Posterior Cruciate Ligament Pathology Treatment & Management
- Author: Matthew Lawless, MD; Chief Editor: Carlos J Lavernia, MD more...
The natural history of posterior cruciate ligament (PCL) insufficiency has been a subject of controversy. Several reports with small cohorts have reported good outcomes with conservative treatment. These reports include patients with acute and chronic PCL insufficiency, as well as isolated and combined PCL injuries.[55, 56, 57] Several authors have reported late chondrosis of the medial femoral condyle and the patellofemoral compartment in patients with PCL insufficiency.[28, 58, 59, 60, 61] The development of meniscus tears and abnormal contact pressures have been reported.[60, 62, 63]
Geissler et al evaluated patients with PCL injuries treated conservatively with arthroscopy at a mean of 2.2 years. They reported that 49% had grade 2 or higher articular cartilage lesions, and 36% had meniscal tears.
Keller et al monitored 40 patients with isolated PCL injuries treated conservatively an average of 6 years. Among the patients, 90% complained of knee pain, 65% had activity limitations secondary to the knee, and 43% had difficulty walking. The patient complaints were correlated with objective measures of posterior laxity. In addition, the incidence of radiographic abnormalities increased in relation to the duration of follow-up.
Boynton et al reported findings in 38 patients at a mean of 13.4 years after an isolated PCL injury treated conservatively. Among the patients, 81% complained of occasional knee pain, and 56% reported occasional knee swelling. Radiographic analysis also correlated the degree of degenerative changes to the duration of follow-up.
Shelbourne et al reported that of 133 athletic patients treated conservatively for isolated acute PCL tears, 68 patients returned for clinical follow-up at a mean of 5.4 years. The other 65 patients complete a modified Noyes Knee Questionnaire. The mean questionnaire score was 84.2. A score of 94 has been found to be normal for athletes of the same age.
Findings in this cohort led to the following conclusions:
Healing of PCL injuries occurs, and residual laxity does not increase over time.
Subjective scores are poorly correlated with the degree of posterior knee laxity.
Objective and subjective knee function is independent of the grade of posterior knee laxity.
A trend toward medial compartment arthrosis exists but does not correlate with the degree of posterior knee laxity.
Meniscus tears are rare.
Independent of laxity, one half of patients can return to the same sport at the same level, one third can return to the same sport at a lower level, and one sixth cannot return to the same sport.
Although these results are comparable to those reported after PCL reconstruction, this cohort had laxity of grade 2 or less, and no distinction between partial and complete PCL tears was made in this study.[11, 64]
Posterior cruciate ligament (PCL) reconstruction begins with an examination with the patient under anesthesia to rule out concomitant ligament injuries. Diagnostic arthroscopy should be performed, and any meniscus or cartilage procedures should be performed. Findings such as abnormal lateral joint opening at 25° of knee flexion during knee arthroscopy are also suggestive of posterolateral corner insufficiency.[29, 65] Arthroscopic findings consistent with an isolated PCL injury are ACL pseudolaxity, medial femoral condyle and patellofemoral compartment chondrosis, and an abnormal relationship of the medial femoral condyle to the medial meniscus.[5, 66]
Arthroscopic debridement of the PCL should be performed, leaving any fibers in continuity to lie over the graft and leaving enough remnants to identify the PCL footprints. A limited notchplasty can be performed for visualization; notch impingement is not a factor for PCL reconstruction, unlike ACL reconstruction. Tibial graft fixation can utilize a tunnel or an inlay technique. The tunnel technique is simpler, avoiding posterior knee dissection. However, the angle the graft must make at the back of the tibial articular surface has been termed the killer turn.[29, 54, 67]
A cadaveric study demonstrated the PCL graft has increased laxity and evidence of degradation after 72 cyclic loads, after tibial tunnel PCL reconstruction. The tibial inlay technique can be performed with the patient in a lateral position or else requires the patient to be turned from supine to prone and back to supine. Decreased posterior tibial translation has been demonstrated after the tibial inlay technique.[68, 70]
Femoral graft placement has been performed with single-tunnel and, more recently, double-tunnel techniques. Single-bundle techniques were designed to recreate the stabilizing effect of the anterolateral bundle of the PCL. This was based on the belief that the anterolateral bundle of the PCL is dominant. The inability of single-tunnel techniques to restore posterior tibial translation throughout knee range of motion (ROM) led to further studies.[28, 72, 73, 74]
Isometric PCL reconstruction has been advocated to recreate normal PCL function. Studies have shown that the isometric region of the PCL is a small portion of the ligament.[29, 67] Isometric reconstructions restored normal posterior translation only at low angles of knee flexion, not at knee flexion greater than 60°. Nonisometric reconstruction with the femoral tunnel placed distal to the isometric region, in the anterior aspect of the PCL footprint, 7-10 mm proximal to the articular surface better restores posterior translational stability throughout knee ROM than isometric reconstruction.[29, 67, 75]
Codominance of the anterolateral bundle (larger aspect of the PCL) is taut in flexion (also becomes tighter in internal rotation), and the smaller posteromedial bundle is taut in extension. The 2 bundles are inseparable. Subsequently, double-tunnel or double-bundle techniques have been developed with the goal of restoring normal knee kinematics.[24, 28, 72, 73, 74, 75, 76] Split- or Y-graft may be used, or else 2 separate grafts are needed. See the image below.
With the double-tunnel technique, the anterolateral bundle graft should be tensioned in 90° of knee flexion with anterior tibial translation.[67, 69] Tension of the posteromedial bundle graft has been advocated with the knee in extension and with the knee in 30° of flexion with the tibia anteriorly translated.[67, 69] Debate also persists as to whether a bone bridge is needed at the articular surface between the 2 femoral tunnels. In vitro studies support the double-bundle technique over the single-bundle technique.[72, 75, 76] The double-bundle technique has been shown to restore results of the posterior drawer test to normal.[76, 77, 78]
Postoperative management should include a wound drain and neurovascular examination in the recovery room. Neurapraxia is the most common complication of posterior cruciate ligament (PCL) reconstruction. Passive range of motion (ROM) from 0-90° and quadriceps-strengthening exercises should be initiated immediately after surgery.
Patients should be restricted to toe-touch weightbearing with an extension brace for the first 2 weeks after surgery. The brace is kept locked in extension for a total of 4 weeks, then 0-90° motion is allowed for the next 4 weeks. Full extension must be achieved by postoperative 3-6 weeks, or intervention is required.
Patients are restricted from squatting, downhill walking, or sudden deceleration for 6 months. At 6 months, patients may begin straight run-walking if quadriceps and hamstring deficits are less than 20%. Once patients can run straight ahead at full speed, they may progress to lateral running, crossovers, cutting drills, and figure-eight exercises.
Neurapraxia is the most common complication of posterior cruciate ligament (PCL) reconstruction.
Outcome and Prognosis
No series of acute isolated posterior cruciate ligament (PCL) reconstruction exists. The results in the literature are difficult to interpret because of variations in case selection and methods of evaluation. Techniques of reconstruction and the lengths of follow-up also vary. Consequently, the reported results vary.
Lipscomb et al reported the results for 25 patients with isolated acute or chronic PCL injuries treated with single-tunnel technique. At an average of 7 years after surgery, 60% had degenerative changes identified on radiographs.
Degenerative joint disease of the medial compartment is the most common late sequelae of PCL injury. Degeneration of the patellofemoral compartment also occurs, but less often.
Stannard et al reported the results of 30 multiligament knee injuries with PCL ruptures. This was the first reported series of PCL reconstructions using the combination of the tibial inlay technique and the double-tunnel technique. At a mean follow-up of 25 months, no statistical difference was found between injured knees and normal knees.
The outcome following PCL reconstruction for chronic PCL insufficiency has been worse than that of reconstruction for acute injuries. Postoperative posterior tibial laxity is greater after reconstruction for chronic PCL insufficiency than it is after acute PCL insufficiency, and patients with this injury cannot safely return to athletics. The diminished results of PCL reconstruction in patients with chronic knee insufficiency are thought to be the result of attenuation of the secondary restraints over time. PCL reconstruction inevitably fails if the posterolateral corner is insufficient or if the patient has developed a lateral thrust and the other pathology is not addressed.
Grade 1 and 2 PCL injuries have been reported to heal without any progression of posterior tibial laxity. Grade 3 tears do not heal and progressive laxity may develop as secondary and tertiary posterior tibial stabilizers are stressed over time.
Future and Controversies
The long-term outcome of posterior cruciate ligament (PCL) insufficiency is difficult to predict, as is the outcome of PCL reconstruction. Current reconstruction techniques (ie, the tibial inlay and double-tunnel methods) are promising with regard to their ability to create more normal knee responses to a posterior tibial force. However, the value of restoring knee posterior-tibial stability has not yet been correlated with patient function and outcome.
Many also believe that PCL reconstruction cannot prevent or delay the onset of degenerative changes in patients who have had a PCL injury. One certainty is that isolated PCL tears are not benign injuries. Reconstruction is advocated for patients with grade 3 PCL injuries. The natural history of isolated grade 1 and grade 2 PCL injuries has been established, and the outcome following PCL reconstruction must prove to be better to warrant the procedure and lengthy rehabilitation.
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