Knee arthroplasty for spontaneous osteonecrosis of the knee: a matched analysis comparing total and unicompartmental

The surgical management of spontaneous osteonecrosis of the knee (SONK) in its advanced stages typically involves joint replacement procedures such as unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). This study aims to compare the risk of complications, revisions, and costs between patients undergoing TKA and UKA for SONK. This study is a retrospective review of the PearlDiver Mariner Database. The patients with a diagnosis of SONK undergoing surgical management were divided into 2 groups: patients with TKA, and patients with UKA. The two groups were matched based on age, gender, the Charlson comorbidity index (CCI), and obesity. There was a higher rate of transfusions at 30 days (< 10 vs. 0%, p = 0.04) and 90 days (< 10 vs. 0%, p = 0.02) in the TKA group. In addition, there was a higher rate of stiffness and manipulation under anesthesia (MUA) in the TKA group at 1 year (3.2% vs. < 10, p = 0.01; and 4.1% vs. < 10, p < .001 respectively), 2 years (3.6% vs. < 10, p = 0.01; and 4.5% vs. < 10, p < .001 respectively), and 3 years (3.8% vs. < 10, p = 0.003; and 4.7% vs. < 10, p < .001 respectively). Furthermore, the TKA group had higher costs at 3 years compared to the UKA group (35,269 ± 61,459 vs. 25,141 ± 25,185, p = 0.001). This study highlights the increased risks of transfusion, stiffness, MUA, and higher costs after TKA compared to patients with UKA for SONK. Our study shows that UKA seems to be a safer and less expensive option for patients with SONK.