[Comparison of anterior knee pain between fixed-bearing prosthesis and mobile-bearing prosthesis after total knee arthroplasty].

OBJECTIVE: To compare the difference of anterior knee pain between mobile-bearing prosthesis and fixed-hearing prosthesis after total knee arthroplasty (TKA).

METHODS: Between January 2008 and October 2008, 72 patients with osteoarthritis were treated with primary TKA. All patients were randomly divided into fixed-bearing prosthesis group (n = 37) and mobile-bearing prosthesis group (n = 35). In fixed-bearing prosthesis group, there were 8 males and 29 females with an average age of 69.6 years (range, 57-76 years), weighing from 55 to 92 kg (mean, 66.7 kg); the locations were the left knee in 20 cases and the right knee in 17 cases; the body mass index (BMI) ranged from 17.6 to 37.3 (mean, 26.2); the disease duration was 3-22 years; the Knee Society Score (KSS) knee score, function score, patellar score, and pain score were 29.4 +/- 15.3, 33.4 +/- 16.8, 7.2 +/- 2.5, and 2.5 +/- 2.2 respectively; and the Insall-Salvati (I-S) index was 1.6 +/- 0.3. In mobile-bearing prosthesis group, there were 9 males and 26 females with an average age of 68.2 years (range, 58-73 years), weighing from 50 to 86 kg (mean, 67.9 kg); the locations were the left knee in 30 cases and the right knee in 5 cases; the BMI ranged from 18.4 to 34.4 (mean, 25.6); the disease duration was 6-18 years; the KSS knee score, function score, patellar score, and pain score were 30.9 +/- 14.7, 31.4 +/- 14.4, 6.8 +/- 3.1, and 2.0 +/- 2.3, respectively; and the I-S index was 1.6 +/- 0.2. There was no significant difference in general data between 2 groups (P > 0.05).

RESULTS: All incisions healed by first intention; no deep vein thrombosis of lower limbs or pulmonary embolism occurred. All patients were followed up 12-16 months. In mobile-bearing prosthesis group, knee infection occurred in 1 case, dislocation of the knee in 1 case, and clicking of the knee in 3 cases; in fixed-bearing prosthesis group, clicking of the knee occurred in 1 case. There was no significant difference in KSS knee score, function score, patellar score, or pain score between 2 groups (P < 0.05) at last follow-up; and there was no significant difference in congruence angle, lateral patellofemoral angle, patellar tilt angle, lateral patellar displacement, patellar displacement, or I-S index between 2 groups at last follow-up (P > 0.05). Anterior knee pain occurred in 7 cases (18.9%) of the fixed-bearing prosthesis group and in 5 cases (14.3%) of the mobile-bearing prosthesis group, showing no significant difference (chi2 = 0.227, P = 0.634). There were significant differences in KSS knee score, function score, patellar score, and I-S index between patients with anterior knee pain and patients without anterior knee pain (P < 0.05).

CONCLUSION: Fixed-bearing prosthesis and mobile-bearing prosthesis have the same short-term effectiveness and the incidence of anterior knee pain.