint; (a) Fibular fracture at the level of or belowthe syndesmosis. (b) Spiral fibular fracture at the level of the syndesmosis with rupture of the AITFL. (c) Fibular frac-ture above the level of the syndesmosis with rupture of the AITFL.

Figure 6 Distal fibular fractures. (a,b) A 64-year-old female after a twisting injury to the left ankle. Frontal (a) and mor-tise (b) views show a subtle linear lucency of the distal fibula (arrows) inferior to the level of the syndesmosis, consis-tent with a Weber A fracture. (c,d) Ankle pain after falling down a set of stairs. Frontal view (c) shows an oblique andangulated fracture of the lateral malleolus at the level of the syndesmosis (arrows). There is also a horizontal fracture ofthe medial malleolus. Lateral view (d) shows the oblique orientation of the fibular fracture (white arrows) as well as afracture of the posterior malleolus (black arrow). (e, f) A 77-year-old female presented after a fall. Frontal view (e) andlateral view (f) show an oblique fracture of the distal fibula proximal to the level of the syndesmosis (arrows).



the criteria advanced by Boden et al derived from cadavericstudies.1 Historically, the location of the distal fibular fracturewas believed to be associated with the likelihood of syndes-motic injury, with Boden et al suggesting the need for syn-desmotic stabilization if the fibular fracture was > 4.5 cmabove the ankle joint. However, van den Bekerom et alshowed that the level of fibular fracture was not correlatedwith interosseous membrane integrity on MRI and therefore,the level of fibular fracture is not a reliable predictor for theneed for syndesmotic stabilization. Still, the “Boden criteria”may find use as an adjunct in the determination of fracturemanagement.31 The Danis-Weber classification is detailed inTable 4. The Lauge-Hansen classification is more prevalentin orthopedic literature and is based on the suspected mecha-nism of injury, the position of the foot at time of injury, anddirection of force applied (Fig. 7).3,32 The classification isdetailed in Table 5.In the setting of an isolated Weber B fracture of the distal

fibula, the integrity of the deltoid ligament becomes animportant factor in determining ankle stability. If the deltoidligament is injured or the mortise is incongruent, the fractureis considered unstable. The detection of mortise incongru-ence or talar shift is important as even 1 mm of shift resultsin a loss of 42% contact area at the tibiotalar articulation,

predisposing to development of early degenerativechanges.20,26 The medial clear space has been used to assessdeltoid ligament integrity with various cutoff values used toindicate injury. Stufkens et al33 suggest using a MCS >4 mmAND >1 mm difference between MCS and superior clearspace as cutoffs to indicate deltoid injury. While Schuberthet al34 demonstrated that the MCS is not a reliable indicatorof deltoid integrity in an isolated fibular fracture, the studydid not use stress radiographs in their analysis. Van Leeuwenet al20 compared gravity stress views with MRI, and showedthat using a MCS cutoff of >6 mm on gravity stress viewshas a sensitivity of 100% and specificity of 91.7% in diagnos-ing deep deltoid ligament disruption. In general, a MCS of>5 mm or a MCS between 4 and 5 mm AND >2 mm shifton stress views can be used as indicators for deltoid ligamentinjury.24

Ankle syndesmotic injury most commonly arises from aWeber C fracture/pronation-external rotation or pronation-abduction force. Up to 18% of ankle sprains and 23% ofankle fractures will have a concomitant syndesmotic injury,although the high prevalence of syndesmotic ossification inhigh-level athletes and after ankle fractures suggests that theactual incidence of syndesmotic injury may be muchhigher.14,22 Disruption of the syndesmosis will cause lateral

Table 4 Danis-Weber Classification1,9

Classification Level of Fracture Associated Injury Treatment

A Level of or inferior toSyndesmosis

� +/- medial malleolar fracture� Syndesmosis and interosseousmembrane intact

Usually conservative

B Spiral fracture of distal fibulaat the level of syndesmosis

� Partial disruption of PITFL� +/- avulsion fracture of distal medialmalleolus

� +/- deltoid ligament injury� +/- posterior malleolar fragment

Medial malleolar fracture ordeltoid ligament injury indi-cates instability = ORIF

C Fibular fracture above thelevel of the syndesmosis

� Tear of PITFL� Injury to interosseous membrane� Medial malleolar fracture/deltoid lig-ament injury

� +/- posterior malleolar fragment

Inherently unstable due toinjury to interosseous mem-brane =ORIFIf the fibular fracture is in theproximal or mid diaphysis,ORIF is indicated if restora-tion of fibular length is inquestion

Table 5 Lauge-Hansen Classification9,32

Subtype Fractures Weber Analogy

Supination-adduction � Fibular avulsion� Vertical shear fracture of the medial malleolus

Weber A

Supination external-rotation � Oblique/spiral fracture of distal fibula� +/- medial malleolar avulsion

Weber B

Pronation-abduction � Transverse fibular fracture at syndesmosis� +/- medial malleolar fracture� +/- butterfly fragment

Weber B

Pronation external-rotation � Suprasyndesmotic fibular fracture� +/- medial malleolar avulsion

Weber C



shift of the talus, and disruption of the interosseous mem-brane can result in significant increases in axial compressiveforces on the tibia.25 These injuries are associated with a lon-ger recovery period compared to lateral ankle sprains, thusnecessitating early and accurate diagnosis.35 CT may be help-ful in the preoperative assessment of syndesmotic stabil-ity.36,37 The presence and identification of a posteriormalleolar fracture is suggestive of instability and possibleneed for surgery.9 Although the gold standard for detectionof syndesmotic injury is intraoperative stress testing orarthroscopy,26 radiologic evaluation can help facilitate appro-priate management.The management of syndesmotic injury is based on the

degree of diastasis, measured as medial clear space wideningon stress or nonstress views, with >2 mm of frank or latentdiastasis indicating the need for ORIF with 2 screw fixation.Those without frank/latent diastasis can be managed conser-vatively.22 Adequate fracture reduction is key and has beenshown to result in better clinical outcomes. Andersen et al38

followed patients treated for syndesmotic injury, and mea-sured the anterior tibiofibular distance (aTFD) 1 cm proximalto plafond in both the injured and noninjured ankle. Theyfound that a difference of 2 mm between the aTFD in theinjured and uninjured ankle predicted inferior clinical out-comes and may be a helpful metric in determining the needfor revision surgery. Up to 50% of patients with syndesmoticinjury will develop heterotopic ossification at the distal tibio-fibular joint; however, these are usually only removed ifsymptomatic.22 Syndesmotic injuries can also develop hyper-trophic scar and synovitis at the inferior margin of the AITFL,which can lead to anterolateral impingement.35

Some work has been done to assess the utility of posteriordisplacement of fibular fractures on lateral films as an inde-pendent predictor of instability. Cavanaugh et al39 foundthat an anterior to posterior fibular gap of 1 mm on lateralfilm was 100% sensitive and 100% specific in predictingMCS widening of 5 mm on stress views, but the study used asmall sample size of 17 patients. Nortunen et al40 definedankle instability as 5 mm MCS widening AND>1 mm differ-ence between MCS and superior clear space on stress viewsand found that posterior displacement >2 mm of the fibularfracture on the lateral film was an independent predictor forinstability. While more and larger studies are needed, thesestudies indicate the possible utility of lateral films for deter-mining ankle instability.The addition of weight-bearing views does not have a sig-

nificant role in determining stability, but may help in deter-mining need for operative intervention. The work ofHoshino et al41 suggested that patients with instability indi-cated by abnormal MCS widening on stress views with a pre-served ankle mortise on weight bearing may not needsurgery. Additionally, Chien et al42 demonstrated that ifpatients can bear weight at the time of fracture, they were 8£more likely to be stablex.

Distal Tibial Fracture—The Pilon FractureThe pilon fracture is a fracture of the distal tibia with exten-sion to the tibiotalar joint (Fig. 8). These injuries result from

high impact axial load or rotational/torsional stress, with thelatter mechanism carrying a better prognosis.1,43 Concomi-tant soft tissue injury is usually present and contributes fur-ther to the already high complication rate associated withpilon fractures. Infection, malreduction with malunion and/or nonunion, post-traumatic osteoarthrosis, and stiffness areall well-described sequelae of this injury.43,44 Some patientsonly regain up to 75% of normal function as a consequenceof this fracture.44,45

The key features to evaluate on initial evaluation of pilonfractures are listed in Table 6. Identification of fibular frac-tures is important since the AITFL and PITFL are not oftentorn in this setting, and thus the tibial fragments attached tothese ligaments move with the fibula. Therefore, malreduc-tion of any displaced fibular fracture will lead to subsequentmalreduction of the tibial fragments attached to the AITFLand PITFL, named Chaput and Volkmann’s fragments,respectively. It is also important to assess the distal tibiofibu-lar joint as up to 15% of tibial plafond fractures are associatedwith syndesmotic or equivalent injury. Identification on ini-tial images is key as post-reduction images may obscure inju-ries.46 The positioning of the posterior malleolar fragmentand/or disruption of the posterior cortex has bearing on thesurgical approach. CT is used for preoperative evaluation,allowing for better depiction of size, location, and displace-ment of fracture fragmentation. It also helps in determiningthe orientation of the primary fracture plane, which affectsthe site of operative incision.47,48

Classically, these fractures are classified by the AO andRuedi Allgower systems, the latter based on the degree of dis-placement, comminution, and impaction of fracture frag-ments.49 However, given the fact that CT plays an essentialrole in preoperative planning,50 Leonetti et al48 proposed anew CT classification system based on articular involvement,displacement and number of fragments, plane of major frac-ture line, and areas of comminution. Their study showedequal prognostic value to the already used classifications,suggesting its potential for widespread acceptance.

The treatment of pilon fractures involves staged manage-ment. Immediate open reduction and internal fixation havebeen shown to have high wound complication rates, so theinitial goal is to provide support with external fixation. Thisallows time for the soft tissues to heal to a point where exten-sive reconstruction can take place with lower risk for woundcomplications. However, even with staged management,there is a 2% superficial wound complication rate. Open frac-tures are first treated with irrigation and debridement, fol-lowed by the same staged management.43,47 Haller et al46

showed that fractures with <10 mm Chaput or Volkmannfragments and/or fibular avulsion injury were less likely todevelop post-traumatic osteoarthrosis when treated with syn-desmotic fixation.

Proximal Fibular Fracture—The Maisonneuve FractureMaisonneuve fractures involve the proximal fibula due totransmission of forces proximally from external rotation inju-ries at the ankle that rupture the anterior and interosseoustibiofibular ligaments (Fig. 9). These can result from either a



Figure 7 Lauge-Hansen classification. (a) Supination-external rotation. Frontal projection shows disruption of theAITFL and an obliquely oriented fracture of the fibula at the level of the tibiotalar joint, which result from stress forceson the lateral ankle structures as the talus rotates. A transverse fracture of the medial malleolus represents the medialankle involvement. Posterior involvement such as injury to the PITFL or posterior malleolus fractures can also be seenin this injury pattern (not shown). (b) Supination-adduction. Frontal projection shows a transverse fracture of the lat-eral malleolus below the level of the joint, which results from stress forces on the lateral ankle. The adduction forcesresult in compression of the medial ankle, giving rise to the oblique fracture of the medial malleolus. (c) Pronation-external rotation. Excessive pronation results in medial stress, shown on this frontal projection as a transverse fracturethrough the medial malleolus. Further external rotation places stress on the lateral structures, shown here as rupture ofthe AITFL and an oblique fibular fracture above the level of the joint. The high location of the fibular fracture can helpdistinguish this pattern from the pronation abduction and supination-external rotation patterns. Posterior involvementsuch as injury to the PITFL or posterior malleolus fractures can also be seen in this injury pattern (not shown). (d) Pro-nation-abduction. Excessive pronation results in medial stress, again demonstrated as a transverse fracture through themedial malleolus. Further rotation places stress on the lateral ankle, shown in this case as rupture of the AITFL and anoblique fracture of the fibula. Posterior malleolus fractures can also be seen in this injury pattern (not shown).

Figure 8 A 35-year-old male after a fall from a height of 15 feet. Frontal (a) and lateral (b) ankle radiographs show acomminuted and angulated fracture of the distal tibia, which extends to the tibial plafond (arrow). There is also anangulated displaced fracture of the distal fibula.



pronation-external rotation injury, or less commonly, a supi-nation-external rotation injury. Up to 80% have an associatedposterior malleolar fracture (Fig. 10), while 50% have a del-toid ligament injury and 37% have a medial malleolar frac-ture.15,51 Pankovich52 described a 5-stage mechanism ofinjury:

1. Rupture or osseous avulsion of the AITFL with inter-osseous ligament rupture

2. Rupture of PITFL or fracture of posterior tibial tubercle3. Rupture or osseous avulsion of anteromedial joint

capsule4. Proximal fibular fracture5. Medial ankle injury (Deltoid ligament tear or medial

malleolus fracture)

This progression helps explain the concomitant syndes-motic injury and also explains why some patients have nomedial injury as it occurs last in the sequence. It is importantto understand the injury mechanism, as direct blunt traumato the proximal fibula will result in an isolated proximal

fibular fracture without associated syndesmotic injury andthe fracture will be stable.51 CT helps better depict the fullanatomic extent of the injury while MRI is useful for evalua-tion of ligamentous injury.15

There is some controversy regarding the need for operativeintervention, with some advocating nonoperative treatmentin the setting of a partial syndesmotic injury.53 However,evaluation of the full extent of syndesmotic injury is difficultto assess on clinical exam, leading most surgeons to nowadvocate for operative intervention. The 3 primary goals oftreatment are to reduce and stabilize the fibular fracture,reduce and stabilize the medial malleolar fracture or repairthe deltoid ligament, and stabilize the syndesmosis. The fibu-lar fracture, due to the usual oblique/spiral orientation, oftenresults in shortening with external rotation of the fibula,which must first be restored to anatomic length. However,due to the risk of injury to the common peroneal nerve,ORIF is not performed for proximal fibular fractures; instead,the proximal fibula is fixed to the tibia via syndesmotic screwplacement. Internal fixation is performed, however, for frac-tures of the distal two-third of the fibula. As ascertainment ofsyndesmotic integrity can be difficult, screw fixation is usu-ally performed. Additionally, stability can be achieved by fix-ation of the posterior malleolar fragment, if present, withoutthe need for a syndesmotic screw. The deltoid injury doesnot require surgery, and a medial malleolar fracture does notrequire operative intervention if anatomical reduction is ade-quate and maintained.51

Tillaux FractureThe Tillaux fracture is an avulsion of the anterolateral tibia atthe site of the AITFL attachment, resulting in avulsion of theanterior tibial tubercle and a vertical fracture extending fromthe articular surface superiorly along the lateral tibial cortex.Due to the location, these may only be seen on oblique radio-graphs, and are best evaluated on CT to characterize lateraldisplacement, which is the critical feature.1 Displacement of

Figure 9 A 39-year-old female with history of trauma. Frontal view(a) of the tibia and fibula shows an oblique fracture of the proximalfibula with mild lateral displacement of the distal fragment. Frontalview of the ankle (b) also shows a horizontal fracture of the medialmalleolus (arrow).

Table 6 Key Features to Evaluate in Pilon Fractures47,48

Presence and plane of fragment displacementPresence and plane of angulationPresence of impactionComminutionPresence or absence of fibular fracturePresence of posterior malleolar fragment

Figure 10 A 31-year-old male who twisted his right ankle with poste-rior pain. Frontal radiograph (a) of the tibia and fibula shows amildly comminuted fracture of the proximal fibula. Lateral radio-graph (b) of the ankle shows a mildly displaced fracture of the pos-terior malleolus.



the fracture fragment >2 mm is an indication for surgical fix-ation. Some advocate for closed reduction with traction andinternal rotation; however, if the gap remains >2 mm afterclosed reduction, ORIF may be necessary.54

Pediatric Ankle FracturesPediatric ankle fractures represent up to 4% of ankle frac-tures, with the triplane fracture accounting for 5%-15% andthe juvenile Tillaux accounting for 3%-5%.55-57 The distaltibial physis has a major role in overall tibial length, account-ing for up to 45% of overall growth. The physis continues togrow until 14-16 years of age, with an 18-month transitionalperiod prior to full closure. This transitional period betweenfully open physis and fully fused physis is the period wherethe triplane and Tillaux fractures can occur, with the poten-tial for devastating complications such as growth disturbanceand joint incongruity.57

The triplane fracture is characterized by fractures in 3planes: a vertical epiphyseal fracture in the sagittal plane, ahorizontal physeal fracture in the transverse plane, and anoblique metaphyseal fracture in the coronal plane.1 Whilethese are usually evident on plain radiographs, CT has beenshown to better characterize the fractures, resulting inchanges in fracture description, reported degree of displace-ment, and alterations in management.56 There is controversyregarding the need for operative management, especially inthe pediatric population, due to the risk of complications.Furthermore, these fractures have an elevated risk for perios-teal entrapment, which reduces the efficacy of nonoperativeclosed reduction.58 While fracture displacement or corticalstep off of >2 mm has classically been used to indicate theneed for surgery,55,57,59 Ryu et al55 found comparable clini-cal and radiographic outcomes between operative and non-operative patients with >2 mm of fracture displacement,which suggests that some of these patients may not need sur-gery. Lurie et al59 recently demonstrated the greatest func-tional benefit of surgery occurs with an intra-articular gap of>2.5 mm; however, the effect of cortical/articular step offwas not adequately evaluated and may have an independentinfluence on the need for surgery.The juvenile Tillaux fracture is a Salter Harris 3 fracture of

the distal tibial epiphysis and is the second most commongrowth plate fracture (Fig. 11). The tibial growth plate fusesin a characteristic pattern, from medial to lateral. Thus, themedial side of the distal tibia is inherently stronger until thelateral aspect can fuse.1 Like the adult Tillaux counterpart,the main force is an external rotation resulting in anterolat-eral distal tibial avulsion, and operative treatment is usuallyindicated for any displacement of fragments >2 mm or trans-lation of >1 mm.57,60

Isolated Ligamentous InjuriesInjury to the lateral ligamentous complex (ATFL, CFL, PTFL)is the most common musculoskeletal system injury, account-ing for »2,000,000 sprains per year. The mechanism is usu-ally plantarflexion and inversion, with the ATFL mostcommonly affected, being injured in »85% of ankle sprains,

followed by the CFL and rarely the PTFL.2,23,35 Radiographsusually serve to exclude associated osseous injury in the set-ting of a suspected ankle sprain. Cortical flake avulsions asthe sites of attachments of the lateral ligaments can be seen.Close attention should be paid to often overlooked associatedfractures, including the talar dome, lateral talar process, ante-rior process of the calcaneus, posterolateral process of thetalus, and base of the fifth metatarsal.35 Ultrasound has excel-lent accuracy for ATFL and CFL injury, manifesting as liga-mentous swelling/hypoechogenicity, partial tearing, or fulldiscontinuity. However, ultrasound is technically challengingand highly operator dependent and as such, is not widelyavailable in the emergency setting. CT is usually not per-formed for ankle sprains, but can be helpful in assessing forassociated osseous injury. MRI also has a limited role in theacute stage, but is superior in detection of ligamentousinjury. Ligamentous edema, swelling, and disruption can allbe seen on MRI, which also carries the added benefit of eval-uating adjacent structures that may be injured.61,62 Fluidextension into the peroneal tendon sheath suggests a com-plete tear of the CFL, which results in continuity between theankle joint and the tendon sheath. Some authors suggestusing the terms “acute interstitial injury” or “partial tear” inplace of “low grade ligament sprain” as the latter isimprecise.35

MRI has excellent sensitivity and specificity in the detec-tion of AITFL and PITFL injuries. Increasing grade of injuryto the AITFL and PITFL by MRI was shown to correlate withnumber of games and practices missed by athletes.22 Poste-rior malleolus bone marrow edema and/or posterolateral tib-ial plafond chondral injury should prompt the search for an

Figure 11 A 12-year-old male who slipped and fell while chasing areceipt. Frontal ankle radiograph (a) shows a fracture of the distaltibial epiphysis (arrowhead) with mild asymmetry of the physis(arrows). CT (b) shows the vertical fracture of the distal tibial epiph-ysis (arrowhead) with subtle widening of the lateral growth plate(arrows), characteristic for a Juvenile Tillaux fracture.



associated PITFL tear.35 Calder et al63 proposed using a newsign—“broken ring of fire”—to help distinguish syndesmoticinjury vs lateral ligamentous injury on MRI. They found thepresence of a sub circumferential ring of edema along the dis-tal tibial periosteum »4-6 cm above the plafond was highlysuggestive of syndesmotic injury over lateral ligament injury,although its absence did not exclude syndesmotic injury.Injury to the Achilles tendon is the most common soft tis-

sue injury to the foot, occurring in 21.5/100,000 people.Quick and accurate diagnosis is imperative as delay in sur-gery leads to poor outcomes.64 Rupture of the Achilles occursfrom sudden forced plantarflexion, although dorsiflexion cancause injury as well. Patients will present with tenderness atthe calcaneal insertion with loss of plantarflexion. Radio-graphic evaluation may show an avulsion fracture off of theposterosuperior calcaneus on lateral radiograph. Secondarysigns such as soft tissue swelling and infiltration of Kager’s fatpad can be helpful in suggesting injury to the Achilles(Fig. 12). It is important to note any signs of insertional ten-dinosis, as this can alter surgical management to includeflexor hallicus longus tendon transfer/augmentation. How-ever, surgery is typically reserved for high-level athletes orthose who wish to return to sports1,9

FootAnatomyThe foot can be divided into the forefoot, midfoot, and hind-foot. The forefoot is made up of the metatarsals, phalanges,and sesamoid bones. It serves as a platform for distributionof load, and its flexibility allows for gait over uneven surfaces.The first metatarsal is the shortest and most resistant to frac-ture, taking up to one-third of the applied force during gait.The sesamoids function as stabilizers of the first digit and

help to increase the mechanical advantage of the flexor halli-cus brevis. Approximately 50% of body weight is distributedthrough the first metatarsophalangeal (MTP) joint, the sesa-moids bearing up to twice the weight as the remaining 4metatarsals, showcasing the importance of first MTP radio-graphic evaluation.9,35,65 The first MTP sesamoids are usuallycomprised of a tibial (medial) and fibular (lateral) sesamoid.Bipartite sesamoids are common normal variants, occurringin up to 30% of people. Bipartite sesamoids are usuallyasymptomatic but they can fracture. The vast majorityinvolve the tibial sesamoid (90%), and 80%-90% are bilat-eral.66 The tibial and fibular sesamoids are linked by theintersesamoidal ligament, with medial and lateral collateralligament complexes providing additional stability against val-gus and varus stress, respectively. The medial and lateralplantar plates are made of the sesamophalangeal ligaments,and provide stability against dorsiflexion stress with helpfrom the surrounding muscles.35

The midfoot consists of the navicular, cuboid, and cunei-form bones. The navicular functions to maintain the longitu-dinal arch and medial column of the foot. The navicularsurface articulating with the talus is concave and controls80% of hindfoot movement. The distal aspect of the navicu-lar is more rigid and contributes to arch stability. The centralone-third of the navicular is a relatively avascular watershedarea. The cuboid bone functions to maintain the integrity ofthe lateral column of the foot, with the calcaneocuboid andcuboid-metatarsal articulations allowing for movement onnonlevel terrain.9,65,67

The hindfoot consists of the calcaneus and talus. The cal-caneus primarily functions to support axial load, most ofwhich is transferred through the posterior facet. The susten-taculum tali is a shelf-like projection arising off of the antero-medial calcaneus and helps to maintain alignment in thesetting of calcaneal fracture, due to its interosseous and

Figure 12 A 57-year-old male who felt a pop in the ankle. Lateral ankle radiograph (a) shows thickening of the Achillestendon (arrows) with proximal retraction of several small avulsion fragments (arrowheads). Follow-up sagittal STIRMRI (b) shows a complete disruption of the Achilles tendon just proximal to the calcaneal insertion in the “watershed”area with a hyperintense, fluid-filled gap.



deltoid ligamentous attachments. The talus has no muscleorigins or insertions and has a tenuous blood supply. The lat-eral talar process forms an articulation with the calcaneus andlateral malleolus and is a common site of occult fracture.1,9,65

The Lisfranc and Chopart joints connect the forefoot to themidfoot and the midfoot to the hindfoot, respectively. TheLisfranc joint complex is composed of 9 articulations amongthe 5 metatarsals, the 3 cuneiforms, and the cuboid bone.The second metatarsal base is recessed between the medialand lateral cuneiforms, acting analogously to an architectural“keystone.” This is a key feature of the Lisfranc joint, as Pei-cha et al68 showed that a shallow recess carries a higher riskof injury. The midfoot joints can be broken down into 3 col-umns (Table 7). The rigidity provided by the middle andmedial columns allows the foot to function as a lever duringnormal gait motion.Additional Lisfranc joint complex stability is provided by a

robust arrangement of ligaments, which provides a founda-tion for the longitudinal and transverse arches of the foot(Fig. 13). The Lisfranc ligament proper is the strongest com-ponent and consists of the interosseous ligament betweenthe medial cuneiform and medial base of the second

metatarsal. The plantar Lisfranc ligament has variable anat-omy, and usually connects the plantar medial cuneiform tothe plantar second and third metatarsals. The dorsal Lisfrancligament connects the dorsum of the medial cuneiform andsecond metatarsal base and is the weakest of the ligamentousstructures, which accounts for the usual dorsal displacementof the second metatarsal seen in Lisfranc injury. The Lisfrancligament is an essential structure, owing to the fact that thereis no intermetatarsal ligament between the first and secondmetatarsals. The intertarsal ligament between the medialand middle cuneiform is another important stabilizer, andwidening of the associated intercuneiform distance suggestsdisruption.

Additional stabilizers include the anterior tibialis tendoninsertion on the medial cuneiform and first metatarsal, theposterior tibialis tendon, the peroneus longus tendon, theplantar fascia, long plantar ligaments, and intrinsic forefootmuscles. These secondary stabilizers are more importantwith regard to reduction of fracture, particularly the anteriortibialis tendon, as entrapment can block adequate reduction.The medial branch of the deep peroneal nerve and the dorsa-lis pedis perforator artery, as they travel between the first andsecond metatarsals, are at risk of associated injury.35,65,69

The normal radiographic alignment of the Lisfranc joint isdescribed in Table 8.

The Chopart joint consists of the talonavicular and calca-neocuboid joints. The talonavicular joint is a ball and sockettype joint, responsible for »80% of hindfoot movement, andis critical for alignment and stability during normal gaitmotion. Ligamentous support is provided by the dorsal talo-navicular ligament and calcaneonavicular component of thebifurcate ligament (Fig. 14). The dorsal talonavicular liga-ment can appear chronically thickened from repetitive nor-mal motion, and does not always indicate acute injury. Thecalcaneocuboid joint is a saddle type joint, and is supported

Table 7 Column Anatomy of the Lisfranc Joint Complex69

Medial � Medial cuneiform and first metatarsal� rigid

Middle � Middle and lateral cuneiforms and second andthird metatarsals

� Most rigidLateral � Cuboid with fourth and fifth metatarsals

� Most mobile� Lower risk of post-traumatic instability andarthritis

Figure 13 Lisfranc ligaments. (a) Dorsal ligaments. The dorsal Lisfranc ligament is shown bridging the dorsal first cunei-form (dC1) to the base of the second metatarsal (M2). Also shown is the intercuneiform ligament which connects themedial and intermediate cuneiforms (C1 and C2, respectively). (b) Plantar ligaments. The plantar Lisfranc ligamenthas variable anatomy, but is shown here connecting the plantar aspect of the first cuneiform (pC1) to the bases of thesecond and third metatarsals (M2M3).



by the dorsal calcaneocuboid, plantar, and calcaneocuboidcomponent of the bifurcate ligaments. The spring ligamentsupports both joints, with additional support provided bythe posterior tibialis and peroneus longus tendons. There is anormal incongruity in the calcaneocuboid articulation thatcan create difficulty in evaluating for instability. The s-shapedcyma line is a smooth curvilinear line that runs along thetalonavicular and calcaneocuboid joints on AP and lateralradiographs, and disruption of the line suggests injury to theChopart joint.2,65,70 The spring ligament has 3 main compo-nents; superomedial, medial plantar oblique, and inferoplan-tar longitudinal bands. It functions as a main stabilizer of theplantar arch during mid stance.2,35

Foot FracturesCalcaneusCalcaneal fracture represents 60% of all major tarsal injuries,and is the most commonly fractured tarsal bone, representing»2% of all fractures. These fractures usually arise from high

energy/direct axial loads such as a fall from a height, andintra-articular extension is common (60%-75%) and essentialto recognize. Fractures of the anterior calcaneal process canbe seen with inversion or plantar flexion forces, and can beconfused clinically for a lateral ankle sprain. Similarly, iso-lated sustentaculum tali fractures can be confused for medialankle sprains, and arise from axial and inversion forces.Avulsion of the posterior calcaneal tuberosity at the attach-ment of the Achilles is usually due to diabetes mellitus orosteoporosis.9

Associated injuries are common, with up to 10% develop-ing compartment syndrome due to the significant soft tissuebleeding and swelling. Up to 10% will have bilateral calca-neal involvement, and »25% will have an additional lowerextremity injury, necessitating the need for bilateral radio-graphs in an axial load injury. There is also a risk of peronealnerve injury, with avulsion from the lateral malleolus andtendon entrapment as possible complications. CT should bewidely employed due to its superior evaluation of the articu-lar surface, ability to better describe fracture alignment andfragmentation, and 3D capabilities which help with preoper-ative planning.9,65,71,72 Evaluation of the thoracolumbarspine should be considered, as up to 10% will have a verte-bral fracture.

The Sanders classification (Table 9) is widely used, and isbased on the number and location of articular fragments.This allows for determination of patient prognosis andappropriateness for surgery. The critical feature to assess isextension of the fracture to the subtalar joint, particularly theposterior subtalar joint, as well as any depression of the pos-terior facet (Fig. 15). Bohler’s angle is a measurement of thetalocalcaneal relation, with values <20⁰ seen in compressiontype fractures. The “critical” angle of Gissane is formed bythe slopes of the calcaneal dorsal surface, with elevated levels>140⁰ suggesting fracture of the posterior calcaneal facet.The “double density” sign appears as a second density on thelateral film and may be the only sign of fracture of the lateralaspect of the posterior facet. Additional important features toevaluate are the degree of incongruence, articular involve-ment (particularly >2 mm gap or presence of intra-articularfragments), and the tendon insertion sites. Involvement ofthe Achilles insertion on the posterior calcaneal tuberosityrequires open surgery. Extra-articular fractures are describedby the involved portion of the calcaneus and any degree ofdisplacement.1,9,71,72

Treatment of calcaneal fractures varies depending on frac-ture morphology. Nonoperative management can beemployed with nondisplaced or minimally displaced extra-articular fractures, nondisplaced intra-articular fractures, and

Table 8 Normal Radiographic Alignment of the Lisfranc Joint35

View Features

AP � Lateral first metatarsal aligns with lateral marginof medial cuneiform

� Medial second metatarsal aligns with medialmargin of middle cuneiform

� Gap between medial cuneiform and secondmetatarsal base <2 mm

Lateral � No dorsal step off� Plantar surface of medial cuneiform is dorsal toplantar surface of fifth metatarsal

� Tarsometatarsal angle <15⁰Oblique � Medial and lateral margins of third metatarsal

align with medial and lateral margins of lateralcuneiform

Figure 14 Ligaments of the midfoot joint. Sagittal projection of themidfoot shows the ligaments of the Chopart joint. The bifurcate lig-ament is shown splitting into its calcaneonavicular and calcaneocu-boid partitions.

Table 9 Sanders Classification of Calcaneal Fractures9,72

Grade Features

1 Nondisplaced, <2 mm displacement2 One fracture line, 2 fragments3 Two fracture lines, 3 fragments4 Three or more fracture lines, gross comminution



fractures of anterior process involving <25% of the calcaneo-cuboid joint. However, nonoperative management is morelikely to result in subtalar arthrodesis. The goal of operativetreatment is to restore calcaneal height and width, reduceincongruence, and remove any fragments. Surgery is ideallyperformed <3 weeks after injury to prevent any significantosseous healing. Surgical management is performed for sig-nificantly displaced extra-articular fractures, any displacedintra-articular fractures, and anterior process fractures >25%of the calcaneocuboid joint. As mentioned above, surgery isalso performed for displaced posterior tuberosity fractures asthe displaced fragments put stress on the posterior skin andlead to soft tissue/skin breakdown.9,65,71,72

TalusTalar fractures are the second most common tarsal fracture(after calcaneus), representing 3%-6% of foot fractures(Fig. 16). Sixty-seven to 77% will have a concomitant frac-ture or dislocation, with medial subtalar dislocation repre-senting 85% of dislocations. Fractures of the talar head areusually due to axial load, and displacement or articular dam-age requires surgery. Fifty percent of talar fractures occur atthe neck, with concomitant increased risk of avascular

necrosis due to the tenuous blood supply. Fractures of thetalar body are usually due to high-energy mechanisms and>2-3 mm displacement requires surgery, so accuratedescription is essential. Impaction type fractures can lead toosteochondral fractures/lesions of the talar dome. CT is oftenrequired for accurate identification and description of frac-ture morphology, and should be widely used.1,9,65,73

The Hawkins classification system is used to describe talarneck fractures. Grade 1 is a nondisplaced talar neck fracture.Grade 2 is a displaced fracture with associated subtalar jointsubluxation/dislocation. Grade 3 has additional posterior dis-placement of the talar body, and grade 4 has associated tibio-talar and talonavicular subluxation/dislocation.9

Nonoperative management can be used in patients with anondisplaced Hawkins grade 1 fracture with an intact subta-lar joint on CT. Nondisplaced talar head fractures and lat-eral/posterior process fractures with <2-3 mm displacementcan be managed nonoperatively as well. Operative interven-tion is reserved for Hawkins grades 2-4, open fractures, dis-placed talar head fractures, lateral process fractures with>2 mm displacement, and large displaced posterior processfractures (>3 mm). Osteonecrosis is a known complication,and correlates with increasing Hawkins grade. The “Hawkins

Figure 15 A 25-year-old male who was in a motor vehicle collision. Lateral ankle radiograph (a) shows a displaced pre-dominantly horizontal calcaneal fracture extending from the posterior tubercle to the subtalar joint. Subsequent CT (b)better shows the fracture line extending to the posterior subtalar joint.

Figure 16 A 63-year-old male after a fall who presented with pain and swelling. Frontal (a) and lateral radiographs (b)show a 1.4 ossific density projecting adjacent to the talus and calcaneus (arrow). Subsequent coronal (c) and sagittal(d) reformatted CT images better show the acute fracture of the lateral process of the talus which extends to the poste-rior subtalar joint (arrows).



Sign” is the presence of disuse osteopenia at the talar sub-chondral surface 6-8 weeks after injury and suggests an intactblood supply. Isolated talar body fractures and talar disloca-tions have a 25% and 50% rate of developing osteonecrosis,respectively.9,73

Talar dislocations are an uncommon but important entityto recognize. The more frequent subtype of peritalar/subtalardislocation involves the talocalcaneal and talonavicular artic-ulations, with maintenance of the tibiotalar relationship. Thistype of dislocation is involved in 15% of talar injury, and rep-resents 1%-2% of all major joint dislocations. The majorityare medial (75%), although lateral dislocations tend to resultfrom more violent mechanisms of injury, 10%-40% of whichare open. The more serious talar dislocation is the total talardislocation, which includes disruption of the tibiotalar articu-lation. These are rare, but represent a severe injury usuallywith associated extensive soft tissue injury, and total talar dis-locations are frequently complicated by talar osteonecrosis.CT is performed to assess for additional injuries as there is ahigh rate of associated intra-articular/peritalar injury.1,65

NavicularFractures of the navicular are rare in isolation, although thisis the most commonly fractured midfoot tarsal bone. Avul-sion fractures of the dorsal navicular lip are the most com-mon, accounting for up to 50% of navicular fractures. Theseare usually the result of sudden or excessive plantarflexionand result from avulsion by the talonavicular joint capsule oranterior deltoid fibers. Avulsion fractures of the naviculartuberosity are also seen, accounting for »20% of fracturesand resulting from eversion injury at the attachment of theposterior tibialis tendon. Fractures of the navicular bodyresult from higher energy and more severe injuries, and assuch are usually associated with midfoot/forefoot fractures.The Sangeorzan classification is used for navicular body frac-tures, based on the orientation of the fracture line and degreeof comminution.1,9,65,67 While radiographs are usually suffi-cient for detecting avulsion and tuberosity fractures, CT isoften required for improved assessment of the fracture pat-tern and degree of articular surface involvement, and is espe-cially helpful for body fractures, with the added benefit offinding occult concomitant injury (Fig. 17).1,65

Nonoperative treatment is reserved for non- or minimallydisplaced cortical avulsions or tuberosity fractures, with thecaveat that a displaced avulsion at the insertion of the poste-rior tibialis tendon may require surgery and should be men-tioned in the report. Nondisplaced body fractures may bemanaged conservatively as well. The goals of operative inter-vention are to restore the length of the medial column andcongruity of the talonavicular joint. Approximately 60% ofthe talonavicular articular surface must be restored to reducelater complications of talonavicular subluxation and post-traumatic arthritis. Navicular body fractures with >1 mmjoint incongruity and >2-3 mm medial column shorteningundergo open repair, as do navicular dislocations as theyremain unstable even after closed reduction. Cortical avul-sion fractures involving >25% of the articular surface arealso candidates for operative intervention.9,65,67

CuneiformsFractures of the cuneiforms are also rare in isolation, account-ing for 1.7%-4.3% of tarsal fractures, and are associated withadditional tarsal fractures, with the medial cuneiform mostcommonly involved. A cuneiform fracture should arouse sus-picion for an associated Lisfranc or Chopart injury. Medialcuneiform dislocation risks injury to the medial plantarartery, and careful inspection of the surrounding musculoten-dinous structures should be performed as the anterior tibialistendon may become entrapped and prevent reduction. Non-displaced fractures are managed conservatively with immobi-lization, while fracture-dislocations are usually surgical.65

Figure 17 A 15-year-old female with anterior and medial ankle painfor 2 months and no known injury. Lateral ankle radiograph (a)shows a small dorsal navicular fracture fragment (arrow). Subse-quent MRI T2-weighted images with fat saturation (T2FS) in thesagittal (b) and axial (c) planes show florid bone marrow edemainvolving the navicular bone with fracture line extending throughthe dorsal navicular best seen on the sagittal image. Subsequent CTaxial (d) and sagittal (e) reformatted images show sclerosis of thesuperior navicular with a subtle linear lucency (arrow) extendinganteriorly from the talonavicular joint, consistent with a nondis-placed fracture of the navicular.



CuboidThe cuboid represents »5% of midfoot fractures, and likethe other tarsal bones is usually associated with additionalmidfoot injury (Fig. 18). Avulsion fractures of the lateralcuboid at the attachment of the plantar calcaneocuboid liga-ment are most common, accounting for »66% of cuboidfractures. Fracture extension to the peroneal groove is animportant feature as this can result in injury/irritation to theperoneal tendons. Compression fractures of the cuboid occurfrom forceful abduction, and the “nutcracker” crush fractureoccurs with high-energy Chopart injuries, resulting frominterposition between the anterior process of the calcaneusand the fourth and fifth metatarsal bases. Nondisplaced orminimally displaced fractures without articular involvementare managed nonoperatively, while >2 mm articular dis-placement, loss of lateral column length, and comminutionundergo internal fixation.9,65

MetatarsalsFractures of the metatarsal bones usually occur secondary toa direct load or excessive torque and are the second mostcommon injury of the forefoot, accounting for »5%-6% offractures in a primary care setting. These are usually wellvisualized on radiographs, with the exception of fractures atthe bases that may be obscured by osseous overlap. Fracturesof the fifth metatarsal can be divided into 4 subtypes(Table 10).Confusion may arise in the pediatric setting, as the normal

unfused apophysis at the base of the fifth metatarsal may bemislabeled as a fracture. However, the apophysis has an obli-que orientation at the base, while a true fracture will have atransverse orientation.1 As mentioned earlier, a fracture atthe base of the second metatarsal should raise concern for aLisfranc injury.Treatment of metatarsal fractures is based on location and

severity. Any displaced or unstable first metatarsal fractureundergoes ORIF. Fractures of the second-fourth metatarsalwill undergo ORIF if there is >10⁰ sagittal angulation or 3-4 mm translation in any plane. Fractures of ALL 3 lessermetatarsals (second-fourth) will require stabilization as thereis loss of intermetatarsal ligamentous stability. Moderate cor-onal plane displacement is NOT an indication for surgery.Fractures of the metatarsal base are generally more stable due

to the complex capsuloligamentous attachments. Metatarsalneck fractures are treated based on symptoms, and if thereare multiple neck fractures, surgery may be needed to pre-vent subsequent rotational deformities.9,65

Figure 18 A 39-year-old male who suffered a parachute accident,landing on both feet. Oblique (a) and lateral foot radiographs (b)show mildly displaced fractures of the lateral cuboid, secondthrough fifth metatarsal bases, and lateral cuneiform (arrows). Notethat the cuboid fracture (arrow) is visible on frontal (c) and lateralankle radiographs (d), a reminder that attention should be paid tothe midfoot on ankle radiographs.

Table 10 Fractures of the Fifth Metatarsal1,9

Type Involvement Treatment

Zone 1 (93% of proximalfractures)

� Avulsion off fifth metatarsal base� Involves tarsometatarsal joint

� Usually conservative� Limited data on surgical intervention

Zone 2 (4%)“Jones fracture”

� Distal to metatarsal tuberosity and the meta-diaphyseal junction

� Encroaches on the fourth-fifth metatarsalarticulation

� Delayed healing, 7%-28% nonunion rate� Screw fixation may improve rates of union

Zone 3 (3%) � Proximal metatarsal shaft � Prone to nonunion� Usually surgical

“Dancers” � Mid or distal diaphysis � Conservative management



PhalangesPhalangeal fractures are the most common injury of the fore-foot, usually involving the fifth proximal phalanx due to ablunt trauma. Interphalangeal dislocation is rare, and mostfractures do well with “buddy taping,” or reduction stabilizedby taping the toe to an adjacent uninjured toe. Internal fixa-tion may be performed for phalangeal fractures with greaterthan one-third articular surface involvement with angulation,or >2-3 mm displacement. Injury to the nail bed, particu-larly in pediatric patients, is a significant feature as the skin atthe nail root attaches directly to the periosteum and thus isconsidered an open fracture, and is at risk for severe compli-cations such as osteomyelitis.65,74

The key features of hallux sesamoid fractures are jaggedand irregular edges, a distinctive feature from the bipartitesesamoid, a normal variant. These are the least common frac-tures of the foot and usually arise from direct trauma, hyper-extension, or overuse. The tibial sesamoid is more frequentlyinjured than the fibular sesamoid, as more weight is distrib-uted medially during gait. Axial sesamoid radiographs canhelp identify subtle fractures, and forced dorsiflexion canhelp accentuate and identify injury to the plantar plate. Onlateral radiographs, using cutoffs of 10.4 mm and 13.3 mmfrom the phalanx to tibial and fibular sesamoids, respectively,results in 99.7% sensitivity for plantar plate rupture.9,65

Lisfranc JointInjuries to the Lisfranc complex can range from high-energyfracture dislocations to lower energy sprains. Higher energyinjuries are rare, occurring in approximately 1/55,000 peoplein the United States per year, and usually result from directforces such as crush or motor vehicle accidents. Lowerenergy sprains are more common and result from indirectforces such as twisting, but these have a significant impacton function, with 18% of patients unable to return to sportafter injury. A high degree of suspicion is needed as »20% ofLisfranc injuries are undiagnosed clinically, and approxi-mately 25% are missed or not evident on initial radiographs(Fig. 19). Weight-bearing views should be routinelyemployed to help expose subtle lower grade sprains as 50%are occult on nonweight-bearing views. Even with weightbearing, some injuries may take up to 6 weeks to becomeapparent on radiographs.9,69

Radiographic evaluation with weight-bearing views is therecommended first-line imaging performed. The most reli-able indicator of Lisfranc injury is malalignment of the sec-ond tarsometatarsal joint, with lateral displacement of thesecond metatarsal relative to the middle cuneiform on the APview (Fig. 20). The “fleck sign” is considered to be a patho-gnomonic fracture, representing an avulsion of the Lisfrancligament off of the second metatarsal base. Avulsions can alsobe seen off of the base of the first metatarsal and medial cune-iform as well. Another radiographic sign is the “double den-sity sign,” which is seen on lateral view and consists of anapparent double layer of cortical bone along the dorsal mid-foot due to dorsal displacement of the metatarsals. Comparedto radiographs, CT can identify up to 50% more metatarsalfractures, twice as many tarsal fractures, and has the added

benefit of 3D reconstruction, as well as the ability to recon-struct along the long and short axes of the Lisfranc joint.MRI has superior soft tissue contrast resolution and can helpevaluate nonosseous involvement such as peroneus longusentrapment that can prevent reduction, as well as deep pero-neal nerve injury, identified as edema in the extensor hallicuslongus brevis and extensor digitorum brevis muscles. A keymeasurement is the difference between the medial cuneiformand second metatarsal base, with a >2 mm diastasis suggest-ing instability and the need for reduction/stabilization. A>2 mm diastasis between the first and second metatarsalbases also suggests the need for reduction/stabilization, while>2 mm diastasis between the medial and middle cuneiformsindicates injury to the intercuneiform ligament.1,9,35,65,69

Lisfranc fracture-dislocations can be classified using theMyerson classification, which is based on complete vs partialincongruity while Lisfranc ligamentous injuries can be classi-fied using the Nunley-Vertullo system (Table 11).

Treatment of Lisfranc injuries depends on severity ofinjury. Low-grade sprains without evidence of subluxationare managed conservatively, while instability or frank dislo-cation in higher grade sprains are indications for operativeintervention in order to restore anatomic alignment. Percuta-neous screw fixation can be undertaken if there is adequate

Figure 19 A 19-year-old with an unspecified injury. Initial frontalfoot radiograph (a) shows no obvious osseous abnormality. Subse-quent T2FS MR images in the coronal (b) and axial (c,d) planesshow a nondisplaced fracture of the second metatarsal base (arrowsin b and c). There is a complete tear of the Lisfranc ligament (c andd, arrowheads) with malalignment of the second tarsometatarsaljoint and edematous signal throughout the Lisfranc joint.



closed reduction, while ORIF is reserved for cases refractoryto closed reduction. Comminution of the first and secondmetatarsal bases may require arthrodesis to provide addedstiffness to the forefoot to stabilize gait. Approximately halfof patients develop post-traumatic osteoarthrosis followingORIF; however, only 8% will develop symptoms severeenough to require arthrodesis.35,69

Plantar Plate/First Metatarsophalangeal JointInjury to the plantar plate has become more common with theadvent of artificial surfaces, such as turf, with the term “turf toe”now applied to a variety of injuries at the first metatarsophalan-geal joint. These can be disabling injuries with persistent symp-toms and can delay return to competition. These are commoninjuries in athletes, particularly those requiring quick turns and

Figure 20 A 47-year-old female who caught her foot between a trampoline and the metal bar frame. Weight-bearing APRadiographs of the feet (a) show a homolateral dislocation of the right first-fifth metatarsals (arrowheads) with widen-ing of the first metatarsal interspace (arrow). Findings are consistent with a Lisfranc ligamentous injury. Comparisonview of the left foot shows the normal alignment of the second metatarsal and middle cuneiform. Lateral foot radio-graph (b) shows mild dorsal subluxation of the second metatarsal (arrow). Coronal reformatted CT better shows thecomminuted fractures involving the bases of the second and third metatarsals (arrows) (c,d). Axial CT again showswidening of the Lisfranc interval (e), with lateral offset of the metatarsals at the TMT joints (arrows). Sagittal reformat-ted CT (f) shows dorsal subluxation of the second metatarsal (arrow) at the TMT joint.



jumps as the metatarsophalangeal joint receives a force 2-3£body weight when running, and up to 8£ body weight whenjumping. The most common injury pattern is a combination ofvalgus stress and hyperextension which disrupts the first meta-tarsal head insertion of the medial collateral ligament complexwith injury to the medial sesamophalangeal ligament. Purehyperextension injuries, in contrast, result in isolated disruptionof the sesamophalangeal ligament with proximal migration ofthe sesamoid/s. A varus force will injure the lateral collateral liga-ment complex, and a pure hyperflexion injury (“sand toe”) willresult in dorsal capsular injury.1,35 Radiographs are most oftennormal but may detect associated capsular avulsion or impac-tion fractures and malalignment. Obtaining radiographs of bilat-eral first metatarsophalangeal joints is helpful to detect subtleproximal retraction of sesamoids which can indicate plantarplate injury. MRI is the preferred modality for direct visualiza-tion of the capsuloligamentous structures.35

Chopart JointMidfoot “Chopart” injuries usually involve low energysprains and higher energy fracture-dislocations (Fig. 21).Approximately 10%-25% are purely ligamentous injuries,while the remaining fracture-dislocations represent up to16.8% of midfoot trauma, second only to the Lisfranccomplex. These injuries often arise from significanttrauma and can be overlooked as there may be severeinjuries elsewhere that distract attention from the mid-foot. Sequelae of midfoot injury include articular incon-gruity leading to post-traumatic osteoarthrosis, shorteningof the medial/lateral columns, and plantar arch alteration.Knowledge of the mechanism of injury can help directfocus toward sites of commonly associated fractures, andCT should be widely used to help assess for occult frac-ture and articular involvement. A single midtarsal fractureshould set off a search for concomitant fracture, and dueto the high-energy nature of most of these injuries, asso-ciated lateral ankle sprain/injury is common and may beoverlooked.2,65,70

Chopart fracture-dislocations can be broken down into inver-sion and eversion injuries (Table 12). The inversion pattern ismore common, and due to distraction of the anterolateral

midfoot, causes stress on the lateral ligaments. Added plantarflexion will stress the dorsal ligaments. Eversion injuries causedistraction of the medial structures and compression of the lat-eral structures. On AP radiographs, the inversion fracture pat-tern includes avulsion of the anterior calcaneal process andimpaction of the navicular and talar head, while eversion frac-ture pattern will show avulsion of the navicular tuberosity andimpaction of the calcaneocuboid joint. On lateral radiographs,the inversion fracture pattern will show avulsion of the anteriorprocess of the calcaneus and dorsal talonavicular joint, while theeversion injury will show impaction at the calcaneocuboid joint.Avulsion fractures of the dorsal talar head/dorsal talonavicular

Table 11 Myerson and Nunley-Vertullo Classifications of Lisfranc Injuries35,69

Myerson (Fracture Dislocations) Nunley-Vertullo (Ligamentous Injury)Subtype Grade

Partial homolateral- Medial shift of first metatarsal OR- Lateral shift of second-fifth metatarsals

1—Low-grade ligament sprain, no diastasis

Complete homolateral- Shift of first-fifth metatarsals as a unit

2—Low-grade ligament insufficiency or tear- <5 mm diastasis at first-second metatarsal interval- Intact plantar ligament

Divergent- (partial) Medial shift of first metatarsal and lateral shift ofsome lesser metatarsals

- (complete) Medial shift of first metatarsal and lateral shiftof all lesser metatarsals

3—Complete tear of interosseous and plantar ligaments- >5 mm diastasis between first and second metatarsals

Figure 21 A 51-year-old male involved in a motorcycle accident. Lat-eral ankle radiograph shows an open and comminuted fracture-dis-location of the Chopart joint with subcutaneous and intra-articulargas (white arrows) and displaced fracture of the cuboid (blackarrow). There is also dislocation of the talonavicular and calcaneo-navicular joints (arrowheads).



ligament are an indirect sign of Chopart instability or transientChopart dislocation.2,65,70

Up to 19% of patients undergoing MRI for acute ankleinjury demonstrate a midtarsal sprain, and identification ofmidfoot injury is imperative as treatment may be moreaggressive or longer compared to a lateral ankle sprain. Thegoals of treatment are to restore joint congruity, ligamentousstability, and anatomic alignment, with management initiallyinvolving closed reduction followed by eventual fixation.Fracture nonunion can occur at the anterior process of thecalcaneus, resulting in a pseudarthrosis.2,75

OsteomyelitisOsteomyelitis is infection of the bone marrow and leads topotentially severe complications and disability. There are 3potential routes of spread for osteomyelitis: contiguous, directinoculation, and hematogenous. Contiguous spread occursfrom adjacent soft tissue infection. Direct inoculation can occurfrom bites, puncture wounds, implanted devices, or open frac-tures. Hematogenous spread of osteomyelitis is more commonin the pediatric population. Once the marrow is infected, reac-tive bone formation and granulation tissue can form over timeto encompass the pus and form an intramedullary abscess,more commonly known as a “Brodie’s Abscess.” There is also anincrease in intramedullary pressure, which can become so severethat it creates a break in the cortex, or a “cloaca.”With extrame-dullary extension, the infection can spread in the subperiosteumor extend to the skin and form a sinus tract. Squamous cell

carcinoma is a rare but reported complication of persistent sinusdrainage tracts.1,76-79

Radiographs are usually negative early in disease and infec-tion may be occult for up to 10-20 days. Radiographic signs ofosteomyelitis include periosteal reaction, cortical destruction,osseous lucency suggesting Brodie’s abscess, and soft tissue signssuch as soft tissue gas or foreign body. MRI is the mainstay ofosteomyelitis imaging and is able to detect bone marrow edema1-2 days after onset of disease. The key feature is diffuse hypoin-tense T1-weighted signal in the affected bone marrow, whichreflects marrow replacement by pus and fluid. Edema, identifiedas T2-weighted/STIR hyperintensity, is also present. Contrast ishelpful to determine viability of osseous structures and in thedemarcation and identification of abscesses and sinus tracts. Anabscess will be defined by a ring of peripheral enhancement.There is often an ulcer or sinus tract adjacent to the involvedbone.1,76-79 CT is useful for guiding intervention such as biopsyand drainage.

Osteitis is an important differential diagnosis and repre-sents reactive bone marrow changes from adjacent soft tissueinfection or cortical infection. While there will be signs ofbone marrow edema evidenced by hyperintense T2/STIR sig-nal, there will be lack of, or minimal lace-like, hypointenseT1 signal.76-78 Another key diagnostic consideration ischronic multifocal reactive osteomyelitis which represents anaseptic osteomyelitis that does not respond to antibioticsoccurring in adolescents and children. Features that help dis-tinguish this entity from infectious osteomyelitis include aprolonged clinical course, atypical location, bilaterality, andlack of adjacent soft tissue abscess or sinus tract.79,80

Neuropathic ArthropathyNeuropathic arthropathy in the United States occurs mostoften in the setting of diabetes and represents the result ofchronic, repetitive trauma in the setting of altered proprio-ception, diminished pain reception, and impaired healing.This leads to unrecognized trauma to weight-bearing joints,usually the tarsometatarsal joints. The acute phase is charac-terized by soft tissue swelling, joint effusions, and bone mar-row changes. Radiographs are often occult in the acutesetting, while MRI will show multifocal areas of T1-weightedhypointensity and periarticular and subchondral enhance-ment, subchondral cysts, and soft tissue enhancement with-out abscess or sinus tract. The chronic phase is characterizedby the “6 Ds”: joint destruction, increased density, articulardisorganization, joint distention, osseous debris, and jointdislocation. These findings will be evident on radiographsand CT, while MRI will show diffuse T1- and T2-weightedhypointensity in the bones, owing to diffuse osteosclero-sis.76-78

Neuropathic arthropathy with superimposed infectionposes a diagnostic challenge as there is considerable overlapin the imaging findings of neuropathic joint and osteomyeli-tis. However, there are several signs that suggest the presenceof superimposed infection (Table 13). The “ghost sign” is aclassic sign and represents the disappearance of bone/marrow

Table 12 Fracture Patterns of Midfoot “Chopart” Fracture-Dislocations2

Fracture Pattern Involved Structures

Inversion—Distractionrelated avulsion alonglateral column

� Anterior process of the calcaneus(dorsal calcaneocuboid ligament)

� Dorsolateral cuboid (calcaneocu-boid ligament of bifurcate liga-ment)

� Larger avulsion fragments offanterior process of the calcaneusmay represent avulsion of theextensor digitorum brevis origin

� Small avulsions along plantaraspect of lateral calcaneus andcuboid

� Plantar navicular fractureInversion—Impactionalong medial column

� Fracture of navicular body� Osteochondral fracture of talarhead

Inversion—plantar flex-ion related avulsion

� Dorsal talar head or navicular(dorsal talonavicular ligament)

Eversion—distraction ofmedial column

� Avulsion of the navicular tuberos-ity (posterior tibialis tendon,spring ligament)

Eversion—impaction oflateral column

� “Nutcracker” compression frac-ture of calcaneocuboid joint



on T1-weighted images, which reappears on T2-weighting,indicating frank bone marrow replacement.

Soft Tissue EmergenciesCellulitis is an infection of the subcutaneous soft tissues, andthe most common mechanism is direct inoculation through abreak in the skin. Radiographs will demonstrate soft tissueswelling and obliteration of fat planes, while CT can be help-ful in delineating superficial disease (skin thickening, subcu-taneous fat septation, septal thickening) and deep disease(osteomyelitis changes, intramuscular abscess). CT can alsodemonstrate soft tissue gas, the hallmark of necrotizing fascii-tis. MRI is the gold standard, demonstrating soft tissueedema and enhancement, with the added benefit of detectingabscesses or tendon involvement.1,18

Septic arthritis is an emergency as delayed diagnosis andtreatment can lead to destruction of the cartilage and osseousstructures of the joint. Like osteomyelitis, seeding can occurfrom hematogenous routes, contiguous spread, and directinoculation. The earliest signs are joint effusion, soft tissueswelling, and periarticular osteoporosis with preservation ofthe joint space. In the absence of trauma, a fat-fluid level in ajoint effusion is highly suggestive of septic arthritis. Latersigns include cartilage destruction which leads to joint spaceloss. A consequence of importance in children is the risk ofpremature growth plate closure, which can lead to earlyosteoarthrosis and bony ankylosis. MRI can show changes asearly as 24 hours after onset, with the presence of joint effu-sion and synovial enhancement showing the highest correla-tion with septic joint. There is also a high incidence of peri-synovial edema. An important caveat in the ankle and foot isthat the absence of joint fluid, particularly in small joints,does not rule out infection.1,18,81

ConclusionEmergencies of the foot and ankle are frequently encounteredand carry significant risk of complication and morbidity.Radiologists should have a robust knowledge of the imagingappearance of foot and ankle emergencies, mechanisms ofinjury, and implications for management in order to bestcontribute prompt and efficacious patient care in the emer-gent setting.

AcknowledgmentAcknowledgment and appreciation is given to ZacharyGrushky and Danielle Dobbs for their help in the review andpreparation of the above manuscript.

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Traumatic Injuries of the Foot and Ankle