Mayo conservative hip stem for proximal femoral bone preservation in developmental dysplasia of the hip in young patients: a median follow-up of more than 10 years

Purpose: Studies on short-stem total hip arthroplasty (THA) in young patients with developmental dysplasia of the hip (DDH) are limited, with no studies on long-term outcomes. Our study aimed to investigate whether the Mayo conservative hip stem demonstrates favourable mid- to long-term outcomes in these patients. Methods: This retrospective study included 42 patients (50 joints) with DDH aged <55 years who underwent THA using the Mayo conservative hip stem and excluded those with a follow-up period <5 years. Radiographic evaluation involved comparison of the immediate postoperative anteroposterior images with those at the final follow-up. Clinical evaluations utilised the Japanese Orthopaedic Association (JOA) hip score and major postoperative complications, including revision surgery. Results: The mean age of the patients was 48.8 years, with a median follow-up of 11 years. According to the Crowe classification, 35, 11, and 4 cases were classified as Types I, II, and III, respectively. According to the Dorr classification, 29 and 21 cases were classified as Types A and B, respectively. Radiographically, spot welds were observed in 98% of joints in zones 2 or 6, whereas stress shielding was evident in 94% (zone 1) and 54% (zone 7) of the joints. Stem sinking >= 3 mm was observed in 2 joints. No periprosthetic femoral fractures, dislocations, or infections were observed. Conclusions: The Mayo conservative stem in young patients with DDH resulted in favourable mid- to long-term outcomes, including stability and bone preservation. The stem is an effective treatment strategy for these patients.