gms | German Medical Science

Objectives: Osteonecrosis of the femoral head (ONFH) is a debilitating disease that often leads to collapse of subchondral bone and destruction of hip joint. Early intervention prior to collapse is usually required to preserve the hip and defer the need for total hip arthroplasty. Interests had been surged in the pharmacologic advantages of bisphosphonates on ONFH. However the clinical results by using the drug alone were not successful. The purpose of the study was to investigate whether a combined therapy of multiple drilling and alendronate would achieve better outcomes than multiple drilling alone.

Methods: From 2001 to 2005, we treated 58 hips in 45 patients with pre-collapsed or early-collapsed (< 2mm) ONFH by multiple drilling. Of them, 19 patients took oral alendronate with variable periods after the surgery. All 58 hips were followed for a mean of 8.4 years (2 - 14), of which 23 were ARCO stage II and 3 stage III in the combined treatment group, 26 stage II and 6 stage III in the multiple drilling alone group. Clinical failure was defined as the need for additional surgeries or Harris hip score < 70. Radiological failure was defined as progression by two stages or further collapse by 2 mm.

Results: At the final follow-up, 50 % (13/26) of hips in the combined treatment group successfully preserved the joints without any additional surgeries, compared with 25 % (8/32) of hips in the drilling alone group (p = 0.049). The mean time of patients undergoing additional surgeries in the combined treatment group was 40.3 months (range, 8 to145 months), compared with that of 22.8 months (range, 2 to 120 months) for the patients in the drilling alone group (p = 0.01). Survival rates using Kaplan-Meier analysis showed significantly better 10-year survival for the combined treatment group than the drilling alone group when either clinical failure or radiological failure was used as the end point (p = 0.004, p = 0.016 , respectively). The adjusted Cox regression model showed that alendronate administration independently decreased the risk of clinical and radiological failure, while advanced ARCO stage was an independent risk factor for both clinical and radiological failure.

Conclusions: The study suggested that multiple drilling combined with oral alendronate increase the clinical and radiological success rates, especially in the precollapse stage. Alendronate may be an effective adjuvant treatment in delaying the progression of collapse and preventing early mechanical failure after decompression.