Vertebral compression fracture within a solid fusion mass without trauma after removal of pedicle screws.

Background Context: Many complications of lumbar fusion have been reported. However, reports of complications related to implant removal after solid fusion are rare. In addition, there are almost no reports of compression fractures occurring within a fusion mass.

Purpose: This work aimed to report a case of vertebral body compression fracture within a solid lumbar fusion mass after removal of fusion instrumentation, and to investigate the contributing factors.

Study Design: A case report was carried out.

Methods: A 67-year-old woman presented with gait disturbance and pain radiating from both lower extremities. She had a history of lumbar fusion at L2-L5 because of degenerative stenosis. We found spinal stenosis at L5-S1 and ossification of the ligamentum flavum at T12-L2. Posterior decompression and fusion were performed for the lesion, and previously inserted fusion instrumentation was removed at L2-L5 in accordance with the patient's request. After surgery, her symptoms decreased and she was discharged. Five weeks after surgery, the patient returned with sudden, severe back pain that occurred without trauma. Compression fracture at the L3 lower end plate was observed via magnetic resonance imaging. We treated her back pain with analgesics and a thoracolumbosacral orthosis. After 2 weeks, her back pain had decreased, and she was discharged.

Results: Before removal of instrumentation, we verified complete union using computed tomography. However, an unexpected compression fracture occurred within the fusion mass, without trauma. We suspect that the causes of the compression fracture were the straight sagittal imbalance of the spine, the cantilever motion in the anterior disc after posterior fusion, and decreased bone strength.

Conclusions: Vertebral compression fracture in a solid fusion mass may occur as a complication of implant removal. Surgeons must take care to maintain normal sagittal alignment during spinal fusion, and they should consider careful removal of instrumentation for patients with risk factors such as osteoporosis, sagittal imbalance, long spine fusion, and certain types of fusion.