Distal Radioulnar Joint Instability

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T HE JOURNAL OF B ON E & JOINT SURGERY JBJS.OR GVOLUME 88-A N UMBER 4 APRIL 2006

D ISTAL R ADIOULNAR J OINT I NSTABILITY

Distal RadioulnarJoint Instability

BY R OBERT M. SZABO, MD, MPH

An Instructional Course Lecture, American Academy of Orthopaedic Surgeons

The distal radioulnar joint is inherentlyunstable. Pathologic instability can beacute or chronic; it can be dorsal, pal-mar, or multidirectional; and it can re-sult primarily from soft-tissue injuryor osseous malunion. Recognition ofthe type and cause of instability is fun-damental in order to provide effectivetreatment.

Anatomy of theDistal Radioulnar Joint

The distal radioulnar joint is a distal ar-ticulation in the biarticulate rotationalarrangement of the forearm. This articu-lation allows only one degree of motion:pronation and supination. The sigmoidnotch of the radius is concave and isshallow with a radius of curvature of15 mm. The ulnar head is semicylin-drical and has an articulate convexityof 220 with a radius of curvature of10 mm 1. The ulnar head is surroundedby an ulnar carpal ligament complex.This consists of the ulnolunate and ul-

notriquetral ligaments, which originatefrom the palmar radioulnar ligamentnear the ulnar styloid process. Whenseen through an arthroscope, these liga-ments appear to be continuous with thetriangular fibrocartilage.

The triangular fibrocartilage is afibrocartilaginous disk originating atthe junction of the lunate fossa and thesigmoid notch and inserting at the baseof the ulnar styloid. Its central portionis cartilaginous, and it is designed for

weight-bearing. It is also avascular. Theperipheral margins are composed ofthick lamellar cartilage designed fortensile loading and are called the dorsaland palmar radioulnar ligaments . Theperipheral margins of the triangular fi-brocartilage are well vascularized fromthe palmar and dorsal branches of theanterior interosseous artery and fromthe ulnar artery. The ulnar styloid is thecontinuation of the subcutaneous ridgeof the ulnar shaft, and it stands as astrut on the end of the ulna to stabilizethe ulnar soft tissues of the wrist. Thesheath of the extensor carpi ulnaris, theulnocarpal ligaments, and the triangu-lar fibrocartilage help to maintain thecongruency of the distal radioulnar joint with attachments at the base of theulnar styloid; together, they are knownas the triangular fibrocartilage complex 2-6 .

The radius of curvature of the ulnadoes not equal that of the sigmoid notch.Full congruity of two articulating sur-faces is therefore not possible. The shal-

low sigmoid cavity and the differencebetween the radii of curvature of thesigmoid notch and the ulnar head causethe ulna to translate volarly in supina-tion and dorsally in pronation. In theextremes of forearm rotation,


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tations of forearm rotation was de-scribed by Kleinman and Graham 17.

The triangular fibrocartilage, theulnar carpal ligaments, the infratendi-

nous extensor retinaculum, the prona-tor quadratus, and the interosseousmembrane provide additional key soft-tissue constraints. The triangular fibro-cartilage attaches to the fovea in theulna by way of the dorsal and palmarradioulnar ligaments. The fibers thatinsert into the fovea are separated fromthose that insert into the styloid by anareolar vascular tissue known as theligamentum subcruentum 18. There is adebate in the literature regarding theradioulnar ligaments. According toSchuind et al., in pronation the dorsalradioulnar ligament tightens as the ulnatranslates dorsally and in supination thepalmar radioulnar ligament tightens asthe ulna translates palmarly 19 (Table I).In contrast, Ekenstam showed that inpronation the palmar radioulnar liga-ment becomes taut (although thedorsal capsule tightens) as the ulnatranslates dorsally, and in supinationthe dorsal radioulnar ligament tightens(although the palmar capsule becomestight) as the ulna translates volarly 20.Ekenstam believed that stability inpronation depends on the tension inthe volar radioulnar ligament and com-pression between the contact areas ofthe dorsal aspect of the sigmoid notchand the ulna, whereas stability in supi-nation depends on the tension in thedorsal radioulnar ligament and the tri-angular fibrocartilage articular disk aswell as compression between the con-tact areas of the volar aspect of the sig-moid notch and the ulna.

Adams and Holley measured strainon the surface of the triangular fibrocar-

tilage articular disk and calculated the

strain at the dorsal and palmar marginsof the disk 21. In supination, strain in-creased dorsally; in pronation, strainincreased palmarly. In a biomechanical

study of eleven fresh cadavers, Ward etal. measured tension in the dorsal andpalmar radioulnar ligaments, joint rota-tion, and radial translation after sequen-tial excision of the disk, interosseousmembrane, joint capsule, and radioulnarligaments 14. This experiment confirmedthat the dorsal ligament tightens duringpronation while the palmar ligament be-comes progressively lax, whereas theconverse occurs during supination.

The preponderance of biome-chanical evidence supports the findingsreported by Schuind et al. 19, and the in-consistency between their observationsand those presented by Ekenstam 20 canbe resolved because, in pronation, thedorsal radioulnar ligament tightens andtends to displace the ulna dorsally. Leftunconstrained, this dynamic tensioningwould lead to subluxation and disloca-tion of the joint. The palmar radioulnarligament checks that force and keeps the joint reduced. If the interosseous mem-brane is disrupted and the palmar radi-oulnar ligament is sectioned, the distalpart of the ulna dislocates dorsally in pro-nation. If the interosseous membrane isdisrupted and the dorsal radioulnar liga-ment is sectioned, the distal part of theulna dislocates palmarly in supination.

ClassificationDisorders of the distal radioulnar jointcan be classified into four categories: (1)impaction, (2) incongruity, (3) inflam-mation, and (4) instability. All of thesedisorders can produce pain around thedistal radioulnar joint and should beconsidered when a patient reports symp-

toms at the distal radioulnar joint. Ulnar

impaction is due to a positive ulnarvariance that causes the distal part ofthe ulna to abut against the lunate, oftenleading to thinning of the triangular fi-

brocartilage and eventually to a centraltear. Some surgeons also refer to this asulnar abutment syndrome. Incongruityrefers to the lack of a smooth interfacebetween the ulnar head and the sigmoidnotch. Incongruity can be due to a post-traumatic condition such as a distal ra-dial fracture into the sigmoid notch,or it can be secondary to osteoarthritisor rheumatoid arthritis. Inflammationaround the distal radioulnar joint isusually due to extensor carpi ulnaristendinitis dorsally or flexor carpi ul-naris tendinitis palmarly, and some-times these disorders can be of acalcific variety.

Instability of the distal radioul-nar joint may be acute or chronic andmay be related to osseous changes aftera fracture or to soft-tissue injury. Soft-tissue injury of the triangular fibrocarti-lage, dorsal radioulnar ligament, palmarradioulnar ligament, interosseous mem-brane, joint capsule, or any combina-tion of those structures is capable ofproducing instability of the distal radi-oulnar joint. Fractures of the distal partof the radius or distal part of the ulnaalter the biomechanics of the distal ra-dioulnar joint 22. It is important to keepin mind that instability can occur aloneor in conjunction with impaction, in-congruity, or inflammation. Treatmentmust be directed at each component ofthe disease complex.

Examination of theDistal Radioulnar JointTo examine the ulnar styloid, oneshould follow the superficial border of

the ulnar shaft distally while the wrist is

TABLE I Effects of Pronation and Supination on the Dorsal and Palmar Radioulnar Ligaments and Joint Capsule

Pronation Supination

Dorsal radioulnar ligament Tight as ulna displaces dorsally. Dorsal capsuleimbrication stabilizes distal radioulnar joint, pre-venting volar translation of radius

Lax

Palmar radioulnar ligament Lax Tight as ulna displaces palmarly. Palmar capsuleimbrication stabilizes distal radioulnar joint,preventing dorsal translation of radius


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in radial deviation. The ulnar styloidcan be found more volarly than antici-pated. This maneuver should be donewith the wrist in a pronated position.The distal radioulnar joint is the mostcomplex structure to evaluate. Themost common pathological finding isradioulnar incongruity secondary to amalunited distal radial fracture withloss of the pronation-supination arc.With loss of the volar tilt of the radius,the distal part of the ulna appears to bemore prominent. With ulnar impac-tion, ulnar deviation and extension arelimited and can be painful. The areasof pronation, supination, and flexion-extension should be determined. To testfor instability of the distal radioulnar

joint, the examiner should supinate thewrist while supporting the hand, per-form a ballottement maneuver of thedistal part of the ulna, and compare theaffected side with the normal side. Dur-ing this maneuver, he or she should feelfor crepitus and ask the patient if painoccurs. To check for instability of theextensor carpi ulnaris tendon, the pa-tient should be asked to flex the elbowand pronate and supinate the forearmwith the hand in slight ulnar deviation

while the examiner looks for abnormalmotion of the extensor carpi ulnaristendon. Peripheral tears of the triangu-lar fibrocartilage complex can produceinstability of the distal radioulnar jointwith the wrist in supination. With thepatients forearm in supination, the ex-aminer should hold the distal part ofthe ulna between the thumb and indexfinger and test for dorsal and volar dis-placement of the distal part of the ulna.The so-called press-test is a simple as-sessment. The patient is asked to pushhimself or herself up from a seated posi-tion with use of the affected wrist. Thistest creates an axial ulnar load and has ahigh sensitivity for detecting a tear ofthe triangular fibrocartilage complex 23.

Pain with this maneuver suggests thatthere is a lesion in the triangular fibro-cartilage complex.

Radiographic TestsStandard radiographs of the distal partof the ulna should be made with com-parison views of the unaffected side. Theimages should include a true lateral ra-diograph made with the forearm in neu-tral rotation. Any deviation of >10 froma true lateral view will greatly reduce the

accuracy of the examination. Ulnar vari-ance should be measured and comparedwith that on the contralateral side on ra-diographs made with the forearm in neu-

tral rotation and the shoulder and elbowin 90 of flexion with the x-ray beamdirected from posterior to anterior 24.Ulnar variance changes by up to a milli-meter as the forearm moves from full su-pination to full pronation; therefore, thisstandard position should be used. Ulnarvariance is measured by drawing a trans-verse line at the level of the lunate fossaand a second transverse line at the levelof the ulnar head, and determining thedistance between the two lines. On theposteroanterior radiograph, one shouldlook for a fleck fracture demonstratingan avulsion of the triangular fibrocarti-lage complex, an ulnar styloid nonunion,and joint widening between the radiusand ulna (Fig. 1). Radiographic signs ofinjury to the distal radioulnar joint in-clude a fracture at the base of the ulnarstyloid, widening of the distal radioul-nar joint space seen on the posteroante-rior radiograph, >20 of dorsal radialangulation, and >5 mm of proximal dis-placement of the distal part of the radius.

Computed tomography scanningis the technique of choice for evaluat-ing congruity of the distal radioulnar joint, but the same information can beobtained with magnetic resonance im-aging (Figs. 2-A and 2-B). There areseveral methods for evaluating sublux-ation of the distal radioulnar joint, in-cluding the method described by Minoet al.25,26, the congruency method 27, theepicenter method 27, and the RUR (radi-oulnar ratio) method 28. Magnetic reso-nance imaging is useful for identifyingtears of the triangular fibrocartilage(Fig. 3), but its specificity and sensitiv-

ity vary 29

. It is necessary to use high-resolution magnetic resonance imagingwith a dedicated wrist coil to obtain ac-curate scans 30-32. Arthrography is still avaluable examination, and it is evenmore useful when it is combined withmagnetic resonance imaging. Arthros-copy is a sensitive method for evaluat-ing tears of the triangular fibrocartilagecomplex and is considered the goldstandard with which to compare theaccuracy of other examinations.

Fig. 1Posteroanterior radiograph showing a distal radioulnar joint with chronic palmar instability in a fif-teen-year-old girl who had sustained a fracture of the distal part of the radius two years previ-ously. Note the large ulnar styloid nonunion fragment and a fleck fracture representing the sitewhere the triangular fibrocartilage complex avulsed from the fovea.


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Subluxation and DislocationBy convention, the ulna is consideredto dislocate with respect to the radius,but it is the radius that moves andtherefore is displaced. With dorsal sub-luxation, the head of the ulna becomesprominent dorsally, particularly in pro-nation, and may snap during wrist rota-tion. This is usually associated with aweak and painful wrist. With completedislocation, the ulnar head is locked inposition, most commonly dorsally buton occasion palmarly. Supination is re-stricted with either type of dislocationbecause the radius cannot slip dorsallyover the ulnar head.

The mechanism of action for adorsal subluxation or dislocation of theulna is extreme pronation and exten-sion with the coiled and tightened ex-tensor carpi ulnaris and ulnar carpalligaments acting as a sling to lift theulnar head through the dorsal capsule.

Weakening of the triangular fibrocarti-lage complex secondary to its avulsion(or a fracture of the ulnar styloid) andattenuation of the palmar radioulnarligament will allow the dislocation.Sheer stress during this mechanismmay produce associated chondral de-fects. The clinical appearance of a dor-sal dislocation of the ulna is a tenderprominent dorsally displaced ulna anda forearm with limited supination orlocked in pronation. Direct pressure

may reduce the dislocation, but the ul-nar head usually springs back into adorsal position if the forearm remainspronated. There is increased anteropos-terior translation of the distal radioul-nar joint with passive motion. Routine

radiographs may be nondiagnostic. Aposteroanterior radiograph can showthe ulna overlapping the distal part ofthe radius. The best study with which tovisualize a subluxation or dislocation isa computed tomography examination

Fig. 2-AT1-weighted magnetic resonance images of both wrists in pronation made to compare the normal wrist (Fig. 2-A) with the wrist that had a dorsal dis-tal ulnar subluxation (Fig. 2-B).

Fig. 2-B

Fig. 3T2-weighted magnetic resonance image showing a complex peripheral tear (double arrows) andradial tear (single arrow) of the triangular fibrocartilage complex.


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of both wrists performed in both pro-nation and supination 25,26,33-35.

Treatment of Acute DislocationsDorsal Subluxation and DislocationAn acute dorsal dislocation can be re-duced with digital pressure on the distalpart of the ulna and forceful supination.The reduction should be maintainedfor six weeks. Some authors 36 have ad-vocated full supination, whereas others 37 have recommended the neutral posi-tion. Nonoperative methods of treat-ment should be used only when thereis congruity of the distal radioulnar joint in two planes. Open reduction

with repair of the triangular fibrocarti-lage complex should be performed ifthe joint is locked and cannot be re-duced, or if it is incongruous followingreduction. Open repair of the triangularfibrocartilage complex is done with adorsal incision through the fifth com-partment with the extensor digiti min-imi reflected radially and the extensorcarpi ulnaris reflected ulnarly, therebyexposing the triangular fibrocartilagecomplex and visualizing the dorsal radi-

oulnar ligament. Nonabsorbable su-tures should be used to reattach thetriangular fibrocartilage complex tothe ulnar styloid 38.

Ulnar styloid fractures have animportant effect on the stability of thetriangular fibrocartilage complex. Thesefractures commonly occur together withfractures of the distal part of the radiusand can be a sign of instability of the tri-angular fibrocartilage complex. Symp-tomatic nonunions of the styloid canoccur. Hauck et al. classified these non-unions as type 1 when the distal radio-ulnar joint is stable and as type 2 whenit is unstable 2. Type-1 fractures occur

through the tip of the styloid, and whenthey become symptomatic they are of-ten treated successfully with excision.Type-2 fractures occur through the baseof the styloid, creating a much largerfragment, and usually open reductionand internal fixation and restoration ofthe integrity of the triangular fibrocarti-lage complex is recommended even ifthere is a nonunion.

The distal part of the ulna can dis-locate or subluxate palmarly as a result of

a fall on a supinated hand or from exer-tional lifting in supination, with failureof the dorsal radioulnar ligament beingthe critical event. Clinically, patientspresent with the forearm held in a supi-nated position. Pronation is painful andrestricted 39. The ulnar head is palpablevolarly, and ulnar dysesthesias may de-velop from pressure on the ulnar nerve.Once again, a diagnosis can be made onthe basis of good standard radiographs(Figs. 4-A and 4-B) and can be con-firmed by comparing computed tomog-raphy scans of the affected and normalwrists. A fracture or erosion of the pal-mar lip of the sigmoid notch may lead

to persistent instability. An acute pal-mar dislocation can be reduced withdigital pressure on the distal part of theulna in a dorsal direction combined withforceful pronation. The treatment foran acute palmar dislocation is closedreduction with immobilization for sixweeks in an above-the-elbow cast in aneutral or slightly pronated position.Open treatment is reserved for patientsfor whom closed reduction has failed.The approach is volar with careful re-

Fig. 4-A

Standard posteroanterior (Fig. 4-A) and lateral (Fig. 4-B) radiographs of the wrist, dem-onstrating palmar dislocation of the ulna.

Fig. 4-B


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traction of the volar neurovascular bun-dle in an ulnar direction.

Tears of the Triangular

Fibrocartilage ComplexTriangular fibrocartilage tears can occurwithout causing instability of the distalradioulnar joint. The most commontear occurs within the articular diskof the triangular fibrocartilage, near itsattachment to the radius, and is not as-sociated with instability of the distalradioulnar joint 40-44. The tears them-selves, however, can be unstable andsymptomatic. Despite the recognitionof specific types of triangular fibrocar-tilage lesions45, the exact mechanismsof injury remain uncertain. Adams etal., using a laboratory model to simu-late distraction of the radius and ulnathrough the distal radioulnar joint, pos-tulated that such a distraction force mayresult from a violent axial load on theforearm 40. This model did not, how-ever, produce the types of tears of thetriangular fibrocartilage complex thatare seen clinically. Probably, a combi-nation of compression across the wristtrapping the disk in the ulnocarpal jointwith distraction or twisting of the distal

radioulnar joint then creates enoughshear forces to tear the disk.

Symptomatic instability and tearsof the triangular fibrocartilage complex

require surgical treatment. The periph-eral rim of the triangular fibrocartilageis well vascularized and has good heal-ing potential. Repair of these lesionswith a variety of techniques can lead tohealing. Historically, open repair wasadvocated 38, but currently most peri-pheral tears can be treated arthros-copically. This arthroscopic approachrepairs only the superficial fibers ofthe triangular fibrocartilage complexto the joint capsule and not the deepportion that inserts onto the fovea.There is much less chance that centraltears of the triangular fibrocartilagecomplex will heal because they are inareas of hypovascularity or avascular-ity. Arthroscopic dbridement of theselesions is recommended 46.

Chronic Distal RadioulnarJoint InstabilityDorsal, Palmar, orBidirectional Instability Chronic distal radioulnar joint instabil-ity is a painful and often disabling con-

dition. Functional bracing, which hasbeen tested in a cadaveric model 47, canbe used for patients who do not wish tohave surgery, but most patients prefer

surgical treatment. It is necessary tocheck the osseous anatomy in patientswith chronic palmar dislocation. Manypatients have had a fracture of the wristor forearm, sometimes many years be-fore symptoms developed at the distalradioulnar joint. Bilateral radiographsof the entire wrist and forearm, madein the same position, should be com-pared. Osseous malalignment shouldbe corrected. The status of the triangu-lar fibrocartilage complex is evaluatedwith either magnetic resonance imagingor arthroscopy. If the triangular fibro-cartilage complex is not repairable, atendon reconstruction is needed andshould be tightened in supination 48,49.

Illustrative Case ReportAn eighteen-year-old, right-hand-dominant man presented with painin the left wrist and forearm that hadbeen increasing during the previoustwo years. He had sustained a fractureof the distal third of the left radius atthe age of twelve years and had been

Fig. 5-APosteroanterior (Fig. 5-A) and lateral (Fig. 5-B) radiographs made three years after plate fixation of a fracture of the distal part of the left radius in atwelve-year-old boy. Note the apex volar angulation of the radius. The normal right side is shown for comparison.

Fig. 5-B


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treated nonoperatively. One monthlater, he fell and sustained a refractureof the radius as well as an ulnar styloidfracture. The fracture of the radius wastreated with open reduction and inter-nal fixation through a volar approach.It healed without complication, and thepatient returned to full participation involleyball, weight-lifting, soccer, andsnowboarding.

Three years later, he noticed swell-ing about the wrist and had pain at thedistal part of the left ulna in association

with many activities. Volar angulationof the radius could be seen on radio-graphs (Figs. 5-A and 5-B). The trian-gular fibrocartilage complex appearednormal on the magnetic resonance im-aging scan. The symptoms were attrib-uted to malunion of the fracture andangular overgrowth of the radius result-ing in palmar subluxation of the distalpart of the ulna and instability of the dis-tal radioulnar joint. The hardware wasremoved, and a dome osteotomy of the

left radius with iliac crest bone-graftingwas done. A closing-wedge osteotomyof the radius was not performed becauseof the potential that it could further de-stabilize the distal radioulnar joint 50.Eight months after the surgery, the os-teotomy site had healed and the patienthad regained the preoperative range ofwrist motion. The distal radioulnar jointwas stable on examination. He resumedall of his previous activities, includingvolleyball and weight-lifting, withoutany symptoms in the left upper extre-

mity, and he was discharged from ourclinic. He subsequently joined the Ma-rine Corps and wrote to say that he hadremained asymptomatic throughout allphysical endeavors involved in his stren-uous active training 51.

Dorsal Subluxation andDislocations with FracturesGaleazzi FracturesA Galeazzi fracture is a diaphyseal frac-ture of the radius associated with a dis-

location of the radioulnar joint 52. AGaleazzi fracture has also been calledthe fracture of necessity because non-operative treatment so often yields apoor result. The radioulnar joint maybe dislocated or subluxated, and it isalways affected (Figs. 6-A through 6-D).Detection of the disorder of the distalradioulnar joint in a patient with a ra-dial shaft fracture requires a high levelof suspicion. Radiographs of the con-tralateral side may be helpful. Rettigand Raskin found that twelve of twenty-

two fractures of the distal third of theradius (within 7.5 cm of the midarticu-lar surface of the distal part of the radius)were associated with intraoperative in-stability of the distal radioulnar joint,whereas only one of eighteen fracturesin the middle third of the radial shaft(>7.5 cm from the midarticular surfaceof the distal part of the radius) was as-sociated with intraoperative instabilityof the distal radioulnar joint 53. Openreduction with internal fixation of the

Fig. 6-BFigs. 6-A through 6-D A twenty-eight-year-old man was seen with a Galeazzi-type fracturewith an entrapped extensor carpi ulnaris tendon preventing reduction of the ulnar styloidthat is attached to the triangular fibrocartilage complex. Note the disrupted distal radioul-nar joint in addition to the fractures of the radius and distal part of the ulna. Fig. 6-A Pos-teroanterior radiograph showing the injury. Fig. 6-B Lateral radiograph showing the injury.

Fig. 6-A


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radial fracture is the first stage of treat-ment of a Galeazzi fracture. If the distalradioulnar joint is stable, early motioncan be initiated. If it is unstable and re-ducible, the wrist should be immobi-

lized in slight supination for four to sixweeks. If a sizable ulnar styloid fractureis present, fixation may allow early mo-bilization and should be considered. Ifthe distal radioulnar joint is irreducible,open reduction of the joint is necessary;this usually requires repair of the trian-gular fibrocartilage or fixation of theulnar styloid fragment. Six weeks of im-mobilization in slight supination is rec-ommended if the distal radioulnar jointrequires surgical treatment. Rarely, the

extensor carpi ulnaris is interposedand prevents reduction; if it is, it needsto be removed from the joint (Figs. 6-Cand 6-D) 54.

Essex-Lopresti InjuriesEssex-Lopresti injuries, which are se-vere and disrupt the entire forearm 55,consist of a radial head fracture withproximal migration of the radius. Themigration indicates complete disrup-tion of the interosseous ligament andthe triangular fibrocartilage complex.These injuries are usually caused by afall on the outstretched hand with axialloading. The primary stabilizer prevent-ing proximal migration of the radius is

the radial head, and the secondary sta-bilizers are the interosseous ligamentand the triangular fibrocartilage. Diag-nosing the wrist injury in this complex

is important. Treatment consists ofopen reduction and internal fixation ofthe radial head if possible, with immo-bilization of the forearm in supination.Pinning of the distal radioulnar joint isan option, but if the pins break they canbe difficult to retrieve. Comminuted ra-dial head fractures often are not repair-able and require replacement, usuallywith a metallic prosthesis. Silicone ra-dial head replacements have not per-formed well in this situation becausethey fracture, causing particulate syno-vitis, when they are placed under load.The operation is best done early as de-layed treatment can lead to poorer re-sults. The options for delayed surgeryinclude radial head replacement witha prosthesis or allograft 56, or a Sauv-Kapandji procedure.

Multidirectional InstabilityThe axis of forearm motion passesthrough the fovea of the distal part ofthe ulna. The deep fibers of the distalradioulnar ligaments, the palmar radi-oulnar ligament, the triangular fibro-cartilage, the ulnolunate ligament, theulnotriquetral ligament, and the ulno-capitate ligament all insert onto the fo-vea57. These ligamentous attachmentsare key to the stability of the distal ra-dioulnar joint. The distal radioulnar joint can be stabilized surgically in oneof three ways: (1) a repair of the trian-gular fibrocartilage complex and thedistal radioulnar ligaments, (2) anextrinsic soft-tissue reconstruction ei-ther with a direct link (i.e., a radioulnartether) or an indirect link (i.e., an ulnar

carpal sling tenodesis), or (3) a distalradioulnar ligament reconstruction.

Procedures for Stabilizationof the Distal Radioulnar JointThe first option for stabilizing the dis-tal radioulnar joint is to repair the tri-angular fibrocartilage complex to thefovea, from which it is usually found tobe ruptured. When repair is not possi-ble, reconstruction is indicated. Thereare several procedures for stabilization

Fig. 6-C

Fig. 6-C Posteroanterior radiograph made after initial fixation of the radial and ulnarfractures. Note the widening of the distal radioulnar joint. Fig. 6-D Lateral radiograph

made after initial fixation of the radial and ulnar fractures. Note the dorsal displace-ment of the ulna. This problem occurred because the initial surgeon did not recognizethe interposition of the extensor carpi ulnaris tendon, which prevented the reductionof the ulnar styloid/triangular fibrocartilage complex. Reoperation was performed,and anatomical reduction and fixation was possible after the extensor carpi ulnaristendon was repositioned dorsally.

Fig. 6-D


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of the distal radioulnar joint, as describedby Hui and Linscheid 58, Tsai and Stil-well59, Breen and Jupiter 60, Fulkersonand Watson 61, and Ellison, Boyes, and

Bunnell1

, just to mention a few. Theabove are all indirect stabilization pro-cedures through an ulnocarpal sling ortenodesis, or a direct radioulnar tetherextrinsic to the joint (the techniquedescribed by Fulkerson and Watson).Johnson described a dynamic muscletransfer involving use of the pronatorquadratus 11. Other distal radioulnar sta-bilization procedures involving recon-struction of the radioulnar ligamentswere described by Scheker et al. 62, Sand-ers and Hawkins 63, and Bowers 64. We arenot aware of any long-term follow-upstudy of an adequate series of patientstreated with such procedures. In a bio-mechanical cadaver model, reconstruc-tions of the radioulnar ligaments werefound to be superior to radioulnar teth-ering procedures although the resultsof capsular repair alone most closelymatched the kinematics of an intactdistal radioulnar joint 65.

I recommend the procedure de-scribed by Adams et al. to reconstructthe ligamentous anatomy (Fig. 7) 48,49.Their indications and criteria for ligamentreconstruction include unidirectional orbidirectional chronic instability of thedistal radioulnar joint, absence of sub-stantial arthritis, and a competent sig-moid notch rim with no residual axialinstability of the forearm. Any malunionshould be mild or corrected concur-rently. Adams and Divelbiss cautionedthat, if the volar or dorsal lip of the sig-moid notch is incompetent (shallow),ligament reconstruction may not besufficient and an opening-wedge os-teotomy of the distal part of the radius

may be required48

. The procedure isdone with use of a dorsal approachthrough the fifth extensor compart-ment, which provides direct access tothe distal radioulnar joint. Typical find-ings are a triangular fibrocartilage com-plex that is torn from the ulna, a tornextensor carpi ulnaris sheath, concomi-tant carpal ligament injuries, and per-haps an ulnar styloid fracture. Adamsand Berger reported that, of twenty pa-tients (twelve with bidirectional insta-

Fig. 8This patient underwent open reduction and in-

ternal fixation to treat a fracture of the distalpart of the radius, but the dorsal subluxationof the ulna was never corrected. Arthriticchanges developed in the distal radioulnar

joint, with pain and limitation of pronation-supination. This problem was treated with aSauv-Kapandji procedure.

Fig. 7Dorsal and palmar ligament reconstruction, as described by Adams and Divelbiss 48, for treat-ment of a chronically unstable distal radioulnar joint. (Reprinted from: Adams BD, Divelbiss BJ.Reconstruction of the posttraumatic unstable distal radioulnar joint. Orthop Clin North Am.2001;32:353-63; with permission from Elsevier.)


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bility and eight with unidirectionalinstability) followed for a minimumof one year after the procedure, eigh-teen recovered stability, with an 80%

recovery of supination, 84% recoveryof pronation, and 88% recovery of gripstrength 49.

SalvageIf there is residual instability after adistal ulnar resection, a flexor carpi ul-naris and extensor carpi ulnaris tenode-sis, as described by Breen and Jupiter 60,66,can be considered. Wolfe et al. reportedthat the distal part of the ulna will re-main stable even after removal of morethan a third of it 67. This may be true af-ter a tumor resection, but it is not areliable assumption after traumaticinjuries. Wide resections of the distalpart of the ulna usually require someadditional form of stabilization, andtenodesis of the flexor carpi ulnaris andextensor carpi ulnaris tendons is rec-ommended. Implantation of a metallicprosthesis to replace the distal part ofthe ulna can also be considered as a sal-vage procedure for treatment of this dif-ficult problem 68. The Sauv-Kapandjiprocedure is a useful salvage techniquewhen there is instability of the distalpart of the ulna and arthritic changes

(Fig. 8). The Sauv-Kapandji procedureinvolves fusion of the distal radioulnar joint and creation of a pseudarthrosis ofthe ulna just proximal to the arthrodesis

to allow forearm rotation69

. There canbe subluxation of the proximal ulnarstump, which can be symptomatic, aftera Sauv-Kapandji procedure, and thiscan be stabilized with either an extensorcarpi ulnaris tenodesis, as described byMinami et al. 70, or a flexor carpi ulnaristenodesis, as described by Lamey andFernandez 71.

OverviewAcute dislocations of the distal radioul-nar joint should be reduced promptlyand treated with cast immobilization.If the dislocation is irreducible, openreduction is warranted. The first at-tempts to treat chronic instabilityshould be directed at repairing the tri-angular fibrocartilage complex, butonly after careful assessment for anyosseous malunions along the forearmaxis, which must also be corrected. If itis not possible to repair the triangularfibrocartilage complex, the osseous ar-chitecture is normal, and no arthritis ispresent, a ligament reconstruction canbe considered, but the competency ofthe sigmoid notch must be evaluated

carefully. If there are arthritic changesat the distal radioulnar joint, a Sauv-Kapandji procedure should be performed,with stabilization of the proximal stump

with a slip of either the flexor carpi ul-naris or the extensor carpi ulnaris.

Robert M. Szabo, MD, MPHDepartment of Orthopaedic Surgery, Univer-sity of California, Davis, School of Medicine,4860 Y Street, Sacramento, CA 95817. E-mailaddress: [email protected]

The author did not receive grants or outsidefunding in support of his research for or prep-aration of this manuscript. He did not receivepayments or other benefits or a commitmentor agreement to provide such benefits from acommercial entity. No commercial entity paidor directed, or agreed to pay or direct, any ben-efits to any research fund, foundation, educa-tional institution, or other charitable ornonprofit organization with which the authoris affiliated or associated.

Printed with permission of the AmericanAcademy of Orthopaedic Surgeons. This arti-cle, as well as other lectures presented at theAcademys Annual Meeting, will be available inFebruary 2007 in Instructional Course Lectures, Volume 56. The complete volume can be or-dered online at www.aaos.org, or by calling800-626-6726 (8 A.M.-5 P.M., Central time).

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Distal Radioulnar Joint Instability