Minimally Invasive Lateral Retropleural Approach to the Thoracic Spine for Salvage of a Subsided Expandable Interbody Cage

Background Cylindrical expandable cages are commonly used as interbody grafts after cervical, thoracic, or lumbar corpectomy 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 use the anatomic strength of the vertebral epiphyseal ring to prevent subsidence. Case Description 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 T9-10 corpectomy, placement of an expandable interbody cage, and posterior instrumented spinal fusion from T7 to T12. On postoperative day 2, upright thoracic radiographs demonstrated cage subsidence of >50% into the T8 vertebral body. The patient was returned 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. Conclusions 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.