Effect of ibandronate on spontaneous osteonecrosis of the knee: a randomized, double-blind, placebo-controlled trial.

UNLABELLED: Based on this double-blind, placebo-controlled study, ibandronate has no beneficial effect on clinical and radiological outcome in patients with spontaneous osteonecrosis of the knee over and above anti-inflammatory medication.

INTRODUCTION: Observational studies suggest beneficial effects of bisphosphonates in spontaneous osteonecrosis (ON) of the knee. We investigated whether ibandronate would improve clinical and radiological outcome in newly diagnosed ON.

METHODS: In this randomized, double-blind, placebo-controlled trial, 30 patients (mean age, 57.3 ± 10.7 years) with ON of the knee were assigned to receive either ibandronate (cumulative dose, 13.5 mg) or placebo intravenously (divided into five doses 12 weeks). All subjects received additional treatment with oral diclofenac (70 mg) and supplementation with calcium carbonate (500 mg) and vitamin D (400 IU) to be taken daily for 12 weeks. Patients were followed for 48 weeks. The primary outcome was the change in pain score after 12 weeks. Secondary endpoints included changes in pain score, mobility, and radiological outcome (MRI) after 48 weeks.

RESULTS: At baseline, both treatment groups (IBN, n = 14; placebo, n = 16) were comparable in relation to pain score and radiological grading (bone marrow edema, ON). After 12 weeks, mean pain score was reduced in both ibandronate- (mean change, -2.98; 95% CI, -4.34 to -1.62) and placebo- (-3.59; 95% CI, -5.07 to -2.12) treated subjects (between-group comparison adjusted for age, sex, and osteonecrosis type, p = ns). Except for significant decrease in bone resorption marker (CTX) in ibandronate-treated subjects (p < 0.01), adjusted mean changes in all functional and radiological outcome measures were comparable between treatment groups after 24 and 48 weeks.

CONCLUSIONS: In patients with spontaneous osteonecrosis of the knee, bisphosphonate treatment (i.e., IV ibandronate) has no beneficial effect over and above anti-inflammatory medication.