Cylindrical expandable cages are commonly used as interbody grafts after cervical, thoracic or lumbar corpectomies in patients with osteomyelitis. Unfortunately, there is a high incidence of hardware subsidence due to small diameter footplates. Newer expandable intervertebral cages with large rectangular endcaps utilize the anatomic strength of the vertebral epiphyseal ring to prevent subsidence.
A 67-year-old man with medically refractory thoracic osteomyelitis and discitis presented to our service for further management of debilitating back pain secondary to a persistent infection and associated progressive spinal kyphotic deformity. He underwent a transpedicular T9-T10 corpectomy, placement of an expandable interbody cage, and posterior instrumented spinal fusion from T7 to T12. On postoperative day (POD) 2, upright thoracic radiographs demonstrated cage subsidence of greater than 50% into the T8 vertebral body. The patient was taken back to the operating room for hardware revision and placement of an expandable intervertebral cage with rectangular endcaps through a minimally invasive lateral retropleural approach to the thoracic spine. The patient tolerated the procedure well, and no evidence of subsidence occurred after the revision after 2 years of follow up.
Expandable intervertebral cages with rectangular endcaps can be used to prevent and/or correct preexisting cage subsidence in patients in need of anterior column instrumentation, especially in those with bone-weakening pathologies. Prospective studies should be entertained to evaluate subsidence rates in cages with cylindrical versus rectangular endcaps.
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