In dysplastic hips, concentration of the weight and load on the lateral peripheral limbus causes its detachment and tearing, which is an important risk factor of coxarthrosis. Arthrograms of 77 hip joins in 40 patients (all female) with dysplastic hips were used to analyze the covering of the acetabulum and limbus. The average age at the time of arthrograms was 26 years (13-48). The limbus covering angle, a supplement to the CE angle, was added to the CE angle to measure the femoral head cover. Our results demonstrated a negative correlation between the degree of acetabular dysplasia and the length of the limbus. Insufficient bony acetabulums tended to be accompanied by proportionally longer limbi. Also, the limbus was significantly longer in cases with tears, suggesting that a long and unstable limbus might be more likely to undergo tearing, thereby increasing the risk of coxarthrosis.