Transient regional osteoporosis of the ankle with shifting bone marrow edema pattern within the joint.

We describe a case of bone marrow edema (BME) shifting within one ankle joint in a 35-year-old - male patient. He presented with increasing pain and no history of trauma. Clinically no local swelling was found and laboratory findings and plain x-ray studies were normal. He did not improve on non-steroidal anti-inflammatory drugs for 2 weeks. A Gadolinium enhanced magnetic resonance imaging showed no evidence of synovitis, but BME was observed in the talus and transient regional osteoporosis was diagnosed. The patient was treated conservatively by protective partial weight bearing of the affected joint and he showed partial improvement after 6 months of daily treatment with Calcitonin Salmon nasal spray. A magnetic resonance imaging after 6 months showed that the BME had shifted anteriorly with complete resolution at the initial site. Transient regional osteoporosis is a rare self-limiting syndrome characterized by sudden onset of joint pain, functional limitations and spontaneous recovery, without preceding trauma. The condition may present as one episode affecting only one joint or recurrent episode that may affect multiple joints. BME between different compartments of the same joint can occur and has been reported only in a few case reports in the knee joint. The case is discussed and the literature is reviewed.