The bone marrow edema syndrome (BMES) is a severely disabling pain syndrome without a definite treatment and refers to transient clinical conditions with unknown pathogenic mechanism, such as transient osteoporosis of the hip, regional migratory osteoporosis, and reflex sympathetic dystrophy. Magnetic resonance imaging is used for early diagnosis and monitoring of its progression. Early differentiation from other aggressive conditions with longterm sequelae is essential in order to avoid unnecessary treatment. The aim of this monocentric trial was to test the efficacy and the safety of amino-bisphosphonate neridronate administered in two different regimens in patients with BMES.

192 patients with BMES secondary to osteoarthritis localized in the knee, hip, wrist or foot were randomly assigned to intravenous (iv) infusion of 100 mg neridronate given four times over 10 days (Group A, 72 subjects) or alternatively to iv infusions of 100 mg every 21 days over 3 months (Group B, 120 subjects). Magnetic resonance image (MRI) was performed at baseline and after 180 days. We assessed a 0-100 mm pain visual analogue scale (VAS) in each patient, too. Outcomes were MRI changes and VAS changes. A control group (35 patients) was enrolled too, treated conservatively with non-steroidal anti-inflammatory drugs and articular rest.

We observed a significant improvement in MRI with the resolution of bone marrow lesions present at the baseline (P<0.01), without a significant difference between Group A and Group B. The VAS score decreased significantly during the study in both groups (P<0.05) without a significant difference between the two treatment groups (P>0.1). Both groups showed a significant clinical and radiologic improvement compared with the control group (P<0.001).

In patients with BMES, the infusions of neridronate 100 mg every 21 days over 3 months or alternately every 3 days over 10 days were associated with clinically relevant and persistent benefits without significant differences between the two treatment schedules. These results provide conclusive evidence that the use of bisphosphonates, at appropriate doses, is the treatment of choice in BMES.