Lateral Center-Edge Angle Is Not Predictive of Acetabular Articular Cartilage Surface Area: Anatomic Variation of the Lunate Fossa

BACKGROUND: Surgical treatment of symptomatic femoroacetabular impingement (FAI) and dysplasia requires careful characterization of acetabular morphology. The lateral center-edge angle (LCEA) is often used to assess lateral acetabular anatomy. Previous work has questioned the LCEA as a surrogate for acetabular contact/articular cartilage surface area because of the variable morphology of the lunate fossa. HYPOTHESIS: We hypothesized that weightbearing articular cartilage of the acetabulum would poorly correlate with LCEA secondary to significant variation in the size of the lunate fossa. STUDY DESIGN: Cohort study (Diagnosis); Level of evidence, 3. METHODS: < .05. Significant variation in surface area was observed within each group such that no patient in any group was outside of 2 SDs of the means of the other groups. When patients were categorized into quartiles established by the articular surface area for the entire population, 40% of patients with overcoverage were observed in the first or second quartile (lower area). CONCLUSION: Lateral acetabular undercoverage based on the LCEA (<25°) correlates with decreased acetabular surface area. Normal or increased acetabular coverage (LCEA, >25°), however, is not predictive of increased, normal, or decreased acetabular surface area.