Robust bone regrowth achieving autofusion across Interlaminar space following lumbar microdiscectomy: Case report

Background: Autofusion of spinal vertebrae is uncommon, but it can occur due to advanced degenerative processes and infection. Post-operative spontaneous fusion following non-fusion surgery (autofusion) of spinal vertebrae is also generally uncommon, but it has been reported after laminoplasty, disc arthroplasty with and without heterotopic ossification, and histiocytosis biopsy. To the best of our knowledge, post-operative autofusion in the lumbar spine following decompressive surgery alone has not been reported previously. Case description: The authors present an occurrence of a 29-year-old woman who underwent uncomplicated left L4-L5 microdiscectomy for spondylosis, low back pain, and left lower extremity radiculopathy. The patient returned to the hospital 6 years post-operatively due to recurrent radiculopathy, and CT imaging showed regrowth of left sided bone at the operative site and also extending across interlaminar space, ranging from the superior lamina to the most inferior part of the decompression. Conclusions: The case indicates that post-operative bone regrowth can extend beyond operative decompression defects and cross over interlaminar space causing autofusion. Autofusion could be due to instability within the lumbar spine via degenerative disc changes, and it may be underreported due to lack of post-operative imaging in most patients undergoing uncomplicated, lumbar decompression surgery.