Eight-year follow-up of uncemented hydroxyapatite coated hip prosthesis for hip osteoarthritis secondary to developmental hip dysplasia

Objectives: This study aims to investigate the mid-term clinical and radiological results of cementless hydroxyapatite coated total hip arthroplasty (THA) for hip osteoarthritis due to developmental dysplasia of the hip (DDH). Patients and methods: Between January 2004 and December 2010, 34 hips (12 Crowe type I, 12 Crowe type II, 4 Crowe type III, 6 Crowe type IV) of 30 patients (22 females, 8 males; mean age 53.4 years; range 30 to 75 years) with degenerative arthritis due to DDH were analyzed in terms of cementless hydroxyapatite coated acetabular component (EPF Plus (R)) over Zweymuller femoral component (Zweymuller SL-PLUS (R)) and porous coating. Clinical assessment was performed using Harris hip scores (HHS) preoperatively and at the last clinic visit, while radiological assessment was done according to the Callaghan and Engh's criteria. Results: The mean follow-up was 48 months (range, 25-91 months). The mean HHS was 44.97 (28-55) preoperatively and 92.25 (69-100) at the last visit. All femoral components were graded as stable according to Callaghan and Engh's criteria. Radiolucency was mostly observed in Gruen zones 1 and zone 7 of the femur [zone 1; 20 hips zone 7; 19 hips zone 2; one hip, zone 3; one hip and zone 6 one hip]. Around acetabular component, radiolucency was detected in zone 2 in 12 hips, zone 3 in 10 hips and zone 1 in six hips. Heterotopic ossification developed in two hips, while neuropraxy Was detected in two hips postoperatively. Femoral fissure in one hip, nonunion in the femoral osteotomy line in one hip, and femoral head autograft nonunion in one hip developed. Conclusion: Mid-term results of uncemented Zweymtuller femoral stem and hydroxyapatite coated press-fit using acetabular components for THA femoral stem are excellent.