[Short-term effectiveness of unicompartmental knee arthroplasty for medial compartmental knee osteoarthritis].

OBJECTIVE: To evaluate the short-term effectiveness of unicompartmental knee arthroplasty (UKA) for medial compartmental osteoarthritis of the knee.

METHODS: Between January 2008 and October 2013, 18 patients with medial compartmental osteoarthritis of the knee were treated by UKA, including 11 males and 7 females with an average age of 67.2 years (range, 60-72 years). The disease duration ranged from 3 to 5 years (mean, 3.7 years). All patients had loading pain and walk-associated pain of the medial compartmental knee. The preoperative visual analogue scale (VAS) score was 6.8 ± 1.4. The full-length radiograph of lower limb and anteroposterior and lateral radiographs of the knee showed medial compartmental osteoarthritis of the knee. According to Ahlback staging, 8 knees were at stage II and 10 knees at stage III. The knee range of motion (ROM) was (112.3 ± 11.3)°, and the angle of genu varus was (13.2 ± 1.3)°. The American Hospital for Special Surgery (HSS) score was 59.0 ± 6.4.

RESULTS: Primary healing of incision was obtained in all patients, and no infection or lower limb deep venous thrombosis occurred. All of the patients were followed up 6-50 months (mean, 28 months). No prosthetic loosening and dislocation or lesions of contralateral compartment and patellofemoral joint developed. At 6 months after operation, the VAS score was significantly reduced to 2.8 ± 1.2 (t = 9.20, P = 0.00); most of patients achieved significant relief of pain. The HSS score was significantly increased to 92.0 ± 3.1 (t = 19.69, P = 0.00); and the results were excellent in 12 cases, good in 5 cases, and poor in 1 case, with an excellent and good rate of 94.4%. The knee ROM was (115.2 ± 10.2)°, showing no significant difference when compared with preoperative one (t = -0.81, P = 0.23). The alignment of limbs showed that the angle of genu varus was significantly reduced to 6.8 ± 2.1)° (t = 10.99, P = 0.00).

CONCLUSION: UKA has satisfactory short-term effectiveness in the treatment of medial compartmental knee osteoarthritis, however, long-term effectiveness need further studies.