Technetium-99m methylene diphosphonate bone scan in evaluation of insufficiency fractures - A pictorial assay and experience from South India.

Insufficiency fractures (IFs) can be challenging to diagnose due to varied presentations, and sometimes, it changes the course of treatment, as in cancer patients in whom it has to be differentiated with metastatic disease. We present the role of Technetium 99m methylene diphosphonate (Tc-MDP) bone scan, which is a low-cost, simple to perform, whole body diagnostic investigation in the diagnosis of IFs. This is a retrospective analysis of all patients who underwent a Tc-MDP bone scan in a tertiary care teaching hospital during 2013-2017 and were diagnosed as having an IF on bone scan. The bone scans were performed on a dual-head gamma camera using low-energy high-resolution collimators. Of all the bone scan performed during 2013-2017, a total of 138 patients with a mean age of 57.5 ± 14.7 years were diagnosed as having IFs based on bone scan and final clinical diagnosis. Among them, the most common complaint was regional bony pain in 62% of patients, while the most common cause was osteoporosis in 47% of patients, both postmenopausal and senile osteoporosis. In all, 265 sites of fractures were identified with a fracture average of 1.9/patient, the most common site being dorsolumbar vertebrae, followed by ribs and lower limb bones. Many unusual sites were also identified such as talus, sternum, clavicle, and scapula. Tc-MDP bone scan, being noninvasive whole-body imaging, is a useful investigation for evaluation of IFs and in correlation with biochemical analysis and other imaging can be used to determine the etiology of IF.