Postoperative alignment and patients reported outcome measures improvement after high tibial osteotomy: a significant interaction with osteoarthritis severity.

purposeOptimal postoperative alignment in high tibial osteotomy (HTO) remains controversial due to inconsistent target definitions and limited evidence supporting osteoarthritis (OA) severity-based strategies. This study evaluated clinical outcomes across postoperative weight-bearing line (WBL) categories stratified by OA severity, hypothesizing that overcorrection would be detrimental in early OA but not in advanced OA.

methodsThis retrospective single-center study included 181 knees that underwent open-wedge or closed-wedge HTO between 2017 and 2023 with a minimum 2-year follow-up. Knees were classified as early OA (Kellgren-Lawrence [KL] ≤ 2) or advanced OA (KL ≥ 3). The corrective angle was defined as the planned angular change required to shift the mechanical axis to the target postoperative alignment, determined by aiming for a postoperative %WBL of 62.5% on double-limb standing full-length radiographs. Overcorrection was defined as %WBL ≥ 70%. Clinical and radiographic outcomes were assessed at baseline and final follow-up. Multivariable regression models identified factors associated with changes (Δ) in Forgotten Joint Score-12 (FJS-12) and Knee Injury and Osteoarthritis Outcome Score (KOOS), and logistic regression evaluated achievement of minimum clinically important difference (MCID) and patient acceptable symptom state (PASS). Each knee was treated as an independent observational unit.

resultsEarly OA (n = 112) and advanced OA (n = 69) showed comparable baseline characteristics. In early OA, postoperative alignment was significantly associated with ΔFJS‑12 and ΔKOOS Sports. Compared with optimal alignment, overcorrection was associated with smaller improvement in ΔFJS‑12 (β = -10.49, 95% CI - 20.46 to - 0.53) and ΔKOOS Sports, whereas undercorrection did not demonstrate a statistically significant association with postoperative improvement. Overcorrection also reduced the likelihood of achieving MCID and PASS in early OA. In advanced OA, postoperative alignment was not associated with PROM improvements or MCID/PASS achievement.

conclusionsOvercorrection was associated with significantly poorer improvement in FJS-12 and KOOS Sports in early OA, whereas postoperative alignment was not associated with differences in PROM improvements in advanced OA. LEVEL OF EVIDENCE: IV.