Increased prevalence of lateral trochlear groove wear among valgus alignment subtypes by coronal knee alignment classification: A retrospective single-center study.

Abstract

The Coronal Plane Alignment of The Knee (CPAK) classification aims to restore the constitutional knee alignment, although it neglects the patellofemoral joint. Therefore, this study aims to examine the correlation between trochlear groove wear (TGW) patterns and CPAK classifications. Our institutional database was queried to include unilateral primary total knee arthroplasties (TKA) between 2021 and 2025. TGW was categorized into central, medial, lateral, and no TGW based on the most prominent wear observed intraoperatively. Using OMNIBotics® surgical navigation system (Corin Ltd.), nine CPAK phenotypes were determined by intraoperative registration of the arithmetic hip-knee-ankle angles (aHKA), joint line obliquity (JLO), lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA). Among 559 cases, central TGW (53.7 %), followed by lateral (21.8 %) and medial (15.2 %), were the most frequent TGW. Lateral TGW had a higher mean of MPTA (88.5 ± 2.3), while medial TGW had a significantly higher mean of LDFA (87.3 ± 2.2) than the other groups. Central TGW was the most prevalent wear in all aHKA groups, with the lateral TGW being more frequent (33 %) in the valgus knees than the medial TGW (8.4 %). Forty-two percent of cases with lateral TGW had CPAK type Ⅲ, followed by CPAK type Ⅱ (30 %) and CPAK type Ⅵ (13.0 %). The most frequently observed CPAK phenotypes with the central TGW were type Ⅱ (40 %), type Ⅲ (25 %), and typeⅠ (17 %). The same trend was detected for medial TGW and those without wear. The interplay between joint health and structural alignment can impact surgical planning, as we observed a significant association between the TGW and CPAK parameters. Surgeons may adjust femoral component rotation in CPAK Ⅲ with lateral TGW to address patellar maltracking, though further research is needed.