Patient sex and race are associated with differences in coronal plane alignment classification in native arthritic knees.

The purpose of this study was to evaluate associations between demographics and Coronal Plane Alignment of the Knee (CPAK) classification in pre-surgical TKA patients. This is a retrospective study of 1167 patients with knee osteoarthritis who underwent TKA. CPAK categories I-IX were determined by arithmetic mechanical hip-knee-ankle angle and joint line obliquity measurements from pre-operative bone length radiographs. Patient age, sex, body mass index (BMI) and race were collected. Chi-square test of independence and adjusted Pearson's residuals evaluated associations between CPAK classification and demographics. There was a significant association between CPAK phenotypes I-IX and patient sex (X = 5.8, < 0.01). A positive association was found between both men and CPAK phenotype I, and women and CPAK phenotype VII. A positive association was found between African American patients and CPAK phenotype III and a negative association was found between African American patients and CPAK phenotype I (X =14.8, -value = 0.01). There was no association between age and BMI with CPAK phenotypes (n.s.). These results indicate that there are unidentified sex and race differences that exist in the CPAK classification of native arthritic knees. Patient characteristics play a significant role in determining patient knee phenotypes. Further research should investigate whether these characteristics warrant inclusion in pre-operative preparations, aiming to enhance the personalization of arthroplasty procedures.