Developmental Dysplasia of the Hip (DDH)

Developmental dysplasia of the hip (DDH) encompasses dislocation, formerly known as congenital dislocation of the hip, and subluxation of the hip as well as acetabular dysplasia. Osteoarthritis resulting from DDH can be associated with high dislocation or subluxation. In Crowe III and IV cases, the hip structure is markedly different from that of a normal hip, with hypoplasia of both the acetabulum and femur leading to reduced bone stock, making implant selection and placement challenging. The cup should ideally be placed in the primary acetabulum; however, if adequate coverage of the host bone is not achieved, positioning the cup at a high hip center may be necessary, and in some cases, bulk bone grafting or metal augmentation might be required. DDH cases often exhibit a high anteversion angle of the femoral neck; therefore, reducing the anteversion of the stem during insertion is crucial to mitigate the risk of dislocation. Significant leg length discrepancy is common in Crowe III and IV cases. To avoid nerve injury, total hip arthroplasty (THA) may be combined with femoral shortening osteotomy. Excessive leg lengthening can lead to joint contractures, necessitating tension reduction through muscle release or detachment to achieve optimal limb positioning and range of motion.