Unicompartmental Knee Arthroplasty Provides Superior Clinical and Radiological Outcomes Compared to High Tibial Osteotomy at a Follow-Up of 5-8 Years

Background: Knee Osteoarthritis (OA) is a debilitating disease. Initially, the medial compartments are affected in most cases. For this pathology, joint preservation is preferable. Two surgical procedures aim to meet this goal: high-tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA). The aim was to compare clinical and radiological outcomes of HTO versus UKA in patients with unicompartmental, medial OA. Method: Retrospective case series. A total of 86 (61 UKA, 25 HTO) patients that received either treatment at a single, specialized center were assessed preoperatively and at a single follow-up examination at 77.13 months (+/- 8.170). The Knee Society Score (KSS), range of motion (ROM), SF36 questionnaire and the Tegner score were used. The Kellgren-Lawrence score was assessed pre- and post-surgically. Survivorship with the endpoint "revision" was assessed. Results: The UKA group showed significantly better improvements in KSS scores for pain (p < 0.006) and function (p < 0.001). OA progression (p < 0.02) and survivorship (p < 0.018) differed, significantly favoring UKA. ROM, SF36 and Tegner score did not differ significantly. Conclusions: The presented mid-to long-term data suggest that UKA provides superior results in selected outcomes. Nevertheless, significant differences in the demographics of treatments indicate the challenge of comparing these two treatments.