Gender‐based differences exist in the functional knee phenotypes classification of the osteoarthritic knee

Abstract

PurposeTo identify gender differences in (1) the coronal alignment of functional knee phenotypes and (2) the JLCA (joint line convergence angle) in relation to the phenotype classification.MethodsThis study is a retrospective data analysis, including 12,099 osteoarthritic knee computed tomography (5025 male, 7074 female) analysed by Medacta software for hip‐knee‐ankle angle (HKA), femoral mechanical angle (FMA), tibial mechanical angle (TMA) and JLCA. The data were grouped into genders and combined according to the Functional Knee Phenotypes Classification.ResultsOut of 127 phenotypes for males and 131 for females, 17 common phenotypes were reported. The commonest four were similar for both genders with VARHKA177° NEUFMA93° NEUTMA87° (9.8% males, 9.50% females), followed by VARHKA174° NEUFMA93°VARTMA84° (7.1%) and VARHKA174°VARFMA90° NEUTMA87° (7.0%) for males and VARHKA174° NEUFMA93° NEUTMA87° (6.1%), VARHKA174° NEUFMA93°VARTMA84° (5.1%) for females. The commonest FMA and TMA (91.5° to 94.5° and 85.5° to 88.5°, respectively) were the same for both genders, however, the rest of the male population observed greater femoral varus than the female population (p < 0.001). JLCA values ranged from −28.4° to 8.2° in the overall study population. Males and females had a mean JLCA of −2.96° (±2.6° SD) and −2.66° (±2.8°7 SD), respectively, p < 0.001.ConclusionsGender differences exist within the osteoarthritic knee phenotype. The male varus phenotype is influenced by FMA, while TMA values are similar across genders. JLCA variations show similarities to both TMA and FMA, suggesting JLCA is influenced by bone morphology more than by gender. These differences inform surgical decision‐making for the personalised approach to the primary TKA.Level of EvidenceLevel III.

Why we should use boundaries for personalised knee arthroplasty and the lack of evidence for unrestricted kinematic alignment

“…In a study of 4884 lower limb computed tomography (CT) scans of patients scheduled for TKA, the distal femoral surface orientation varied between 11.0°varus and 15.5°v algus (mean of 2.7°valgus), while the tibial surface orientation ranged between 20.5°varus and 20.5°valgus (mean 2.9°varus) [1]. Moreover, Chelli et al, evaluating 12,099 osteoarthritis (OA) knees CT scans, found that although the most common phenotype was the same for both men and woman, there were gender-based differences in knee phenotype, as well as in hip-knee-ankle angle (HKA), and femoral mechanical angle [6]. Generally, the scientific definition of normality, when a criterion is normally distributed and follows the Gaussian curve, is objectively defined using mean, standard deviation and confidence intervals.…”