Natural History of Residual Hip Dysplasia

Developmental dysplasia of the hip describes a spectrum of abnormal hip morphology characterized primarily by deficient acetabular coverage of the femoral head. In acetabular dysplasia, increased load transmission through a reduced surface area coupled with structural instability leads to development of pain, functional limitations, and eventual joint degeneration. Symptom onset is most often insidious and pain is typically located in the groin or laterally and made worse by activity. Mechanical symptoms may be present. The rate at which joint degeneration occurs is variable and depends on the severity of the deformity. Joint degeneration is predictable for dysplastic hips with subluxation or with a lateral center edge angle (LCEA) less than 20°. For hips with borderline or mild dysplasia, the exact relationship between radiographic metrics of dysplasia and development of hip problems is less clear. Most, but not all, studies show that hips with a lateral center edge angle less than 25° are at increased risk of development of hip pain and eventual joint degeneration over time.