Fragility fracture of pelvis caused by amenorrheic osteoporosis operated upon using computed-tomography-3D-fluoroscopy matching navigation system: a case report

INTRODUCTION: Low-energy trauma fractures of older people cause fragility fractures of the pelvis (FFPs), and secondary amenorrhea triggers osteoporosis that might lead to FFPs. Anorexia nervosa is a major causative factor in secondary amenorrhea, thus, FFPs might be a problem for young anorexia nervosa patients as well as older people. Here, we report a rare case of a young woman with anorexia nervosa who had an FFP, followed by gradual progression of severe sacral deformity. CASE: A 49-year-old woman with hypothalamic amenorrhea (a subtype of secondary amenorrhea) caused by anorexia nervosa fell from a chair. She visited a nearby hospital and was diagnosed with an undisplaced sacral fracture; however, she chose to stay at home since the pain was slight and she could still walk. She fell to the floor several times while injured, and 3 months later, she had walking difficulty accompanied with severe pain, and was admitted to our facility. On radiological examination, she was diagnosed with FFP with severe sacral deformity, and was treated surgically. Because of the severe sacral deformity, a computed tomography (CT)-3D-fluoroscopy matching navigation system was used during surgery to support appropriate placement of percutaneous iliosacral (IS) and transiliac–trans-sacral (TITS) screws. DISCUSSION: To our knowledge, this is the first report of FFP caused by amenorrheic osteoporosis, treated by matching navigation. This matching navigation could be a supportive tool in inserting IS and TITS screws during surgery for FFPs, especially in cases with severe deformity.