Clinical results after very early, early and late arthroscopic arthrolysis of the knee

PURPOSE: Impaired patient outcome can be directly related to a loss of motion of the knee following surgical procedures. If conservative therapy fails, arthroscopic arthrolysis is an effective procedure to improve range of motion (ROM). The purpose of this study was to evaluate the outcome of patients undergoing very early (< 3 months), early (3 to 6 months), and late (> 6 months) arthroscopic arthrolysis of the knee. METHODS: With a follow-up on average at 35.1 ± 15.2 (mean ± SD, 24 to 87) months, 123 patients with post-operative motion loss (> 10° extension deficit/ < 90° of flexion) were included between 2013 and 2018 in the retrospective study, while eight patients were lost to follow-up. A total of 115 patients were examined with a minimum follow-up of two years. Twenty percent (n = 23) of patients of this study population had a post-operative motion loss after distal femoral fracture, 10.4% (n = 12) after tibial head fracture, 57.4% (n = 66) after anterior/posterior cruciate ligament (ACL/PCL) reconstruction, 8.7% (n = 10) after infection of the knee, and 3.4% (n = 4) after patella fracture. Thirty-seven patients received very early (< 3 months, mean 1.8 months) arthroscopic arthrolysis, and 37 had early (3 to 6 months, mean 4.3 months) and 41 late (> 6 months, mean 9.8 months) arthroscopic arthrolysis after primary surgery. RESULTS: The average ROM increased from 73.9° before to 131.4° after arthroscopic arthrolysis (p < 0.001). In the group of very early (< 3 months) arthroscopic arthrolysis 76% (n = 28) of the patients had a normal ROM (extension/flexion 0/140°), in the group of early (3–6 months) arthrolysis 68% (n = 25) of the patients and in the group of late arthrolysis 41.5% (n = 17) of the patients showed a normal ROM after surgery (p = 0.005). The total ROM after arthrolysis was also significantly increased in the group of very early and early arthrolysis (136.5° and 135.3° vs. 123.7°, p < 0.001). A post-operative flexion deficit occurred significantly less in the group of very early and early arthroscopic arthrolysis compared to the late arthroscopic arthrolysis (3.9° and 4.2° vs. 16.6°, p < 0.001). Patients treated with very early (< 3 months) and early (3 to 6 months) showed a significantly increased post-operative Tegner score of 4.8 ± 1 and 4.7 ± 1.1 compared to 3.8 ± 1.1 in the group of late arthroscopic arthrolysis (> 6 months, p < 0.001). CONCLUSIONS: An arthroscopic arthrolysis is highly effective and leads to good to excellent mid-term results. An early arthroscopic arthrolysis within 6 months after primary surgery leads to significantly improved ROM and functional scores compared to the late arthrolysis (> 6 months).