Introduction: Necessity for re-intervention due to instrumentation failure is a well-known complication of pedicle subtraction osteotomy (PSO). However, the neurosurgical approach to the management of collapsed PSO combined with cage subsidence from the inferior disc space is not well-established. The authors present a case of a collapsed L4 PSO with L4-L5 TLIF cage subsidence, resulting in severe low back and radicular pain.
Methods: A 59-year-old male presented with low back and lower extremity pain in the L5 distribution. Pain began 3 months post-extension of fusion (T10-pelvis), with L3-L5 laminectomies and PSO at L4, performed 15 months prior at an outside institution. Myelogram and X-Ray revealed L4 PSO collapse and subsidence of an L4-L5 intervertebral spacer into the L4 vertebra. A procedure was undertaken to revise the T10-pelvis fusion and the PSO at L4-L5 and achieve indirect intraforaminal decompression with an L4-L5 XLIF.
Results: Rod locking caps were dislodged at T10 and T11, consistent with instrumentation failure at the proximal segment of the construct. Locking caps, long rods, and L4-L5 quad rods were removed. The L4-L5 fusion mass and the remainder of pedicles above and below L4 were removed. Bone from the central laminectomy defect was drilled laterally toward the foramen, resecting bone between the intersecting L4 and L5 segments to revise the PSO. A temporary rod was placed in the L4-L5 area for stabilization during patient repositioning for L4-L5 XLIF. The L4-L5 disc area was also the area of a previously attempted TLIF with graft subsidence into the L4 vertebral body. A cage was chosen to achieve intraforaminal indirect decompression with elevation of the PSO defect to maintain lordosis. Finally, revision of the T10-ilium fusion was completed. The patient tolerated the procedure well and immediately noted pain relief in the lower extremities. He was discharged home on postoperative day 5. At two-week follow-up, he is recovering well with greatly improved low back pain and complete resolution of radicular symptoms.
Conclusion : This case demonstrates a novel approach to the correction of collapsed PSO, in which XLIF for support of the anterior column in addition to revision of PSO allowed for successful decompression of the neural foramina.
