Surgical treatment of avulsion fracture of the posterior cruciate ligament and postoperative management

BACKGROUND: Avulsion fractures of the posterior cruciate ligament have long been regarded as rare injuries. In the past, it was common practice to use cast immobilization as an external adjunct after open reduction and internal fixation of fractures. METHODS: Sixteen patients with displaced avulsion fractures of the posterior cruciate ligament were treated with open reduction and internal fixation between August 1989 and July 1993. Malleolar screws were chosen as fixation devices in 14 patients. In the other two, pull-through sutures were used because the size of the fractured fragments was too small to obtain purchase of screws. The postoperative management protocol evolved from an initial regimen of 6 weeks' immobilization in a cast with the knee flexed to 40 degrees for the first five patients (group I), to 4 weeks' immobilization in a cast for the next six patients (group II), to the present protocol of immediate postoperative range of motion (40-70 degrees) with muscle-strengthening exercises in a functional brace for the last five patients (group III). The average follow-up period was 36 months (range, 24-58 months). Hughston's criteria were used to assess the clinical results. RESULTS: Overall, there were 12 (75%) good and 4 fair (25%) results. There was no poor result. CONCLUSION: Avulsion fractures of the posterior cruciate ligament should be treated with open reduction and stable internal fixation if any displacement is seen on initial radiographs at presentation. With the use of functional brace and aggressive postoperative rehabilitation program (i.e., immediate range of motion of 40-70 degrees with muscle-strengthening exercises), satisfactory results can be expected and achieved.