Popliteofibular Ligament The popliteofibular ligament represents a direct static attachment of the popliteus tendon from the posterior aspect of the fibular head to the anterior aspect o
Trang 1Injuries involving the posterolateral
structures of the knee are significantly
less common than those affecting the
medial or anterolateral structures,
but may result in greater degrees of
disability The overall incidence of
acute posterolateral rotatory
instabil-ity (PLRI) has been reported to be
less than 2% of all acute ligamentous
knee injuries.1 Because the complex
anatomy and biomechanics of the
posterolateral structures are not
com-pletely understood, PLRI of the knee
represents a challenging diagnostic
and therapeutic problem for the
orthopaedic surgeon
Historically, PLRI has been
de-fined as the instability pattern that
results from an injury to the arcuate
ligament complex It has been
pos-tulated that the lateral tibial plateau
externally rotates around the axis of
the intact posterior cruciate
liga-ment (PCL) and subluxates
posteri-orly in relation to the lateral
fe-moral condyle.2 This concept of the
PCL as the center of rotation of the
knee has been challenged; it is now believed that a coupled relationship exists between the posterolateral structures and the cruciate liga-ments As a result, a high incidence
of combined injury patterns is observed clinically, including an-terolateral and anteromedial insta-bility in addition to PLRI Hugh-ston et al2 observed that 12 of 28 patients (43%) with chronic PLRI exhibited combined injury patterns
Baker et al3 observed a similar trend in 10 (59%) of 17 patients, as did DeLee et al1 in 22 (65%) of 34 patients and Hughston and Jacob-son4 in 77 (80%) of 96 patients
Thus, concurrent ligamentous in-juries in other areas of the knee should be suspected in cases of acute and chronic PLRI
Anatomy
There is a close structural relation-ship among the structures of the
posterolateral corner of the knee Some studies have suggested that it
is impossible for an isolated popli-teus tendon injury to occur without associated weakening of other components of the posterolateral complex.5 The overall functional and clinical significance of these interrelated structures is not yet completely understood Hughston
et al2defined the arcuate ligament complex as the functional tendi-nous and ligamentous complex consisting of the lateral collateral ligament (LCL), the arcuate liga-ment, the popliteus muscle and tendon, and the lateral head of the gastrocnemius These constituents form a sling that functions stati-cally and dynamistati-cally to control rotation of the lateral tibiofemoral articulation
Dr Chen is Chief Resident Physician, Department of Orthopaedic Surgery, Hospital for Joint Diseases, New York Dr Rokito is Assistant Director, Sports Medicine Service, Department of Orthopaedic Surgery, Hospital for Joint Diseases Dr Pitman is Director, Sports Medicine Service, Department of Orthopaedic Surgery, Hospital for Joint Diseases.
Reprint requests: Dr Chen, Department of Orthopaedic Surgery, Hospital for Joint Diseases, 301 East 17th Street, New York, NY 10003.
Copyright 2000 by the American Academy of Orthopaedic Surgeons.
Abstract
Isolated posterolateral rotatory instability of the knee is an uncommon injury
pattern that may result in significant degrees of functional disability This
in-jury complex can be a challenging diagnostic and therapeutic problem for the
orthopaedic surgeon The presence of associated ligamentous and soft-tissue
injuries, resulting in combined instability patterns, further complicates
man-agement The results of recent research have enhanced our understanding of the
complex anatomy and biomechanics of the posterolateral aspect of the knee.
Numerous surgical techniques have been described for both repair and
recon-struction of the injured posterolateral structures; however, long-term functional
results have been only moderately successful.
J Am Acad Orthop Surg 2000;8:97-110
Rotatory Instability of the Knee
Frank S Chen, MD, Andrew S Rokito, MD, and Mark I Pitman, MD
Trang 2Seebacher et al6developed a
three-layer concept of the posterolateral
structures (Fig 1) Layer I, the most
superficial layer, consists of the
ilio-tibial band with its expansion
ante-riorly and the superficial portion of
the biceps femoris with its expansion
posteriorly The peroneal nerve lies
deep and posterior to the biceps
ten-don at the level of the distal femur
Layer II consists of the quadriceps
retinaculum anteriorly and the
pa-tellofemoral ligaments posteriorly
The most important and deepest
layer, layer III, is composed of (1) the
lateral joint capsule and coronary
ligament, (2) the popliteus tendon,
(3) the LCL, and (4) the fabellofibular
and arcuate ligaments (Fig 2) There
is significant anatomic variability
in the structures of this deepest layer
The arcuate and fabellofibular
liga-ments are both present in
approxi-mately 67% of patients The
fabello-fibular ligament is present alone in
20% of casesÑusually denoted by
radiographic evidence of a large
fa-bella The arcuate ligament is
pres-ent alone in the remaining 13% of the
population, as suggested by the
absence of the fabella or its
cartilagi-nous remnant.6
Iliotibial Band
The iliotibial band, which runs
between the supracondylar tubercle
on the femur and GerdyÕs tubercle
on the proximal tibia, is an
impor-tant stabilizer of the lateral
com-partment The most important
por-tion of this structure acts as an
accessory anterolateral ligament.7
During knee flexion, the iliotibial
band becomes tight and moves
pos-teriorly, exerting an external
rota-tional and backward force on the
lateral tibia During knee
exten-sion, it moves anteriorly and is thus
spared in most cases of varus stress
and posterolateral injury
Lateral Collateral Ligament
The LCL originates proximally
on the lateral femoral condyle and
inserts on the fibular head, rein-forcing the posterior third of the capsule The LCL is the primary static restraint to varus stress of the knee.1,8 In addition, the LCL also provides resistance to external rota-tion Biomechanical studies have shown that more than 750 N of force is required to cause failure of the LCL.8 Isolated injuries to the LCL are uncommon and usually oc-cur in conjunction with injuries to other ligamentous and soft-tissue structures
Popliteus
The obliquely oriented popli-teus, which originates from the posterior aspect of the tibia and passes through a hiatus in the coro-nary ligament to insert onto the lat-eral femoral condyle, reinforces the posterior third of the lateral cap-sule and forms the lower part of the floor of the popliteal fossa.9 The popliteus also possesses at-tachments to the lateral meniscus
in most of the population, poten-tially contributing to the dynamic stability of this structure Electro-myographic studies have shown that the popliteus plays a major role in both dynamic and static sta-bilization of the lateral tibia on the femur, including restriction of pos-terior tibial translation, restriction
of external and varus rotation of the tibia, and dynamic internal rotation of the tibia
Popliteofibular Ligament
The popliteofibular ligament represents a direct static attachment
of the popliteus tendon from the posterior aspect of the fibular head
to the anterior aspect of the lateral femoral epicondyle.9,10 It provides
a significant share of the overall mechanical resistance to posterior tibial translation, external rotation, and varus rotation; a force of more than 400 N is required to cause fail-ure of this ligament.8,10 In one study,10it was present in 10 of 11
Figure 1 Coronal section of the knee illustrates the three-layer concept of the anatomy of the posterolateral structures, as described by Seebacher et al (Adapted with permission from Seebacher JR, Inglis AE, Marshall JL, Warren RF: The structure of the posterolateral
aspect of the knee J Bone Joint Surg Am 1982;64:536-541.)
Prepatellar bursa (I)
Patellar retinaculum (II) Iliotibial tract (I) Lateral meniscus Joint capsule (III) Popliteus tendon (III)
Popliteus
Fibular head
Arcuate ligament (III) Ligament of
Wrisberg
Oblique popliteus ligament
LCL (III)
Fabellofibular ligament (III)
Biceps tendon
Common peroneal nerve
Patella Fat pad
Anterior and posterior cruciate ligaments
I - First layer
II - Second layer III - Third layer
Trang 3(91%) of cadaveric specimens
de-spite the overall variability noted in
the remainder of the posterolateral
complex Many authors have stressed
the importance of this ligament in
maintaining posterolateral stability
and function
Arcuate Ligament
Spanning the junction from the
fibular styloid process to the lateral
femoral condyle, the arcuate
liga-ment reinforces the posterolateral
capsule.11,12 Possessing both a
medi-al and a latermedi-al limb, this Y-shaped
ligament is composed of the lateral
portion of the popliteus tendon and
the fascial condensation over the
posterior surface of the popliteus
muscle The fabellofibular, or short
collateral, ligament may also be pres-ent in conjunction with the arcuate ligament, providing a variable con-tribution to overall posterolateral stability.6,12
Biceps Femoris
The biceps femorisÑconsisting
of a long and a short head with nu-merous armsÑcourses posterior to the iliotibial band and inserts pri-marily on the fibular head It also sends strong attachments to the ilio-tibial bands, GerdyÕs tubercle, the LCL, and the posterolateral cap-sule.1,12 In conjunction with the ilio-tibial band, the biceps femoris acts
as a powerful external rotator of the tibia, as well as a strong dynamic lateral stabilizer of the knee.12
In-jury to the biceps femoris complex frequently occurs in PLRI
Additional Structures
The middle third of the capsular ligament blends with the capsule over the LCL and inserts slightly posterior to GerdyÕs tubercle.11,12 Although this structure is most
like-ly a secondary restraint to varus stress, DeLee et al1have reported a 33% incidence of injury to this liga-ment in acute PLRI The lateral head of the gastrocnemius provides varying degrees of posterolateral stability and blends with the arcu-ate ligament.12 The lateral menis-cus, which is stabilized by a portion
of the popliteus tendon as well as the capsule, also contributes to lat-eral stability by adding concavity to the lateral tibial plateau.12 The pos-terior capsule is attached proximally
to the lateral femoral condyle and is covered by the lateral gastrocne-mius and plantaris The distal cap-sular attachment is complex; the popliteus muscle and aponeurosis blend into the tibial attachment lat-eral to the PCL, whereas the distal corner is stabilized to the fibula by the arcuate, popliteofibular, and fabellofibular ligaments.12
Biomechanics
The lateral ligamentous structures
of the knee differ from the medial structures in that the lateral struc-tures are stronger and more sub-stantial and are subjected to greater forces during the normal gait cycle During the stance phase, the medial compartment is under compression, while the lateral structures are un-der tension secondary to the relative position of the normal mechanical axis of the lower extremity, which lies slightly medial to the center of the knee
The structures of the posterolat-eral corner function primarily to resist posterior translation as well
Plantaris muscle
Medial head of
gastrocnemius
muscle
Lateral head of
gastrocnemius
muscle
Fabella
Arcuate ligament
Fabellofibular ligament
Medial collateral ligament
Lateral inferior
geniculate artery
Popliteus muscle
Medial head of
gastrocnemius muscle
Lateral head of
gastrocnemius muscle
Semimembranosus
muscle
Femur
Patella
Prepatellar bursa
Patellar retinaculum
Apex of fibular head
Biceps tendon
Iliotibial tract
Common peroneal nerve
Figure 2 Oblique view of the posterolateral aspect of the knee after removal of the two
superficial layers.
Trang 4as external and varus rotation of the
tibia The posterolateral structures,
however, act in concert with the
PCL in providing this overall
stabil-ity The complex structure of the
knee does not allow for pure
rota-tional and translarota-tional motions;
consequently, abnormal
pathome-chanics usually result from a
com-bination of coupled rotation and
translation.5,12
Cadaveric studies have been
conducted in which sectioning of
the posterolateral structures and
the PCL was performed to
deter-mine their individual effects on
various motions in the knee The
findings of these studies will be
briefly summarized
Anterior-Posterior Translation
Sectioning of the posterolateral
structures alone results in an
in-crease in posterior translation of the
lateral tibial plateau primarily at 30
degrees of flexion, with a minimal
increase at 90 degrees of
flex-ion.5,13,14 However, when the
pos-terolateral structures and the PCL
are sectioned, increases in posterior
translation of both the medial and
the lateral tibial plateaus are
ob-served at both 30 and 90 degrees of
knee flexion.13-15 Thus, the
postero-lateral structures appear to provide
resistance to posterior tibial
transla-tion primarily at lesser degrees
(e.g., 30 degrees) of flexion, whereas
the PCL provides secondary
resis-tance throughout a full range of
motion
Varus-Valgus Rotation
Sectioning of the PCL alone does
not affect varus rotation of the tibia
Isolated sectioning of the
postero-lateral complex, primarily the LCL,
results in increased varus rotation
from 0 to 30 degrees of flexion, with
the maximal increase observed at
30 degrees.5,14,15 Combined
section-ing of the PCL and posterolateral
structures results in increased varus
rotation (as much as 19 degrees) of
the knee at all angles of flexion, with the maximal increase observed
at 60 degrees.14,15 Thus, the pos-terolateral structures act as a re-straint to varus rotation primarily
at lesser degrees of knee flexion (maximal restraint at 30 degrees)
Internal-External Rotation
Isolated sectioning of the poste-rolateral structures has been shown
to result in increased external rota-tion of the lateral tibial plateau when subjected to a posteriorly directed force, with maximal exter-nal rotation observed at 30 degrees
of flexion Insignificant increases
in external rotation are observed at
90 degrees of flexion with an intact PCL.5,14,15 Combined sectioning of the PCL and posterolateral struc-tures results in an increase in exter-nal rotation of the tibia on the femur at all angles of knee flexion, with the maximal increase (as much as 20 degrees of external rotation) noted at 90 degrees.14,15 Thus, the posterolateral structures appear to provide maximal re-straint to tibial external rotation primarily at lesser degrees of knee flexion and also play an important overall role in coupled tibial exter-nal rotation in conjunction with the PCL It should be noted, however, that isolated sectioning of the PCL does not result in increased tibial external rotation at any flexion angle Thus, in the presence of clinically increased tibial external rotation, an injury to the posterolat-eral complex should be suspected
Intra-articular Pressures
Sectioning of both the posterolat-eral structures and the PCL results
in increased medial and lateral compartment pressures, as well as increased patellofemoral pressures secondary to a Òreverse MaquetÓ effect These elevated compartment pressures may predispose to the de-velopment of early degenerative joint disease.16 Sectioning of the
LCL and posterolateral structures has also been shown to result in increased stresses on the anterior cruciate ligament (ACL) with inter-nal rotation, as well as on the PCL with external rotation.17
Mechanism of Injury
Most cases of PLRI are secondary
to trauma, with approximately 40% occurring as a result of sports in-juries It has been suggested that certain factors may predispose to PLRI, such as genu varum, congen-ital ligamentous laxity, and various developmental factors (e.g., recur-vatum, epiphyseal dysplasia).12 The usual mechanism of injury involves hyperextension with a varus moment combined with a twisting force With the knee in extension, the posterolateral cap-sule is the principal restraint to injury A posterolaterally directed blow to the medial tibia with the knee in extension is the most com-mon mechanism of injury.12 This results in forceful hyperextension with simultaneous external rota-tion of the knee Much less com-monly, these injuries occur due to noncontact hyperextension and external rotation Sudden upper leg and body deceleration with the lower leg fixed may result in injury
to the posterolateral structures.12 It
is important to note, however, that all of these mechanisms can result
in injury to the cruciate ligaments and other knee structures, account-ing for the high incidence of com-bined injury patterns
Clinical Presentation
In cases of acute PLRI, patients usu-ally describe a history of trauma and present with pain over the posterolat-eral aspect of the knee Patients may also report motor weakness as well
as numbness and paresthesias in the
Trang 5lower leg secondary to an associated
peroneal nerve palsy This has been
reported to occur in as many as 30%
of patients with acute PLRI.12
After the initial pain and
swell-ing of acute injuries have subsided,
patients may also report instability,
primarily with the knee in extension
(e.g., during toe-off), such that the
knee buckles into
hyperexten-sion.12,15 This functional instability
is characteristic of patients with
chronic PLRI as well Patients may
have difficulty in ascending and
descending stairs, as well as with
cutting activities requiring lateral
movement In addition to their
functional knee instability, patients
with chronic PLRI may describe
pain localized along the lateral joint
line Patients may also present with
gait abnormalities and may describe
symptoms secondary to associated
ligamentous injuries.12,15
Physical Examination
Physical examination should
in-volve an overall inspection of the
limb, including gait pattern, limb
alignment, and mechanics
Pa-tients typically exhibit gait
abnor-malities characterized by a varus
thrust at the knee coupled with
knee hyperextension in stance
phase.12,15 Patients may require the
use of shoe lifts or high-heeled
shoes to maintain ankle equinus
and prevent knee hyperextension.12
Patients often maintain the tibia in
internal rotation while ambulating
to prevent subluxation, as the knee
is more unstable in external
rota-tion In addition, patients may
exhibit varus malalignment with
the mechanical axis shifted medially,
resulting in an increased adduction
moment of the knee that further
exacerbates their symptoms This
overall varus alignment is an
im-portant factor that may lead to
fail-ure of operative treatment if not
corrected at the time of surgery
Patients may present with an abrasion or an area of ecchymosis over the anteromedial tibia after recent trauma One should have a high index of suspicion for knee dislocations in cases of multiple lig-amentous injuries A careful neuro-logic examination, focusing on the peroneal nerves, should be per-formed In addition, there are numerous specific tests that are valuable in the diagnosis of sus-pected PLRI These individual tests are most useful when used in con-junction with clinical suspicion and other physical examination find-ings Assessment of an awake pa-tient may be difficult; in many instances, especially with acute injuries, examination under anes-thesia may be helpful
Anterior-Posterior Translation
In cases of isolated posterolateral injury, patients will demonstrate evidence of increased posterior tib-ial translation on the femur only at
30 degrees of flexion However, in cases of combined posterolateral and PCL injury, patients will have increased posterior tibial translation
at both 30 and 90 degrees of flexion
A quadriceps active test should then be performed to further assess the integrity of the PCL This test is performed by having the patient actively contract the quadriceps with the knee flexed 70 degrees and the foot fixed Anterior translation
of the tibia from its posteriorly sub-luxated position is observed with PCL deficiency
Varus-Valgus Rotation (Adduction Stress Test)
Combined LCL and posterolat-eral injuries will result in increased varus opening at both 0 and 30 de-grees of flexion, with the maximal increase at 30 degrees With the patient lying supine and the knee flexed 20 to 30 degrees, a varus or adduction force is then applied to the leg with gentle internal rotation
of the tibia while supporting the thigh Opening of the lateral com-partment is indicative of injury to the posterolateral corner and corre-lates with injury to the LCL and the arcuate ligament.18 A large degree
of varus laxity in full extension may indicate combined injuries of the posterolateral corner, the PCL, and possibly the ACL as well
External-Rotation Recurvatum Test
This test is performed with the patient supine (Fig 3) The examiner grasps the great toes of both feet simultaneously and lifts the lower limbs off the examining table Posi-tive findings indicaPosi-tive of postero-lateral injury and instability include hyperextension (recurvatum) of the knee, external rotation of the tibia,
Figure 3 Demonstration of recurvatum and relative tibia vara at the knee on the external rotational recurvatum test suggests posterolateral instability (Adapted with permission from Hughston JC, Norwood
LA Jr: The posterolateral drawer test and external rotational recurvatum test for pos-terolateral rotatory instability of the knee.
Clin Orthop 1980;147:82-87.)
Trang 6and increased varus deformity of
the knee The sensitivity of this test,
as reported in the literature, ranges
from 33% to 94%.1,3
Posterolateral Drawer Test
This test is performed with the
patient supine with the hip flexed
45 degrees, the knee flexed 80
de-grees, and the tibia in 15 degrees of
external rotation With the foot fixed,
pressure is applied to the tibia in
a similar fashion to the posterior
drawer test Lateral tibial external
rotation and posterior translation
relative to the lateral femoral
con-dyle are indicative of injury to the
posterolateral structures.19 This test
is not specific for PLRI, and its
diag-nostic sensitivity is variable
(report-edly as high as 75%).1,3
Tibial External Rotation Test
This test is performed at both 30
and 90 degrees of knee flexion with
the patient either prone or
su-pine.15,20 The degree of external
rotation of the foot relative to the axis of the femur is evaluated while palpating the tibial plateau (Fig 4)
In cases of PLRI, the lateral plateau moves posteriorly In anteromedial rotatory instability, the medial plateau moves anteriorly A differ-ence in external rotation of more than 10 degrees between the nor-mal and the affected side is consid-ered evidence of a pathologic con-dition With isolated posterolateral injury, an increase in external rota-tion compared with the
contralater-al limb is noted only at 30 degrees;
an increase at both 30 and 90 de-grees is indicative of a combined posterolateral and PCL injury.15,20
Posterolateral External Rotation Test
This test is a combination of the posterolateral drawer and external rotation tests and is performed at both 30 and 90 degrees of knee flex-ion as a coupled force of posterior translation and external rotation of
the tibia is applied (Fig 5) Postero-lateral subluxation of the Postero-lateral tib-ial plateau only at 30 degrees is indicative of isolated PLRI (corre-lated with injuries to the LCL and the lateral head of the gastrocne-mius) Subluxation at both 30 and
90 degrees is indicative of com-bined PLRI and PCL injury.18
Reverse Pivot-Shift Test
With the patient lying supine, a valgus stress is applied to the tibia while bringing the knee from 90 degrees of flexion to full extension with the foot in external rotation This test is positive for PLRI if there
is a palpable shift or jerk as the lat-eral tibial plateau (which is sublux-ated posteriorly in flexion) reduces with extension.18 This test is not specific for PLRI; it has been reported
to be positive in 11% to 35% of nor-mal, asymptomatic subjects.12,21 Positive findings may be correlated with generalized ligamentous laxity and are significant only if the symp-toms are reproduced
Other Clinical Tests
Other diagnostic tests described for the diagnosis of PLRI include the dynamic posterior shift test and the standing apprehension test The latter is performed with the patient slightly flexing the knee while bearing weight on the affected leg Increased internal rotation of the lateral femoral condyle relative
to the fixed tibial plateau combined with the subjective experience of Ògiving wayÓ is considered to be 100% sensitive for the presence of PLRI.22
Radiologic Evaluation
Standard plain radiographs (ante-roposterior and lateral views) of the knee in cases of suspected injury to the posterolateral complex may show a proximal fibular tip avulsion
or occasionally a fibular head
frac-Figure 4 The tibial external rotation test (supine) Excessive external tibial rotation as
well as posterior translation of the lateral tibial plateau is noted in cases of PLRI (Adapted
with permission from Loomer RL: A test for knee posterolateral rotatory instability Clin
Orthop 1991;264:235-238.)
Trang 7ture.1,12 Avulsion of GerdyÕs
tuber-cle may also be observed secondary
to iliotibial band injury.12 This must
be distinguished from a Segond
frac-ture, which is indicative of lateral
capsular avulsion as a result of ACL
disruption In cases of more severe
injury with associated ligamentous
disruption, additional findings, such
as tibial plateau fractures or even
knee dislocation, may be seen In
cases of chronic PLRI, evidence of
patellofemoral or tibiofemoral
de-generative changes may be
ob-served Most commonly,
involve-ment of the lateral compartinvolve-ment is
more advanced than that of any
other compartment Lateral tibial
osteophytes may be seen, along with
evidence of lateral compartment
involvement, such as joint-space
narrowing and subchondral
sclero-sis of the tibial plateau
Varus stress radiographs may be
helpful in determining the degree
of injury A constant force is placed
on the knee in the frontal and
sagit-tal planes to demonstrate both the
direction and the degree of
instabil-ity In addition, full-length
weight-bearing radiographs of both lower
extremities may be helpful in deter-mining overall limb alignment, es-pecially in cases of chronic PLRI
Valgus osteotomies, if needed, can then be planned and templated in anticipation of correction of varus limb alignment, along with surgical reconstruction of the posterolateral complex
Magnetic resonance imaging is
an excellent diagnostic tool in the evaluation of posterolateral injuries, providing visualization of individ-ual posterolateral structures A bone contusion on the anteromedial femoral condyle indicative of pos-terolateral injury is frequently ob-served Magnetic resonance imag-ing is also useful for evaluation of the cruciate ligaments and other lig-amentous and soft-tissue structures
in the knee to determine the pres-ence of associated injuries
Treatment
The natural history of isolated PLRI has not yet been clearly delin-eated The results of early studies indicated that most professional
and recreational athletes who sus-tain isolated posterolateral injury have no evidence of impaired func-tion initially.3,12 However, it has been postulated that there may be a predisposition to early degenera-tive joint disease It is also believed that there is an increased degree of disability when a combined liga-mentous injury pattern exists The role of early surgical intervention is still unclear However, surgical repair or reconstruction of the pos-terolateral structures should be performed before degenerative changes develop in the knee joint
In general, nonoperative man-agement should be prescribed for patients with mild instability with-out significant symptoms or func-tional limitations These patients may be treated with a brief period
of initial immobilization (2 to 4 weeks), followed by an extensive rehabilitation program that in-cludes protected range-of-motion and quadriceps-strengthening exer-cises Sport-specific drills may be begun and gradually progressed as strength increases Baker et al3 ob-served that 14 of 31 patients with mild instability were able to return
to their preinjury level of athletic participation with nonoperative treatment.3
Currently, the indications for surgical treatment of PLRI of the knee include symptomatic instabil-ity with functional limitations as confirmed by significant objective physical findings (e.g., 2+ or greater varus opening at 30 degrees or a positive external-rotation recurva-tum, tibial external rotation, or pos-terolateral external-rotation test)
In general, surgical repair is recom-mended within the first 2 weeks, if possible Results of chronic PLRI repair have been shown to be infer-ior to those for acute PLRI In addi-tion, simultaneous evaluation and treatment of associated ligamentous injuries is mandatory ÕBrien et
al23 noted that the most common
Figure 5 The posterolateral external rotation test at 30 degrees Left, Patient is supine
with the knee flexed at 30 degrees and in neutral rotation Center, A coupled force of
pos-terior translation and external rotation is applied to the tibia while palpating the
postero-lateral aspect of the knee Right, Abnormal posteropostero-lateral subluxation of the postero-lateral tibial
plateau indicative of PLRI is shown by the arrow (Adapted with permission from
LaPrade RF, Terry GC: Injuries to the posterolateral aspect of the knee: Association of
anatomic injury patterns with clinical instability Am J Sports Med 1997;25:433-438.)
Trang 8identifiable cause of ACL
recon-struction failures was unrecognized
and untreated concomitant PLRI
In cases of combined injury
pat-terns, reconstruction of the ACL or
PCL should be performed either
prior to or concurrently with repair
or reconstruction of the
posterolat-eral structures
In addition to addressing
con-comitant ligamentous injuries, it is
also important to correct any varus
knee alignment that may be
pres-ent A valgus osteotomy of the
proximal tibia with distal
advance-ment of the iliotibial band with a
bone block can be performed.24
This should be done either prior to
or at the time of surgical
recon-struction of the posterolateral
struc-tures Uncorrected varus
lower-limb alignment may lead to failure
of the posterolateral reconstruction
secondary to chronic repetitive
ten-sile stresses and stretching of the
surgically reconstructed structures
In general, the common goal of the
numerous surgical procedures
described is to restore stability of
the knee by resisting varus stress,
posterior tibial translation, and
tib-ial external rotation Surgical
op-tions can be divided into four main
categories: primary repair,
augmen-tation, advancement, and
recon-struction
Surgical Approach
Despite the numerous surgical
techniques described for
posterolat-eral repair and reconstruction, no
single universal surgical approach
has been adopted In general, a
lat-eral skin incision is made with the
knee slightly flexed and is carried
from the midlateral aspect of the
distal thigh along the iliotibial band,
extending distally past GerdyÕs
tubercle Terry and LaPrade11
re-cently described a surgical approach
consisting of three fascial incisions
along with a capsular incision for
exposure of the posterolateral
struc-tures The first fascial incision
bisects the iliotibial band; the sec-ond is made between the posterior border of the iliotibial band and the short head of the biceps femoris;
and the third is made along the pos-terior border of the long head of the biceps femoris The capsular inci-sion is made along the anterior bor-der of the LCL
Direct Primary Repair
Direct repair of the posterolateral structures should be attempted ini-tially if the tissues are of good
quali-ty, in order to restore both the ten-sion in the popliteal complex and the overall stability provided by the posterolateral corner.12,24-26 Primary repair may be possible in many acute cases, but in chronic cases in which extensive scarring precludes the definition of individual struc-tures, direct repair is usually not possible Repair of the posterolat-eral structures should be performed with the knee in approximately 60 degrees of flexion and the tibia in either neutral or slight internal rota-tion.12,25
Disruption of the tibial attach-ment of the popliteus can be re-paired by reattaching the popliteus tendon by means of either sutures
or a cancellous screw to the postero-lateral tibia24,25(Fig 6) Avulsion of the femoral insertion of the popli-teus usually occurs along with avul-sion of the femoral origin of the LCL; these structures can be reat-tached to an osseous bed in the lat-eral femoral condyle by means of sutures through transosseous drill holes.12,25 Disruption of the fibular attachment of the popliteofibular ligament can be addressed by teno-desing the popliteus tendon to the posterior aspect of the fibular head and reinforcing it with the fabello-fibular ligament (if present).24,25 Avulsions of the LCL and the arcu-ate ligament from the fibular styloid process can also be repaired through transosseous drill holes in the fibu-lar head.12
Augmentation of Posterolateral Structures
Augmentation of the posterolat-eral structures is recommended when the popliteus and its related structures are attenuated and the quality of the primarily repaired tis-sues is tenuous.24,25 In this instance, the tibial attachment of the popliteus can be augmented with a strip of the iliotibial band that is left attached distally to GerdyÕs tubercle The ilio-tibial band strip is passed from ante-rior to posteante-rior through a drill hole
in the proximal tibia and then sutured to the popliteus tendon24,25 (Fig 7, A) When the popliteofibular ligament is disrupted and irrepa-rable, a central slip of the biceps ten-don can be utilized to augment and reconstruct this structure While leaving its distal attachment to the fibular head intact, the central slip of the biceps is sutured to the posterior
Figure 6 Direct repair of popliteus tendon injury Disruption of the tibial attachment
of the popliteus or the popliteus muscle-tendon junction may be treated by tenode-sis of the popliteus tendon to the posterolat-eral aspect of the proximal tibia (Adapted with permission from Maynard MJ, Warren RF: Surgical and reconstructive technique for knee dislocations, in Jackson DW [ed]:
Reconstructive Knee Surgery New York:
Raven Press, 1995, pp 161-183.)
Trang 9fibula, passed under the remaining
biceps, and secured to the lateral
femur24(Fig 7, B)
Advancement of Posterolateral
Structures
Arcuate complex advancement
has been recommended by
numer-ous authors for cases in which the
posterolateral structures are
insuffi-cient or incompetent for direct
pri-mary repair.1,3,4,26,27 Advancement
of the posterolateral complex (i.e.,
LCL, popliteus muscle and tendon,
posterolateral capsule, arcuate
liga-ment, and lateral gastrocnemius
tendon) can be performed either
proximally or distally back to its
anatomic location on the femur or
tibia In cases of chronic PLRI with
an LCL of normal integrity,
proxi-mal advancement of the
posterolat-eral structures can be performed if
the popliteofibular ligament is
intact Superior and proximal advancement of the posterolateral complex is performed in line with the LCL into a trough in the distal femur (Fig 8) Tensioning is per-formed with the knee in 30 degrees
of flexion and neutral tibial rota-tion It has been suggested that recession of the popliteus at the femoral insertion will restore stabil-ity and tension in the posterolateral complex, but this technique alone is ineffective in cases of injury to the distal structures, such as the popli-teofibular ligament.12
Numerous authors have reported good results with advancement of the arcuate complex DeLee et al1 reported that 8 (73%) of 11 patients with acute PLRI had good objective and functional results at the 7.5-year follow-up examination, with no evi-dence of degenerative joint disease and no revisions Hughston and
Jacobson4 reported that of 19 pa-tients with isolated chronic PLRI treated with proximal arcuate com-plex advancement combined with distal primary repair, 12 (63%) had good functional results at 4 years Noyes and Barber-Westin27reported
on 21 patients with combined PLRI and ACL or PCL injuries treated with proximal advancement of the posterolateral structures, noting good functional results at 42 months
in 14 (67%), with a failure rate of 9% (2 patients) The disadvantage of proximal arcuate complex advance-ment lies in the fact that the inser-tion sites of the popliteus and LCL are shifted anterior to the center of knee rotation, which theoretically may lead to stretching and eventual failure of the repair over time
Surgical Reconstruction
Reconstruction of the posterolat-eral complex is performed in cases
of acute PLRI when the tissues are
Figure 7 A,Augmentation of the attenuated tibial attachment of the popliteus tendon can
be performed by using a portion of the iliotibial band passed from anterior to posterior
through a bone tunnel in the proximal tibia (Adapted with permission from Maynard MJ,
Warren RF: Surgical and reconstructive technique for knee dislocations, in Jackson DW
[ed]: Reconstructive Knee Surgery New York: Raven Press, 1995, pp 161-183.) B, A central
slip of the biceps is used to reconstruct the popliteofibular ligament The central slip is
tubularized, sutured to the posterior fibula, and then passed under the biceps tendon and
subsequently secured to the lateral femoral condyle (Adapted with permission from
Veltri DM, Warren RF: Operative treatment of posterolateral instability of the knee Clin
Sports Med 1994;13:615-627.)
Iliotibial graft secured to popliteus tendon
Figure 8 Proximal arcuate complex advancement The structures of the pos-terolateral region are advanced en bloc in line with the LCL into a bone trough in the lateral femoral condyle to restore tension in the posterolateral complex (Adapted with permission from Hughston JC, Jacobson KE: Chronic posterolateral rotatory
insta-bility of the knee J Bone Joint Surg Am
1985;67:351-359.)
Popliteus tendon
Lateral capsular ligament
Arcuate ligament complex
Fibular collateral ligament
Tendon of lateral head of gastrocnemius
Trang 10irreparable or in symptomatic
pa-tients with chronic PLRI In cases of
chronic PLRI with a deficient LCL,
graft reconstruction of both the LCL
and the surrounding posterolateral
structures is recommended
Recon-struction of the LCL restores the
pri-mary restraint to varus stress and
replaces the tensile-bearing tissues
in the lateral aspect of the knee
This can be performed by using
numerous techniques and grafts,
including Achilles tendon allograft
and patellar tendon autograft or
allograft.17,24-31 A central slip of the
biceps tendon can also be used to
reconstruct the LCL; the distal
inser-tion of the biceps is left intact while
a central slip is tubularized, brought
proximally, and secured on the
lat-eral femoral condyle near the origin
of the LCL24(Fig 9, A) Plication or
advancement of the residual
pos-terolateral structures to control ex-ternal rotation can be performed if the tissues are of sufficient quality
Noyes and Barber-Westin28 re-ported significant subjective im-provement in symptoms and func-tion at the 42-month follow-up of
21 patients with chronic PLRI who had been treated with LCL recon-struction with use of an Achilles tendon allograft combined with either plication of the posterolateral structures to the allograft or proxi-mal advancement of these struc-tures on the femur Sixteen (76%) patients had good to excellent func-tional results Failure of the recon-struction occurred in only 2 pa-tients (10%)
Clancy et al29have described bi-ceps tenodesis for advancement and tensioning of the posterolateral structures The entire biceps
ten-don is transferred anteriorly to the lateral femoral epicondyle while leaving the distal insertion intact (Fig 9, B) The proposed advan-tages of this technique are that the LCL is recreated while the arcuate complex is tightened In vitro ca-daveric studies have shown that biceps tenodesis at a fixation point
1 cm anterior to the LCL femoral origin is effective in decreasing external rotation and varus laxity at
up to 90 degrees of knee flexion.30 Clancy et al29reported good func-tional results in 90% of a small num-ber of patients at 2-year follow-up, including maintenance of stability and return to preinjury level of ac-tivity; no notable loss of hamstring strength was observed However, a disadvantage of this technique is that the popliteus and popliteofibular lig-aments are not anatomically re-produced Because the biceps is brought anterior to its normal func-tional axis, the normal biomechanical advantage and dynamic stabilizing effect of this muscle are disrupted The tissue quality of the advanced posterolateral structures may also
be tenuous In vitro studies have shown that tenodesis at a fixation point other than 1 cm anterior to the LCL femoral origin results in a Ònon-isometricÓ graft position that does not reduce external rotation or varus stress at any degree of flexion.30 Salvage posterolateral reconstruction after a failed biceps tenodesis proce-dure may be quite difficult
In cases of chronic PLRI with a deficient LCL in which the postero-lateral structures are insufficient for advancement, primary recon-struction of the entire LCL and pos-terolateral complex is necessary
An Achilles tendon allograft, patel-lar tendon autograft or allograft, or free semitendinosus autograft passed through a tibial tunnel just below GerdyÕs tubercle and a tun-nel in the lateral femoral condyle can be used to reconstruct the popliteus.29 This, however, does
Figure 9 A,Reconstruction of the LCL utilizing a central slip of the biceps tendon, which
is tubularized (as shown) and then secured proximally on the lateral femoral condyle
while leaving the remainder of the biceps attachment intact (Adapted with permission
from Veltri DM, Warren RF: Operative treatment of posterolateral instability of the knee.
Clin Sports Med 1994;13:615-627.) B, Biceps tenodesis The entire biceps tendon is
trans-ferred anteriorly and secured to the lateral femoral condyle, thereby recreating the LCL
and restoring tension to the residual posterolateral structures (Adapted with permission
from Clancy WG, Meister K, Craythorne CB: Posterolateral corner collateral ligament
reconstruction, in Jackson DW [ed]: Reconstructive Knee Surgery New York: Raven Press,
1995, pp 143-159.)
Biceps tendon