MANAGEMENT OF COMBINED INSTABILITIES:ANTERIOR CRUCIATE LIGAMENT/MEDIALCOLLATERAL LIGAMENT AND ANTERIOReRUCIATE LIGAMENT/LATERAL SIDE

RICHARD A. RUBINSTEIN, JR, MD andK. DONALD SHELBOURNE, MD

In our experience, combined injuries of the anterior cruciate ligament (ACL) and the medial collateral ligament(MCL) or lateral side knee structures can occur in noncontact as well as contact sports. The MCL usually healswithout surgical intervention. Repair of the ACL should be delayed (4 to 8 weeks) until the acute inflammatoryphase subsides, motion is restored, the MCL heals, and quadriceps strength is relatively the same as that of thenoninvolved leg. Decisions for total management depend on the patient's age, activities, demands, and desires.We recommend ACL reconstruction for those patients at high risk for recurrent instability and subsequent injuryand modification of activities and/or brace use for low-risk patients. For patients with associated lateral sideinjuries, we test for varus laxity at 30° and the presence of anterior laxity. Varus laxity in extension andposterior laxity are absent. We perform a magnetic resonance imaging scan routinely for defining the lateralside injuries. Because lateral side injuries do not heal well with conservative treatment, we do not have the:luxury of significantly delaying surgical management of ACUlateral side injuries as we do for ACUMCL injuries;hence, we perform reconstruction of the ACL and lateral direct repair of structures 7 to 10 days after injury.These patients, treated in the manner described and rehabilitated by our program, which emphasizes kneemotion and early weight bearing, are able to predictably return to full activities with a stable functional knee.KEY WORDS: anterior cruclate ligament, associated Injuries, preoperative rehabilitation

When the anterior cruciate ligament (ACL) is injured,the medial collateral ligament (MCL) is involved 21% ofthe time; the lateral side is involved in 1% of these cases(Table 1). This incidence of combined injuries reflects ourexperience in a sports-based orthopedic practice. Theseinjuries most often occur from direct contact to the knee,although we have also found that these combination in­juries can occur in noncontact situations. The historyand physical examination are diagnostic in the majority ofcases . A large effusion may be present if capsular integ­rity exists, although the effusion may be minimal in gradeIII (complete) injuries because of capsular disruption.The standard clinical tests (Lachman, pivot shift, andposterior drawer) are performed to evaluate the cruciateligaments. Varus and valgus knee stressing is done atboth 0° of extension and at 30° of flexion to evaluate thecollateral structures. An ACL tear combined with themedial or lateral side injury with an intact posterior cru­ciate ligament (PCL) should have minimal 9r only phys­Iological laxity in extension and increased laxity at 30°,with no end point if there is a complete disruption. Re­peat examinations may be necessary to establish the cor­rect diagnosis. In difficult diagnostic cases, a magnetic

From The Methodist Sports Medicine Center, Indianapolis, IN.Address reprint requests to K. Donald Shelbourne, MD, The Meth·

odist Sports Medicine Center, 1815 N Capitol Ave, Suite 530, India­napolis , IN 46202.

Copyright © 1993 by W. B. Saunders Company1060·187219310101-0010$05.0010

resonance imaging (MRI) scan can be helpful in furtherdefining and confirming the injury.

This article is divided into two subsections: ACUMCLinjuries and ACLllateral structure injuries. The diagnosisand management of these combined injuries are con­trasted by predictable MCL healing without surgical in­tervention and subsequent delayed ACL reconstruction,whereby the lateral structures should be surgically man­aged as soon as the acute phase is over (7 to 10 days) witha combined lateral side repair and ACL reconstruction.

ACLlMCL INJURIES

In the combined ACUMCL tear it is important to accu­rately define the medial injury as well as to know thelikelihood of associated injuries, including both meniscaland chondral. A positive Lachman test is considered di­agnostic of an ACL tear. In our experience the majorityof clinically detectable ACL injuries are complete tearswith few, if any, being partial tears . The MeL injury isgraded on a scale of I to III based on tenderness, laxity,and end point. A grade I MCL injury has tenderness, nolaxity at 30°, and a solid end point, and the grade II MCLinjury is similar, although there is some medial laxity butan intact end point on valgus stressing. In contrast, thegrade III MCL injury is a complete tear with significantlaxity at 30° and no firm end point with valgus stress.

In a study by Shelbourne and Nitz.! 60 patients withcombined ACL and MCL injuries were evaluated regard-

66 Operative Techniques in Sports Medic ine. Vol 1, No 1 (January). 1993: pp 66-71

TABLE 1. Acute ACl Injuries (1982 to 1992-KDS)

Number (%)

23 (70)26

4 (15)5 (19)

17 (66)

6 (18)61 (17)1 (17)4 (66)

Patients with LMTNumber of LMT

RepairedRemovedLeft alone

Patients with MMTNumber of MMT

RepairedRemovedLeft alone

Category

=v

Abbreviations : LMT, lateral meniscus tear; MMT, medial meniscustear.

TABLE 2. Operative ACUMCl Patients Since January 1990(N = 33)

!II

ACL. In our experience, because of the pattern and lo­cation, most meniscal tears that are nonrepairable remainasymptomatic independent of any specific treatment.Lateral meniscus tears tend to be radial and/or peripheral,and the few medial meniscus tears are peripheral; all ofthese tears are generally stable with a high propensitytoward healing or being asymptomatic. During the pe­riod 1990 to date (lune 1992), we treated 33 patients withan ACLIMCL injury by a subacute ACL reconstruction.Of these patients, 23 had lateral meniscal tears, and 6 hadmedial tears, two thirds of which were left alone at thetime of reconstruction. The remaining tears were eitherrepaired or partially excised (Table 2). None of these pa­tients have required subsequent surgery for their me­nisci, and all remain asymptomatic. As our knowledgeabout the natural history of unrepaired menisci increases,we have been salvaging more menisci and performingfewer partial meniscectomies, especially on the lateralside.

Fig 2. Distribution of meniscal tears in acute ACUgrade IIIMCl tears. Note that 32% are Isolated lateral menlscal tears~, 8% are isolated medial menlscal tears §I, and 60% are nomeniscus tears D.

Percent

1007821

1

Number

5364201.10

6

Total numberIsolated ACL tearACUMCL tearACUlateral side

/

Fig 1. Distribution of menlscal tears In acute ACUgrade IIMCl Injuries. Note that 60% are isolated lateral meniscaltears ~, 11% are both lateral and medial menlscal tears I.§,and 29% are no meniscus tears D.

ing the presence of meniscal or other intra-articular in­jury. The investigators noted that only 10% of these pa­tients had medial meniscus tears (11% when grade II and8% when grade III), all of which were repairable. How­ever, 71% of those with grade II MCL injuries and 32% ofthose with grade III MCL injuries had lateral meniscustears, of which 50% were repairable (Figs 1 and 2). Inaddition, lateral chondral fractures were noted in 17% ofgrade II MCL injuries and in 8% of grade III MCL injuries.Meniscal injury was absent in 60% of grade III MCL tears.The conclusion of this study was that the classic triad ofACL-MCL-medial meniscus tear is rare in our athletic pa­tient population, and, in grade II MCL injuries associatedwith ACL disruption, a lateral meniscus injury is morecommon than a medial meniscus injury. Also, grade IIIMCL tears associated with ACL disruption most com­monly have no associated intra-articular injury, whichmay be explained by the distractive as opposed to com­pressive nature of the injury.

By clinical examination, coupled with knowledge ofour operative findings, we can accurately diagnose and/or predict the extent of the injury. Adjunctive tools, suchas MRI and/or arthroscopy, are usually not indicated inacute injuries. : Even in those cases involving meniscaltears, we focus the initial treatment on the MCL and

MANAGEMENT OF COMBINED LIGAMENT INSTABILITY 67

Our treatment philosophy for ACLlMCL injuries isbased on the following principles. First, predictable heal­ing of the MCL can be obtained by treating the MCLportion of the ACLIMCL injury nonoperatively, regard­less of its grade. Second, the associated nonligamentousknee injuries that can occur with an ACIJMCL tear do notrequire any immediate surgical treatment and generallydo well without surgical treatment. Last, delaying thesurgical reconstruction of the ACL knee until the acuteinflammatory phase subsides and full range of motion isrestored wiII result in a significantly decreased incidenceof postoperative complications. This latter observation isespecially true for the combined ACIJMCL injury. Thedecisions for subsequent treatment will depend on thepatient's age, activities, demands, and desires.

Our approach to acute ACLIMCL injuries is similar tothat used for acute isolated ACL tears: delay surgical re­construction until range of motion is restored, swellingdiminishes, and the inflammatory knee phase subsides.However, during this time the MCL injury needs to beaddressed. All grades of isolated MCL injuries, includ­ing grade III tears, can heal with excellent stability andfunctional results, equal to those after operative repair,"

. with nonoperative treatrnent.F" Although there are con­flicting laboratory data in regard to nonoperative MCLhealing in the face of an ACL-deficient knee,5,6 these datacome from biomechanical studies in animals and do notreflect our clinical experience. In clinical studies, initialnonoperative treatment of the MCL injury associatedwith an acute ACL tear has resulted in stable and pre­dictable MCL healing and leads to a similar decision­making process as one would have with an isolated ACLtear. 7

-10 In humans the compressive forces of the medialside of the knee appear to enhance MCL healing. Satis­factory MCL healing can occur as long as secondary giv­ing-way episodes are not allowed during this healingphase. Over the past 7 years we have not repaired anyMCL tears, whether isolated or combined, and have seenno clinical sequelae.

The initial treatment of the ACL tear combined with agrade I or II MCL injury centers around restoring motion,decreasing swelling, and providing a short period of kneeprotection for patient comfort. The patient participates ina progressive rehabilitation program including kneerange-of-motion activities (emphasizing extension) andquadriceps rehabilitation. Cold compression (CryoCuff,Aircast, Inc, Summit, NJ) is applied; a knee immobilizerprovides support until the patient is comfortable duringambulation.

Grade III MCL injuries are treated with a similar non­operative approach, although there is initially more em­phasis on protecting the knee. Treatment for the MCLinjury may vary depending on the location of the tear.In our experience the knees in which the MCL tears fromthe femoral origin (the majority) or in its midsubstancetend to become more stiff with little residual laxity; there­fore-rehabilitation should be directed toward restoringrange of motion with the added protection of a temporarybrace. In contrast, the knees in which the MCL tearsfrom the tibial insertion tend to heal with some mild val­gus laxity; therefore, we immobilize these patients forapproximately 2 weeks before beginning motion. During

68

this period the MCL injury "scars down." This immobi­lization promotes some initial knee stiffness, which webelieve helps the MCL heal with little residual laxity. Inthose few knees in which there is laxity to valgus stress­ing at 0° despite an intact PCL, the posteromedial struc­tures, including the posterior oblique ligament, may beinjured. Rehabilitation for these knees should still focuson early motion, although full extension is not advisableduring the first several weeks. As with the lesser-degreeMCL tears, the CryoCuff and immobilizer can providesatisfactory support until quadriceps control and strengthreturns sufficient to allow a normal gait pattern.

Even when an ACL reconstruction is anticipated, thecombined ACLIMCL tears are approached as nonemer­gencies irrespective of the degree of MCL laxity. BecauseMCL healing can be predictably obtained nonoperatively,our decisions in regard to the ACL tear tend to reflectthose principles of treating an isolated ACL tear. If sur­gery is done immediately, the incidence of arthrofibrosismay be unacceptably high.8, 11,12 In addition, some ofthese combined injuries heal with sufficient scar, becomequite stable, and may not require subsequent surgical re­construction of the ACL. In our experience the majorityof young athletic patients as well as high-demand pa­tients, regardless of age, ultimately have surgical recon­struction of the ACL. This treatment is also based on thepatient's desires and sport-specific risks, but it is doneonly after the knee has been fully rehabilitated. The re­construction can then be scheduled at a convenient time.

Those patients who elect nonoperative treatment arecounseled regarding activity modification, which may re­quire a change in their sport and/or level of participation.A custom ACL brace can be fitted for use during higherrisk activities. The final rehabilitation phase emphasizesfunctional progression, which is an ordered sequence ofactivities that enables the athlete to re-acquire the skillsnecessary for safe and effective return to athletic endeav­ors.

Patients at high risk for subsequent instability whoelect surgery are treated with subacute arthroscopy andautogenous bone-patellar-tendon-bone ACL reconstruc­tion. We routinely wait a minimum of 3 to 4 weeks afterinjury to allow sufficient time for MCL healing. In recentyears the average time from injury until ACL reconstruc­tion has been between 7 and 8 weeks. During this timerehabilitation is emphasized as previously described. Inour experience these patients have a tendency to becomestiff initially and therefore we delay ACL reconstructionuntil full knee motion is restored, which may take severalmonths in a grade III MCL/ACL injury. By using thisphilosophy we have had a significantly lower incidenceof postoperative eoblems in regaining full range of mo­tion of the knee. ,8,11 All patients participate in our re­habilitation program' postoperatively.

Shelbourne and Baele" examined 27 patients with com­bined ACLIMCL grade III injuries. Thirteen patients un­derwent ACL reconstruction using autogenous patellartendon graft and MCL repair, and 14 underwent ACLreconstruction alone. They found that knees in whichthe MCL was repaired developed more stiffness and dif­ficulty in regaining range of motion than those in whichonly ACL reconstruction was performed. None of the

RUBINSTEIN AND SHELBOURNE

patients in either group had any functional or objectiveMCL laxity at follow-up. It was concluded that: (1) repairof the MCL is not necessary in ACLIMCL injuries, (2)reconstruction of the ACL with autogenous patellar ten­don graft is sufficient to restore stability in this setting, (3)limited surgery may facilitate early functional rehabilita­tion; and (4) acute"surgical repair of the MCL combinedwith ACL reconstruction results in a higher incidence ofpostoperative motion problems. Ballmer et alB also havereported good results when treating combined ACLIMCLtears with ACL reconstruction alone.

We recommend ACL reconstruction for those patientsat high risk for recurrent instability and subsequent in­jury. Alternatively, for those patients at lower risk werecommend activity modification and/or a knee brace ini­tially and ACL reconstruction later only if necessary. Allpatients participate in the rehabilitation program beforeand after surgery for an optimal period depending on theextent of the structures injured.

ACULATERAL STRUCTURE INJURIES

Combined ACLIlateral .side injuries are much less com­mon than ACLIMCL injuries. This injury is differentthan the anterolateral rotatory instability commonly seenin cases of ACL insufficiency. In addition to an ACL tear,the lateral side injuries usually include partial or completedisruption of the lateral capsule, iliotibial band, fibularcollateral ligament, arcuate ligament, and, less often, thebiceps femoris, popliteus, and/or lateral head of the gas­trocnemius. The key to the clinical diagnosis of an ACLIlateral side injury is increased varus laxity, comparedwith the normal knee, at 30° of flexion and minimal orphysiological varus laxity in extension. The clinical find­ings for anterior laxity are also present, and those of pos­terior laxity are absent. When testing the knee at 30°,grade I laxity (compared with the noninjured knee) willdemonstrate mild opening on varus stressing with a goodend point. The grade II laxity typically has a J-cm differ­ence in opening compared with the opposite side, butsome end point is present. The grade III laxity has evengreater laxity with no firm end point. It is essential todetermine the integrity of the PCL because medial kneedislocations are more common (disruption of the lateralstructures, ACL, and PCL) than ACL/lateral side injuriesalone. The physical examination can be diagnostic in themajority of cases; but an MRI scan may be helpful inconfirming the clinical diagnosis.

Avulsion fractures of the lateral tibial plateau havebeen described by Woods et al I4 as the "lateral capsularsign," indicating presence of significant anterolateral in­stability. They described this fracture (Segond fracture)as an avulsion of the meniscotibial portion of the middlethird of the lateral capsular ligament, which is seen inconjunction with injury t~ .the ACL. In ~ur experien:e,unless a patient has a significant preoperative varus laxity(grade II or Ill) irrespective of whether a Segond fractureis present, we perform a primary intra-articular autoge­nous patellar tendon ACL reconstruction alone. This ap­proach has been highly successful and has eliminated theneed for extra-articular procedures, both acutely and

MANAGEMENT OF COMBINED LIGAMENT INSTABILITY

chronically. This type of injury, which is common, mustbe differentiated from the less common combined ACUlateral side injury in which the lateral structures are dis­rupted in addition to the lateral capsule.

Routine initial evaluation includes standard radio­graphs, with care to look for the Segond fracture (fractureof the lateral plateau) or any other bone lesion that maybe present, in addition to physical examination of boththe injured and noninjured knees. Delee et a11S, 16 re­ported proximal fibula fractures in 5 of 12 patients withacute isolated posterolateral instability and in 5 of 10 pa­tients with acute straight lateral instability. The neuro­vascular status of the leg must also be carefully assessed .Suspicion of a spontaneously reduced knee dislocationshould alert the physician to the possibility of a vascularinjury, although in this scenario the PCl is usually torn.Peroneal nerve dysfunction was reported in 24% of pa­tients with lateral ligament injuries of the knee. I S-17 In astudy at our clinic, 6 of 10 patients with ACl/lateral sideinjuries had initial peroneal nerve dysfunction; 3 hadtransient hypesthesia or paraesthesia, and 3 had motorand sensory deficits.

An MRI scan is now routinely performed for the pur­pose of defining the injury and determining its location.The MRI scan is helpful in preoperative planning, partic­ularly when there is doubt about the integrity of the cru­ciate ligaments. Fischer et al l B reported an accuracy levelof 93% for ACl injuries and 99% for PCL injuries. MRIalso has been accurate in determining the status of themenisci, lateral collateral ligament, biceps femoris in­sertion, popliteus tendon, and other lateral structures(Fig 3).

In acute injuries to the lateral side as well as disruptionof the ACL, we recommend acute repair of the lateralstructures in addition to performing an autogenous pa­tellar tendon ACl reconstruction. Unlike the medial sidein which we allow even more time for rehabilitation andhealing before surgery, we do not have the luxury on thelateral side. lateral side tears may retract proximally,making delayed primary repair more difficult. Lateralside injuries also do not cause the stiffness that is seenwith medial side injuries. Therefore, surgery can be per­formed 7 to 10 days after injury despite the inflammatory

Fig 3. The lateral collateral ligament and biceps femoris ten­don are avulsed from their Insertions on the proxImal fibula.

69

stage only being partially resolved. In contrast to thecompressive forces on the medial side, the lateral side ofthe knee is under distraction forces, and this probablycontributes to the residual lateral laxity when these in­jured structures are not repaired. When chronic laterallaxity exists, it is far more disabling for the patient than asimilar degree of laxity on the medial side. Results afteracute lateral side repair are better than those after latereconstruction.l?

At surgery the lateral structures are repaired, and theACL is reconstructed with an autogenous bone-patellartendon-bone graft (Fig 4). A lateral incision is used forthe lateral side repair. We routinely explore and decom­press the peroneal nerve at the time of the surgical expo­sure. Even in those cases in which the peroneal nerve isnot functioning before surgery, we have always foundthe nerve in continuity, although it may appear edema­tous and hemorraghic. The injured lateral structures areusually avulsed from their distal insertions, which facili­tates direct repair. The iliotibial band and lateral capsule,including the arcuate ligament, are most often torn from

. the tibia, and the lateral collateral ligament and bicepstendon are commonly avulsed from the proximal fibula.The popliteus.tendon, if torn, usually occurs at its femo­ral attachment. These tears can also occur either in themidsubstance or in the proximal portion of the involvedstructure, although these are less common than the distalavulsions. Any combination of these structures can betorn for any given patient. Anatomic repair of the in­jured lateral structures is the goal. When avulsed fromthe bone, these structures may be reattached with eithera screw and soft tissue washer and/or suture through drillholes . After the lateral side is exposed and repaired, anopen ACL reconstruction is performed. The arthroscopicACL technique may be contraindicated because of thecapsular disruption.

Fig 4. Anteroposterior radiographic appearance of a kneeafter acute lateral side repair and autogenous patellar tendonACL reconstruction.

70

After reconstruction and repair, the knee is initially po­sitioned in extension by using a removable knee immo­bilizer. Rehabilitation follows our standard program, 19

although passive hyperextension of the knee is limitedduring the first month. Weight bearing as tolerated isallowed in the extension splint and/or custom brace.

Ten patients have been surgically treated at our clinicfor acute ACL tears combined with grade III lateral sideinjuries. All patients were treated in a similar fashion, aswe have described. Three of these patients have follow­up that is less than 1 year and are not included in ouranalysis. The other 7 patients, having long-term follow­up averaging 30 months, have had satisfactory results.Each patient has clinically demonstrated normal or nearnormal anterior stability. Maximum manual KT-1000 ar­thrometer (Medmetric, San Diego, CA) testing showedan average side-to-side difference of 3.8 mm. No patienthad varus laxity in extension. Six of 7 patients had novarus laxity at 30°, and the other had grade I laxity. Allpatients, including 2 in college football and- 1 in minorleague baseball, returned to their preinjury sports.

We recommend surgical repair of the lateral structuresof the knee and an autogenous bone-patellar tendon­bone ACL reconstruction within 7 to 10 days after injury(after the acute inflammatory stage). Postoperatively, thepatients follow our accelerated rehabilitation, althoughhyperextension is avoided during the first month.

COMMENT

Our approach to ACL tears combined with injuries to themedial or lateral capsuloligamentous complexes oftheknee is based on functional anatomy, clinical data, and adecade of experience. In an acute injury to both the me­dial capsular structures and ACL, the initial treatmentprogram is nonoperative, with emphasis on protected re­habilitation and early range of motion. A subacute ratherthan acute autogenous patellar tendon ACL reconstruc­tion can be performed in the high-risk patient (youngage, sport-specific risks, and/or high demands), with theresults being predictable stability and a significantly de­creased incidence of postoperative complications. In thecombined ACL and lateral side injury with significantvarus laxity, acute surgical repair of the lateral structuresand patellar tendon ACL reconstruction is indicated.Surgical intervention combined with our rehabilitationprogram predictably results in stable and functionalknees.

REFERENCES

1. Shelbourne KD, Nitz P: The O'Donoghue triad revisited: Combinedknee injuries involving anterior cruciate and medial collateralliga­ment tears. Am J Sport s Med 19:474-477, 1991

2. Ellsasser [C, Reynolds FC, Omohundro JR:The non-operative treat­ment of collateral ligament injuries of the knee in professional foot­ball players. J Bone Joint Surg [Am]1l8S-1190, 1974

3. Hastings DE: The non-operative management of collateral ligamentinjuries of the knee joint. Clin Orthop 147:22-28, 1980

4. Indelicato PA: Non-operative treatment of complete tears of the

RUBINSTEIN AND SHELBOURNE

medial collateral ligament of the knee. J Bone Joint Surg [Am] 65:323-329, 1983

5. Woo SL, Young EP, Ohland KJ, et al: The effects of transection ofthe anterior cruciate ligament on healing of the medial collateralligament. J Bone Joint Surg [Am] 72:382-392, 1990

6. Lechner CT, Dahners LE: Healing of the medial collateral ligamentin unstable rat knees. Am J Sports Med 19:508-512, 1991

7. Shelboume KD, Porter DA: Anterior cruciate ligament-medial col­lateral ligament injury: Nonoperative management of medial collat­eral ligament tears with anterior cruciate ligament reconstruction: Apreliminary report. Am J Sports Med 20:283-286, 1992

8. Shelbourne KD, Baele JR: Treatment of combined anterior cruciateligament and medial collateral ligament injuries. Am J Knee Surg1:56-58, 1988

9. Mok DW, Good C: Non-operative management of acute grade IIImedial collateral ligament injury of the knee: A prospective study.Injury 20:277-280, 1989

10. Sandberg R, Balkfors B, Nilsson B, et al: Operative versus non­operative treatment of recent injuries to the ligaments of the knee.J Bone Joint Surg [Am] 69:1120-1126, 1987

11. Shelbourne KD, Wilckens JH, Mollabashy A, et al: Arthrofibrosis inacute anterior cruciate ligament reconstruction: The effect of timing

MANAGEMENT OF COMBINED LIGAMENT INSTABILITY

of reconstruction and rehabilitation. Am J Sports Med 19:332-335,1991

12. Mohtadi NG, Webster-Bogaert S, Fowler PJ: Limitation of motionfollowing anterior cruciate ligament reconstruction: A case-controlstudy. Am J Sports Med 19:620-625, 1991

13. Ballmer PM, Ballmer FT, Jakob RP: Reconstruction of the anteriorcruciate ligament alone in the treatment of a combined instabilitywith complete rupture of the medial collateral ligament: A prospec­tive study. Arch Orthop Trauma Surg 110:139-141, 1991

14. Woods GW, Stanley RF, Tullos HS: Lateral capsular sign: x-ray clueto a significant knee instability. Am J Sports Med 7:27-33, 1979

15. DeLee JC, Riley MB, Rockwood CA: Acute posterolateral rotatoryinstability of the knee. Am J Sports Med 11:199-207, 1983

16. DeLeeJC, Riley MB, Rockwood CA: Acute straight lateral instabilityof the knee. Am J Sports Med 11:404-411, 1983

17. Grana WA, Janssen T: Lateral ligament injury of the knee. Ortho­pedics 10:1039-1044, 1987

18. Fischer SP, Fox JM, Pizzo WD, et al: Accuracy of diagnoses frommagnetic resonance imaging of the knee. J Bone Joint Surg [Am]73:2-10, 1991

19: Shelbourne KD, Nitz P: Accelerated rehabilitation after anterior cru­ciate ligament reconstruction. Am J Sports Med 18:292-299, 1990

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