Posterior Laxity after Conservative Treatment of the Acute Injured Posterior Cruciate Ligament

ABSTRACT

PURPOSE: This study analyzed the contributing factors on posterior stability after conservative treatment for the posterior cruciate ligament(PCL) injury. MATERIALS AND METHODS: During the period from June 1996 to February 2002, 16 cases had been followed for more than 12 months after conservative treatment for acute PCL injury. We analyzed associated injury, continuity and location of PCL injury by magnetic resonance imaging(MRI) also subjective scores and serial stress radiogram. RESULTS: The average posterior displacement after conservative treatment was 4.0 mm. At last follow up, posterior drawer radiogram showed average 3.3 mm in isolated PCL injury, 4.6 mm in associated injuries. In serial posterior drawer radiogram, side to side difference was average 9.1 mm at injured time, 6.0 mm at 3 months after injury, 4.5 mm at 9 months after injury, 4.0 mm at 12 months after injury. In MRI findings, twelve cases showed interstitial tear of PCL, four cases complete disrupted, respectively and their posterior displacement was at last follow op 3.7 mm, 5.0 mm. The PCL tear location was in the proximal third in 3 cases, the middle third in 8 cases, and the distal third in 5 cases. Lysholm knee score improved from 73.3 points at 6 months after injury to 86.1 points at final follow up. Lysholm knee score was 84.6 points in patients > 5 mm posterior tibial translation, 86.1 points in patients < 5 mm posterior tibial translation. CONCLUSION: The isolated PCL injury usually heals with some residual knee laxity which increase with associated injury. we recommend to protect the injured PCL for healing period, because significant improvement was found in serial stress radiogram until 6 months after injury. We also recommend aggressive treatment of associated injury.