Improved clinical outcomes when maintaining a neutral joint line obliquity at high tibial osteotomy and subsequent total knee arthroplasty.

Maniar, Adit R; Mackay, Nicola D; Somerville, Lyndsay; Litchfield, Robert; Lanting, Brent A; Getgood, Alan M J · J Exp Orthop · 2026

retrospective_cohort · Level III

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Abstract

The primary aim was to study the impact of joint line obliquity (JLO) on clinical outcomes and survivorship in patients undergoing total knee arthroplasty (TKA) after a previous high tibial osteotomy (HTO). The secondary aim was to study how maintaining neutral JLO at both HTO and TKA affected clinical outcomes of TKA. A retrospective review of patients undergoing TKA following valgus-producing HTO, having a minimum 1-year follow-up, was performed. Using the coronal plane alignment of the knee (CPAK) classification, three groups of JLO were formed: distal JLO (<177°), neutral JLO (177-183°) and proximal JLO (>183°). Clinical outcomes were assessed using the Western Ontario and McMaster University Osteoarthritis Index (WOMAC). The level of significance was 0.05. The study included 110 TKA (mean follow-up: 5.8 years). Prevalence of a proximal JLO post-TKA was higher (<i>p</i> < 0.05) in those with a proximal JLO pre-TKA (40%) as compared to those with a neutral JLO pre-TKA (13%). The odds ratio of having a proximal JLO post-TKA was 4 (95% confidence interval: 1.4-11.1, <i>p</i> < 0.05) in those having a proximal JLO pre-TKA. Revision rate in the proximal JLO post-TKA, neutral JLO post-TKA and distal JLO post-TKA groups was 20%, 8% and 4% respectively, with no statistical difference (<i>p</i> > 0.05). Post-TKA, the stiffness, function and total WOMAC were significantly better (<i>p</i> < 0.05) in patients with a neutral JLO pre-TKA and neutral JLO post-TKA as compared to those with a proximal JLO pre-TKA and proximal JLO post-TKA or a proximal JLO pre-TKA and neutral JLO post-TKA. While a proximal JLO after conversion TKA did not show a statistically higher revision rate, maintaining a neutral JLO during HTO and at the time of subsequent TKA was associated with higher post-operative clinical scores. However, further research in different and larger populations is needed to confirm these findings. Level IV.