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

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

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.

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).

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