Long-term outcomes and factors associated with revision after medial open-wedge high tibial osteotomy in 274 knees: a Kellgren-Lawrence grade-stratified analysis.

PURPOSE: We aimed to investigate long-term outcomes and factors associated with revision after medial open-wedge high tibial osteotomy (OWHTO) according to Kellgren-Lawrence (KL) grade.

METHODS

This retrospective study included 274 knees (158 KL grade 4 [KL4] knees and 116 KL grades 2-3 [KL2-3] knees; mean age 64.7 ± 7.2 years) with a minimum follow-up of 10 years (mean follow-up, 12.5 ± 2.6 years) after OWHTO. Revision surgery (conversion to total knee arthroplasty [TKA] or unicompartmental knee arthroplasty [UKA]) was defined as the endpoint. Clinical and radiographic outcomes were evaluated. Multivariate logistic regression analyses were performed separately for KL4 and KL2-3 knees to identify factors associated with revision.

RESULTS

The mean Japanese Orthopaedic Association (JOA) score improved from 60.6 preoperatively to 91.0 at plate removal, followed by gradual deterioration during long-term follow-up. Final JOA scores were significantly lower in KL4 knees than in KL2-3 knees (71.6 versus 83.1; p < 0.001). Revision surgery was performed in 43 knees (15.7%) and was significantly more frequent in KL4 than in KL2-3 knees (22.2% versus 6.9%; p < 0.01). Ten-year joint preservation rates were 90.5% in KL4 knees and 96.5% in KL2-3 knees (log-rank p = 0.006). In KL4 knees, postoperative percentage mechanical axis (%MA) at the time of plate removal was independently associated with revision risk (odds ratio [OR] 0.94, 95% confidence interval [CI] 0.91-0.98; p = 0.004). In KL2-3 knees, an exploratory multivariate analysis suggested an association between progression of joint line convergence angle during follow-up (ΔJLCA) and revision (OR 3.31, 95% CI 1.52-7.21; p = 0.003), whereas postoperative %MA showed no significant association.

CONCLUSIONS

Long-term outcomes after OWHTO differed according to KL grade. KL4 knees demonstrated higher revision rates and inferior joint preservation survival, and postoperative weight-bearing line position was associated with revision risk. In contrast, revision was uncommon in KL2-3 knees, and exploratory analysis suggested a possible association with longitudinal changes in joint line convergence rather than postoperative alignment. These findings suggest that factors associated with revision may differ according to disease severity.

LEVEL OF EVIDENCE: This was a level IV, retrospective cohort study.