Treatment of osteonecrosis of the hip: comparison of extracorporeal shockwave with shockwave and alendronate

Background and purpose Extracorporeal shockwave therapy (ESWT) and alendronate are reported effective in early osteonecrosis of the femoral head (ONFH). We hypothesized that joint effects of ESWT and alendronate may produce superior results. This prospective study compared the results of ESWT and alendronate with that of ESWT without alendronate in early ONFH. Patients and methods Forty-eight patients with 60 hips were randomly divided into tow groups. There were 25 patients with 30 hips in group A and 23 patients with 30 hips in group B. Both groups showed similar demographic characteristics. All patients were treated with 6,000 impulses of ESWT at 28 KV (equivalent to 0.62 mJ/mm(2)) to the affected hip as a single session. Patients in group B also received alendronate 70 mg per week for 1 year, whereas patients in group A did not. The evaluations included clinical assessment, radiograph and MR image of the affected hip. Both groups were compared statistically using paired t, Mann-Whitney and Chi square tests with statistical significance at P < 0.05. The primary end point is the need for total hip arthroplasty (THA). The secondary end point is the improvement in pain and function of the hip. The third end point is the progression or regression of the lesion on image study. Results The overall clinical outcomes were improved in 83%, unchanged in 7% and worsened in 10% for group A; and improved in 77%, unchanged in 13% and worsened in 10% for group B. THA was performed in 10% of group A and 10% of group B (P = 1.000). Significant improvements in pain and function of the hip were noted in both groups (P < 0.001), however, the differences between the two groups were not significant (P = 0.400, 0.313). On MR images, the lesions showed progression in 10%, regression in 47% and unchanged in 43% in group A, and progression in 7%, regression in 53% and unchanged in 40% in group B (P = 0.830). Conclusion ESWT and alendronate produced comparable result as compared with ESWT without alendronate in early ONFH. It appears that ESWT is effective with or without the concurrent use of alendronate. The joint effects of alendronate over ESWT in early ONFH are not realized in short-term.