Aseptic Discitis with Instability after Posterior Spine Surgery.

INTRODUCTION: Lumbar canal stenosis is a common cause of low back pain occurring in elderly population. It is treated with posterior decompression with or without fusion surgery. However, decompression can lead to iatrogenic instability in some cases, and if suspected, must be assessed intraoperatively and treated with instrumented fusion. If not addressed, it can lead to progressive degeneration and instability.

CASE REPORT: A 58-year-old male presented with severe low back pain and functional limitation 2 years after undergoing an L4 wide laminectomy for lumbar canal stenosis. While initial post-operative recovery was favorable, the patient developed progressive pain and immobility within 2 months post-surgery, ultimately becoming bedridden. Clinical examination revealed localized lumbosacral tenderness with a Visual Analogue Scale (VAS) score of 7/10 and no neurological deficits. Laboratory investigations were unremarkable, ruling out infection. Radiological evaluation demonstrated severe osteoporosis, significant angular instability at L4-L5, and intra-discal degeneration, consistent with iatrogenic post-operative spinal instability. Given the patient's compromised bone quality, a surgical plan was devised involving posterior fixation spanning two levels above and below the instability, using pedicle screws and a bone graft mixture without a cage to minimize the risk of implant failure. Intraoperatively, clear discal fluid was aspirated for culture and tuberculosis testing, both of which returned negative. Postoperatively, the patient was placed on strict bed rest. At 1-month follow-up, substantial clinical improvement was noted with reduced pain (VAS 4/10), improved mobility, and radiological evidence of stable instrumentation and early fusion.

CONCLUSION: This case reports the highlights the importance of recognizing progressive post-operative instability as a potential delayed complication of lumbar laminectomy, particularly in osteoporotic patients, which should be addressed with management strategy tailored to bone quality and biomechanical demands. Posterior Instrumentation with interbody fusion using bone graft and bone graft substitutes has shown accelerated fusion results.