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

Objectives: We evaluated the midterm results of total hip arthroplasty (THA) for femoral neck osteonecrosis. Method s : The study included 59 patients (23 females, 36 males; mean age 45.6 years; range 24 to 66 years) who under¬went THA in 72 hips. Osteonecrosis was secondary to frac¬ture 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 DʹAubigne and Postel. Bone-implant rela¬tions were assessed radiographically using the Gruenʹs seven zones in the femur and Charnleyʹs three zones in the acetabu¬lum. The mean follow-up was 4.1 years (range 2 to 7 years). Resu l t s: The mean DʹAubigne-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 expan¬sion 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 sig¬nificantly 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 polyethyl¬ene wear was detected in eight hips, two of which also had focal osteolysis in Gruen zone 1. Conclusion: Thanks to improvements in implant technolo¬gy and surgical techniques, the results of both c e m e n t l e s s and hybrid systems are satisfactory in hip osteonecrosis, regardless of the etiology.