Spacer-type tibial osteotomy versus open wedge high tibial osteotomy and unicompartmental knee arthroplasty for Kellgren-Lawrence grade 3-4 medial unicompartmental knee osteoarthritis in patients younger than 65 years.

Background: Spacer-type tibial osteotomy have been proven a novel and effective osteotomy to treat osteoarthritis, while lack of comparison with other surgical methods in younger patients. This study aims to evaluate the short-term clinical outcomes of spacer-type tibial osteotomy versus open wedge high tibial osteotomy (OWHTO) and unicompartmental knee arthroplasty (UKA) for Kellgren-Lawrence (K-L) grade 3-4 osteoarthritis (OA) in patients younger than 65 years.

Methods: This retrospective study analyzed a total of 224 patients with K-L grade 3-4 knee OA treated from March 2018 to November 2020. Three groups were created according to the operation type. The clinical outcomes recorded preoperatively and at 6, 12 and 24 months postoperatively were the range of motion (ROM), visual analogue scale (VAS), American Knee Society Score (KSS), Western Ontario and McMaster Universities Global (WOMAC) score, operation time, length of incision, relevant complications and failures. Radiographic parameters were measured to evaluate the correction of varus deformity.

Results: The cohort comprised 224 patients; 70 underwent spacer-type tibial osteotomy, 73 underwent OWHTO, and 81 underwent UKA. The spacer group had the shortest incision (P = 0.000), least amount of bleeding (P = 0.000), and shortest operation time (P = 0.000). UKA achieved the most significant pain relief based on VAS (P = 0.014), KSS pain score (0.030), and WOMAC score (P = 0.000) at 6 months postoperatively, but there were no differences between three groups at 12 and 24 months postoperatively. The spacer and OWHTO groups achieved significantly greater ROM changes compared with the UKA group (all P = 0.000). The complication rate did not significantly differ between the three groups. No surgical failures were identified in HTO but two spacer dislocations in spacer group and three polyethylene dislocations in UKA.

Conclusion: For younger patients with K-L grade 3-4 OA, OWHTO seems to be the most appropriate method through clinical comparisons. Although spacer-type tibial osteotomy offers shorter operation time and comparable clinical outcomes, it also has extended recovery phase, additional fibular incision and the risk of spacer dislocation, which did not appear to be superior to OWHTO and UKA under the indications outlined in this study.

Trial Registration: Retrospectively registered, QYFY WZLL 27,021.