Is hip-knee-ankle alignment enough? Long term influence and clinical relevance of postoperative radiological alignment parameters after high tibial osteotomy

While correction of mechanical axis using hip-knee-ankle (HKA) alignment has been used traditionally for planning and assessment of outcomes after medial opening wedge high tibial osteotomy (MOWHTO), long-term influence of other postoperative radiographic alignment parameters—mechanical medial proximal tibial angle (mMPTA), joint line convergence angle (JLCA), and joint line obliquity (JLO)—has not been extensively studied. This study aimed to evaluate the temporal behavior of these parameters and their association with long-term clinical outcomes and survivorship after MOWHTO. This study included 203 knees that underwent MOWHTO (mean follow-up - 11.5 years). mMPTA, JLCA, and JLO were assessed preoperatively, at 6 months postoperatively, and at final follow-up. Temporal changes were analysed using Friedman and Wilcoxon signed-rank tests. Clinical outcomes (KSS, KSSF, OKS and WOMAC) were assessed using Spearman correlation. Survivorship, defined as conversion to total knee arthroplasty, was evaluated using Kaplan–Meier analysis and multivariable Cox proportional hazards regression adjusted for age and BMI. All alignment parameters showed significant correction from the preoperative assessment to 6 months postoperatively (p < 0.001). Between 6 months and final follow-up, mMPTA and JLO remained stable, suggesting durable bony correction, while JLCA showed mild variation over time. Correlations between postoperative alignment parameters and long-term patient-reported outcomes were weak (|ρ| < 0.30). Survivorship was 97.5% at 5 years, 89.2% at 10 years, and 76.2% at final follow-up. On multivariable Cox regression, mMPTA, JLCA, and JLO were not independently associated with conversion to total knee arthroplasty. However, extreme values of mMPTA and JLO showed a non-significant trend toward higher risk of failure. HKA remains a dependable reference for assessing overall alignment after MOWHTO. However, mMPTA, JLCA, and JLO show different long-term patterns and offer additional insight during postoperative evaluation. Although these parameters were not independently linked to long-term outcomes or survivorship, extreme alignment values may be associated with poorer durability