In this study, the factors causing stiff knee after primary total knee arthroplasty (TKA) in patients with medial compartment osteoarthrosis were evaluated.
Primary TKA surgery was performed in fifty-three knees in 48 patients (42 females, 6 males; mean age 67.2±8.5; range 59 to 76 years) diagnosed with medial compartment osteoarthrosis. Five patients (10%) out of forty-eight underwent bilateral primary TKA. In the patients who had bilateral TKA, the second operation was performed six months later. Patello-femoral arthroplasty was performed in none of the patients. In the final follow-up, the knees, which had more than 10° of extension limitation and less than 95° of flexion, were defined as post-TKA stiff knee. The patients who developed stiff knee were classified as group 1 and the patients who did not develop stiff knee were classified as group 2. The possible factors that may cause stiff knee after TKA such as age, gender, range of knee flexion and extension, flexion arc, tibiofemoral angle, tibial slope angle, the change in the height of the joint line, the length of the patellar tendon, the change in the American Knee Society scores, body mass index, and the sizes and positions of the components were evaluated and compared pre- and postoperatively within and between both groups.
Stiff knee was found in eight knees of six patients (16%) after TKA. In group 1, the mean extension range was 14.9°±4.6° and the mean flexion range was 82.6°±7.4°. In group 1, among the factors that may cause knee stiffness; preoperative flexion range and American Knee Society scores were found to be significant (p=0.028 and p=0.036, respectively). The American Knee Society scores were observed to be significantly lower in group 1 when compared to group 2 postoperatively (p=0.018).
If the preoperative flexion range is limited and the American Knee Society scores are low, then the stiff knee is more likely to occur in patients who will undergo TKA. Age, gender, tibiofemoral angle, tibial slope angle, the change in the height of the joint line, the length of the patellar tendon, and the sizes and positions of the components have no significant effect on the development of stiff knee after TKA.