Post-operative bracing after ACL reconstruction has no effect on knee joint effusion. A prospective, randomized study.

Background: It is unclear what factors contribute to knee joint effusion after anterior cruciate ligament (ACL) injury and reconstruction. Knee homeostasis after injury and surgery is crucial for rehabilitation and knee well-being. We examined if effusion was affected by post-operative bracing, and if patients with effusion fit into a common profile.

Methods: Patients were randomized to wearing or not wearing a post-operative brace for three weeks after ACL reconstruction with semitendinosus-gracilis tendons. Knee joint effusion was detected by computed tomography in 60 patients (22 women), before and three and 12 months after surgery. Joint effusion, clinical and subjective tests were analyzed.

Results: This is the first prospective, randomized study on post-operative bracing for patients with a semitendinosus-gracilis graft showed that bracing had no effect on three-months presence of joint effusion. Excessive joint effusion was present in 68% of the patients three months after surgery and was associated to prior meniscus injury (p=0.05) and higher prior Tegner activity level (p=0.006). We found a positive association between longer time from injury to surgery and joint effusion three months post-operatively (rho=0.29, p<0.05). Twelve months post-operatively, joint effusion had diminished to baseline levels. Subjective scores and activity levels were lower for women. Three-months joint effusion predicted lower final outcome scores in women.

Conclusion: Prior meniscus injury and pre-injury Tegner activity levels are predictive significant variables for excessive knee joint effusion after ACL reconstruction. Post-operative bracing had no effect. A larger clinical cohort is needed to confirm findings of this logistic regression.