Traditionally, nonoperative treatment of isolated PCL injuries has been favored, especially with lower grade injuries. This is based on both the capacity of the ligament to heal and some outcome studies demonstrating excellent results in these patients. It appears that individuals are often able to compensate for PCL insufficiency via agonistic muscle function developed through a well-designed therapy program.
Nonoperative management is currently recommended for isolated, asymptomatic PCL injuries with minimal or mild laxity.6,10 If posterior translation is less than 10mm (i.e., grade
I or II injuries), as it is in majority of isolated injuries, aggres sive rehabilitation is instituted. This may also be used in cases with small tibial avulsion fractures and translation less than 5 to
10 mm. Rehabilitation for these injuries usually consists of 2 to
4 weeks of immobilization with the knee in full extension, often with protected weight bearing. This results in tibial reduction and prevents any posterior sag. Quadriceps strengthening is encouraged, while hamstring loading is prohibited to prevent posterior tibial subluxation. After 4 weeks, active-assisted range of motion and progressive weight bearing are begun.9 Patients can usually be expected to return to sports 1 to 3 months after injury.5 Rehabilitation focuses on closed-chain exercises, with the goal to regain 90% of quadriceps and hamstring strength (compared with the contralateral side). PCL braces have not been found helpful in low-grade chronic injuries. It is recom mended that patients treated conservatively be followed yearly for any symptoms or signs of progressive instability or degener ative joint changes.5,14
Treatment of acute grade III injuries (displacement greater than 1 0 to 15 mm) is more controversial. Historically, these injuries have been treated similarly to lower grade tears, but most authors now recommend surgical intervention for all acute injuries resulting in severe tibial subluxation and for combined multiligamentous injuries.1,6,10 Surgery is also recommended for avulsion injuries with translation greater than 10 mm. If the fragments are small, the PCL should be reconstructed, but if the fragments are sufficiently large, internal fixation may be attempted. Combined injuries are best treated within 2 weeks, after which capsular scarring develops and direct repair of collateral and posterolateral corner structures is usually not possi-ble.9 ACL reconstruction may be delayed, however, in order to regain knee motion and allow capsular healing. Multiple surgical options exist for ligament reconstruction, including choice of graft, single- versus double-bundle techniques, and tibial tunnel versus tibial inlay techniques. These are discussed in more detail in the next section.
The treatment of chronic instability should be based on the degree of instability, presence or absence of degenerative changes, and response of symptoms to nonoperative management. Nonoperative treatment, including physical therapy and activity modification, is successful for the majority of patients with chronic PCL instability. Surgery may be recommended if posterior displacement is greater than 10 mm and nonoperative modalities have failed to relieve symptoms. In addition, progressively increasing activity on bone scan, indicative of increased metabolic activity due to altered knee biomechanics and progressive degeneration, may be a useful evaluative factor. In the presence of medial compartment wear, valgus osteotomy with or without PCL reconstruction may be considered. One should rarely, if ever, attempt to reconstruct the PCL in patients with a fixed (irreducible) posterior drawer, and direct repair instead of reconstruction of a chronic PCL injury is also strongly discouraged.
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