[Midterm results of total hip replacement in osteonecrosis of the hip joint]

We evaluated the midterm results of total hip arthroplasty (THA) for femoral neck osteonecrosis.

The study included 59 patients (23 females, 36 males; mean age 45.6 years; range 24 to 66 years) who underwent THA in 72 hips. Osteonecrosis was secondary to fracture in the femoral neck in 11 hips (15.3%), was associated with steroid use in 23 hips (31.9%), and was idiopathic in 38 hips (52.8%). Functional evaluations were made with the hip scoring system of D'Aubigne and Postel. Bone-implant relations were assessed radiographically using the Gruen's seven zones in the femur and Charnley's three zones in the acetabulum. The mean follow-up was 4.1 years (range 2 to 7 years).

The mean D'Aubigne-Postel hip score was 11.8 (range 7 to 16), with good or excellent results in all hips. While no significant difference was found between cementless and hybrid systems (p>0.05), the mean hip score was significantly higher with press-fit acetabular systems compared to expansion cups (p<0.001). The effects of the following were found insignificant on the clinical outcome (p>0.05): etiology, metal-on-metal or metal-on-polyethylene surfaces, and development of stress shielding in the proximal femur or of varus-valgus angulation in the femoral stem. However, the results were significantly less favorable in cases in which complications arose (p<0.001). Intraoperative complications were fissure in five patients and isolated trochanteric fracture in five patients, all of which occurred in cementless THA. Heterotopic ossification was seen in six hips. At the end of 6.5 years, mild polyethylene wear was detected in eight hips, two of which also had focal osteolysis in Gruen zone 1.

Thanks to improvements in implant technology and surgical techniques, the results of both cementless and hybrid systems are satisfactory in hip osteonecrosis, regardless of the etiology.