Developmental dysplasia of the hip (DDH) - Crowe classification of severity of adult DDH

Crowe et al. classified adult developmental dysplasia of the hip (DDH) into four grades according to the extent of underlying subluxation on AP x-ray of the pelvis.

Crowe grade Dislocation Description
Grade 1 <50% subluxation femur and acetabulum show minimal abnormal development
Grade 2 50 - 70% subluxation the acetabulum shows abnormal development, femoral head articulates with false acetabulum, which partially covers the true acetabulum
Grade 3 70 - 100% subluxation the acetabulum is developed without a roof
Grade 4 >100% subluxation (luxation) the acetabulum is deficient but remains recognizable


1. Crowe JF, Mani VJ, Ranawat CS. Total hip replacement in congenital dislocation and dysplasia of the hip. J Bone Joint Surg Am. 1979 Jan;61(1):15–23.