Does cast immobilization contribute to posterior stability after posterior cruciate ligament reconstruction?

PURPOSE: The purpose of this study was to confirm the contribution of long leg cast immobilization to posterior stability after reconstruction of isolated posterior cruciate ligament (PCL) injuries.

METHODS

Of 84 patients who underwent arthroscopic PCL reconstruction between November 2006 and December 2009, 44 patients were randomly assigned to 2 groups and analyzed prospectively. For 22 patients (the cast group), long leg cast immobilization was applied until postoperative week 5 and then a 0° locking brace was worn until week 12. Full weight bearing was allowed immediately after operation. For the other 22 patients (the brace group), only a 0° locking brace was applied until postoperative week 12 without cast immobilization. Range of motion (ROM), clinical scores, Telos device (Telos, Marburg, Germany) posterior stress radiographic assessment results and International Knee Documentation Committee (IKDC) grades of both groups were analyzed preoperatively and at postoperative years 1 and 2.

RESULTS

The mean preoperative side-to-side difference on Telos posterior stress radiographs was 11.3 ± 2.5 mm in the cast group and 12.7 ± 2.1 mm in the brace group, revealing no differences between the 2 groups (P = .743), but postoperatively the mean difference measured 2.5 ± 1.9 mm and 4.8 ± 2.4 mm, respectively, showing a significantly smaller difference in the cast group (P = .004); the improvement was 8.8 mm and 7.9 mm, respectively, and was statistically significant (P = .021). Preoperative IKDC grades were not different between the 2 groups (P > .05), but 2 years postoperatively, the cast group showed a significantly better distribution of grades (P = .012). The mean ROM, Lysholm scores, IKDC subjective scores, and Tegner scores 2 years postoperatively were not significantly different between the 2 groups (P > .05).

CONCLUSIONS

The patients immobilized with long leg casts until 5 weeks after PCL reconstruction showed significantly better results in Telos posterior stress radiographs and distribution of IKDC grades 2 years postoperatively and did not show limited ROM when compared with the patients who wore braces only. However, IKDC subjective scores were not found to be different between the 2 groups.

LEVEL OF EVIDENCE: Level I, prospective randomized comparative study.