Iatrogenic lumbar scoliosis aggravated by hardware irritation in the iliac bone after pedicle screw fixation: Case report

Background Although many complications of the spinal implant have been reported previously, to the best of our knowledge, this is the first report on a delayed implant complication of the ilium, leading to buttock pain and aggravated scoliosis. Case description A 78-year-old woman underwent transforaminal lumbar interbody fusion with pedicle screws at the L4–L5 level at another institution. Preoperative symptoms, left leg pain, disappeared soon after surgery. However, 6 months post surgery, she experienced severe pain in her left buttock and sacroiliac joint area, which was treated only at our pain clinic. Based on our initial consultation 5 years after the operation, her plain radiography findings showed a 29° convex left-sided scoliosis spanning from the L1–L5. Computed tomography scan revealed apparent iliac bone erosion at the point of contact with the left-side screw head and rod at L5. The patient had painful scoliosis owing to implant irritation. Soon after the removal of the left implant, the pain was relieved and the degree of scoliosis decreased to 17°. Conclusion This study reports the presence of an unexpected complication caused by pedicle screw fixation at the L4–L5 level. Although the implant was far from the iliac bone, at the L4–L5 fusion, it could cause erosion of the bone after the progression of L3–L4 and L5–S1 disk degeneration and aggravate scoliosis. Neurosurgeons should be aware that patients may present with buttock pain and unprecedented scoliosis by hardware irritation.