Implant Failure Following Posterior Spinal Fusion-Caudal Migration of a Fractured Rod: Case Report

Study Design: Case report. Objectives: To describe a patient who experienced rod fracture with subsequent caudal migration into the gluteal region after minimally invasive posterior spinal fusion for adult idiopathic scoliosis. Summary of Background Data: Rod fracture occurs in approximately 6.8% of patients who undergo multilevel instrumented arthrodesis for spinal deformity. Rod fracture can result in substantial morbidity including pain, loss of deformity correction, and pseudoarthrosis. Methods: A retrospective chart review was used to describe the clinical course and radiographic findings after rod fracture. Previous methods of implant failure were reviewed in the literature. Results: The patient underwent a minimally incisional posterior spinal fusion and experienced bilateral rod fracture caused by pseudarthrosis within 2 years. One of these fractured rods disengaged from the pedicle screw sleeves and migrated caudally to the gluteal region and proximal posterior thigh. The fractured rod was surgically removed from the gluteal region without complication. Conclusions: The patient presented with a highly unusual method of implant failure after posterior spinal fusion. Although uncommon, spine surgeons should be aware of the possibility of caudal migration after rod fracture.