Age-related differences in radiographic parameters for femoroacetabular impingement in hip arthroplasty patients.

Abstract

To compare the prevalence of femoroacetabular impingement (FAI) radiographic findings between patients aged younger than 50 years and those aged 50 years or older who underwent total hip arthroplasty. Total hip arthroplasty patients aged younger than 50 years and those aged 50 years or older were identified retrospectively from a facility medical record database. Fifty patients from each group were randomly selected, and preoperative radiographs were collected. Dysplastic, inflammatory, post-traumatic, and osteonecrosis patients were excluded. Radiographs were evaluated for FAI-specific findings. Intraobserver and interobserver reliability was evaluated with κ statistics for categorical variables and intraclass correlation coefficients for continuous variables. An independent t test was used to compare continuous variables, χ(2) analysis was used for discrete variables, and a z ratio was used to analyze proportions. The mean age between the subgroups of patients aged younger than 50 years and those aged 50 years or older (43 years and 68 years, respectively) was significantly different (P < .05). Findings in the subgroup aged younger than 50 years included significantly more men (P < .001), decreased lateral joint space with maintained medial joint space (P < .05), significantly greater alpha angle on both the anteroposterior view and the frog-leg lateral view (P < .05), significantly higher Tönnis and Sharp angles (P < .01), and significantly lower center-edge angle (P < .001). This retrospective case series shows an increased prevalence of FAI findings (specifically cam pathology) in a patient population aged younger than 50 years undergoing total hip arthroplasty when compared with a cohort aged 50 years or older. Level III, retrospective comparative study.