Anterior knee pain causes after total knee arthroplasty

Abstract

The objective of the study was to determine the causes of postoperative anterior knee pain after total knee arthroplasty for preventing its occurrence and improving the surgery results.The treatment results of 77 (112 cases) patients with cruciate-retaining total knee arthroplasty without patellar replacement were analyzed. The study involved 62 (80.5 %) women and 15 (19.5 %) men. The average age (Me (25‒75 %)) of the patients was 65 (60‒70) years. There were 97 cases (87 %) with varus deformity of the knee joint, 15 cases with valgus deformity (13 %). The average angle of varus deformity was 11.22 ± 3.81°, the average angle of valgus deformity was 11 ± 4.27°. After the anterior pain appeared, patients were examined in 2‒3, 4‒5 and 6‒7 months after surgery using clinical, X-ray (anterior-posterior, lateral and axial projections, topogram of lower extremities), and EMG methods.The causes of anterior postoperative knee pain were: implant components misplacement, patellar microcirculation disorders (chondrolysis, avascular necrosis due to circular patella denervation), patellofemoral joint imbalance, and functional causes. Pain manifested itself at active leg loading and knee motion because of implant components misplacement within 2‒3 months in 34 cases (94 %), 4‒5 months ‒ in 2 cases (6 %). Patellar microcirculation disorders within 4‒5 months ‒ in 5 cases (21 %), 6‒7 months ‒ in 19 (79 %) cases. Imbalance in the patellofemoral joint within 2‒3 months ‒ in 29 cases (69 %), 4‒5 months ‒ in 13 cases (31 %). Functional causes of pain appeared within 2‒3 months ‒ in 7 cases (70 %), 4‒5 months ‒ in 3 cases (30 %).The causes of postoperative anterior pain in total knee arthroplasty can be incorrect surgical technique, changes in patellar blood supply or in the biomechanics of the patellofemoral joint due to the imbalance of the thigh muscles.