Pathomechanism of intravertebral clefts in osteoporotic compression fractures of the spine

Background context Intravertebral cleft (IVC) associated with vertebral collapse is not uncommon in osteoporotic compression fracture. However, the pathomechanism of IVC is poorly understood. Bone ischemia is indicated in the current hypothesis. Purpose To clarify the pathomechanism of IVC in delayed posttraumatic vertebral collapse, referred to as Kummell's disease. Study design Magnetic resonance (MR) angiography and histology of segmental arteries and vertebral bodies in delayed posttraumatic vertebral collapse were investigated. Patient sample All elderly patients admitted to the authors' spine clinic of tertiary referral center for a 105-month period. Outcome measures All imaging tests including plain radiographs, computed tomography, and MR angiography were reviewed by authors using a double-blind method. All operations were performed by one experienced surgeon. The statistical data were analyzed using SPSS program. Methods Evaluations using MR angiography and computed tomography were performed in 22 patients. Twelve of the 22 patients underwent corpectomy and anterior interbody fusion. At operation, segmental artery and bone surrounding IVC were harvested and microscopically evaluated. Results Magnetic resonance angiography showed occlusions of bilateral segmental arteries in nine of 22 patients. Seven patients had unilateral occlusion. In six patients, no occlusion was seen. Microscopically, the left segmental arteries of three patients were completely obstructed by thrombosis. Histologic examination of necrotic bone showed fragile trabecular bone and sparse osteocytes. Conclusions The findings of thrombosis of the segmental arteries of the vertebral body with IVC could suggest a mechanism by which IVC is formed, and the progressive collapse may develop following osteoporotic spinal fracture.