Clinical Efficacy of Unicompartmental Knee Arthroplasty in the Treatment of Spontaneous Osteonecrosis of the Knee

Background: This retrospective study aimed to evaluate the short-term effectiveness of unicompartmental knee arthroplasty (UKA) in the treatment of spontaneous osteonecrosis of the knee (SONK). Methods: The patients who were diagnosed as SONK and received UKA in our hospital from January 2012 to January 2018 were retrospectively analyzed. The patients were diagnosed and staged by X-ray and MRI techniques before surgery. The range of motion (ROM), femorotibial angle (FTA), and visual analog scale (VAS) score of patients' knee joints were assessed before and after surgery. Clinical outcomes were evaluated by the hospital for special surgery (HSS) knee score. Results: A total of 18 patients with spontaneous osteonecrosis (4 males and 14 females; mean age: 62.5 years) met the inclusion criteria participated in this study. According to the Mont grades, 12 cases (66.7%) were in stage III, and 6 cases (33.3%) were in stage IV. The average follow-up was 19.6 months. At the last follow-up, it was found that the hospital for HSS score was increased from 61.22 ± 2.90 to 91.0 ± 2.89 (P < 0.05); VAS score was decreased from 6.44 ± 1.04 to 1.94 ± 0.99 (P < 0.05); FTA was improved from 178.42 ± 0.84 to 176.17 ± 0.87 (P < 0.05); ROM (120.17 ± 5.88) was not significantly different from that before surgery (119.61 ± 5.56, P = 0.601). Conclusion: The encouraging results of this study indicate that UKA has an excellent short-term clinical effect in the treatment of SONK.