1. Current Orthopaedics (2003) 17, 223--233
2003 Elsevier Science Ltd. All rights reserved.
c
doi:10.1016/S0268 - 0890(03)00024 - 0
THE KNEE
Posterolateral instability of the knee: its diagnosis
and management
M.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 that results from injuries
tothe posterolateral stabilising structures ofthe knee.Thisinstabilityis posterior, varus
and externalrotation.Isolated posterolateralligamentousinstabilityofthe knee is how-
ever uncommon. Instability usually occurs in association with other ligamentous inju-
ries, in particular, injuries to either the anterior cruciate ligament (ACL), the
posterior cruciate ligament (PCL), or both.
The recognition and adequate management of this injury pattern is crucial, particu-
larly as anycruciateligamentreconstructionwillbe compromisedifthereis a combined
injury and repair ofthe posterolateral corner is omitted.There should always therefore
be a high degree of suspicion when examining the knee, particularly in those patients
where the mechanism of injury and symptoms are suggestive of a complex knee in-
jury 2003 Elsevier Science Ltd. All rights reserved.
.c
ANATOMY head is made up of two tendinous components, the di-
rect and the anterior arms. The direct arm inserts into
The anatomy of the posterolateral corner is complicated the posterolateral head of the fibula whilst the anterior
and variable.This has been compounded by the fact that arm attaches to the lateral edge of the fibular head. The
there are numerous descriptions of this anatomical re- short head of biceps femoris also has two tendinous in-
gion in the literature, often with different terminologies sertions.The direct arm inserts into the superior surface
being used. To simplify the description Seebacher1 di- of the fibular head just lateral to the styloid process but
vided the posterolateral corner into three layers: medial to the lateral collateral ligament (LCL). Its ante-
Layer I consists of the fascial layer, the iliotibial band rior arm extends anteriorly, medial to the LCL, and in-
(ITB) and biceps femoris (Fig. 1). The deep fascial layer of serts on to the posterior aspect of the tibial tuberosity.
the thigh, the fascia lata, inserts distally into the margins The biceps tendon therefore folds around the LCL at its
of the patella, the inferior margins of the tibial condyles insertion. Also within this layer is the common peroneal
and the head of the fibula. A vertical band-like thickening nerve, which descends inferolaterally to the biceps
of the fascia lata, the ITB, extends from the level of the femoris tendon. It then runs lateral to the lateral head
greater trochanter and passes distally down the lateral of gastrocnemius before reaching the posterior aspect
aspect of the thigh and makes up the anterior aspect of of the fibular head.
this first layer. Layer II is formed by the lateral quadriceps retinacu-
The superficial layer of the ITB crosses the lateral con- lum, the LCL and the two patellofemoral ligaments.
dyle of the femur to insert into a facet on the anterior The LCL is a round cord-like structure, approximately
surface of the lateral condyle of the tibia, Gerdy’s tuber- 5 cm long, which is attached to the lateral epicondyle of
cle. The deep layer of the ITB inserts into the lateral in- the femur and slopes inferiorly and posteriorly to insert
termuscular septum at the distal femur. into the head of the fibula. The ligament is not attached
The combined short and long heads of the biceps to either the capsule or lateral meniscus. The inferior
femoris make up the posterior aspect of Layer I.The long lateral genicular vessels and the popliteus tendon sepa-
rate it from the capsule and lateral meniscus, respec-
Correspondence to: RLA. Tel.: +44 -1753- 6330 - 40; Fax: +44 -1344 - tively. Biomechanically the LCL is attached behind the
8743- 40; Email: robin.allum@hotmail.com, msfalworth@yahoo.com axis of flexion of the femoral condyle thus becoming

2. 224 CURRENT ORTHOPAEDICS
Figure 1 A view of the right knee joint from above after removal of the right femur. Note the three layers of the lateral side and the
division of the posterolateral part of the capsule (Layer III) into deep and superficiallaminae which are separated by the lateralinferior
genicular 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.
taut and limiting extension when the knee reaches full forms part of the arcuate complex, which includes the
extension. LCL, popliteus and the lateral head of gastrocnemius.
Layer III is the deepest of the three layers of the pos- The popliteus tendon arises from a depression just be-
terolateral corner. It is composed of the joint capsule, low the epicondyle on the lateral surface of the femoral
coronary ligament, fabellofibular ligament, popliteus ten- condyle. This rope-like structure descends infero-medi-
don, arcuate ligament and the popliteofibular ligament ally, passing through a hiatus of the coronary ligament
(PFL). and inserts into the popliteal surface of the tibia above
The coronary ligament is that part of the capsule that the soleal line. Medial to the popliteus tendon is an apo-
connects the lateral aspect of the lateral meniscus to a neurotic attachment to the posterior capsule and to the
level just distal to the articular margin of the lateral tibial lateral meniscus.3 This has been termed the posterior in-
condyle.The laxity of this ligament allows for a very mo- ferior popliteomeniscal fascicle by Staubi4 but its pre-
bile meniscus. There is a hiatus in the posterolateral sence has also been refuted.5
border of the coronary ligament through which the The PFL, previously known as the short external lat-
popliteus tendon and bursa pass. This portion of the lat- eral ligament,3 also arises from the popliteus tendon. In-
eral meniscus is referred to as the bare area. deed the popliteus tendon is split into two fascicles of
The arcuate ligament is a ‘Y’ shaped structure that is nearly equal size; the first continues to form the muscu-
made up of several elements. The lateral limb of the lotendinous junction of the popliteus muscle whilst the
ligament inserts into the styloid process of the fibula. It second forms the PFL.6 This lies deep to the lateral limb
arches medially, superficial to the popliteus muscle and of the arcuate ligament and inserts into the most proxi-
tendon, to attach into the posterior joint capsule. The mal and posterior projection of the fibula with smaller
oblique popliteal ligament (the ligament of Winslow) insertions into the lateral limb of the arcuate ligament
forms the medial limb. This ligament is formed from the and the fabellofibular ligament. The inferior lateral geni-
union of the oblique popliteal expansion of the semi- culate artery separates these two latter insertions from
membranosus and the capsular arm of the posterior ob- the fibular insertions.
lique ligament, which originates from the medial side of The fabellofibular ligament arises from the lateral
the knee.2 The oblique popliteal ligament arches ante- aspect of the fabella, or in its absence, the posterior as-
riorly to insert into the posterior joint capsule overlying pect of the supracondylar process of the femur.2 It des-
the lateral femoral condyle. The arcuate ligament also cends distally and laterally, running parallel with the

3. POSTEROLATERAL INSTABILITYOF THEKNEE: ITS DIAGNOSIS AND MANAGEMENT 225
T able 1 Dynamic and static stabilisers of the postero- Varus instability
lateral corner.
In an intact knee, varus and valgus rotation is at it’s least
Structure in extension and increases with increasing flexion to 901.
Although no increase in valgus rotation was noted with
Dynamic Biceps femoris
stabilisers Popliteus* either collective or individual sectioning of the PCL, LCL
Lateral head of and the arcuate complex there was an effect on the de-
gastrocnemius * gree of varus rotation. The amount of varus rotation in-
creased by 1--41 in all angles of knee flexion when
Static Iliotibial band selective sectioning of the LCL was performed. This in-
stabilisers Lateral collateralligament* creased to 5--91 when the arcuate complex was divided
Arcuate ligament* and 14--191 when the PCL was also sectioned. Maximum
Popliteofibular ligament varus rotation was noted at 601 of knee flexion when the
Fabellofibular ligament PCL, LCL and popliteus and arcuate complex were di-
Lateral meniscus vided.7
*These structures make up the arcuate complex.
Primary internal and external rotational
instability
tendon of the long head of biceps femoris muscle before This is the degree of rotational instability recorded when
inserting into the styloid process of the fibula just medial internal or external tibial torque is applied to the knee. In
to the insertion of the short head of the biceps femoral an intact knee combined internal and external rotation
muscle. was at a maximum at 451 of knee flexion and at it’s least
Although the anatomy of the posterolateral corner at 01. No isolated or combined sectioning of the PCL,
has been described on an anatomical basis it can LCL or deep lateral structures produced any increase in
also be classified functionally with respect to the internal rotation, however changes were noted in exter-
structures that provide static and dynamic stability to nal rotation.
the knee (Table 1). Isolated sectioning of the LCL produced a small 2--31
increase of external rotation at 301, 601 and 901 of flex-
ion. An increase of 61731 was recorded with isolated
BIOMECHANICS sectioning of the arcuate complex at 901 of flexion. The
combined sectioning of the LCL and arcuate complex re-
Biomechanical analysis of the posterolateral corner sulted in an increase in external rotation at all flexion an-
can best be investigated by selective sectioning of gles but it was at its greatest at 301 of flexion. Although
ligaments in cadavaric knees. By measuring the degree isolated division of the PCL resulted in no change of ex-
of laxity after applying forces to the knee the role of ternal rotation when it was performed in association
the sectioned ligament in stabilising the knee can be with division of the LCL and arcuate complex further sig-
determined. The sequence of sectioning can also be nificant increases in external rotation were noted at 601
varied. and 901 of knee flexion.7
Posterior translation Coupled internal and external rotational
instability
The selective sectioning of the PCL and the structures
of the posterolateral corner can be used to investigate If an anterior force is applied to the tibia of an intact knee
posterior translation. Gollehon7 demonstrated that the tibia will rotate internally. Conversely, if a posterior
although division of the PCL resulted in no increase in force is applied, the tibia will rotate externally. These
anterior translation, it did result in increasing posterior movements in which motion is in a different direction to
translation with increasing knee flexion. However, it had the applied force are referred to as coupled movements.
no affect on either varus or external rotation. Selective If selective sectioning studies are performed on the
sectioning of the LCL, popliteus and arcuate ligament LCL, the deep structures, or the PCL there is no increase
complex resulted in no significant increase in posterior in internal rotation when an anterior force is applied to
translation between 01 and 301 of flexion when com- the tibia. This however is not the case with a posterior
pared to isolated PCL sectioning. However, if all the force. The selective sectioning of the LCL and deep
structures of the posterolateral corner and the PCL structures recorded a significant increase in the
were divided there is a significant increase in the poster- external rotation. Isolated section of PCL however elimi-
ior translation between 01 and 901 when compared to nated the coupled external rotation but had no effect on
selective sectioning. internal rotation when an anterior force was applied.

4. 226 CURRENT ORTHOPAEDICS
Furthermore, when the PCL, LCL and other deep common complaint with hyperextension often occur-
structures were sectioned there was an increase in the ring. Difficulties ascending and descending stairs are fre-
external rotation recorded after the application of a quently reported as the knee cannot be locked in full
posterior force when compared with the change extension.The presence of medial joint line pain may also
measured when the LCL and deep ligament complex be a feature and may result in a misdiagnosis of medial
were sectioned, however this was not significant.7 meniscal pathology.8 In cases where knee dislocation
The interpretation of this biomechanical data is im- has been reported common peroneal nerve lesions may
portant as it enables the clinician to accurately assess be present.
different ligamentous structures of the knee at different
degrees of knee flexion. The isolated sectioning, or in- Signs
jury, of the PCL will result in an increase in the posterior
translation of the knee in all degrees of knee flexion, but In the acute phase there may be swelling and induration
it is maximal at between 701 and 901. The continuity of over the posterolateral corner. However, in the event of
the PCL is therefore best tested with the knee in 901 of a capsular disruption an effusion may not be present. In
flexion. cases of direct trauma contusions and bruising may be
Isolated sectioning of the LCL shows maximal varus present over the anteromedial aspect of the proximal
rotation at 301 of knee flexion. Similarly, isolated injury tibia.
to 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 of DIAGNOSTIC TESTS
flexion. A posterolateral corner injury can therefore be
best determined by testing the knee at both 301 and 901 Examination of the acute knee can be difficult due to as-
of flexion. If there is an increase in primary varus rota- sociated swelling, pain and muscle guarding.
tion and external rotation at 301, but not 901 of rotation, Examination of the standing patient may show the ti-
then a posterolateral corner injury is confirmed. If bia to be positioned with increased recurvatum, a varus
increases are noted at both 301 and 901 then both a deformity and internal rotation. Furthermore, as the pa-
posterolateral corner and PCL injury have occurred. tient’s gait is assessed varus thrust may be noted. This
presents as an apparent lateral displacement of the tibia
and occurs due to the external rotation of the tibia
during the stance phase of gait when the knee is in full
INJURY MECHANISM extension.
Posterolateral knee injuries commonly occur following A more accurate knee examination may be achieved in
mechanisms involving high-energy forces. Both direct the anaesthetised patient, particularly in those with an
and indirect mechanisms have been reported.8 A direct acute knee injury. Generalised ligamentous laxity may be
blow to the anteromedial aspect of the knee or proximal present and therefore the opposite non-injured knee
tibia, with the knee in full extension is commonly de- should also be examined prior to any assessment of the
scribed. This often occurs with pedestrians involved in injured side.
road traffic accidents or in contact sports where the
knee is forced into a varus deformity with associated hy- Posterior drawer test
perextension and external rotation of the tibia.
Grood9 demonstrated that at 51 of flexion most of Anteroposterior translation should be examined at both
the restraint from the lateral capsule was due to the pos- 301 and 901 of flexion. If posterior translation is noted at
terior arcuate complex. Posterolateral corner injuries 301 but not at 901 then a posterolateral injury is likely. If
may therefore also occur after a varus force is applied with posterior translation is noted at both 301 and 901 then
the knee in varying degrees of flexion.8, 10 Knee disloca- an isolated PCL or combined injury is present.
tion and indirect mechanisms involving twisting injuries
to the knee may also result in posterolateral instability. Quadriceps active test
The quadriceps active test is used to demonstrate the
presence of posterior tibial subluxation and is therefore
CLINICAL ASPECTS important in establishing the presence of an associated
PCL injury. With a relaxed patient in a supine position
Symptoms
the hip and knee are flexed to 451 and 901, respectively.
Unlike ACL injuries, where instability may be present A gentle quadriceps contraction should be undertaken
only during sporting activities, PCL and posterolateral to shift the tibia without extending the knee by fixing
insufficiencies often result in instability during everyday the position of the foot. In a normal knee the patellar
activities. Instability whilst the knee is in extension is a tendon is angled slightly posteriorly and there is

5. POSTEROLATERAL INSTABILITYOF THEKNEE: ITS DIAGNOSIS AND MANAGEMENT 227
Figure 2 The 901 quadriceps active test.Keeping the eyes at
the level of the subject’s flexed knee, the examiner rests the
elbow on the table and uses the ipsilateral hand to support the
subject’s thigh and to confirm thatthe thigh muscles are relaxed.
The foot is stabilised by the examiner’s other hand, and the sub-
ject is asked to slide the foot gently down the table.Tibial displa-
cement resulting fromthe quadriceps contractionis noted.Taken
from Daniel DM, Stone M,Barnett P Sachs R.Use of the quadri-
,
ceps active test to diagnose posterior cruciate--ligament disrup-
tion and measure posterior laxity of the knee. J Bone Joint Surg
(Am) 1988;70A:387.
Figure 3 External rotational recurvatum test demonstrating
11
posterolateral rotatory instability in the right knee with its rela-
therefore no resultant anterior shift. (Fig. 2) If the PCL tive tibia vara.
is ruptured the patellar tendon becomes angled ante-
riorly because of posterior subluxation of the tibia and a
contraction of the quadriceps results in a slight anterior
shift of the tibia. This is not reproduced in an isolated hip and knee are flexed to 451 and 801, respectively. The
posterolateral corner injury. tibia is then externally rotated by 151 and a posterior
drawer test is performed with the foot held in a fixed
Varus stress test position. If the lateral tibial condyle externally rotates re-
lative to the lateral femoral condyle the test is consid-
A varus stress test assesses the degree of lateral instabil- ered positive. This manoeuvre may be most easily
ity in one plane. This can be performed at 01 and 301 reproduced by using the examiners thumbs to mark the
whilst the ankle is stabilised. Instability at 301 of flexion is patellar tendon and tibial tubercle. (Fig. 4) As a posterior
due to an isolated posterolateral corner injury. If the test force is applied the tibial tubercle will rotate posterolat-
is positive in full extension then a posterolateral corner erally in a posterolateral deficient knee.
and associated cruciate injury is present. It has been shown in biomechanical studies7 that
external rotation of the knee is normally coupled with
External rotation recurvatum test posterior translation. Furthermore, where excessive
external rotation is noted injuries to both the postero
Hughston first described this test in1980.12 The patient is
placed in a supine position and encouraged to relax the lateral corner and the PCL should be suspected. However,
when the posterolateral drawer test is repeated in 301
quadriceps. The great toe of each foot is then grasped
of flexion, a positive result can be considered to be more
and the legs are lifted off the examination couch. If pos-
specific for an isolated posterolateral corner injury.13
terolateral instability is present there will be varus and
hyperextension deformities at the knee. The tibia will
also fall into external rotation (Fig. 3). Tibial external rotation test (Dial)
This test is used to determine the degree of external ro-
Posterolateral external rotation drawer test
tation of the tibia relative to the femur at both 301 and
This test is used to test the integrity of the arcuate liga- 900 of flexion. Although this can be performed in the su-
ment complex.12 With the patient in a supine position the pine position we prefer examining the patient prone

6. 228 CURRENT ORTHOPAEDICS
Figure 4 Posterolateral drawer test: (A) demonstrates the starting position; (B) illustrates a positive posterolateral drawer test with
posterior and external rotation of the lateral tibial condyle.
where a more reproducible and quantifiable measure- repeated under general anaesthesia. However, the re-
ment can be made.The degree of external rotation is re- versed pivot shift test is not a specific test.14, 15 Positive
ferenced from the medial border of the foot. Once the tests can be found in individuals with increased general-
knee is held in the appropriate degree of flexion the ex- ised ligamentous laxity and mild varus alignment of the
aminer forcibly externally rotates the foot. The degree knee. The contralateral side should therefore always be
of external rotation is determined by measuring the an- examined to exclude false positives.
gle between the medial border of the foot and the verti- One can link the clinical deformity to the anatomical
cal axis.This measurement should be compared with the injury. Injuries to the LCL are demonstrated by increased
contralateral side (Fig. 5). The nature of the test is such varus instability at 301. External rotation at 301 is consis-
that the rotation noted at the time of examination may tent with an injury to the popliteus, arcuate ligament,
not be solely due to the degree of tibial rotation. The PFL and fabellofibular ligament. Hyperextension and an
joints of the midfoot, hindfoot, and ankle can all influ- increased varus deformity at 01 indicates a posterolat-
ence the degree of external rotation,14 comparison with eral capsule and PCL disruption (Table 2).
the contralateral side is therefore imperative.
Reversed pivot shift test
The reversed pivot shift test is performed by extending
the knee from a position of 70--801 whilst the foot is held
in external rotation and a valgus strain is applied to the
knee.15 In a posterolateral deficient knee the lateral tibial
plateau will be subluxed posteriorly relative to the lateral
femoral condyle whilst the knee is in flexion.This can be
recognised as posterior sag of the proximal tibia. As the
knee is extended the examiner should be able to feel and
observe that the lateral tibial plateau abruptly shifts into
its reduced position at approximately 20--301 of flexion.
This sudden shift or jerk is considered a positive reversed
pivot shift and will reproduce the patients discomfort
and simulate their feeling of the knee giving way.This re-
versed pivot shift therefore describes the shift of the lat-
Figure 5 Illustration ofthe prone externalrotationtest, which
eral tibial plateau in the opposite direction from the true is performed at both 301 and 901 of knee flexion.Forceful exter-
pivot shift sign.16 nalrotationis exerted by the examiner and the amount of exter-
As in the pivot shift test the success of this test is de- nal rotation is measured by comparison of the axis of the medial
pendent on the skill of the examiner and on the ability of border of the foot with the femur. (Reprinted from: Veltri DM,
the patient to relax his or her muscles. More accurate Warren RFIsolated and combined posteriorcruciateligamentin-
findings may therefore be achieved when the test is juries.J Am Acad Orthop Surg1993;1:70.)

7. POSTEROLATERAL INSTABILITYOF THEKNEE: ITS DIAGNOSIS AND MANAGEMENT 229
Table 2 Specificity of clinical examination. MANAGEMENT
Test PCL PLC PCL/ PLC The need to repair the structures of the posterolateral
corner depends on the nature and extent of injury. In
Posterior drawer at 301 7 + ++
flexion those patients who have evidence of an isolated post-
Posterior drawer at 901 + À ++ erolateral corner injury, but have no significant symp-
flexion toms or functional impairment, conservative measures
Quadriceps active + À + may prove successful.19 Initial immobilisation for 2--4
Varus stress at 01 flexion À 7 + weeks is followed by a rehabilitation programme.
Varus stress at 301 flexion* À + ++ Surgical reconstruction should be performed in those
External rotation À + ++ patients where there is functional impairment and clear
recurvatum* symptoms associated with posterolateral rotatory in-
Posterolateral external À + ++ stability. The timing of surgery is however controversial.
rotation drawer at
It has been suggested that acute repair of the posterolat-
301flexion*
eral corner is more successful than chronic repair10, 19--21
Posterolateral external 7 7 ++
rotation drawer at 90 o although there is some degree of uncertainty regarding
flexion this. Surgery should however, usually be deferred for
Tibial external rotation test À + ++ about 2 weeks or until the acute inflammatory phase of
(Dial) at 30o flexion* the injury has subsided. Care should be taken during
Tibial external rotation test 7 + ++ acute arthroscopic procedures, as there is a risk of com-
(Dial) at 90o flexion partment syndrome due to the leakage of irrigation fluid
Reversed pivot shift* À + ++ through a capsular defect.Furthermore, concomitant in-
*Denotes a test specific for posterolateral injury. juries to the PCL or ACL may be present and these
should be reconstructed prior to, or concurrently with,
the posterolateral corner. Indeed, failure to recognise
and repair posterior lateral corner injuries when recon-
INVESTIGATION structing the ACL is a common cause of failure of ACL
reconstruction.22
Radiography Limb alignment and a pathological gait cannot be cor-
Plain radiographs utilising a standing anteroposterior rected with a soft-tissue procedure alone and hence the
view and lateral view can be used to demonstrate evi- assessment of limb alignment is crucial in the manage-
dence of osteoarthritis and varus malalignment. The de- ment of all patients with chronic posterolateral instabil-
gree of varus alignment may be evaluated with a long leg ity. Patients who demonstrate a lateral thrust in the
standing anteroposterior film and varus stress films. stance phase of gait and who have a varus knee deformity
require a proximal valgus tibial osteotomy.23 The valgus
osteotomy may be performed either before a posterolat-
MRI eral reconstruction or as a combined procedure. Failure
Magnetic resonance imagining utilisingT1 imaging techni- to correct the limb alignment prior to reconstruction is
ques can prove helpful in the assessment of posterolat- likely to result in failure. When performed prior to pos-
eral knee injuries.17 Although its use is no substitute for terolateral reconstruction some of the symptoms of in-
an adequate examination in can be a useful adjunct to stability may resolve such that a further reconstructive
clinical examination, particularly in the assessment of an procedure is no longer required.
acute injury.
Acute repair
Arthroscopy
Where possible direct repair of the posterolateral
A full assessment of the knee is beneficial prior to plan- structures should be attempted. Access is achieved via a
ning reconstruction of the posterolateral deficient knee. curvilinear skin incision. A detailed assessment of the
This may be particularly relevant in chronic insufficiency injured structures can then be made and if the tissues
where associated meniscal and articular cartilage injury are of good quality primary repair can be attempted.
may be evident. The cruciate ligaments can also be as- Avulsion injuries of the popliteus tendon and the lat-
sessed. Evidence of posterolateral insufficiency includes eral collateral and arcuate ligaments may occur either
a positive lateral compartment ‘drive through sign’18 and proximally or distally. These can be repaired with either
the presence of greater than 1cm of lateral joint laxity direct suturing to the periosteum or through transoss-
with the application of varus stress.The popliteus tendon eous drill holes.19 If necessary these repairs may be aug-
can be also assessed, particularly in the acute injury. mented with either staples or screws and soft-tissue

8. 230 CURRENT ORTHOPAEDICS
washers. If the popliteus tendon is stretched but intact, femoral condyle with a screw and washer.21 By placing a
it can be retensioned by detaching its femoral insertion Kwire at the proposed position the graft can be draped
with a bone plug and then recessing it into a femoral drill over the wire and the knee flexed and extended. The
hole.21 Midsubstance injuries can be repaired primarily by isometric point is where minimal movement of the
using Kessler suture techniques. graft is noted relative to the wire during flexion and
If the repair is insufficient to correct the instability, extension.
augmentation is warranted.
Advancement
Augmentation
Proximal advancement of the posterolateral structures
For popliteus tendon injuries this can be achieved by can be considered in cases of chronic instability where
using a strip of the ITB which is harvested whilst main- the PFL and LCL are lax but intact, and where the soft
taining its tibial insertion to Gerdy’s tubercle. It is then tissues are felt to be of satisfactory thickness. A LCL
fed through an anteroposterior tibial tunnel and sutured. width of 5--7 mm and thickness of at least 3--4 mm is the
If a popliteus tendon injury occurs at the popliteal liga- minimum requirement for successful advancement; the
ment or the popliteus musculotendinous junction the in- presence of poor quality scar tissue is a contraindica-
jury may be treated with a tenodesis of the popliteus tion.25
tendon to the posterolateral corner of the tibia.24 The The surgical approach is made through either a
reconstruction should be tensioned in 601 of flexion and straight lateral or curvilinear incision. An incision is made
with the lateral tibia drawn forward to its neutral along the anterior border of the ITB and the structures
position. of the posterolateral corner exposed. A 10 mm vertical
If the PFL cannot be repaired it may be augmented by incision is made in the joint capsule along the anterior
using biceps femoris. A central slip of the tendon is har- border of the popliteus tendon. The size of the popli-
vested whilst preserving its distal insertion in the fibular teus--arcuate complex is then defined and a superior in-
head. It is tubed, sutured to the posterior aspect of the cision, superior and proximal to the LCL, is made along
fibula and then passed under the remaining biceps ten- with a posterior incision parallel to the lateral gastrocne-
don before it is fixed to the lateral aspect of the femur mius tendon.
with a screw and washer21 (Fig. 6B). The intended advancement site is prepared by decor-
Midsubstance injuries of the LCL may also be augmen- ticating an area proximal to the LCL with the knee in
ted in a similar way with a central slip of biceps tendon 301 of flexion and neutral rotation. The posterolateral
which is fixed to the isometric point of the lateral complex is osteotomised, advanced and fixed to the
Figure 6 Biceps tendon augmentation of the posterolateral corner usually involves moving the entire distal tendon to the femur and
securing it with a screw and ligament washer (A); the authors prefer to anatomically reconstructthe popliteofibular ligament with the
central slip of the biceps tendon, which is then tubed and sutured to the posterior fibula (B).The strip is then passed under the remain-
ing biceps tendon and secured to the lateral femur with a screw and ligament washer. Taken from Veltri DM,Warren RF. Operative
treatment of posterolateral instability of the knee.Clin Sports Med1994;13:619 .

9. POSTEROLATERAL INSTABILITYOF THEKNEE: ITS DIAGNOSIS AND MANAGEMENT 231
rupted PFL and LCL.The biceps tendon is tenodesed be-
tween the isometric point on the lateral femoral
epicondyle and the fibular head. This can be used as an
isolated technique or in combination with primary re-
pairs, advancement or reefing procedures.
A lateral curvilinear incision is used to mobilise the bi-
ceps muscle and tendon. The distal 5 cm of the muscle
should be removed from the medial side of the tendon
thus preventing any muscle interposition between the
lateral femoral condyle and tendon.To further aid healing
a bony trough is made by decorticating the lateral femor-
al condyle where the tendon will sit.Within this trough a
Kirschner wire is positioned at the isometric point of the
lateral femoral condyle. This is positioned just superior
to the proximal edge of the insertion of the fibular collat-
eral ligament.The biceps tendon can then be brought un-
derneath the iliotibial tract and hooked around the
Kirschner wire. A large cannulated screw and soft-tissue
washer is then used to hold the tendon (Fig. 6A). The
screw should be tightened with the knee internally ro-
tated and flexed to 301.
Figure 7 Advancement of the posterolateral structures. The Several variations to this technique have also been
posterolateral capsule is incised horizontally for 10 --15 mm at its suggested where only a portion of the biceps tendon is
posterior femoral attachment just above the femoral condyle. utilised. One such technique to augment LCL injuries
The release of the capsule is continued distally for 10 --15 mm
was described earlier.21 Biomechanically it acts by creat-
under direct visualisation. A limited incision into the posterome-
dial capsule may be necessary to allow proximal advancement
ing a new PFL.
of the entire posterolateral complex. Taken from Noyes FR, The use of this technique is dependent on the preser-
Barber-Westin SD. Surgical reconstruction to treat chronic defi- vation of the biceps femoris insertion into the fibular
ciency of the posterolateral complex and cruciate ligaments of head, an intact tibiofibular joint and intact posterolateral
the knee joint. Am J Sports Med1996;24:419 . capsular attachments to the common biceps tendon.
prepared donor site using staples and/or cancellous bone Lateral collateralligament and popliteofibular
screws (Fig. 7). This results in the ligamentous complex reconstruction
being retensioned. Larson28 described a technique where a free semitendi-
nosus tendon graft is used to reconstruct the PFL and
Reconstruction LCL. The semitendinosus graft is harvested from the
ipsilateral knee in the standard fashion (the authors have
Many different techniques have been described for the adapted this technique to use both semitendinosus and
reconstruction of the posterolateral corner. Autografts, gracilis to produce two strands in each limb).
allografts and synthetic materials have all been sug- A curvilinear incision is used to expose the lateral fe-
gested.26 The authors prefer hamstrings as a primary moral condyle and fibular head.
graft choice. Based on the principle that a graft placed from the
Clearly the aim of reconstructive surgery is to prevent posterior aspect of the fibular head to the lateral femor-
instability through a wide range of movement.To achieve al condyle is in an isometric position an anterior--poster-
this grafts should be placed at the isometric position. ior drill hole is placed in the fibular head to accommodate
Structures that link the posterior aspect of the fibular the graft.The isometric point on the lateral femoral con-
head to the lateral femoral condyle are isometric, how- dyle is determined as described earlier under augmenta-
ever, techniques that utilise the posterolateral aspect of tion.Once it has been located a socket of 30 mm is drilled
the tibia are not. If non-isometric grafts are used the to accommodate the graft ends. The graft is then fed
graft will not remain tensioned during a normal range of through the drill hole in the head of the fibula and its ends
knee movement. passed beneath the biceps tendon and ITB .The graft ends
are shortened to allow 20 mm penetration into the fe-
Biceps tenodesis moral socket and a passing suture is passed through the
Clancy27 introduced a biceps tenodesis procedure in socket to the medial side of the knee. The prepared
which the biceps tendon is used to reconstruct a dis- grafts are then delivered into the socket, tensioned from

10. 232 CURRENT ORTHOPAEDICS
the medial side of the knee and fixed with a soft-tissue bearing as pain permits. At 2 weeks a hinged brace is ap-
interference screw (Fig. 8). plied which protects the knee from translation, rotation
This method of reconstruction is such that the ante- and varus/valgus forces. Full weight bearing is permitted
rior band of the graft reconstructs the LCL and the pos- in the brace. No restriction is placed on active and pas-
terior band reconstructs the PFL, thus restoring the sive ranges of movement or quadriceps and hamstring ac-
anatomy, biomechanics and stability of the posterolat- tivity. The brace is removed at 6 weeks. If flexion is less
eral corner. than 901 at that stage a manipulation under anaesthetic
This procedure can be modified in cases where there followed by treatment with continuous passive motion
is minimal varus laxity. In such cases the anterior band should be considered. If the posterolateral reconstruc-
can be redirected through a parallel anteroposterior drill tion is part of a combined procedure then the above
hole in the fibular head. This double graft then extends may need to be modified to fit in with a specific regime.
from the posterior fibular head to the lateral femoral
condyle where it can be fixed in the same manner.
There are many variations of the previously described
technique. However, the aim remains the same, to pro-
RESULTS
vide posterolateral stability by creating tissue bands be- As yet there are few reports in the literature of the re-
tween the lateral femoral condyle and the fibular head or sults of posterolateral corner reconstruction and cer-
posterolateral tibia. Veltri and Warren21 describe one tainly no long-term series with large numbers of cases.
such technique where either a split patellar tendon auto- Fanelli et al.28 reported on the use of a split biceps fe-
graft or Achilles tendon allograft is used to reconstruct moris tendon transfer augmentation procedure in the
both components of the popliteus. A tunnel is created in management of10 consecutive ACL/ PCL/ posterolateral
the lateral femoral epicondyle into which the bone plug corner injuries and17 PCL / posterolateral corner recon-
of the graft is inserted and fixed. The graft is then split structions. He concluded that posterolateral stability
into two distally and each end is placed and fixed in ante- was restored in 90% of the former group and 94% of
roposterior fibular head and tibial tunnels. the latter after a follow up of1--6 years.
The use of a LCL allograft reconstruction has also
been reported.26 Twenty consecutive patients were
treated with Achilles tendon allografts and had a
REHABILITATION followed up of 24--73 months. A 76% success rate
For the first 2 weeks following surgery the knee is was reported with respect to knee stability and
rested in an extension splint, mobilising partial weight stress radiographs. Thirteen patients had concomitant
Figure 8 Lateral collateral and popliteofibular ligament reconstruction: Fixation of the grafts at the epicondyle is accomplished by
creating a tunnel approximately 25--30 mm in depth. The grafts are then delivered into the femoral socket and tensioned from the
medial side ofthe knee.Fixation is accomplished by placing aninterference fit screw1--2 mmlarger than the drilled tunnel. Supplemen-
tal fixation is accomplished if necessary by tying the passing suture over a button on the medial aspect of the knee.It is important that
the grafts be shortened so thatthey extend only approximately 20 mmintothe 25 to 30 mm socketthus allowing the ability to fine tune
the tension. A‘bulleting’circumferential stitch around the free ends facilitates passage into the socket.Taken from Fanelli GC,Larson RV.
Practical management of posterolateral instability of the knee. Arthroscopy 2002;19:5.

11. POSTEROLATERAL INSTABILITYOF THEKNEE: ITS DIAGNOSIS AND MANAGEMENT 233
ruptures of their ACL, three of their PCL and three of 7. Gollehon DL, Torzilli PA, Warren RF. The role of the poster-
their medial collateral ligaments, all were treated at the olateral and cruciate ligaments in the stability of the human knee.
same time as the index operation. J Bone Joint Surg (Am) 1987;69A:233--242.
8. Hughston JC, Jacobson KE. Chronic posterolateral rotatory
It is fair to say that at present interest and enthusiasm instability of the knee. J Bone Joint Surg (Am) 1985;67A:351--359.
are not matched by experience. 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
SUMMARY 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
The management of injuries to the posterolateral corner active test to diagnose posterior cruciate-ligament disruption and
is both complex and challenging. A thorough under- measure posterior laxity of the knee. J Bone Joint Surg (Am)
1988;70A:386--391.
standing of the anatomy and biomechanics of the region 12. Hughston JC, Norwood LA. The posterolateral drawer test and
is essential for diagnosis and management of these diffi- external recurvatum test for posterolateral rotatory instability of
cult injuries. Instability is predominantly posterior, varus the knee. Clin Orthop Rel Res 1980;147:82--87.
and external rotation maximal at 301 of flexion. As pos- 13. LaPrade RF, Terry GC. Injuries to the posterolateral aspect of the
terolateral corner injuries rarely occur in isolation great knee. Am J Sports Med 1997;25:433--438.
14. Cooper DE. Tests for posterolateral instability of the knee in
care should be taken to determine the presence of any normal subjects. J Bone Joint Surg (Am) 1991;73A:30--36.
associated injuries to the other knee ligaments, in parti- .
15. Jakob RP, Hassler H, Staubli HN. Observations on rotatory
cular the ACL and PCL.Conversely failure to recognise a instability of the lateral compartment of the knee. Acta Orth of
posterolateral corner injury is likely to compromise any Scan 1981;191:1--32.
reconstruction of an ACL or PCL injury. 16. Galway RD, Beaupre A, MacIntosh DL. Pivot shift: a clinical sign of
symptomatic anterior cruciate insufficiency. J Bone Joint Surg (Br)
Much has been written on the management of this 1972;54:763--764.
condition however very little objective analysis of out- 17. LaPrade RF, Gilbert TJ, Bollom TS, Wentorf F, Chaljub G. The
comes has been reported. This is largely due to difficul- magnetic resonance imaging appearance of individual structures of
ties in comparing patient cohorts due to the variable the posterolateral knee. Am J Sports Med 2000;28:191--199.
nature of the associated injuries and the use of different 18. LaPrade RF. Arthroscopic evaluation of the lateral compartment of
knees with grade 3 posterolateral knee complex injuries. Am J
surgical techniques. Sports Med 1997;25:596--602.
The choice of surgical technique should be based on 19. Baker CL, Norwood LA, Hughston JC. Acute posterolateral
the nature of the specific injury causing the instability. rotatory instability of the knee. J Bone Joint Surg (Am)
Early reconstruction may give more favourable results 1983;65A:614--618.
by preventing the instability causing secondary injury to 20. Baker CL, Norwood LA, Hughston JC. Acute combined posterior
cruciate and posterolateral instability of the knee. Am J Sports Med
the knee. 1984;12:204-- 208.
There is no definite reported evidence that acute re- 21. Veltri DM, Warren RF. Posterolateral instability of the knee.
construction of the posterolateral corner gives any bet- J Bone Joint Surg (Am) 1994;76A:460--472.
ter stability than reconstruction of a chronic injury. 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.
FURTHER READING 23. Noyes FR, Barber-Weistin SD, Simon R. High tibial osteotomy and
ligament reconstruction in varus angulated, anterior cruciate
1. Seebacher JR, Inglis AE, Marshall JL, Warren RF. The structure of ligament deficient knees. Am J Sports Med 1993;21:2--12.
the posterolateral aspect of the knee. J Bone Joint Surg (Am) 24. Maynard MJ, Warren RF. Surgical and reconstructive techniques
1982;64A:536--541. for knee dislocations. In: Jackson DW (ed). Reconstructive Knee
2. Terry GC, LaPrade RF. The posterolateral aspect of the knee; Surgery. New York: Raven Press, 1995;161--183.
anatomy and surgical approach. Am J Sports Med 1996;24:732-- 25. Noyes FR, Barber-Westin SD. Surgical reconstruction to treat
739. chronic deficiency of the posterolateral complex and cruciate
3. Last RJ. The popliteus muscle and the lateral meniscus. J Bone Joint ligaments of the knee joint. Am J Sports Med 1996;24:415--426.
Surg (Br) 1950;32B:93--99. 26. Noyes FR, Barber-Westin SD. Surgical reconstruction of severe
.
4. Staubli H-U, Birrer S. The popliteus tendon and its fascicles at the chronic posterolateral complex injuries of the knee using allograft
popliteal hiatus: gross anatomy and functional arthroscopic tissues. Am J Sports Med 1995;23:2--12.
evaluation with and without anterior cruciate ligament deficiency. 27. Clancy WG, Meister K, Craythorne CB. Posterolateral corner
Arthroscopy 1990;6:209--220. collateral ligament reconstruction. In: Jackson DW (ed).
5. Tria AJ, Johnson CD, Zawadsky JP. The popliteus tendon. J Bone Reconstructive Knee Surgery. New York: Raven Press,
Joint Surg 1989;71A:714--716. 1995;143--159.
6. Maynard MJ, Deng X, Wickiewicz TL, Warren RF. Am J Sports 28. Fanelli GC, Larson RV. Practical management of posterolateral
Med 1996;24:311--316. instability of the knee. Arthroscopy 2002;19:1--8.