Overcoming surgical challenges in total hip arthroplasty in dysplastic high-riding hips

Developmental dysplasia of the hip (DDH) is the most common congenital disease of the musculoskeletal system in newborns [1]. If left untreated, limping can occur starting at walking age and premature hip arthritis can occur with severe osteoarthritis detected by the second decade [1, 2]. Severe cases of DDH-related arthritis are more frequently seen in Asia than in the US and Europe, probably because infant screening programs in the US and Europe are more prevalent [3]. The severity of DDH can vary from a subtle dysplasia to mild subluxation to complete dislocation. Due to the highly deformed femur and pelvis, performing total hip arthroplasty (THA) in severe cases of DDH is technically challenging; the complication rate can be high and the survivorship of the implants can be low. In Part 1 of this series, Seung Beom Han from the Department of Orthopedics, Korea University Medical Center, Seoul, South Korea, will discuss what the current practices are in performing THAs in highly deformed, high-riding hips.

Classification of dysplastic hips

Crowe's classification system is the most used system in adult DDH, although the newer system described by Hartofilakidis et al [6] is also a reliable and commonly used system [2–6].
Crowe et al [7], based on their understanding that the degree of difficulty of THAs is associated with the severity of the dislocation and the subsequent distortion of normal bone and soft-tissue anatomy, grouped the dysplastic hips into four types based on the amount of dislocation (subluxation): < 50% in type I, 50–75% in type II, 75–100% in type III, and more than 100% in type IV.

As shown in Figure 1, the amount of deformity in DDH can progress from mild subluxation with a shallow socket (type I) to high dislocation of the hip joint accompanied by an absence of the femoral head and neck and a deformed pelvis (type IV). While a THA in DDH where subluxation is less than 50% has "no greater technical difficulty at surgery than a hip with severe osteoarthritis" [7], THAs in highly deformed DDHs are challenging and require special skills and consideration [2, 7].

The Hartofilakidis classification divides DDH into three types: A) dysplasia, B) low dislocation, and C) high dislocation (Table 1).