Chấn thương dây chằng ppsx

Although these mechanisms are less commonly the cause of isolated PCL injuries, it is important to recognize them, as they often lead to combined liga-ment injuries.4 Anatomy The PCL ori

Treatment recommendations for

posterior cruciate ligament (PCL)

injuries have evolved as our

under-standing of the natural history of the

injury increases and surgical

tech-niques improve Experience with

treatment of PCL tears lags behind

that of anterior cruciate ligament

(ACL) tears because they are less

common and are more difficult to

treat surgically Some surgeons

have ample experience treating ACL

tears; however, because of the

het-erogeneity of PCL injuries, relatively

few surgeons have accumulated

suf-ficient numbers of patients to study

the effects of different treatment

modalities The PCL treatment

con-troversy has been difficult to resolve

because of the diverse nature of PCL

injuries, the poor understanding of

the natural history of untreated

in-juries, and the limitations of the

clin-ical studies performed The most controversial issue remains the indi-cations for surgical intervention

Epidemiology

Posterior cruciate ligament tears have historically been underdiag-nosed because they are often asymp-tomatic It now appears that PCL tears occur more frequently than has been previously appreciated, ac-counting for one fifth or more of all knee ligament injuries Shelbourne

et al1 recently reviewed the litera-ture and reported that PCL tears occur in 1% to 44% of all acute knee injuries A renewed interest in PCL injuries has led to improved under-standing of both the injury mecha-nism and the presenting signs and symptoms

Mechanism of Injury

Posterior cruciate ligament injuries can be a consequence of both trauma and sports participation The most common mechanism is a posteriorly directed force to the proximal tibia

of the flexed knee.2 This frequently occurs during a motor vehicle acci-dent when a knee of the driver or the front-seat passenger strikes the dashboard on impact A similar mechanism can occur in contact sports such as wrestling and foot-ball when striking an opponent’s lower leg can drive the tibia back-ward, rupturing the PCL (Fig 1) The posterior force can be combined with a varus or rotational force, leading to concomitant lateral or posterolateral injury Another mech-anism is a fall onto a flexed knee, particularly when the foot is plantar-flexed This is a common cause of isolated PCL tears in sports.3 For example, this mechanism is ob-served in football when a player lands forcefully on a flexed knee

Dr Cosgarea is Associate Professor, Depart-ment of Orthopaedic Surgery, Johns Hopkins Sports Medicine, Baltimore, Md Dr Jay is in private practice in Williamsville, NY Reprint requests: Dr Cosgarea, Johns Hopkins Sports Medicine, Suite 215, 10753 Falls Road, Lutherville, MD 21093.

Copyright 2001 by the American Academy of Orthopaedic Surgeons.

Abstract

Posterior cruciate ligament (PCL) injuries commonly occur during sports

par-ticipation or as a result of motor vehicle accidents Careful history taking and a

comprehensive physical examination are generally sufficient to identify PCL

injuries Most authors recommend nonoperative treatment for acute isolated

PCL tears This involves initial splinting in extension followed by

range-of-motion and strengthening exercises Recovery of quadriceps strength is

neces-sary to compensate for posterior tibial subluxation and to facilitate return to

preinjury activity levels In isolated PCL tears, surgical treatment is reserved

for acute bone avulsions and symptomatic chronic high-grade PCL tears.

Arthroscopic single-tunnel reconstruction techniques will improve posterior

laxity only moderately Newer double-tunnel and tibial-inlay techniques offer

theoretical advantages, but the available clinical results are only preliminary.

When a PCL injury occurs in combination with other ligament injuries, most

patients will require surgical treatment.

J Am Acad Orthop Surg 2001;9:297-307

Evaluation and Management

Andrew J Cosgarea, MD, and Peter R Jay, MD

Other indirect mechanisms of injury

that occur during athletic

par-ticipation involve cutting, twisting,

and hyperextension Although

these mechanisms are less commonly

the cause of isolated PCL injuries, it

is important to recognize them, as

they often lead to combined

liga-ment injuries.4

Anatomy

The PCL originates in an irregular

semicircle on the lateral border of

the medial femoral condyle where

the roof of the intercondylar notch

joins the wall.2,5 The midpoint of

the PCL attachment is approximately

1 cm posterior to the articular

car-tilage.2 The PCL inserts

approxi-mately 1.0 to 1.5 cm inferior to the

posterior rim of the tibia in a

de-pression between the posterior

medial and lateral tibial plateaus

called the PCL facet, or fovea The

location of the tibial insertion may

complicate reconstruction tech-niques due to the close proximity of the popliteal neurovascular bundle

The average length of the PCL is

38 mm, and its average width is 13

mm.6 The PCL originates in an anterior-to-posterior direction on the femur and attaches in a lateral-to-medial direction on the tibia The PCL can be described as having multiple bundles or fiber regions

In a simplified functional model, the PCL can be considered to have two bundles (anterolateral and postero-medial bands), which are named for their specific insertion positions on the femur (anterior or posterior) and tibia (lateral or medial)7 (Fig 2)

The anterolateral band is larger and stronger than the posteromedial band

Biomechanics

Biomechanical studies of PCL fiber-attachment sites have shown that very little of the PCL is truly iso-metric during the knee flexion arc

Because of differences in anatomic origin and insertion, the anterolat-eral band becomes tighter (and is, therefore, relatively more impor-tant) in knee flexion, while the pos-teromedial band plays a relatively greater role in stabilizing the knee

during extension.7 During the flexion-extension cycle, tension in the two bundles develops in a reciprocal fashion; this fact explains some of the difficulty surgeons have had in trying to reproduce normal knee kinematics with a single-graft PCL reconstruction Biomechanical studies have also shown that alter-ation of the normal femoral attach-ment sites leads to greater differ-ences in graft tension during knee flexion than alteration of the tibial attachment site This has led to an emphasis on determining the proper placement of the femoral tunnel during PCL reconstruction.7

The PCL is the primary restraint

to posterior tibial translation It re-sists 85% to 100% of a posteriorly directed knee force at both 30 and 90 degrees of flexion.8 The lateral col-lateral ligament (LCL), posterocol-lateral corner, and medial collateral liga-ment (MCL) are important second-ary restraints.7 They play a minimal role in resisting posterior translation when the PCL is intact, but play a vital role in maintaining stability during rehabilitation of a patient with a torn PCL.7 The amount of pathologic displacement increases substantially when both primary and secondary restraints are torn Loss of the PCL results in an increase in

pos-Figure 1 Mechanism of a PCL tear during

a football tackle (Adapted with permission

from Miller MD, Harner CD, Koshiwaguchi

S: Acute posterior cruciate ligament

in-juries, in Fu FH, Harner CD, Vince KG

[eds]: Knee Surgery Baltimore: Williams &

Wilkins, 1994, p 750.)

Figure 2 Anatomy of the PCL insertion A, Outline of the anterolateral bundle (AL) and

posteromedial bundle (PM) of the PCL tibial insertion B, Femoral origin (Adapted with

permission from Harner CD, Hoher J: Evaluation and treatment of posterior cruciate

liga-ment injuries Am J Sports Med 1998;26:471-482.)

AL PM

AL

PM

terior translation to a maximum of 15

to 20 mm at 90 degrees of flexion.8

Concomitant loss of the LCL, MCL,

or posterolateral corner results in

even greater increases in posterior

translation The PCL is also a

sec-ondary restraint to external rotation,

an important fact when dealing with

concomitant posterolateral corner

injuries.7 The posterolateral corner is

the primary restraint to external

rota-tion and aids the PCL in preventing

pathologic posterior translation.3,7

Damage to posterolateral structures

results in higher forces in the intact

native PCL.3,7

Clinical Evaluation

Careful history taking is an essential

part of evaluating the patient with a

PCL injury Patients with partial or

even complete isolated PCL tears

usually present with relatively benign

symptoms Therefore, it is essential

that the clinician have a thorough

understanding of the spectrum of

pathologic changes in the knee in

order to be able to deduce which

mechanism of injury described by

the patient may be responsible for a

PCL injury Being cognizant of the

time interval from injury to

evalua-tion is very important, as the

pre-sentation and the findings from the

physical examination moderate

sub-stantially as time passes

The physical examination should

begin by observing gait and

check-ing static weight-bearcheck-ing alignment

The skin is assessed for signs of

ex-ternal trauma, such as an abrasion

or contusion, particularly over the

proximal tibia Evaluation of acute

knee injuries can be challenging, as

patients who have sustained an

iso-lated PCL tear may have very little

pain and only a small effusion Knee

motion may be nearly symmetrical

compared with the normal

contra-lateral knee or substantially

de-creased if there are concomitant

in-juries It is crucial to examine the

knee for signs of collateral ligament and posterolateral corner disorders

After palpating the LCL and MCL, varus and valgus stress testing should be performed with the knee

in both full extension and 30 de-grees of flexion

The posterior drawer test, per-formed at 90 degrees of flexion, is the most accurate test for PCL in-jury.3,5,6 It is critical to recognize that if the tibia is resting in a poste-riorly subluxated position, the result may be a false-positive Lachman or anterior drawer test In most normal knees, the medial tibial plateau is approximately 1 cm anterior to the adjacent medial femoral condyle.3,7

If the examiner cannot palpate the normal 1-cm step-off or if the consis-tency of the end point on posterior drawer testing is soft, a PCL injury should be suspected

If the PCL tear is incomplete, pal-pation of the tibial plateau–medial femoral condyle step-off forms the basis for the most commonly used grading scheme With a grade 1 tear, the tibial plateau remains ante-rior to the medial femoral condyle

with manual posterior translation

In grade 2 tears, the tibial plateau is palpated flush with the condyle In grade 3 tears, the plateau is poste-rior to the condyle Many authors believe that a grade 3 PCL tear must involve other ligamentous struc-tures, most commonly the postero-lateral corner.7,9 Shelbourne et al1

have pointed out that only 2 weeks from injury, patients often have no pain and a firm end point on poste-rior drawer testing.1 The KT-1000 arthrometer (MEDmetric Corp, San Diego, Calif) can be used to objec-tively quantify posterior translation This kind of instrumented laxity measurement is particularly useful when trying to compare or report surgical results

The posterior sag test is performed with the knee flexed 90 degrees and the foot resting on the examination table When the PCL is torn, the examiner may see an abnormal con-tour or sag centered at the proximal anterior tibia With the quadriceps active test (Fig 3), the examiner stabilizes the foot and then asks the patient to slide the foot down the

Figure 3 Quadriceps active test The examiner asks the patient to slide the foot down the

table Quadriceps contraction causes the tibia to translate anteriorly from a subluxated position, confirming PCL insufficiency (Adapted with permission from DeLee JC, Bergfeld JA, Drez D Jr, Parker AW: The posterior cruciate ligament, in DeLee JC, Drez D Jr

[eds]: Orthopaedic Sports Medicine: Principles and Practice Philadelphia: WB Saunders, 1994,

vol 2, p 1383.)

examination table When the

quadri-ceps muscles contract, the examiner

will observe reduction of the

posteri-orly subluxated tibia Interpretation

of these tests is easier with

higher-grade and chronic PCL tears

The dynamic posterior shift test

is performed with the patient’s hip

flexed 90 degrees Starting with the

knee flexed, the examiner slowly

extends the patient’s knee until the

posteriorly subluxated tibia suddenly

reduces with a clunk as the knee

reaches full extension

The reverse pivot shift test is used

to evaluate posterolateral stability.2,3

The examiner externally rotates the

foot and brings the knee into

exten-sion as a valgus stress is applied to

the knee Palpable reduction of the

displaced tibia is considered a

posi-tive test, but is present bilaterally in

one third of normal subjects

The posterolateral drawer test is

performed with the knee flexed 90

degrees and externally rotated 15

degrees With a positive test, the

tibia rotates posteriorly and laterally off the lateral femoral condyle.2

The tibial external rotation test (also called the dial test) is per-formed with the knee in both 30 and

90 degrees of flexion It is consid-ered positive when the medial bor-der of the foot or the tibial tubercle externally rotates 10 to 15 degrees or more than the contralateral side.10

Increased external rotation at 30 and

90 degrees is consistent with a pos-terolateral corner injury With a com-bined PCL and posterolateral corner injury, greater increases in external rotation are noted, especially at 90 degrees.8

Radiologic Evaluation

Patients who sustain knee trauma should undergo a complete radio-graphic evaluation consisting of anteroposterior (AP), lateral, sun-rise, and tunnel views Occasion-ally, avulsion fractures of the PCL

tibial insertion will be identified Avulsion fractures may also be seen

at the LCL attachment on the fibular head (Fig 4, A) Oblique views are sometimes helpful in ruling out tib-ial plateau fractures Calcification adjacent to the medial femoral epi-condyle (Pellegrini-Stieda lesion) suggests an old MCL injury (Fig 4, B) Gross posterior subluxation can oc-casionally be seen on lateral views Patients with chronic PCL tears are more likely to have evidence of degenerative changes in the medial and patellofemoral compartments Weight-bearing 45-degree-flexed PA views are helpful in demonstrating tibiofemoral joint-space narrowing Stress radiographs, with or without instrumentation, and contralateral comparison views can be helpful in borderline cases (Fig 4, C)

Magnetic resonance (MR) imag-ing is highly accurate in establish-ing the diagnosis and location of an acute tear, as well as in identifying concomitant ligamentous lesions

Figure 4 Radiographic appearance of PCL lesions A, AP radiograph demonstrating an avulsion fracture of the fibular head (arrow) in a

patient with combined PCL, posterolateral corner, and LCL injuries B, AP radiograph demonstrates a Pellegrini-Stieda lesion (arrow), indicative of a chronic MCL injury C, Posterior subluxation of the tibia seen on a lateral stress radiograph of a patient with combined

grade 3 PCL and MCL injury.

(Fig 5).7,11 There is some evidence

that PCL tears can heal in an

elon-gated position much like MCL

tears Chronic PCL tears may then

look relatively normal on MR

im-aging.12 Meniscal tears are less

common with PCL tears than with

ACL tears.1 This is probably

be-cause the pathologic posterior tibial

translation decreases the load on

the posterior horns of the medial

and lateral menisci Bone bruises are

also seen less commonly than with

ACL tears

Bone scans may be helpful for

evaluating patients with chronic

PCL injuries who present with pain

and instability.7 Patients with

chronic PCL tears have a higher

risk of patellofemoral and

medial-compartment degenerative changes

If bone scans show increased

activ-ity in these areas but no frank

arthri-tis, the patient may be a candidate

for PCL reconstruction.3,11

Natural History of

PCL Injury

To compare the results of operative

and nonoperative treatment, one

must first know the natural history

of the injury The natural history of

isolated PCL tears is relatively

benign It is not unusual to discover

a PCL insufficiency as an incidental

finding during routine preseason

sports examinations Parolie and

Bergfeld13 reported in 1986 that

about 2% of college-senior football

players at the National Football

League predraft examination were

consistently found to have chronic

PCL-deficient knees

There are few natural history

studies in the literature Fowler and

Messieh14prospectively followed 13

athletes with arthroscopically

con-firmed isolated PCL injuries treated

with physical therapy The average

age at injury was 22 years, and the

average follow-up interval was 2.6

years All patients were able to

return to their previous activities without limitation At follow-up examination, all 13 had slight trans-lation on a posterior drawer test

The MR imaging studies of 3 patients with arthroscopically docu-mented complete midsubstance tears revealed continuity of the liga-ment at 2-year follow-up

Parolie and Bergfeld13evaluated

25 athletes with isolated PCL tears

at a mean of 6.2 years after injury

Eleven patients with acute injuries were treated with early range-of-motion and quadriceps-strengthening exercises Patients returned to sports

in a PCL brace at an average of 6 weeks after injury Seventeen pa-tients (68%) were able to return to sports at the preinjury level; 4 (16%),

at a decreased level of performance

Twenty patients (80%) were satis-fied with their knee function Pos-terior laxity as measured with a

KT-1000 arthrometer did not correlate with patient satisfaction or ability to return to sports Mean quadriceps strength was 100% of that on the normal contralateral side or greater

in patients who returned to sports and was less than 100% in patients who did not The authors concluded that most athletes with isolated PCL injuries who are able to maintain quadriceps strength are able to suc-cessfully return to sports without surgery

Torg et al15documented the clin-ical course of 14 patients with iso-lated PCL instability Eleven of the

14 sustained their injuries during sports activities KT-1000 arthrom-eter testing showed a mean side-to-side difference of 5 mm (range, 3 to

8 mm) at 20 lb Five patients (36%) were rated as having an excellent result (full return to the same or a similar sport) Seven patients (50%) were rated as having a good result (mild instability during sports par-ticipation, no problems with activi-ties of daily living) They found no correlation between laxity or chro-nicity of injury and functional status

The authors concluded that individ-uals with isolated PCL insuffi-ciency do not require surgical treat-ment

Shelbourne et al1 prospectively followed up 133 athletes with isolated PCL tears treated nonoperatively over a mean interval of 5.4 years Patients completed yearly question-naires, and approximately half re-turned for long-term follow-up ex-amination The authors found little change in PCL laxity grade from the initial injury to the final examina-tion, and there was no correlation between objective and subjective knee scores and the PCL laxity grade When a progression in laxity occurred, there was no deterioration

in outcome They were unable to identify particular characteristics that predisposed to deterioration of function Regardless of the laxity grade, 50% of the patients were able to resume sports at the same level or higher, and 50% were un-able to do so

Nonoperative Treatment

Patients with acute isolated partial (grade 1 or 2) PCL tears can be treated with a brief period of splinting and

Figure 5 MR image demonstrates an acute

complete PCL tear.

protected weight bearing followed

by an early range-of-motion and

quadriceps-strengthening

rehabilita-tion program Recovery of strength

and motion generally occurs quickly,

and many patients are able to return

to sports within 4 weeks.7

Treatment of an acute grade 3

PCL tear is more controversial

Be-cause of the possibility of

unrecog-nized posterolateral corner damage,

which may result in further

sublux-ation, the current recommendation

is that the knee be splinted in full

extension for 2 to 4 weeks.7

Immo-bilization in extension decreases

tension on the anterolateral bundle

fibers and minimizes the

antagonis-tic effect on the hamstring muscles

Cast immobilization may be

indi-cated when such an injury happens

in a pediatric patient, which is an

infrequent occurrence

Early rehabilitation should

emphasize range-of-motion and

quadriceps-strengthening exercises;

hamstring-strengthening exercises

are initiated later Use of functional

braces may facilitate the return to

sports activities, but has had limited

success in patients with

sympto-matic chronic tears

Surgical Treatment

The history of PCL reconstruction

has been summarized by Andrews

and Soffer,16who credit Hey Groves

with the first report in the literature

(in 1917) The semitendinosus

ten-don was detached distally, rerouted

through femoral and tibial tunnels,

and then reattached to the anterior

tibial periosteum Multiple

varia-tions of this technique have been

subsequently described; these

in-volve the use of the proximally or

distally detached semitendinosus

tendon with or without the gracilis

tendon In general, these techniques

have yielded disappointing results

Other grafts have been used to

reconstruct the PCL, including a slip

of iliotibial band, the proximally detached popliteus, and the lateral

or medial meniscus Since the early 1980s, there have been several series

in which primary suture repair of the PCL was used, but most researchers have concluded that this technique does not restore PCL function.5,16-19

The use of a bone–patellar tendon–

bone autograft became popular in the 1980s Clancy et al17demonstrated the efficacy of this technique in the rhesus monkey in a 1981 study In

1983, Clancy et al20reported the re-sults in a human series Of the 23 pa-tients, 21 had good to excellent objec-tive results at a minimum follow-up interval of 2 years The use of allo-graft patellar tendon and Achilles tendon has the advantage of de-creased morbidity compared with autograft.2,3,5-7 More recently, qua-druple hamstring and quadriceps free grafts have been used with increasing frequency.3,7

Bone Avulsion

Most authors agree that acute surgical intervention is indicated when there is a displaced PCL bone avulsion.6,7 Avulsion fractures usu-ally involve the tibial insertion and can be seen on routine lateral radio-graphs The avulsion site is exposed through a standard posterior ap-proach with the patient in the prone position If the bone fragment is large, fixation is accomplished with one or two screws, with or without washers For smaller or comminuted bone fragments, suture fixation through small drill holes may be nec-essary The knee is braced in exten-sion, and weight bearing is initially protected The nature of postopera-tive rehabilitation is based on the quality of fixation In all cases, once bone healing has occurred (6 to 8 weeks after surgery), rehabilitation can proceed more aggressively As with other knee stabilization proce-dures performed in the acute setting, postoperative stiffness is a common complication

Suture Repair

Primary repair with sutures is most efficacious when treating insertion-site avulsions To be suc-cessful, repair must be done in the acute period (less than 3 weeks after injury) Most of these injuries are the result of avulsion from the fem-oral insertion Cooper9reported that

as many as 80% of PCL tears found

in knee dislocations were either avulsed or stripped subperiosteally Repair can be performed by placing nonabsorbable sutures through the avulsed ligament The sutures are passed through drill holes at the avulsion site and tied over a bone bridge or suture button The results

of suture repair of acute midsub-stance or chronic tears have generally been unsatisfactory, and reconstruc-tion is typically recommended in that situation.5,16-19

Single-Bundle Reconstruction

Both open and arthroscopic PCL reconstructions have been per-formed with a single graft bundle through a single femoral tunnel Be-cause of the size of the femoral ori-gin, only a portion of the PCL can be reconstructed with a single-bundle technique Since the anterolateral bundle is larger and stronger than the posteromedial bundle, the fem-oral tunnel is drilled where the an-terolateral fibers of the PCL origi-nate on the femoral condyle.3,7

The procedure is performed with the patient supine After treating any meniscal or chondral lesions, the torn PCL is debrided to enhance visualization A posteromedial por-tal is established under direct ar-throscopic visualization to gain access to the tibial insertion, which extends well below the posterior joint line Use of a cannula with a one-way valve can decrease fluid extravasation from the posterome-dial portal and facilitate repeated introduction and removal of instru-ments The PCL insertion fibers are meticulously debrided with a shaver

placed through a posteromedial

portal The arthroscope is passed

through the intercondylar notch in

order to debride the stump The

70-degree scope can be particularly

useful at this point for visualization

over the back of the tibial plateau

Once the space has been cleared, a

PCL drill guide is placed through the

femoral notch A Kirschner wire is

inserted just distal and medial to the

tibial tubercle and is passed

proxi-mal and posterior in a line roughly

parallel to the proximal tibiofibular

joint The wire is placed so that the

tunnel exits the posterior tibial cortex

in the distal lateral aspect of the PCL

“footprint” (Fig 6) Passage of the

wire and subsequent drilling should

be visualized either arthroscopically

or under fluoroscopic guidance A

curette or ribbon retractor is used to

protect the posterior neurovascular

structures during drilling The rough

inner edge of the tibial tunnel is then

gently smoothed with a bone rasp

When preparing the femoral

tun-nel, it is helpful to leave the PCL

femoral insertion fibers intact so that

the outline of the PCL footprint can

be readily appreciated The

antero-lateral bundle origin is best described

as being in the anterior half of the

femoral PCL insertion, 8 to 9 mm

proximal to the articular surface of

the medial femoral condyle A drill

guide is used to place a Kirschner

wire in position so that the femoral

tunnel entrance into the joint is

lo-cated at the origin of the anterolateral

bundle fibers A small incision is

made over the medial femoral

con-dyle midway between the patella

and the medial epicondyle The

entry point should be proximal to

maintain sufficient subchondral bone

and reduce the risk of osteonecrosis

of the medial femoral condyle.5,19,21

A Kirschner wire is passed

antero-grade, entering the joint at the tip of

the drill guide The lateral condyle

should be protected with an

instru-ment during passage of the wire and

subsequent overdrilling

Alterna-tively, the femoral tunnel can be drilled retrograde through an acces-sory inferolateral portal, either leav-ing a blind tunnel or exitleav-ing through the femoral cortex.3

The most popular choice for graft material has been Achilles tendon allograft, although ipsilateral or contralateral patellar tendon auto-grafts, patellar tendon alloauto-grafts, and the hamstring and quadriceps tendons are reasonable alternatives

One of the more difficult parts of the procedure is passing the graft around the sharp turn at the back of the tibial plateau and into the proxi-mal tibial tunnel A looped wire is inserted in the anterior opening of the tibial tunnel, retrieved inside the joint with a grabber, and directed out the femoral tunnel The soft-tissue end of the Achilles tendon graft can then be passed anterograde through the femoral tunnel, into the joint, around the back of the tibia, and into the tibial tunnel Femoral fixa-tion is achieved with use of an inter-ference screw The knee is cycled, and the graft is tensioned and fixed

at 90 degrees of flexion while an anterior drawer force is applied to the tibia Tibial fixation can be achieved by using a variety of post

and spiked-washer devices with or without concomitant metal or bio-absorbable interference screws Postoperatively, the extremity is braced in extension, and range-of-motion exercises are started in the first week Most surgeons allow crutch-assisted ambulation with progression to weight bearing as tolerated in the brace Closed-chain quadriceps-strengthening exer-cises are initiated early Bent-knee hamstring-strengthening exercises are avoided so as to minimize the risk of posterior subluxation of the tibia Use of crutches is discontinued

at 8 weeks, and balance and pro-prioception exercises are initiated Progression to treadmill walking and pool jogging begins after 3 months It may take 6 months to achieve full knee motion Patients generally return to regular sporting activities after 9 months The few studies reporting results of single-tunnel PCL reconstruction show that most patients do have some improvement, but many continue to have persistent posterior laxity.22

Double-Bundle Reconstruction

Single-tunnel PCL reconstruction techniques replace only the

antero-Figure 6 Optimal position for tibial (A) and femoral (B) tunnels for single-bundle PCL

reconstruction (Adapted with permission from Miller MD, Harner CD, Koshiwaguchi S:

Acute posterior cruciate ligament injuries, in Fu FH, Harner CD, Vince KG [eds]: Knee

Surgery Baltimore: Williams & Wilkins, 1994, p 753.)

lateral bundle fibers The major

the-oretical advantage of the

double-bundle technique is that it also

re-places the posteromedial bundle

fibers and is therefore

biomechani-cally superior to single-bundle

tech-niques In a recent cadaveric study,

Harner et al23showed that use of the

additional posteromedial bundle

decreased posterior laxity by 3.5 mm

(Fig 7) Although the two-bundle

technique is conceptually attractive,

it is technically more challenging,

and clinical experience is limited

The superiority of this approach

over less demanding methods has

yet to be documented clinically

The technique of double

recon-struction is identical to the

single-bundle technique through the tibial

tunnel preparation A tunnel is

drilled in the anterior portion of the

femoral footprint for the

anterolat-eral bundle, and a smaller posterior

femoral tunnel is drilled for the

pos-teromedial bundle (Fig 8) The

Achilles tendon allograft is still

fre-quently utilized for the larger

an-terolateral bundle; a double

semi-tendinosus or gracilis graft can be used for the posteromedial bundle

Both grafts are routed through a sin-gle tibial tunnel The anterolateral graft is tensioned and fixed at 90 de-grees The posteromedial graft is tensioned and separately fixed at 30 degrees

Tibial Inlay Technique

In 1990, Burks and Schaffer24 de-scribed a posterior approach to PCL tibial avulsion fixation In one of their two cases, they used this ap-proach to fix a patellar tendon graft during PCL reconstruction

Berg18 subsequently described the tibial inlay technique in 1995

He devised the procedure to cir-cumvent the technical difficulties caused by using the long tibial tun-nel that is necessary with an

anteri-or approach Not only is it difficult

to pass a graft around the sharp angle at the back of the tibial tun-nel, but the close proximity of the neurovascular structures puts these structures at risk during tunnel preparation and graft passage

Several authors have theorized that abrasion of graft where it passes around the sharp turn at the back of the tibia might be a cause of failure Berg reported improvement in all four patients in his study at a mini-mum follow-up interval of 2 years The KT-1000 arthrometer measure-ment of posterior translation de-creased 4 mm postoperatively to within 2 mm of the value on the normal side

The procedure is performed with the patient in the lateral decubitus position with the operative leg up (Fig 9) Once the initial arthroscopic work has been completed, single or double femoral tunnels are drilled The patient is then repositioned for the posterior approach by extending the knee and placing the leg on bol-sters or a Mayo stand An oblique incision over the medial head of the gastrocnemius allows exposure so that the interval between the medial head of the gastrocnemius and semi-membranosus can be developed Lateral retraction protects the neu-rovascular structures and allows access to the posterior capsule The posterior tibial facet and preposi-tioned wire loop can be palpated The posterior capsule is incised ver-tically, and the PCL insertion is visualized

Figure 7 Comparison of the double-bundle PCL reconstruction with the single-bundle

tech-nique demonstrated significantly less (P<0.05) posterior tibial translation in response to a

134-N posteriorly directed load (Reproduced with permission from Harner CD, Janaushek

MA, Kanamori A, Yagi M, Vogrin TM, Woo SLY: Biomechanical analysis of a double-bundle

posterior cruciate ligament reconstruction Am J Sports Med 2000;28:144-151).

Intact

Full extension 30°

25

20

15

10

5

0

PCL-deficient Single-bundle Double-bundle

P<0.05

Knee Flexion

*

*

*

Figure 8 Optimal positions for placement

of dual femoral tunnels during double-bundle PCL reconstruction (Adapted with permission from Miller MD, Harner CD, Koshiwaguchi S: Acute posterior cruciate ligament injuries, in Fu FH, Harner CD,

Vince KG [eds]: Knee Surgery Baltimore:

Williams & Wilkins, 1994, p 753.)

The posterior tibial plateau is

ex-posed subperiosteally and prepared

for placement of the bone block A

unicortical window can be

fash-ioned to fit the dimensions of the

bone block The popliteus muscle

fibers can be undermined if

neces-sary The graft is inlayed flush and

fixed with one or more screws with

or without washers The femoral

bone block is then passed through

the femoral tunnel for standard

fixa-tion It is possible to estimate the

length of the PCL and patellar

ten-don on the basis of the preoperative

radiographs If the patellar tendon

graft is too long, the femoral bone

block will protrude from the

fem-oral tunnel If that is the case, it is

possible to place the tibial bone

block distally on the posterior tibia

or to use an alternative graft source

Combined Ligament Reconstruction

Patients with multiple ligament injuries who are treated nonopera-tively have relanonopera-tively poor functional results Torg et al15reported the re-sults in a group of 29 patients with other ligament injuries associated with their PCL tears Four patients (14%) were rated as having an excel-lent result (full return to the prein-jury sport or a similar sport), and 10 (34%) were rated as having a good result (mild instability with sports,

no problems with activities of daily living) KT-1000 arthrometer testing showed a mean side-to-side

differ-ence of 7.1 mm (range, 2 to 21 mm)

at 20 lb From these data, the authors concluded that serious consideration should be given to surgical treatment for patients with combined ligament injuries

Knee injuries that are severe enough to result in multiple liga-ment tears are usually the result of a collision or motor vehicle accident.3

In some cases, damage to the second-ary restraints leads to a greater de-gree of laxity; in other cases, the liga-ment damage results in instability in multiple planes In most individuals, surgical treatment of each ligament

is necessary to address combined in-stabilities

In most cases, a PCL tear com-bined with a posterolateral corner injury causes grade 3 posterior lax-ity.19 This combination produces much more posterior translation and external rotation than either in-jury alone.9 Patients are less likely

to compensate and more likely to experience functional instability Failure to address combined liga-ment injuries leads to a higher fail-ure rate after surgical treatment.7

Persistent posterolateral laxity after PCL reconstruction may increase forces in the graft that predispose it

to ultimate failure.3,7 The results of acute posterolateral corner repair are better than those of reconstruction; therefore, when feasible, posterolat-eral corner repair is preferable Scar formation quickly obscures the anat-omy, making repair difficult after 2

to 3 weeks.3,7

Arthroscopic cruciate ligament reconstruction can usually be per-formed 2 to 3 weeks after the injury because of capsular sealing.11 If sub-stantial fluid extravasation occurs during the procedure, causing an appreciable increase in calf or thigh pressure, it may be necessary to abandon arthroscopy and proceed with an open surgical technique With acute injuries, an attempt should be made to repair all dam-aged structures However, this is

Figure 9 Tibial inlay technique A, Lateral decubitus position for initial arthroscopy and

graft harvesting B, With the knee extended and the leg abducted, the popliteal fossa is

accessible for exposure of the posterior tibial graft-fixation site (Adapted with permission

from Berg EE: Posterior cruciate ligament tibial inlay reconstruction Arthroscopy

1995;11:69-76.)

B

A

not always possible, especially when

a ligament fails in midsubstance In

the chronic setting, or if tissue is

inadequate for suture repair,

aug-mentation or reconstruction should

be performed Lateral collateral

lig-ament augmentation and

recon-struction can be performed by using

a portion of the biceps tendon, the

ipsilateral hamstring tendon, or an

Achilles tendon allograft The LCL

and popliteofibular ligament can be

reconstructed together with use of a

looped hamstring graft.9 In cases of

chronic severe posterior and lateral

laxity, consideration should be given

to reconstructing both structures

individually Chronic injuries in

in-dividuals with varus alignment may

require valgus osteotomy,

particu-larly when a dynamic varus thrust is

present

A PCL tear combined with an

ACL tear may represent an

unrecog-nized knee dislocation, with a

sub-stantially higher incidence of

con-comitant neurovascular injuries.7

After neurovascular injury has been

ruled out, the knee can be splinted,

and early rehabilitation can be

initi-ated One of the complications of

multiple ligament surgery is

arthro-fibrosis; therefore, some authors

recommend initiating early

range-of-motion exercises and delaying

surgery for a few weeks or more if

necessary Others advocate doing

the reconstruction within 2 weeks,

especially if there is any indication

of a collateral ligament or posterolat-eral corner lesion Magnetic reso-nance imaging is particularly helpful

in evaluation In either case, an elec-tive reconstruction should be per-formed under optimal circum-stances after adequate preoperative planning, rather than emergently

Treatment of a combined PCL-MCL injury is dictated largely by the extent of medial laxity.25 A low-grade MCL tear will often heal with brace protection and joint mobiliza-tion When a high-grade MCL tear occurs together with a high-grade PCL tear, the prognosis is worse.25

Clinically, these patients will have gross valgus instability in full exten-sion and may be functionally unsta-ble even during simple gait Acute injuries should be treated with early repair of the parallel and posterior oblique portions of the superficial MCL, as well as repair or recon-struction of the PCL In chronic cases, patellar or Achilles tendon allograft or hamstring autograft may be necessary for reconstruction

of the MCL; in this situation, it is much more difficult to restore nor-mal valgus laxity

Complications

The most serious complication of PCL surgery is iatrogenic neurovas-cular injury The popliteal artery is especially at risk for injury during

tibial tunnel drilling and graft pas-sage The most common complica-tion after PCL surgery is residual laxity.21 Other potential complica-tions include loss of motion, infec-tion, medial femoral condyle osteo-necrosis, anterior knee pain, and painful hardware

Summary

Injuries to the PCL commonly occur during sports participation or as a result of a motor vehicle accident

A careful history and physical examination will identify most PCL injuries Most authors recommend nonoperative treatment for acute isolated PCL tears This involves initial splinting in extension fol-lowed by range-of-motion and strengthening exercises Recovery

of quadriceps strength is necessary

to compensate for posterior tibial translation and to allow a return to preinjury activity levels Surgical treatment is reserved for acute com-bined ligament injuries, acute bone avulsions, or symptomatic chronic high-grade PCL tears Single-tunnel reconstruction techniques improve posterior laxity only moderately Newer double-tunnel and tibial in-lay techniques offer theoretical ad-vantages; however, few studies have been done, and clinical results are only preliminary

References

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The natural history of acute, isolated,

nonoperatively treated posterior

cru-ciate ligament injuries: A

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2 DeLee JC, Bergfeld JA, Drez D Jr, Parker

AW: The posterior cruciate ligament, in

DeLee JC, Drez D Jr (eds): Orthopaedic

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