Falworth instabilidade póstero lat do joelho - diagn e tto

THEKNEE

Posterolateral instability of the knee: its diagnosisandmanagementM.S.Falworth and R.L. Allum

Department of Orthopaedics,Wexham Park Hospital,Wexham Street, Slough, Berkshire, SL2 4HL,UK

Abstract Posterolateralinstabilityis defined as the instability thatresults frominjuriestotheposterolateralstabilisingstructuresoftheknee.Thisinstabilityisposterior, varusandexternalrotation.Isolatedposterolateralligamentousinstabilityofthekneeishow-ever uncommon. Instability usually occurs in association with other ligamentous inju-ries, in particular, injuries to either the anterior cruciate ligament (ACL), theposterior cruciate ligament (PCL), or both.The recognition and adequatemanagement of this injury pattern is crucial, particu-

larlyas anycruciateligamentreconstructionwillbe compromisedifthereis a combinedinjuryandrepairoftheposterolateralcorneris omitted.There should always thereforebe a high degree of suspicionwhen examining the knee, particularly in those patientswhere the mechanism of injury and symptoms are suggestive of a complex knee in-jury.�c 2003 Elsevier Science Ltd.Allrights reserved.

ANATOMYThe anatomyof the posterolateral corner is complicatedand variable.This has been compounded by the fact thatthere are numerous descriptions of this anatomical re-gion in the literature, often with different terminologiesbeing used. To simplify the description Seebacher1 di-vided the posterolateral corner into three layers:

Layer I consists of the fascial layer, the iliotibial band(ITB) and biceps femoris (Fig.1).The deep fascial layer ofthe thigh, the fascia lata, inserts distally into themarginsof the patella, the inferior margins of the tibial condylesand the head of the fibula. Avertical band-like thickeningof the fascia lata, the ITB, extends from the level of thegreater trochanter and passes distally down the lateralaspect of the thigh and makes up the anterior aspect ofthis first layer.

The superficial layer of the ITB crosses the lateral con-dyle of the femur to insert into a facet on the anteriorsurface of the lateral condyle of the tibia,Gerdy’s tuber-cle.The deep layer of the ITB inserts into the lateral in-termuscular septum at the distal femur.

The combined short and long heads of the bicepsfemorismakeup theposterior aspectof Layer I.The long

head is made up of two tendinous components, the di-rect and the anterior arms.The direct arm inserts intothe posterolateral head of the fibula whilst the anteriorarm attaches to the lateral edge of the fibular head.Theshort head of biceps femoris also has two tendinous in-sertions.The direct arm inserts into the superior surfaceof the fibular head just lateral to the styloid process butmedial to the lateral collateral ligament (LCL). Its ante-rior arm extends anteriorly, medial to the LCL, and in-serts on to the posterior aspect of the tibial tuberosity.The biceps tendon therefore folds around the LCL at itsinsertion. Also within this layer is the common peronealnerve, which descends inferolaterally to the bicepsfemoris tendon. It then runs lateral to the lateral headof gastrocnemius before reaching the posterior aspectof the fibular head.

Layer II is formed by the lateral quadriceps retinacu-lum, the LCL and the two patellofemoral ligaments.

The LCL is a round cord-like structure, approximately5 cm long, which is attached to the lateral epicondyle ofthe femur and slopes inferiorly and posteriorly to insertinto the head of the fibula.The ligament is not attachedto either the capsule or lateral meniscus. The inferiorlateral genicular vessels and the popliteus tendon sepa-rate it from the capsule and lateral meniscus, respec-tively. Biomechanically the LCL is attached behind theaxis of flexion of the femoral condyle thus becoming

Correspondence to: RLA. Tel.: +44-1753-6330-40; Fax: +44-1344-8743-40; Email: [email protected], [email protected]

Current Orthopaedics (2003) 17, 223--233�c 2003 Elsevier Science Ltd. All rights reserved.doi:10.1016/S0268-0890(03)00024-0

taut and limiting extension when the knee reaches fullextension.

Layer III is the deepest of the three layers of the pos-terolateral corner. It is composed of the joint capsule,coronary ligament, fabellofibular ligament, popliteus ten-don, arcuate ligament and the popliteofibular ligament(PFL).

The coronary ligament is that part of the capsule thatconnects the lateral aspect of the lateral meniscus to alevel just distal to the articularmargin of the lateral tibialcondyle.The laxity of this ligament allows for a verymo-bile meniscus. There is a hiatus in the posterolateralborder of the coronary ligament through which thepopliteus tendon and bursa pass.This portion of the lat-eralmeniscus is referred to as the bare area.

The arcuate ligament is a ‘Y’ shaped structure that ismade up of several elements. The lateral limb of theligament inserts into the styloid process of the fibula. Itarches medially, superficial to the popliteus muscle andtendon, to attach into the posterior joint capsule. Theoblique popliteal ligament (the ligament of Winslow)forms the medial limb.This ligament is formed from theunion of the oblique popliteal expansion of the semi-membranosus and the capsular arm of the posterior ob-lique ligament, which originates from the medial side ofthe knee.2 The oblique popliteal ligament arches ante-riorly to insert into the posterior joint capsule overlyingthe lateral femoral condyle. The arcuate ligament also

forms part of the arcuate complex, which includes theLCL, popliteus and the lateral head of gastrocnemius.

Thepopliteus tendon arises from a depression just be-low the epicondyle on the lateral surface of the femoralcondyle. This rope-like structure descends infero-medi-ally, passing through a hiatus of the coronary ligamentand inserts into the popliteal surface of the tibia abovethe soleal line.Medial to the popliteus tendon is an apo-neurotic attachment to the posterior capsule and to thelateralmeniscus.3 This has been termed the posterior in-ferior popliteomeniscal fascicle by Staubi4 but its pre-sence has also been refuted.5

The PFL, previously known as the short external lat-eral ligament,3 also arises from the popliteus tendon. In-deed the popliteus tendon is split into two fascicles ofnearly equal size; the first continues to form the muscu-lotendinous junction of the popliteus muscle whilst thesecond forms the PFL.6 This lies deep to the lateral limbof the arcuate ligament and inserts into the most proxi-mal and posterior projection of the fibula with smallerinsertions into the lateral limb of the arcuate ligamentand the fabellofibular ligament.The inferior lateral geni-culate artery separates these two latter insertions fromthe fibular insertions.

The fabellofibular ligament arises from the lateralaspect of the fabella, or in its absence, the posterior as-pect of the supracondylar process of the femur.2 It des-cends distally and laterally, running parallel with the

Figure 1 Aview of the right knee joint from above after removal of the right femur.Note the three layers of the lateral side and thedivision ofthe posterolateralpartofthe capsule (Layer III) into deep and superficiallaminaewhich are separatedby the lateral inferiorgenicular vessels.Taken from Seebacher JR, Inglis AE,Marshall JL,Warren RF.The structure of the posterolateral aspect of the knee.JBone Joint Surg (Am) 1982;64A:537.

224 CURRENTORTHOPAEDICS

tendon of the long head of biceps femoris muscle beforeinserting into the styloidprocess of the fibula justmedialto the insertion of the short head of the biceps femoralmuscle.

Although the anatomy of the posterolateral cornerhas been described on an anatomical basis it canalso be classified functionally with respect to thestructures that provide static and dynamic stability tothe knee (Table1).

BIOMECHANICSBiomechanical analysis of the posterolateral cornercan best be investigated by selective sectioning ofligaments in cadavaric knees. By measuring the degreeof laxity after applying forces to the knee the role ofthe sectioned ligament in stabilising the knee can bedetermined. The sequence of sectioning can also bevaried.

Posterior translation

The selective sectioning of the PCL and the structuresof the posterolateral corner can be used to investigateposterior translation. Gollehon7 demonstrated thatalthough division of the PCL resulted in no increase inanterior translation, it did result in increasing posteriortranslation with increasing knee flexion.However, it hadno affect on either varus or external rotation. Selectivesectioning of the LCL, popliteus and arcuate ligamentcomplex resulted in no significant increase in posteriortranslation between 01 and 301 of flexion when com-pared to isolated PCL sectioning. However, if all thestructures of the posterolateral corner and the PCLwere divided there is a significant increase in the poster-ior translation between 01 and 901 when compared toselective sectioning.

Varus instability

In an intact knee, varus and valgus rotation is at it’s leastin extension and increases with increasing flexion to 901.Although no increase in valgus rotation was noted witheither collective or individual sectioning of the PCL, LCLand the arcuate complex there was an effect on the de-gree of varus rotation.The amount of varus rotation in-creased by 1--41 in all angles of knee flexion whenselective sectioning of the LCL was performed.This in-creased to 5--91 when the arcuate complex was dividedand14--191 when the PCL was also sectioned.Maximumvarus rotationwas noted at 601 of knee flexionwhen thePCL, LCL and popliteus and arcuate complex were di-vided.7

Primary internal and external rotationalinstability

This is the degree of rotational instability recordedwheninternal or external tibial torque is applied to theknee. Inan intact knee combined internal and external rotationwas at a maximum at 451 of knee flexion and at it’s leastat 01. No isolated or combined sectioning of the PCL,LCL or deep lateral structures produced any increase ininternal rotation, however changes were noted in exter-nal rotation.

Isolated sectioning of the LCL produced a small 2--31increase of external rotation at 301, 601 and 901 of flex-ion. An increase of 61731 was recorded with isolatedsectioning of the arcuate complex at 901 of flexion.Thecombined sectioning of the LCL and arcuate complex re-sulted in an increase in external rotation at all flexion an-gles but it was at its greatest at 301 of flexion. Althoughisolated division of the PCL resulted in no change of ex-ternal rotation when it was performed in associationwith division of the LCL and arcuate complex further sig-nificant increases in external rotationwere noted at 601and 901 of knee flexion.7

Coupled internal and external rotationalinstability

If an anterior force is applied to the tibia of an intactkneethe tibia will rotate internally. Conversely, if a posteriorforce is applied, the tibia will rotate externally. Thesemovements in whichmotion is in a different direction tothe applied force are referred to as coupledmovements.

If selective sectioning studies are performed on theLCL, the deep structures, or the PCL there is no increasein internal rotation when an anterior force is applied tothe tibia. This however is not the case with a posteriorforce. The selective sectioning of the LCL and deepstructures recorded a significant increase in theexternal rotation. Isolated section of PCL however elimi-nated the coupled external rotation buthad no effect oninternal rotation when an anterior force was applied.

Table 1 Dynamic and static stabilisers of the postero-lateral corner.

Structure

Dynamic Biceps femorisstabilisers Popliteus*

Lateralheadofgastrocnemius *

Static Iliotibial bandstabilisers Lateral collateralligament*

Arcuate ligament*Popliteofibular ligamentFabellofibular ligamentLateralmeniscus

*These structuresmake upthe arcuate complex.

POSTEROLATERALINSTABILITYOF THEKNEE:ITSDIAGNOSISANDMANAGEMENT 225

Furthermore, when the PCL, LCL and other deepstructures were sectioned there was an increase in theexternal rotation recorded after the application of aposterior force when compared with the changemeasured when the LCL and deep ligament complexwere sectioned, however this was not significant.7

The interpretation of this biomechanical data is im-portant as it enables the clinician to accurately assessdifferent ligamentous structures of the knee at differentdegrees of knee flexion. The isolated sectioning, or in-jury, of the PCLwill result in an increase in the posteriortranslation of the knee in all degrees of knee flexion, butit is maximal at between 701 and 901. The continuity ofthe PCL is therefore best tested with the knee in 901 offlexion.

Isolated sectioning of the LCL shows maximal varusrotation at 301 of knee flexion. Similarly, isolated injuryto the posterolateral corner, when the PCL remains in-tact, results in the largest increase in posterior transla-tion, varus rotation and external rotation at 301 offlexion. A posterolateral corner injury can therefore bebest determinedby testing the knee at both 301 and 901of flexion. If there is an increase in primary varus rota-tion andexternal rotation at 301, butnot 901 of rotation,then a posterolateral corner injury is confirmed. Ifincreases are noted at both 301 and 901 then both aposterolateral corner and PCL injury have occurred.

INJURYMECHANISMPosterolateral knee injuries commonly occur followingmechanisms involving high-energy forces. Both directand indirect mechanisms have been reported.8 A directblow to the anteromedial aspectof theknee or proximaltibia, with the knee in full extension is commonly de-scribed. This often occurs with pedestrians involved inroad traffic accidents or in contact sports where theknee is forced into a varus deformity with associated hy-perextension and external rotation of the tibia.

Grood9 demonstrated that at 51 of flexion most oftherestraint from the lateral capsulewas due to the pos-terior arcuate complex. Posterolateral corner injuriesmay therefore also occur after avarus force is appliedwiththe knee in varying degrees of flexion.8, 10 Knee disloca-tion and indirect mechanisms involving twisting injuriesto the kneemay also result in posterolateral instability.

CLINICALASPECTS

Symptoms

Unlike ACL injuries, where instability may be presentonly during sporting activities, PCL and posterolateralinsufficiencies often result in instability during everydayactivities. Instability whilst the knee is in extension is a

common complaint with hyperextension often occur-ring.Difficulties ascending and descending stairs are fre-quently reported as the knee cannot be locked in fullextension.Thepresence ofmedial joint line painmay alsobe a feature and may result in a misdiagnosis of medialmeniscal pathology.8 In cases where knee dislocationhas been reported common peroneal nerve lesions maybe present.

Signs

In the acute phase there may be swelling and indurationover the posterolateral corner.However, in the event ofa capsular disruption an effusion may not be present. Incases of direct trauma contusions and bruising may bepresent over the anteromedial aspect of the proximaltibia.

DIAGNOSTICTESTSExamination of the acute knee can be difficult due to as-sociated swelling, pain andmuscle guarding.

Examination of the standing patient may show the ti-bia to be positioned with increased recurvatum, a varusdeformity and internal rotation.Furthermore, as the pa-tient’s gait is assessed varus thrust may be noted. Thispresents as an apparent lateral displacement of the tibiaand occurs due to the external rotation of the tibiaduring the stance phase of gait when the knee is in fullextension.

Amore accurate knee examinationmaybe achieved inthe anaesthetised patient, particularly in those with anacute knee injury.Generalised ligamentous laxitymay bepresent and therefore the opposite non-injured kneeshould also be examined prior to any assessment of theinjured side.

Posterior drawer test

Anteroposterior translation shouldbe examined at both301 and 901 of flexion. If posterior translation is noted at301 but not at 901 then a posterolateral injury is likely. Ifposterior translation is noted at both 301 and 901 thenan isolated PCL or combined injury is present.

Quadriceps active test

The quadriceps active test is used to demonstrate thepresence of posterior tibial subluxation and is thereforeimportant in establishing the presence of an associatedPCL injury. With a relaxed patient in a supine positionthe hip and knee are flexed to 451 and 901, respectively.A gentle quadriceps contraction should be undertakento shift the tibia without extending the knee by fixingthe position of the foot. In a normal knee the patellartendon is angled slightly posteriorly and there is


therefore no resultant anterior shift.11 (Fig. 2) If the PCLis ruptured the patellar tendon becomes angled ante-riorly because of posterior subluxation of the tibia and acontraction of the quadriceps results in a slight anteriorshift of the tibia. This is not reproduced in an isolatedposterolateral corner injury.

Varus stress test

Avarus stress test assesses the degree of lateral instabil-ity in one plane. This can be performed at 01 and 301whilst the ankle is stabilised. Instability at 301 of flexion isdue to an isolatedposterolateral corner injury. If the testis positive in full extension then a posterolateral cornerand associated cruciate injury is present.

External rotation recurvatumtest

Hughston first described this test in1980.12 Thepatient isplaced in a supine position and encouraged to relax thequadriceps. The great toe of each foot is then graspedand the legs are lifted off the examination couch. If pos-terolateral instability is present there will be varus andhyperextension deformities at the knee. The tibia willalso fall into external rotation (Fig. 3).

Posterolateral external rotation drawer test

This test is used to test the integrity of the arcuate liga-mentcomplex.12With thepatient in a supineposition the

hip and knee are flexed to 451 and 801, respectively.Thetibia is then externally rotated by 151 and a posteriordrawer test is performed with the foot held in a fixedposition. If the lateral tibial condyle externallyrotates re-lative to the lateral femoral condyle the test is consid-ered positive. This manoeuvre may be most easilyreproduced by using the examiners thumbs to mark thepatellar tendon and tibial tubercle. (Fig. 4) As a posteriorforce is applied the tibial tubercle will rotate posterolat-erally in a posterolateral deficient knee.

It has been shown in biomechanical studies7 thatexternal rotation of the knee is normally coupled withposterior translation. Furthermore, where excessiveexternal rotation is noted injuries to both the posterolateral corner and the PCL shouldbe suspected.However,when the posterolateral drawer test is repeated in 301of flexion, a positive result can be considered to bemorespecific for an isolated posterolateral corner injury.13

Tibial external rotation test (Dial)

This test is used to determine the degree of external ro-tation of the tibia relative to the femur at both 301 and900 of flexion. Although this can be performed in the su-pine position we prefer examining the patient prone

Figure 2 The 901 quadriceps active test.Keeping the eyes atthe level of the subject’s flexed knee, the examiner rests theelbow on the table and uses the ipsilateral hand to support thesubject’s thigh and to confirmthatthe thighmuscles are relaxed.The foot is stabilised by the examiner’s otherhand, and the sub-ject is asked to slide the foot gently down the table.Tibial displa-cementresulting fromthequadricepscontractionisnoted.Takenfrom Daniel DM, Stone M,Barnett P, Sachs R.Use of the quadri-ceps active testto diagnose posterior cruciate--ligament disrup-tion andmeasure posterior laxity of the knee. JBone Joint Surg(Am) 1988;70A:387.

Figure 3 External rotational recurvatum test demonstratingposterolateral rotatory instability in the right knee with its rela-tive tibia vara.


where a more reproducible and quantifiable measure-ment can bemade.The degree of external rotation is re-ferenced from the medial border of the foot. Once theknee is held in the appropriate degree of flexion the ex-aminer forcibly externally rotates the foot. The degreeof external rotation is determined by measuring the an-gle between themedial border of the foot and the verti-cal axis.Thismeasurement should be comparedwith thecontralateral side (Fig. 5). The nature of the test is suchthat the rotation noted at the time of examination maynot be solely due to the degree of tibial rotation. Thejoints of the midfoot, hindfoot, and ankle can all influ-ence the degree of external rotation,14 comparison withthe contralateral side is therefore imperative.

Reversed pivot shift test

The reversed pivot shift test is performed by extendingtheknee from a position of 70--801whilst the foot is heldin external rotation and a valgus strain is applied to theknee.15 In a posterolateral deficientknee the lateral tibialplateauwillbe subluxedposteriorlyrelative to the lateralfemoral condyle whilst the knee is in flexion.This can berecognised as posterior sag of the proximal tibia. As theknee is extended the examiner shouldbe able to feel andobserve that the lateral tibial plateau abruptly shifts intoits reduced position at approximately 20--301 of flexion.This sudden shiftor jerk is considered a positive reversedpivot shift and will reproduce the patients discomfortand simulate their feeling of the knee giving way.This re-versedpivot shift therefore describes the shift of the lat-eral tibial plateau in the opposite direction from the truepivot shift sign.16

As in the pivot shift test the success of this test is de-pendent on the skill of the examiner and on the ability ofthe patient to relax his or her muscles. More accuratefindings may therefore be achieved when the test is

repeated under general anaesthesia. However, the re-versed pivot shift test is not a specific test.14, 15 Positivetests can be found in individuals with increased general-ised ligamentous laxity and mild varus alignment of theknee.The contralateral side should therefore always beexamined to exclude false positives.

One can link the clinical deformity to the anatomicalinjury. Injuries to the LCL are demonstratedby increasedvarus instability at 301. External rotation at 301 is consis-tent with an injury to the popliteus, arcuate ligament,PFL and fabellofibular ligament. Hyperextension and anincreased varus deformity at 01 indicates a posterolat-eral capsule and PCL disruption (Table 2).

Figure 4 Posterolateraldrawer test: (A) demonstrates the startingposition; (B) illustrates apositiveposterolateraldrawer testwithposterior and externalrotation ofthe lateral tibial condyle.

Figure 5 Illustrationoftheprone externalrotationtest, whichisperformedatboth 301 and 901 of knee flexion.Forceful exter-nalrotationis exertedby the examiner andthe amountof exter-nal rotation ismeasured by comparison of the axis of themedialborder of the foot with the femur. (Reprinted from:Veltri DM,WarrenRFIsolatedandcombinedposteriorcruciateligamentin-juries.J AmAcad Orthop Surg1993;1:70.)


INVESTIGATION

Radiography

Plain radiographs utilising a standing anteroposteriorview and lateral view can be used to demonstrate evi-dence of osteoarthritis and varus malalignment.The de-gree of varus alignmentmay be evaluatedwith a long legstanding anteroposterior film and varus stress films.

MRI

Magnetic resonance imagining utilisingT1imaging techni-ques can prove helpful in the assessment of posterolat-eral knee injuries.17 Although its use is no substitute foran adequate examination in can be a useful adjunct toclinical examination, particularly in the assessment of anacute injury.

Arthroscopy

A full assessment of the knee is beneficial prior to plan-ning reconstruction of the posterolateral deficient knee.This may be particularly relevant in chronic insufficiencywhere associated meniscal and articular cartilage injurymay be evident. The cruciate ligaments can also be as-sessed. Evidence of posterolateral insufficiency includesa positive lateral compartment ‘drive through sign’18 andthe presence of greater than 1cm of lateral joint laxitywith the application of varus stress.Thepopliteus tendoncan be also assessed, particularly in the acute injury.

MANAGEMENTThe need to repair the structures of the posterolateralcorner depends on the nature and extent of injury. Inthose patients who have evidence of an isolated post-erolateral corner injury, but have no significant symp-toms or functional impairment, conservative measuresmay prove successful.19 Initial immobilisation for 2--4weeks is followedby a rehabilitation programme.

Surgical reconstruction should be performed in thosepatients where there is functional impairment and clearsymptoms associated with posterolateral rotatory in-stability.The timing of surgery is however controversial.It has been suggested that acute repair of the posterolat-eral corner is more successful than chronic repair10, 19--21

although there is some degree of uncertainty regardingthis. Surgery should however, usually be deferred forabout 2 weeks or until the acute inflammatory phase ofthe injury has subsided. Care should be taken duringacute arthroscopic procedures, as there is a risk of com-partment syndrome due to the leakage of irrigation fluidthrough a capsular defect.Furthermore, concomitant in-juries to the PCL or ACL may be present and theseshould be reconstructed prior to, or concurrently with,the posterolateral corner. Indeed, failure to recogniseand repair posterior lateral corner injuries when recon-structing the ACL is a common cause of failure of ACLreconstruction.22

Limb alignment and a pathological gait cannot be cor-rected with a soft-tissue procedure alone and hence theassessment of limb alignment is crucial in the manage-ment of all patients with chronic posterolateral instabil-ity. Patients who demonstrate a lateral thrust in thestancephase of gait andwhohave avaruskneedeformityrequire a proximal valgus tibial osteotomy.23 The valgusosteotomymaybeperformedeither before aposterolat-eral reconstruction or as a combined procedure. Failureto correct the limb alignment prior to reconstruction islikely to result in failure.When performed prior to pos-terolateral reconstruction some of the symptoms of in-stability may resolve such that a further reconstructiveprocedure is no longer required.

Acute repair

Where possible direct repair of the posterolateralstructures should be attempted. Access is achieved via acurvilinear skin incision. A detailed assessment of theinjured structures can then be made and if the tissuesare of good quality primary repair can be attempted.

Avulsion injuries of the popliteus tendon and the lat-eral collateral and arcuate ligaments may occur eitherproximally or distally.These can be repaired with eitherdirect suturing to the periosteum or through transoss-eous drill holes.19 If necessary these repairs may be aug-mented with either staples or screws and soft-tissue

Table 2 Specificityof clinical examination.

Test PCL PLC PCL/PLC

Posteriordrawer at 301flexion

7 + ++

Posteriordrawer at 901flexion

+ � ++

Quadriceps active + � +Varus stress at 01 flexion � 7 +Varus stress at 301 flexion* � + ++Externalrotationrecurvatum*

� + ++

Posterolateral externalrotation drawer at301flexion*

� + ++

Posterolateral externalrotation drawer at 90o

flexion

7 7 ++

Tibial externalrotationtest(Dial) at 30o flexion*

� + ++

Tibial externalrotationtest(Dial) at 90o flexion

7 + ++

Reversedpivot shift* � + ++

*Denotes a test specific for posterolateral injury.


washers. If the popliteus tendon is stretched but intact,it can be retensioned by detaching its femoral insertionwith a bone plug and then recessing it into a femoral drillhole.21Midsubstance injuries canberepairedprimarilybyusing Kessler suture techniques.

If the repair is insufficient to correct the instability,augmentation is warranted.

Augmentation

For popliteus tendon injuries this can be achieved byusing a strip of the ITB which is harvested whilst main-taining its tibial insertion to Gerdy’s tubercle. It is thenfed through an anteroposterior tibial tunnel and sutured.If a popliteus tendon injury occurs at the popliteal liga-ment or the popliteusmusculotendinous junction the in-jury may be treated with a tenodesis of the popliteustendon to the posterolateral corner of the tibia.24 Thereconstruction should be tensioned in 601 of flexion andwith the lateral tibia drawn forward to its neutralposition.

If the PFL cannot be repaired it may be augmented byusing biceps femoris. A central slip of the tendon is har-vestedwhilst preserving its distal insertion in the fibularhead. It is tubed, sutured to the posterior aspect of thefibula and then passed under the remaining biceps ten-don before it is fixed to the lateral aspect of the femurwith a screw andwasher21 (Fig. 6B).

Midsubstance injuries of the LCLmay also be augmen-ted in a similar way with a central slip of biceps tendonwhich is fixed to the isometric point of the lateral

femoral condyle with a screw and washer.21 By placing aKwire at the proposed position the graft can be drapedover the wire and the knee flexed and extended. Theisometric point is where minimal movement of thegraft is noted relative to the wire during flexion andextension.

Advancement

Proximal advancement of the posterolateral structurescan be considered in cases of chronic instability wherethe PFL and LCL are lax but intact, and where the softtissues are felt to be of satisfactory thickness. A LCLwidth of 5--7mm and thickness of at least 3--4mm is theminimum requirement for successful advancement; thepresence of poor quality scar tissue is a contraindica-tion.25

The surgical approach is made through either astraight lateral or curvilinear incision. An incision ismadealong the anterior border of the ITB and the structuresof the posterolateral corner exposed. A 10mm verticalincision is made in the joint capsule along the anteriorborder of the popliteus tendon. The size of the popli-teus--arcuate complex is then defined and a superior in-cision, superior and proximal to the LCL, is made alongwith a posterior incisionparallel to the lateral gastrocne-mius tendon.

The intended advancement site is prepared by decor-ticating an area proximal to the LCL with the knee in301 of flexion and neutral rotation. The posterolateralcomplex is osteotomised, advanced and fixed to the

Figure 6 Biceps tendon augmentation ofthe posterolateral corner usually involvesmoving the entire distal tendontothe femur andsecuring it with a screwandligamentwasher (A); the authorsprefer to anatomicallyreconstructthe popliteofibular ligamentwiththecentral slip ofthe biceps tendon, which is thentubed and sutured totheposterior fibula (B).The strip is thenpassedunder theremain-ing biceps tendon and secured to the lateral femur with a screw and ligament washer.Taken fromVeltri DM,Warren RF.Operativetreatmentof posterolateral instabilityof theknee.Clin Sports Med1994;13:619.


prepared donor site using staples and/or cancellous bonescrews (Fig. 7). This results in the ligamentous complexbeing retensioned.

Reconstruction

Many different techniques have been described for thereconstruction of the posterolateral corner. Autografts,allografts and synthetic materials have all been sug-gested.26 The authors prefer hamstrings as a primarygraft choice.

Clearly the aimofreconstructive surgery is topreventinstability through awide range ofmovement.To achievethis grafts should be placed at the isometric position.Structures that link the posterior aspect of the fibularhead to the lateral femoral condyle are isometric, how-ever, techniques that utilise the posterolateral aspect ofthe tibia are not. If non-isometric grafts are used thegraft will not remain tensioned during a normal range ofkneemovement.

Biceps tenodesisClancy27 introduced a biceps tenodesis procedure inwhich the biceps tendon is used to reconstruct a dis-

rupted PFL and LCL.The biceps tendon is tenodesed be-tween the isometric point on the lateral femoralepicondyle and the fibular head. This can be used as anisolated technique or in combination with primary re-pairs, advancement or reefing procedures.

A lateral curvilinear incision is used tomobilise the bi-ceps muscle and tendon. The distal 5 cm of the muscleshould be removed from the medial side of the tendonthus preventing any muscle interposition between thelateral femoral condyle and tendon.To further aidhealinga bony trough ismadebydecorticating the lateral femor-al condylewhere the tendonwill sit.Within this trough aKirschner wire is positioned at the isometric pointof thelateral femoral condyle. This is positioned just superiorto theproximal edge of the insertion of the fibular collat-eral ligament.Thebiceps tendon can thenbebrought un-derneath the iliotibial tract and hooked around theKirschner wire. A large cannulated screw and soft-tissuewasher is then used to hold the tendon (Fig. 6A). Thescrew should be tightened with the knee internally ro-tated and flexed to 301.

Several variations to this technique have also beensuggested where only a portion of the biceps tendon isutilised. One such technique to augment LCL injurieswas described earlier.21Biomechanically it acts by creat-ing a new PFL.

The use of this technique is dependent on the preser-vation of the biceps femoris insertion into the fibularhead, an intact tibiofibular joint and intact posterolateralcapsular attachments to the common biceps tendon.

Lateral collateralligament and popliteofibularreconstructionLarson28 described a technique where a free semitendi-nosus tendon graft is used to reconstruct the PFL andLCL. The semitendinosus graft is harvested from theipsilateral knee in the standard fashion (the authors haveadapted this technique to use both semitendinosus andgracilis to produce two strands in each limb).

A curvilinear incision is used to expose the lateral fe-moral condyle and fibular head.

Based on the principle that a graft placed from theposterior aspect of the fibular head to the lateral femor-al condyle is in an isometric position an anterior--poster-ior drill hole is placed in the fibular head to accommodatethe graft.The isometric pointon the lateral femoral con-dyle is determined as described earlier under augmenta-tion.Once ithasbeen located a socketof 30mmis drilledto accommodate the graft ends. The graft is then fedthrough the drill hole in theheadof the fibula and its endspassedbeneath thebiceps tendon and ITB .Thegraft endsare shortened to allow 20mm penetration into the fe-moral socket and a passing suture is passed through thesocket to the medial side of the knee. The preparedgrafts are then delivered into the socket, tensioned from

Figure 7 Advancement of the posterolateral structures.Theposterolateral capsule is incised horizontally for10--15mm at itsposterior femoral attachment just above the femoral condyle.The release of the capsule is continued distally for 10--15mmunderdirect visualisation. A limited incision into theposterome-dial capsule may be necessary to allow proximal advancementof the entire posterolateral complex. Taken from Noyes FR,Barber-Westin SD.Surgical reconstruction to treatchronic defi-ciency of the posterolateral complex and cruciate ligaments oftheknee joint. Am JSports Med1996;24:419.


the medial side of the knee and fixed with a soft-tissueinterference screw (Fig. 8).

This method of reconstruction is such that the ante-rior band of the graft reconstructs the LCL and the pos-terior band reconstructs the PFL, thus restoring theanatomy, biomechanics and stability of the posterolat-eral corner.

This procedure can be modified in cases where thereis minimal varus laxity. In such cases the anterior bandcanberedirected through a parallel anteroposteriordrillhole in the fibular head. This double graft then extendsfrom the posterior fibular head to the lateral femoralcondylewhere it can be fixed in the samemanner.

There aremany variations of the previously describedtechnique. However, the aim remains the same, to pro-vide posterolateral stability by creating tissue bands be-tween the lateral femoral condyle and the fibular head orposterolateral tibia. Veltri and Warren21 describe onesuch techniquewhere either a split patellar tendon auto-graft or Achilles tendon allograft is used to reconstructboth components of the popliteus. A tunnel is created inthe lateral femoral epicondyle into which the bone plugof the graft is inserted and fixed. The graft is then splitinto two distally and each end is placed and fixed in ante-roposterior fibular head and tibial tunnels.

REHABILITATIONFor the first 2 weeks following surgery the knee isrested in an extension splint, mobilising partial weight

bearing as pain permits. At 2weeks a hingedbrace is ap-pliedwhich protects the knee from translation, rotationand varus/valgus forces. Full weight bearing is permittedin the brace. No restriction is placed on active and pas-siveranges ofmovementorquadriceps andhamstring ac-tivity. The brace is removed at 6 weeks. If flexion is lessthan 901 at that stage a manipulation under anaestheticfollowed by treatment with continuous passive motionshould be considered. If the posterolateral reconstruc-tion is part of a combined procedure then the abovemay need to bemodified to fit inwith a specific regime.

RESULTSAs yet there are few reports in the literature of the re-sults of posterolateral corner reconstruction and cer-tainly no long-term series with large numbers of cases.Fanelli et al.28 reported on the use of a split biceps fe-moris tendon transfer augmentation procedure in themanagement of10 consecutive ACL/ PCL/ posterolateralcorner injuries and17 PCL /posterolateral corner recon-structions. He concluded that posterolateral stabilitywas restored in 90% of the former group and 94% ofthe latter after a follow up of1--6 years.

The use of a LCL allograft reconstruction has alsobeen reported.26 Twenty consecutive patients weretreated with Achilles tendon allografts and had afollowed up of 24--73 months. A 76% success ratewas reported with respect to knee stability andstress radiographs. Thirteen patients had concomitant

Figure 8 Lateral collateral and popliteofibular ligament reconstruction: Fixation of the grafts at the epicondyle is accomplished bycreating a tunnel approximately 25--30mm in depth.The grafts are then delivered into the femoral socket and tensioned from themedial side oftheknee.Fixationis accomplishedbyplacinganinterference fit screw1--2mmlarger thanthe drilledtunnel. Supplemen-tal fixation is accomplished if necessary by tying the passing suture over a button onthemedial aspectof the knee.It is importantthatthegraftsbe shortenedsothattheyextendonlyapproximately 20mmintothe 25 to 30mmsocketthus allowing the ability to finetunethetension.A‘bulleting’circumferential stitch aroundthe free ends facilitatespassageintothe socket.Taken from Fanelli GC,Larson RV.Practicalmanagementof posterolateral instabilityoftheknee.Arthroscopy 2002;19:5.


ruptures of their ACL, three of their PCL and three oftheir medial collateral ligaments, all were treated at thesame time as the index operation.

It is fair to say that at present interest and enthusiasmare notmatched by experience.

SUMMARYThemanagementof injuries to the posterolateral corneris both complex and challenging. A thorough under-standing of the anatomy and biomechanics of the regionis essential for diagnosis and management of these diffi-cult injuries. Instability is predominantly posterior, varusand external rotation maximal at 301 of flexion. As pos-terolateral corner injuries rarely occur in isolation greatcare should be taken to determine the presence of anyassociated injuries to the other knee ligaments, in parti-cular theACL and PCL.Conversely failure to recognise aposterolateral corner injury is likely to compromise anyreconstruction of an ACL or PCL injury.

Much has been written on the management of thiscondition however very little objective analysis of out-comes has been reported. This is largely due to difficul-ties in comparing patient cohorts due to the variablenature of the associated injuries and the use of differentsurgical techniques.

The choice of surgical technique should be based onthe nature of the specific injury causing the instability.Early reconstruction may give more favourable resultsby preventing the instability causing secondary injury tothe knee.

There is no definite reported evidence that acute re-construction of the posterolateral corner gives any bet-ter stability than reconstruction of a chronic injury.

FURTHERREADING

1. Seebacher JR, Inglis AE, Marshall JL, Warren RF. The structure of

the posterolateral aspect of the knee. J Bone Joint Surg (Am)

1982;64A:536--541.

2. Terry GC, LaPrade RF. The posterolateral aspect of the knee;

anatomy and surgical approach. Am J Sports Med 1996;24:732--

739.

3. Last RJ. The popliteus muscle and the lateral meniscus. J Bone Joint

Surg (Br) 1950;32B:93--99.

4. St.aubli H-U, Birrer S. The popliteus tendon and its fascicles at the

popliteal hiatus: gross anatomy and functional arthroscopic

evaluation with and without anterior cruciate ligament deficiency.

Arthroscopy 1990;6:209--220.

5. Tria AJ, Johnson CD, Zawadsky JP. The popliteus tendon. J Bone

Joint Surg 1989;71A:714--716.

6. Maynard MJ, Deng X, Wickiewicz TL, Warren RF. Am J Sports

Med 1996;24:311--316.

7. Gollehon DL, Torzilli PA, Warren RF. The role of the poster-

olateral and cruciate ligaments in the stability of the human knee.

J Bone Joint Surg (Am) 1987;69A:233--242.

8. Hughston JC, Jacobson KE. Chronic posterolateral rotatory

instability of the knee. J Bone Joint Surg (Am) 1985;67A:351--359.

9. Grood ES, Stowers SF, Noyes FR. Limits of movement in the

human knee. J Bone Joint Surg (Am) 1988;77A:88--97.

10. DeLee JC, Riley MB, Rockwood CA. Acute posterolateral rotatory

instability of the knee. Am J Sports Med 1983;11:199--206.

11. Daniel DM, Stone M, Barnett P, Sachs R. Use of the quadriceps

active test to diagnose posterior cruciate-ligament disruption and

measure posterior laxity of the knee. J Bone Joint Surg (Am)

1988;70A:386--391.

12. Hughston JC, Norwood LA. The posterolateral drawer test and

external recurvatum test for posterolateral rotatory instability of

the knee. Clin Orthop Rel Res 1980;147:82--87.

13. LaPrade RF, Terry GC. Injuries to the posterolateral aspect of the

knee. Am J Sports Med 1997;25:433--438.

14. Cooper DE. Tests for posterolateral instability of the knee in

normal subjects. J Bone Joint Surg (Am) 1991;73A:30--36.

15. Jakob RP, Hassler H, St.aubli HN. Observations on rotatory

instability of the lateral compartment of the knee. Acta Orth of

Scan 1981;191:1--32.

16. Galway RD, Beaupre A, MacIntosh DL. Pivot shift: a clinical sign of

symptomatic anterior cruciate insufficiency. J Bone Joint Surg (Br)

1972;54:763--764.

17. LaPrade RF, Gilbert TJ, Bollom TS, Wentorf F, Chaljub G. The

magnetic resonance imaging appearance of individual structures of

the posterolateral knee. Am J Sports Med 2000;28:191--199.

18. LaPrade RF. Arthroscopic evaluation of the lateral compartment of

knees with grade 3 posterolateral knee complex injuries. Am J

Sports Med 1997;25:596--602.

19. Baker CL, Norwood LA, Hughston JC. Acute posterolateral

rotatory instability of the knee. J Bone Joint Surg (Am)

1983;65A:614--618.

20. Baker CL, Norwood LA, Hughston JC. Acute combined posterior

cruciate and posterolateral instability of the knee. Am J Sports Med

1984;12:204-- 208.

21. Veltri DM, Warren RF. Posterolateral instability of the knee.

J Bone Joint Surg (Am) 1994;76A:460--472.

22. O’Brien SJ, Warren RF, Pavlov H, Panariello R, Wickiewicz TL.

Reconstruction of the chronically insufficient anterior cruciate

ligament with the central third of the patellar ligament. J Bone Joint

Surg (Am) 1991;73A:278--286.

23. Noyes FR, Barber-Weistin SD, Simon R. High tibial osteotomy and

ligament reconstruction in varus angulated, anterior cruciate

ligament deficient knees. Am J Sports Med 1993;21:2--12.

24. Maynard MJ, Warren RF. Surgical and reconstructive techniques

for knee dislocations. In: Jackson DW (ed). Reconstructive Knee

Surgery. New York: Raven Press, 1995;161--183.

25. Noyes FR, Barber-Westin SD. Surgical reconstruction to treat

chronic deficiency of the posterolateral complex and cruciate

ligaments of the knee joint. Am J Sports Med 1996;24:415--426.

26. Noyes FR, Barber-Westin SD. Surgical reconstruction of severe

chronic posterolateral complex injuries of the knee using allograft

tissues. Am J Sports Med 1995;23:2--12.

27. Clancy WG, Meister K, Craythorne CB. Posterolateral corner

collateral ligament reconstruction. In: Jackson DW (ed).

Reconstructive Knee Surgery. New York: Raven Press,

1995;143--159.

28. Fanelli GC, Larson RV. Practical management of posterolateral

instability of the knee. Arthroscopy 2002;19:1--8.


Documents

Falworth instabilidade póstero lat do joelho - diagn e tto