Bone Abstracts

Delayed healing of stress fractures constitutes a significant clinical problem causing prolonged pain and disability for the patients affected. All stress fractures exhibit Bone Marrow (edema) Lesions (BMLs) with and without fracture lines on MRI, and in cases of delayed union these lesions persist. Previous studies on transient osteoporosis and osteoarthritis have demonstrated that bisphosphonates can reduce BMLs. We therefore wanted to test, whether treatment with iv. zoledronic acid (5 mg) given twice with an interval of 3 months causing reduction of BMLs, could promote healing in such patients.

Seven female and two male patients (aged 30–72) with non-union of stress fractures for more than 12 months were enrolled. Pain was monitored using VAS (1–10) and MRI was performed in six of the patients at baseline, 3, 6 and 12 months after the first infusion. All patients received Ca (0.5–1 g Ca per day) and vitamin D supplementation (800–1000 IE per day).

All patients experienced clinical healing with significant reduction of pain at the fracture site and improvement of ambulation within 1–3 months after the first infusion. Four patients experienced further alleviation of pain after the second infusion. At 6 months, ambulatory functions were completely restored in all patients and a highly significant reduction of VAS scores from an average of 7.3 before treatment to 1.1 at 6 months and 0.9 at 12 months (P<0.0001) was registered. The alleviation of pain was accompanied by partial or total resolution of the BML on MRI. Except for two cases of flu-like symptoms after the first infusion, no adverse effects were recorded.

In conclusion, treatment with iv zoledronic acid, represents a safe and effective treatment of delayed union of stress fractures in the foot, thus avoiding surgical intervention. This small observational study needs to be corroborated in a larger randomized, controlled trial.