Evaluation of clinical and magnetic resonance imaging results after treatment with casting and bracing for the acutely injured posterior cruciate ligament

Purpose: The purpose of this study was to evaluate the clinical and magnetic resonance imaging (MRI) outcomes of nonoperative management of acute, isolated posterior cruciate ligament (PCL) injuries.

Methods: From February 2001 to January 2008, 49 consecutive patients with acute (<4 weeks), isolated PCL injuries underwent nonoperative treatment with cast immobilization and PCL braces. Of these patients, 38 who satisfied our inclusion criteria and could be followed up for a minimum of 24 months (median, 51 months) were enrolled in our study. Functional outcomes were evaluated at follow-up with the Lysholm knee scoring system, Hospital for Special Surgery knee scoring system, and International Knee Documentation Committee subjective and objective knee scoring systems. PCL injury status on MRI was assessed using a different scale for initial and follow-up MRI.

Results: The grade of posterior instability was significantly improved from initial grades of I in 13 patients (34%) and II in 25 patients (66%) to follow-up grades of 0 in 3 patients (8%), I in 21 patients (55%), and II in 14 patients (37%) (P = .007). The mean side-to-side difference in posterior translation measured with the KT-1000 arthrometer (MEDmetric, San Diego, CA) was initially 6.7 mm and significantly improved to 5.2 mm at the latest follow-up (P < .001). At latest follow-up, the mean Lysholm knee score, Hospital for Special Surgery knee score, and International Knee Documentation Committee subjective score were 88, 91, and 83, respectively. The continuity of the PCL on follow-up MRI showed statistically less posterior instability on both physical examination (P = .010) and KT-1000 arthrometer testing (P = .003).

Conclusions: Our active, nonoperative method of casting and bracing with attached tibial supporters, which was designed to prevent posterior displacement at the knee, yielded satisfactory functional and MRI results in the majority of patients at intermediate-term follow-up. The continuity of the PCL with low signal intensity on follow-up MRI was a predictable factor for a favorable prognosis in patients with acute PCL injuries.

Level of evidence: Level IV, therapeutic case series.