diagnosis and treatment of posterolateral knee injuries€¦ · posterolateral knee injuries can be...

110

CLINICAL ORTHOPAEDICS AND RELATED RESEARCHNumber 402, pp. 110–121© 2002 Lippincott Williams & Wilkins, Inc.

Posterolateral knee injuries can be very debili-tating. It is important to understand the com-plex anatomy and pertinent diagnostic tests toproperly treat posterolateral knee injuries. Thefibular collateral ligament, popliteus tendon,and the popliteofibular ligament are the mainstatic stabilizers against abnormal varus andposterolateral translational moments. Impor-tant radiographic imaging studies for the pos-terolateral knee include full length anteroposte-rior radiographs, taken with the patient standing,to assess for varus alignment in patients withchronic injuries and high field (1.5 tesla or higher)magnetic resonance imaging with specific pos-terolateral knee sectioning. A physical examina-tion that includes the external rotation recurva-tion test, varus stress test at 30!, dial test at 30!and 90!, posterolateral drawer test, reversepivot shift, and an assessment for a varus thrustgait are essential to properly diagnose a pos-terolateral knee injury. Patients with acute (< 3weeks) anatomic repairs of Grade III postero-lateral knee injuries have the best functionaloutcome. Although various surgical reconstruc-tion techniques have been developed to treatchronic or irreparable acute posterolateral kneeinjuries, these techniques have not achieved out-comes comparable with the treatment of other

ligament injuries of the knee. Techniques foranatomic reconstructions of these structures arejust being developed. Improved education ofclinicians as to the proper diagnosis of postero-lateral knee injuries is necessary because a largenumber of these injuries still are missed on ini-tial examinations. In addition, additional re-search into the most optimal posterolateral kneereconstruction techniques and outcome studiesare needed to improve the treatment of this de-bilitating knee injury.

Injuries to the posterolateral corner of the kneeincreasingly have been recognized as a sourceof disability in patients. During the past sev-eral years, a concerted effort has been made todefine more precisely the specific anatomicstructures that comprise the posterolateralknee.13,14,20,25–28 Through that work, morespecific means to diagnose these injuries clin-ically, radiographically, and arthroscopicallyhave been found.11,13,17

Posterolateral knee injuries have been foundto be one of the most debilitating ligament in-juries of the knee. Because of the convex op-posing surfaces of the lateral femoral condyleand lateral tibial plateau, patients with postero-lateral knee injuries may have instability evenwith normal gait. This is because the lack of thestatic posterolateral corner structures at footstrike, combined with the convex surfaces ofthe opposing lateral femoral condyle and lateraltibial plateau, results in lateral compartment

Diagnosis and Treatment of Posterolateral Knee Injuries

Robert F. LaPrade, MD*; and Fred Wentorf, MS**

From the *Department of Orthopedic Surgery and the**Biomechanics Laboratory, University of Minnesota,Minneapolis, MN.Reprint requests to Robert F. LaPrade, MD, Departmentof Orthopedic Surgery, 420 Delaware Street SE, MMC#492, Minneapolis, MN 55455.DOI: 10.1097/01.blo.0000026222.49620.4d

opening. This varus-thrust gait pattern can bevery disabling. In addition, if this injury is notrecognized when there is a concurrent anteriorcruciate ligament or posterior cruciate liga-ment tear, failure to repair or reconstruct theposterolateral corner structures at the time ofcruciate ligament reconstruction places thecruciate ligament grafts at significant risk forfailure.7,16,18,19,23

Applied Anatomy of the PosterolateralCorner of the KneeIt is important to understand the anatomy ofthe main static stabilizers of the posterolateralaspect of the knee to understand their biome-chanical function, to observe them on mag-netic resonance imaging (MRI) scans, or to re-pair or reconstruct these structures at the timeof surgery. An overview of the main static sta-bilizers of the posterolateral aspect of the kneefollows.

The fibular collateral ligament is the pri-mary static stabilizer to varus opening of theknee.4,5 It is thought to be most important inpreventing varus instability of the knee in theinitial 0! to 30! arc of knee flexion and hasbeen observed to become slightly lax with ad-ditional degrees of knee flexion in the statictesting condition.4,5 However, these static testsdiscount the dynamic effect of the aponeuroticlayers of the long and short heads of the bicepsfemoris on providing tension on the fibularcollateral ligament dynamically.

The main attachment site of the fibular col-lateral ligament on the femur is at a pointslightly proximal and posterior to the lateralepicondyle.28 Its overall length is approxi-mately 70 mm.14 Its main attachment site dis-tally is to the lateral aspect of the fibular head.At its more distal attachment site, the fibularcollateral ligament’s attachment on the fibularhead is identified easily by making a horizon-tal incision through the anterior arm of thelong head of the biceps femoris and enteringthe fibular collateral ligament-biceps bursa.14

This has been found to be a common site ofdistal avulsion or midsubstance injuries to thisligament.13,17

The popliteus muscle and tendon complexon the posterolateral aspect of the knee hasmany components that provide a static and dy-namic stabilizing effect to posterolateral rota-tion of the knee.6,25,28 The popliteus tendon’smain attachment is at the proximal fifth of thepopliteus sulcus of the femur. From this point,the popliteus tendon courses distally and pos-teriorly, where it gives off three fascicles tothe lateral meniscus (anteroinferior, postero-superior, and posteroinferior fascicles).25,28

These fascicles have been shown to have im-portance in providing stability to motion of thelateral meniscus.12 After this point, the popli-teus tendon continues more distally to themusculotendinous junction. At the musculo-tendinous junction, there are two divisions ofthe popliteofibular ligament that course later-ally and distally from the musculotendinousjunction to attach on the posteromedial aspectof the fibular styloid.25,28 The popliteofibularligament complex has been found to be an im-portant stabilizer of external rotation of theknee.20 In addition to the structures previouslymentioned, the popliteus muscle also has anaponeurotic layer that courses from the popli-teus muscle belly up to the posterior horn ofthe lateral meniscus.28

The midthird lateral capsular ligament is athickening of the lateral capsule of the knee.28

It is thought to be semiequivalent to the deepmedial collateral ligament complex of the me-dial aspect of the knee.12 This thickening of thelateral capsule extends from the capsular at-tachments from just anterior to the popliteustendon attachment on the femur to the lateralgastrocnemius attachment. It then extends dis-tally to its tibial attachment from slightly poste-rior to Gerdy’s tubercle to the popliteal hiatus.

The midthird lateral capsular ligament canbe divided into two components. The menis-cofemoral component extends from the femurdown to the meniscus. The meniscotibial com-ponent extends from the meniscus to the tibia.The meniscotibial component is found to beinjured more frequently, most commonly withan avulsion off the tibia with or without a bonyfragment (Segond fracture).13,15 The midthird

Number 402September, 2002 Posterolateral Knee Injuries 111

lateral capsular ligament is thought to be animportant secondary stabilizer to varus insta-bility of the knee.12

The long head of the biceps femoris has fivecomponents at the knee27,28 (Fig 1). The mostimportant of these are the direct arm attach-ment to the posterolateral aspect of the fibularstyloid, the anterior arm that courses lateral tothe fibular collateral ligament, and the lateralaponeurotic attachment to the posterolateralaspect of the fibular collateral ligament.

The short head of the biceps femoris also hasfive major attachments at the knee.27,28 The firstmajor component of these is the capsular arm ofthe short head of the biceps femoris. The cap-sular arm extends from the main tendon of theshort head of the biceps to the posterolateral as-pect of the capsule and attaches just lateral tothe tip of the fibular styloid. It provides a stoutattachment to the posterolateral capsule, lateralgastrocnemius tendon, and the capsuloosseouslayer of the iliotibial band. The more distal edgeof the capsular arm is the fabellofibular liga-ment.13,15,17,28 The fabellofibular ligament isfound to be tight in extension and difficult toidentify with increasing degrees of knee flexionas it becomes lax. Other important structures ofthe short head of the biceps femoris at the knee

are a direct arm attachment to the posterolateralaspect of the fibular styloid and an anterior armattachment that passes medial to the fibular col-lateral ligament and attaches with the menisco-tibial portion of the midthird lateral capsularligament on the tibia. The anterior arm of theshort head of the biceps femoris frequently isfound to be avulsed with a Segond fracture or asoft tissue Segond injury. This injury patternfrequently is recognized on coronal MRI scansthrough this area.13

The iliotibial band26,28 also is important inpreventing increasing varus opening of theknee.9 The superficial layer is a layer first en-countered after dissecting through the subcu-taneous tissues on the lateral aspect of the knee(Fig 1). It attaches to Gerdy’s tubercle and ex-tends proximally. In addition, a deep layer at-taches this to the region of the lateral inter-muscular septum. The capsuloosseous layeralso extends from the region of the lateral in-termuscular septum, blends with a confluencefrom the short head of the biceps femoris, andattaches to the anterolateral aspect of the tibiajust posterior to Gerdy’s tubercle. In this re-gard, it acts as an anterolateral sling to the knee.Because the superficial layer of the iliotibialband is infrequently injured with a posterolat-eral knee injury, it serves as an important ref-erence for many of these other structures, andmany of the surgical incisions for posterolat-eral corner repairs or reconstructions are basedthrough it.11,28

Diagnosis of Posterolateral Knee InjuriesA history and physical examination that isdone properly, with the knowledge of the pa-tient’s history and how to do examinationsspecific to the posterolateral knee, will allowthe clinician to arrive at a diagnosis of pos-terolateral knee injuries in the majority ofcases. In those instances where it is difficult todetermine whether there is a posterolateralknee injury, such as in cruciate ligament orother ligament injury, the use of radiographs,MRI scans, or both may be a useful adjunct inthe assessment of the location and severity ofposterolateral knee injuries.

Clinical Orthopaedics112 LaPrade and Wentorf and Related Research

Fig 1. A lateral view of a right knee shows the su-perficial layer of the iliotibial band, the tendinousportion of the long head of the biceps femoris,and the muscular portion of the short head of thebiceps femoris. The fibular collateral ligament’soutline is seen deep to the lateral aponeuroticlayers of the biceps.

The majority of posterolateral knee injuriesare caused by a blow to the anteromedial as-pect of the knee, a contact or noncontact hy-perextension injury, or a varus noncontact in-jury.17 The majority of posterolateral kneeinjuries have been found to occur in combina-tion with other ligamentous injuries. The mostcommon combined injuries are anterior cruci-ate ligament and posterolateral corner andposterior cruciate ligament and posterolateralcorner.17 In this regard, it is important that theclinician not overlook a potential posterolat-eral corner injury in a patient with a cruciateligament injury. In addition, 15% of patientswith posterolateral knee injuries have beenfound to have a common peroneal nerve in-jury.17 It is important to ask these patients atthe time of their examination whether they hada history of any tingling or numbness in theirlower extremity or any associated muscleweakness, especially for ankle dorsiflexionand great toe extension.

One of the first tests that is done as part ofthe posterolateral knee examination is the ex-ternal rotation recurvatum test.8,12,16 In doingthis test, the clinician lifts up the great toewhile stabilizing the patient’s thigh as neces-sary, to determine whether there is any in-crease in recurvatum (hyperextension) of theeffected knee. If there is, there is also com-monly a component of relative varus align-ment to the knee. A positive external rotationrecurvatum test usually is indicative of a se-vere knee ligament injury. It has been found tobe positive most commonly with a posteriorcruciate ligament or bicruciate ligament in-jury. Measurement of the external rotation re-curvatum test usually is expressed in negativedegrees of knee motion or in increased heelheight difference compared with the contralat-eral side.

The varus stress test at 0! and 30! knee flex-ion can be done next.12,17 This test is done bystabilizing the thigh against the examining bedand applying a varus force across the knee bymeans of grasping the foot or ankle. The cur-rent authors do not recommend that this test bedone solely by grabbing the distal leg because

it does not allow for any rotation to occur atthe joint, which may underestimate the amountof abnormal motion caused by injury.

A positive varus stress test at 0! knee flex-ion usually is indicative of a severe postero-lateral knee injury. In addition, there is likelya component of a cruciate ligament injury be-cause of the stabilizing effect of the anteriorcruciate ligament and posterior cruciate liga-ment to varus stress in this position. When thistest is positive, the posterolateral knee struc-tures that are injured most commonly are thefibular collateral ligament, the meniscotibialportion of the midthird lateral capsular liga-ment, the popliteus tendon, and possibly thesuperficial layer of the iliotibial band.17

The varus stress test at 30! knee flexion isdone next. This is done over the side of the ex-amining table, while the distal thigh is stabi-lized. While doing this test, the examinershould place his or her fingers directly over thejoint line to have an estimation of the amountof joint line opening in millimeters. Concur-rent with this test, the contralateral healthyknee also needs to be examined. This is be-cause some patients have a physiologic in-crease in varus joint line opening, especially inpatients with an underlying amount of genu re-curvatum.3,17 The current authors classify thegrade of joint line opening according to theguidelines of the American Medical Associa-tion.1 Grade 1 injuries have 0 to 5 mm of open-ing, Grade 2 injuries have 5 to 10 mm of open-ing, and Grade 3 injuries have greater than 1cm of joint line opening compared with thecontralateral side. Smaller grades of joint lineopening are indicative of a partial posterolat-eral corner injury, usually with a partial tear ofthe fibular collateral ligament or an isolatedtear of the meniscotibial portion of the midthirdlateral capsular ligament. Higher amounts ofvarus opening at 30! knee flexion usually areindicative of a complete tear of the fibular col-lateral ligament and injuries to other varus-stabilizing structures on the posterolateral as-pect of the knee.17

The dial test, or posterolateral rotation test,is done at 30! and 90! knee flexion. It has been


found in the laboratory to provide a good as-sessment of the amount of posterolateral kneeinjury.4,5,29 However, it is slightly more diffi-cult to assess in the clinical situation. This testcan be done with the patient either prone orsupine. The current authors prefer to do the testwith the patient supine, with the knee flexedover the side of the examining bed12,15 (Fig 2).The thigh is stabilized and one foot is used toapply a rotation force through the foot and an-kle. The examiner then looks for the amount ofexternal rotation of the tibial tubercle, andcompare it with the contralateral healthy knee.

An increase of 10! to 15! external rotationat 30! knee flexion, compared with the con-tralateral side, indicates a concurrent postero-lateral knee injury.2,4,5 Once the test has beendone at 30! knee flexion, it is repeated at 90!.Normally, in an isolated posterolateral kneeinjury, there will be a decrease in external ro-tation at 90! compared with 30!.5 If there is anincrease of external rotation in the dial test at30! knee flexion, it is indicative of a combined

posterior cruciate ligament and posterolateralcorner knee injury.5

The posterolateral drawer test first was de-scribed by Hughston and Norwood in 1980.8This test assesses the amount of posterolateralrotation of the knee at 90! knee flexion. An in-crease of posterolateral rotation in this test,compared with the contralateral knee, usuallyis indicative of a popliteus complex injury. Itis important to differentiate this test from theposterior drawer test in neutral rotation (whichtests the integrity of the posterior cruciate lig-ament). In the posterolateral drawer test, theknee is flexed to approximately 90!, similar tothe starting position for a posterior drawer test,but the foot is rotated externally to 15!. Thecurrent authors prefer to sit on the foot to en-sure that the foot is stabilized.12,17 A gentleposterolateral rotation force then is applied toassess the amount of posterolateral rotation inthe knee. It is important to compare increasedamounts of posterolateral rotation with thehealthy contralateral knee because there issome normal laxity seen in patients with phys-iologic genu recurvatum.3

The reverse pivot shift first was describedby Jakob et al in 1981.9 In this test, which isalmost like the reverse of the normal pivotshift test of the knee, the knee is flexed to 45!to 60!, the foot is rotated externally, and a val-gus stress is applied to the knee. The knee thenis extended slowly. If the knee is subluxed (ordislocated) in flexion, it will be reduced by theiliotibial band as it changes function from aflexor to an extender of the knee at approxi-mately 25! to 30! knee flexion. Basically, thistest is a dynamic posterolateral drawer test. Itis important to compare a positive reversepivot shift test with the contralateral knee, be-cause this test has been found to have the largestvariability among all knee motion tests.3 In1991, Cooper3 found it to be present in 35% ofhealthy knees examined with the patients un-der anesthesia.

In addition to the aforementioned clinicaltests, it also is important to assess the patient’sgait pattern, especially in a patient with a poten-tial chronic posterolateral corner injury. Some


Fig 2. A photograph shows the dial test at 30! ina left knee. The examiner looks for an increasedamount of external rotation of the tibial tubercle,compared with the contralateral healthy knee.

of these patients will have evidence of a varusthrust gait pattern, in which the lateral com-partment of the knee opens up at foot strikeand the joint is subluxed in varus and is read-ily visible by observing the patient from eitheranterior or posterior. Many of these patientshave an underlying genu varus alignment. Insome patients with a propensity toward this typeof gait pattern, with time, they have learned toadapt with a flexed knee gait such that they donot thrust at foot strike. It also is important torecognize that not all patients who have avarus thrust gait have a posterolateral knee in-jury. Some patients who have this gait patternhave a component of medial compartment ar-thritis whereby they collapse on the medialcompartment rather than truly open up the lat-eral compartment at foot strike. Plain radi-ographs of the knee and a clinical assessmentwill help to differentiate the difference be-tween these two conditions.

Plain radiographs can be useful in the as-sessment of posterolateral knee injuries. A plainanteroposterior (AP) view will help to differ-entiate medial compartment arthritis from anormal medial compartment in patients whomay have a varus thrust gait pattern. An AP ra-diograph with the knee in varus thrust also canbe useful to assess the amount of lateral com-partment joint line opening.12 In addition, theAP view of the knee can be very helpful to ob-serve Segond and arcuate avulsion fractures ofthe lateral capsule and fibular head, respec-tively.13,17,24 In addition, it is important to ob-tain AP long leg (from hip to ankle) radiographstaken with the patient standing in patients whohave chronic injuries to determine whether theyhave an underlying varus alignment of the in-jured extremity.

The use of high quality MRI scans has beenfound to be very useful in the assessment of in-juries to individual structures of the postero-lateral aspect of the knee.13 In addition to thestandard coronal, sagittal, and axial cuts, it hasbeen found that the addition of thin-sliced (2mm) proton density coronal oblique images,which include the entire fibular head and sty-loid, are very useful to obtain images of the

fibular collateral ligament and popliteus ten-don13 (Fig 3). The current authors have foundit to be very difficult to evaluate injuries to theposterolateral structures of the knee on lowsignal magnets. It is recommended that theseMRI scans be obtained on 1.5 T magnets (orhigher). Using these techniques, it was foundthat an MRI scan is very useful to assess in-juries to the iliotibial band (superficial anddeep layers), long head of the biceps femoris(direct and anterior arms), short head of the bi-ceps femoris (direct arm and anterior arm),fibular collateral ligament, popliteus complex(femoral attachment, popliteomeniscal fasci-cles, and popliteofibular ligament), and the fa-bellofibular ligament.13

In addition to the history and physical ex-amination and radiographic imaging tech-niques, arthroscopic evaluation of the lateralcompartment of the knee also has been foundto be very useful in the assessment of postero-lateral knee injuries.11 This can be useful inpatients in whom it is still difficult to deter-mine whether there is an underlying compo-nent of posterolateral knee injury. In a prospec-tive series of 30 patients who had Grade 3posterolateral knee injuries, all patients had adrive-through sign present, whereby there wasgreater than 1 cm of lateral joint line openingto a varus stress applied to the joint at the time


Fig 3. A coronal MRI scan of a left knee showsan arcuate fracture of the fibular head and styloid(arrow).

of arthroscopic evaluation11 (Fig 4). The use ofarthroscopy was found to be helpful in the sur-gical planning of incisions and the identifica-tion of injuries to individual structures of theposterolateral aspect of the knee. It was foundto be especially helpful in determining injuriesto the coronary ligament of the posterior hornof the lateral meniscus, avulsions of the popli-teus tendon off the femur, tears of the popli-teomeniscal fascicles, and in helping to assesswhether the major component of the postero-lateral knee injury was meniscofemoral ormeniscotibial based. Injuries to individualstructures of the posterolateral knee that arefound to be readily identified include the popli-teus tendon attachment on the femur, the popli-teomeniscal fascicles, the meniscofemoral andmeniscotibial portions of the midthird lateralcapsular ligament, and the coronary ligamentto the posterior aspect of the lateral meniscus.

Treatment of Injuries to the Posterolateral Corner of the KneeTreatment of Isolated Posterolateral Knee InjuriesThe recommended treatment for patients withGrade 1 to 2 posterolateral knee complex in-juries (partial injuries) initially is nonopera-tive. The current authors generally tend totreat patients who have these injuries with aknee immobilizer in full extension for 3 to 4

weeks with no knee motion allowed. The pa-tients may do quadriceps sets and straight legraises in their immobilizer only. They also arenonweightbearing at this time. At the end ofthis period of immobilization, the patients areallowed to work on range of motion (ROM) oftheir knee and may initiate weightbearing atthat point. They are allowed to increase theirweightbearing as tolerated and may ambulateoff crutches when they can walk without alimp. Closed chained quadriceps exercises,with the avoidance of active hamstring exer-cises for the first 6 to 10 weeks after injury, areallowed.

Patients who complain of pain or instabilityafter this period of nonoperative treatmentneed to be reevaluated carefully to determinewhether they have any instability present intheir knee or whether they have any gait ab-normalities. The specific tests used to deter-mine abnormal knee motion for patients withposterolateral knee injuries should be re-peated. In addition, a small percentage of thesepatients may have lateral knee pain with ac-tivities. In most instances, their MRI scanshave been found to be normal. If the pain is ac-centuated by the examiner placing the knee ina figure-four position (the figure-of-four test),these patients may have a tear of their popli-teomeniscal fascicles. Tearing of these fasci-cles results in increased lateral meniscal hy-permobility and the meniscus is entrapped inthe joint when the knee is put in the figure-fourposition. It is important to determine whetherthese patients have a reproduction of theirsymptoms with this maneuver. If they do,these patients have been found to benefit fromrepair of the lateral meniscus back to the popli-teomeniscal fascicles of the popliteal hiatus.

In general, patients who have Grade 3 in-juries to the posterolateral corner of the kneehave been found to do poorly with nonopera-tive treatment.10 It has been shown that the re-sults of acute repairs are much better than theresults of chronic repairs of posterolateralknee injuries.15 In addition, it has been foundthat after approximately 3 weeks after injury,there is a significant development of scar tis-


Fig 4. An arthroscopic drive-through sign of thelateral compartment of a right knee with a pos-terolateral knee injury is shown.

sue planes along the posterolateral knee. Iden-tification of the common peroneal nerve iscomplicated greatly by these scar tissue planes.For this reason, the current authors recom-mend that an attempted anatomic repair of in-dividual structures of the posterolateral kneeshould be done within the first 1 to 2 weeks af-ter injury.12,15

Repair of the injured posterolateral kneestructures usually are treated with direct suturerepair back to bone, suture anchors, a recessprocedure, or supplemental fixation with localtissues (a portion of the iliotibial band or bi-ceps femoris tendon). The current authors rec-ommend that an avulsion of the popliteus ten-don or the fibular collateral ligament off oftheir femoral attachment be repaired with a re-cess procedure. In the recess procedure, asmall bone tunnel is drilled at the normal at-tachment site of the avulsed structure. Suturesthen are placed in a whip stitch type patterninto the avulsed structure and then are passedover to the medial aspect of the knee with theuse of a stylette pin. The sutures then arepulled medially and the avulsed structure thenis pulled up into the bony tunnel. The suturesthen are tied over a button on the anteromedialaspect of the femur. The recess procedure re-sults in a secure repair that allows for earlyROM.12,15

Tears of the meniscotibial portion of themidthird lateral capsular ligament usually areable to be repaired back directly to the tibiawith sutures put directly through bone. Thebone in this area of the anterolateral tibia usu-ally is soft enough to be able to place a largeneedle through the bone and to obtain a securefixation of a soft tissue Segond or a bonySegond avulsion injury of this area.13,15 Directsuture repair back to bone also allows for earlyROM without the fear of slippage of the tis-sues in the early postoperative period.

Avulsions of the direct arms of the bicepsfemoris, the fibular collateral ligament, or thepopliteofibular ligament off the fibular headand styloid can be repaired directly back tobone with the use of suture anchors or directsuture repair through drill holes. The authors

most commonly use suture anchors to achievea more secure fixation. Avulsion fractures ofthe fibular head and the styloid (arcuate frac-tures)24 usually include the popliteofibular lig-ament, direct arms of the long and short headsof the biceps femoris, and the fibular collateralligament.13 The avulsion fractures usually arerepaired back to an anatomic position with acerclage nonabsorbable suture or wire. Occa-sionally, large fractures may be able to befixed by an open reduction and internal fixa-tion. The most important factor is to attempt toobtain an anatomic reduction with secure fix-ation such that early ROM can be initiated.12,15

Other structures that may be injured on theposterolateral aspect of the knee usually arerepaired by side to side suture repair. These in-clude tears of the coronary ligament of theposterior horn of the lateral meniscus, thepopliteomeniscal fascicles, portions of the ili-otibial band, and other components of the longand short heads of the biceps femoris.

The main goal with an anatomic repair ofinjured posterolateral structures is to achieve astable and secure repair such that early ROMcan be initiated. In patients in whom there istenuous fixation after suturing, especially inpatients who may be 3 weeks or more fromtheir acute injury, a period of cast immobiliza-tion may be necessary to allow healing.15 Inpatients who do need some form of cast im-mobilization as part of their treatment regi-men, the current authors recommend that acast be applied at 60! knee flexion with thetibia internally rotated for 3 to 6 weeks. Toprevent external rotation in the cast during thisperiod of immobilization, the current authorscommonly use a dowel rod placed at the baseof the foot of the cast and positioned to preventexternal rotation.

The postoperative treatment regimen forpatients who have a primary repair of injuredposterolateral structures includes a minimumof nonweightbearing on that affected extrem-ity for 6 weeks after surgery. In addition, it isrecommended that hamstring activity be min-imized, which may be deleterious on the pos-terolateral corner repair, for the first 4 months


after surgery. Postoperative rehabilitation ofpatients with this surgical repair involvesachieving ROM first, and then a program ofprogressive strengthening of the extremity gen-erally is followed. As mentioned previously,hamstring strengthening exercises are avoidedfor the first 4 months after surgery. Closedchained quadriceps exercises, such as the use ofan exercise bicycle usually are initiated at 6 to8 weeks after surgery with progression to gen-tle leg presses and squats allowed at 3 monthsafter surgery. Patients are allowed to jog and toparticipate in progressive strengthening exer-cises at 4 to 6 months after surgery (dependingon the severity of the original injury).

Treatment of Isolated Chronic PosterolateralKnee Complex InjuriesIn the assessment of chronic posterolateralknee injuries, it is important to recognize thatthe effect of bony alignment on a proposedsurgical repair or reconstruction is important.It is well-recognized that a failure to correct avarus aligned limb before soft tissue recon-structions on the lateral and posterolateral as-pect of the knee places these reconstructions athigh risk for failure, because of the high riskof stretching out with time because of the ex-tra stress placed on the limb because of thisalignment. Therefore, it is recommended thata full length AP radiograph taken with the pa-tient standing is obtained in all patients to as-sess the underlying extremity alignment on theeffected side.

For patients who have normal or valgusalignment of their extremity, an anatomic re-pair or reconstruction (with allograft or auto-graft tissue) is recommended. An MRI scanhas been found to be helpful to discern the lo-cation of injury of individual posterolateralstructures and whether a surgical repair isfeasible, because of the structures beingavulsed, or whether a surgical reconstructionis recommended (for popliteus musculo-tendinous junction injuries or midsubstanceavulsions of the fibular collateral ligament orpopliteus tendon). The same principles for aprimary repair in the acute situation would

hold for a primary repair in the chronic situ-ation. However, the majority of patients willneed to have a reconstruction of these struc-tures to restore stability to the effected kneeover the long-term.

In patients who have a varus alignmentconcurrent with a Grade 3 posterolateral kneeinjury, it is recommended that they first have aproximal tibial osteotomy to correct the un-derlying varus alignment.12,15,22 The currentauthors prefer the proximal tibial openingwedge osteotomy because it seems to tightenup some of the posterior structures of the kneeand avoids surgery and scar tissue formationon the posterolateral aspect of the knee (Fig 5).The authors generally wait until at least 6months after the osteotomy to ensure that theosteotomy has healed completely, the quadri-ceps mechanism is rehabilitated, and strengthis regained before making a determination


Fig 5. A radiograph taken 1 year postoperativeshows a healed opening wedge proximal oste-otomy in the right knee of a 28-year-old man withchronic Grade 3 posterolateral knee instability.

whether the patient would need a second stageposterolateral corner reconstruction.12,21 Thissecond stage surgery only is recommended ifthe patient still has problems with perceived in-stability with gait or during functional activities.

Treatment of Combined Grade 3Posterolateral Knee Injuries and OtherGrade 3 Ligament Injuries of the KneeAcute Combination Grade 3 PosterolateralKnee and Other Ligament InjuriesThe recommendations for patients who haveGrade 3 posterolateral knee injuries in combi-nation with other ligament injuries is the sameas the treatment for patients with an acute iso-lated posterolateral knee injury.12,15 The currentauthors recommend that a primary repair bedone of the injured posterolateral knee struc-tures within the first 2 to 3 weeks of injury andthat a repair or reconstruction of the concurrentother ligament injuries of the knee be done con-currently with this. Ideally, stout and secure fix-ation is desired such that an early ROM pro-gram can be initiated so that arthrofibrosis doesnot develop in the knee. At a minimum, the sur-geon needs to determine the safe zone for ROMon the table such that this minimum amount ofmotion can be done in the early postoperativeperiod. A brief period of immobilization of 1 to2 weeks may be indicated in some instanceswhen there is a significant amount of tissue in-jury present in the knee.

Chronic Combined Grade 3 PosterolateralKnee and Other Ligament InjuriesChronic Grade 3 posterolateral injuries usu-ally are seen in combination with chronic cru-ciate ligament injuries. It has been shown clin-ically that unrecognized or untreated Grade 3posterolateral corner injuries are a major causeof failure of cruciate ligament reconstruc-tions.15,22,23 In addition, it has been shown inseveral laboratory studies that a significant in-crease in force is seen on the anterior cruciateligament and posterior cruciate ligament re-construction grafts when there is a concurrentposterolateral corner injury present.7,16,18,19

Therefore, it is recommended that Grade 3posterolateral corner injuries be repaired or re-constructed when they are present at the sametime that an anterior cruciate ligament or aposterior cruciate ligament reconstruction isdone.15,16

There still is no clear consensus as to thetype of repair or reconstruction that should bedone when there is a chronic Grade 3 postero-lateral knee injury. However, these same prin-ciples of treatment for an isolated chronic pos-terolateral knee injury need to be followed.First, the patient’s alignment must be assessedto ensure that there is no varus alignment pre-sent that could cause a posterolateral knee re-pair or a reconstruction graft to stretch outwith time.

If a proximal tibial osteotomy must be donebecause of the patient’s underlying varus align-ment with a concurrent posterolateral knee andother knee ligament injury, it is recommendedthat the patient wait until there is evidence ofcomplete healing of the osteotomy, and have sig-nificant rehabilitation of that quadriceps mecha-nism, before proceeding with a second stagemultiligament reconstruction. If the patientshave continued instability with gait or with func-tional activities after the osteotomy is healed, thecurrent authors then would recommend pro-ceeding with multiligament knee reconstruc-tion (including the posterolateral corner).

In patients with chronic knee instability, theauthors recommend doing a reconstruction ofall the injured ligaments at the same time. Thesame principles that would hold for an anteriorcruciate ligament or posterior cruciate liga-ment reconstruction are true in a chronic pos-terolateral corner injury. Although rarely seen,the authors also would recommend doing thereconstruction of a chronic medial cruciateligament complex instability concurrently withthe posterolateral corner reconstruction to con-trol rotational stability of the knee.

A primary repair of chronic posterolateralknee injuries in multiligament instability rarelyis possible. It may be an option in a small num-ber of patients. A careful analysis of the loca-tion of the injury should be based on the clini-


cal evaluation and the MRI scan to assess forthe integrity and presence or absence of the keyposterolateral structures.12,15

In patients in whom the posterolateral cor-ner structures are deficient, the authors rec-ommend an allograft reconstruction of thefibular collateral ligament and/or popliteustendon and popliteofibular ligament complex.An anatomic reconstruction of these structures,with the allografts placed in the exact attach-ment sites of the normal structures, allows forearly postoperative motion and restoration ofthe static function over the posterolateral cor-ner of the knee.

The rehabilitation program that is followedin patients with combined posterolateral andother ligament repair needs to be individual-ized for each patient depending on the qualityof the tissue repair at the time of surgery. It isdesired that early ROM be achieved as soon aspossible. It is recommended that the surgeondetermine the safe zone that can be achievedwithout putting significant tension on the sur-gical repair or reconstruction just before clo-sure to determine the minimum ROM that canbe achieved. The patient’s extremity then canbe placed into a hinged knee brace within thislimitation of motion, or placed into a knee im-mobilizer and allowed to work on passive mo-tion through this range. In addition, a continu-ous passive motion machine may be used withinthis safe zone and then slowly advanced withtime to achieve additional ROM. It is the usualgoal with these complex knee reconstructionsthat full ROM is achieved between 6 to 8weeks postoperatively.

Weightbearing is not allowed for patientswith chronic posterolateral corner repairs or re-constructions until 6 to 8 weeks postopera-tively.12,15 This allows time for the posterolat-eral structures to heal in place. At that point,patients are allowed to slowly increase theirweightbearing and may wean off the crutcheswhen they can walk without a limp. Patients areallowed to do quadriceps setting exercises andstraight leg raises, in their immobilizer only,four times daily. Patients are allowed to start onthe exercise bicycle at 6 weeks postoperatively

if they have at least 105! to 110! knee flexion.Light leg presses, to a maximum of 70! kneeflexion, to between 20 and 30 kg, are initiatedat 8 weeks after surgery. Hamstring exercisesare not allowed for 4 months postoperativelybecause of their potential deleterious effects ofthe hamstrings pulling against the posterolat-eral repair or reconstruction. At this point, pa-tients are allowed to progress on the rehabili-tation program based on the other combinedligament reconstructions present.

References1. American Medical Association: Standard Nomen-

clature of Athlete Injuries. Chicago, American Med-ical Association 1966.

2. Bleday RM, Fanelli GC, Giannotti BF, Edson LJ,Barrett TA: Instrumented measurement of the pos-terolateral corner. Arthroscopy 14:489–494, 1998.

3. Cooper DE: Tests for posterolateral instability of theknee in normal subjects. J Bone Joint Surg 73A:30–36,1991.

4. Gollehan DL, Torzilli PA, Warren RF: The role ofthe posterolateral and cruciate ligaments in the sta-bility of the human knee: A biomechanical study. JBone Joint Surg 69A:233–242, 1987.

5. Grood ES, Stowers SF, Noyes FR: Limits of move-ment in the human knee: Effect of sectioning the pos-terior cruciate ligament and posterolateral structures.J Bone Joint Surg 70A:88–97, 1988.

6. Harner CD, Höher J, Vogrin TM, et al: The effectsof a popliteus muscle load on in situ forces in the pos-terior cruciate ligament and on knee kinematics. AmJ Sports Med 26:669–673, 1998.

7. Harner CD, Vogrin TM, Höher J, et al: Biomechan-ical analysis of a posterior cruciate ligament recon-struction: Deficiency of the posterolateral structuresas a cause of graft failure. Am J Sports Med28:32–39, 2000.

8. Hughston JL, Norwood LA: The posterolateraldrawer test and external rotation recurvatum test forposterolateral rotatory instability of the knee. ClinOrthop 147:82–87, 1980.

9. Jakob RP, Hassler H, Stäubli H-U: Observations onrotatory instability of the lateral compartment ofthe knee: Experimental studies on the functionalanatomy and pathomechanism of the true and reversepivot shift sign. Acta Orthop Scand 52 (Suppl 119):1–32, 1981.

10. Kannus P: Nonoperative treatment of grade II and IIIsprains of the lateral ligament compartment of theknee. Am J Sports Med 17:83–88, 1989.

11. LaPrade RF: Arthroscopic evaluation of the lateralcomparison of knees with grade 3 posterolateral com-plex knee injuries. Am J Sports Med 25:596–602,1997.

12. LaPrade RF: The Medial Collateral Ligament Com-plex and the Posterolateral Aspect of the Knee. InArendt EA (ed). Orthopaedic Knowledge Update,


Sports Medicine 2. Rosemont, IL, American Acad-emy of Sports Medicine 327–340, 1999.

13. LaPrade RF, Bollom TS, Gilbert TJ, Wentorf FA,Chaljub G: The MRI appearance of individual struc-tures of the posterolateral knee: A prospective studyof normal and surgically verified grade 3 injuries.Am J Sports Med 28:191–199, 2000.

14. LaPrade RF, Hamilton CD: The fibular collateral lig-ament-biceps femoris bursa. Am J Sports Med25:439–443, 1997.

15. LaPrade RF, Hamilton CD, Engebretsen L: Treat-ment of acute and chronic combined anterior cruci-ate ligament and posterolateral knee ligament in-juries. Sports Med Arthrosc Rev 5:91–99, 1997.

16. LaPrade RF, Resig S, Wentorf FA, Lewis JL: The ef-fects of grade 3 posterolateral knee injuries on forcein an ACL reconstruction graft: A biomechanicalanalysis. Am J Sports Med 27:469–475, 1999.

17. LaPrade RF, Terry GC: Injuries to the posterolat-eral aspect of the knee: Association of injuries withclinical instability. Am J Sports Med 25:433–438,1997.

18. Markolf KL, Slauterbeck JL, Armstrong KL, et al: Abiomechanical study of replacement of the posteriorcruciate ligament with a graft: Part II: Forces in thegraft compared with forces in the intact ligament. JBone Joint Surg 79A:381–386, 1997.

19. Markolf KL, Wascher DC, Finerman GA: Direct invitro measurement of forces in the cruciate ligaments:Part II: The effect of section of the posterolateralstructures. J Bone Joint Surg 75A:387–394, 1993.

20. Maynard MJ, Deng X-H, Wickiewicz TL, et al: Thepopliteofibular ligament: Rediscovery of a key ele-ment in posterolateral stability. Am J Sports Med24:311–316, 1996.

21. Noyes FR, Barber-Westin SD: Surgical reconstruc-tion of severe chronic posterolateral complex in-juries of the knee using allograft tissues. Am J SportsMed 23:2–12, 1995.

22. Noyes FR, Barber-Westin SD, Hewitt TE: High tib-ial osteotomy and ligament reconstruction for varusangulated anterior cruciate ligament-deficient knees.Am J Sports Med 28:282–296, 2000.

23. O’Brien SJ, Warren RF, Pavlov H, Panariello R,Wickiewicz TL: Reconstruction of the chronicallyinsufficient anterior cruciate ligament with the cen-tral third of the patellar ligament. J Bone Joint Surg73A:278–286, 1991.

24. Shindell R, Walsh WM, Connolly JF: Avulsion frac-ture of the fibula: The “arcuate sign” of posterolat-eral knee instability. Neb Med J 69:369–371, 1984.

25. Stäubli H-U, Birrer S: The popliteus tendon and itsfascicles at the popliteus hiatus: Gross anatomy andfunctional arthroscopic evaluation with and withoutanterior cruciate ligament deficiency. Arthroscopy6:209–220, 1990.

26. Terry GC, Hughston JL, Norwood LP: The anatomyof the iliopatellar band and iliotibial tract. Am JSports Med 14:39–45, 1986.

27. Terry GC, LaPrade RF: The biceps femoris complexat the knee: Its anatomy and injury patterns associ-ated with acute anterolateral-anteromedial rotatoryinstability. Am J Sports Med 24:2–8, 1996.

28. Terry GC, LaPrade RF: The posterolateral aspect ofthe knee: Anatomy and surgical approach. Am JSports Med 24:732–739, 1996.

29. Veltri DM, Deng X-H, Torzilli PA, et al: The role ofthe cruciate and posterolateral ligaments in stabilityof the knee: A biomechanical study. Am J SportsMed 23:436–443, 1995.


diagnosis and treatment of posterolateral knee injuries€¦ · posterolateral knee injuries can be...

Documents