Introduction: The purpose of this study is to assess the long-term outcomes of patients undergoing non-instrumented postero-lateral fusion of the lumbar spine.

Methods: We present 376 patients who underwent in situ, non-instrumented arthrodesis for lumbar degenerative disease over a 20-year period at a single institution. Patients were followed for an average of 83.2 ± 65.5 months after the index lumbar arthrodesis procedure.

Results: The average age for these patients was 61.1 ± 13.54 years, and 185 (49.2%) patients were male. Of the total 376 patients, 344 (91.5%) presented with back pain, 304 (95.9%) with radiculopathy, 20 (5.32%) with motor weakness, and 7 (1.86%) with pre-operative bowel/bladder dysfunction. An average of 1.76 ± 0.82 spinal levels were fused. Autograft was used in 345 (91.75%) patients, while allograft was utilized in 31 (8.24%) patients. Average blood loss was 625 ± 487 milliliters. 15 (3.99%) patients experienced intra-operative durotomy during the surgery. Peri-operatively, the average length of stay was 5.98 ± 5.78 days. Post-operatively, patients experienced a significant improvement in back pain (p<0.0001) and radiculopathy (p<0.0001). At last follow-up, 228 (60.64%) patients experienced continued or recurrent back pain, while 217 (57.71%) patients experienced continued or recurrent radiculopathy. The cumulative rate of adjacent segment disease development over time was 18.35%. The pseudoarthrosis rate was 5.59%. In total, the rate of reoperation due to non-improvement or worsening of symptoms was 30.59%.

Conclusions: We present one of the largest cohorts of patients undergoing in situ fusion for degenerative lumbar spine disease. We also present a cohort with one of the longest follow-up times, an average of over 7 years. We show that patients undergoing non-instrumented fusion have statistically significant improved back pain and radiculopathy post-operatively. Notably, while 18.35% of patient developed adjacent segment disease, 30.6% of patients required re-operation due to recurrent or worsening symptomsduring the follow-up period.

Patient Care: This research aims to further our understanding of in situ non-instrumented fusion. This procedure may be a viable alternative to instrumented fusion in select patients.

Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the surgical outcomes of non-instrumented fusion; 2) Identify the role of non-instrumented fusion in the treatment of spinal degenerative disease.

References: 1. Kaito T, Hosono N, Mukai Y, Makino T, Fuji T, Yonenobu K. Induction of early degeneration of the adjacent segment after posterior lumbar interbody fusion by excessive distraction of lumbar disc space. J Neurosurg Spine. Jun 2010;12(6):671-679. 2. Kanayama M, Hashimoto T, Shigenobu K, et al. Adjacent-segment morbidity after Graf ligamentoplasty compared with posterolateral lumbar fusion. J Neurosurg. Jul 2001;95(1 Suppl):5-10. 3. Kumar MN, Baklanov A, Chopin D. Correlation between sagittal plane changes and adjacent segment degeneration following lumbar spine fusion. Eur Spine J. Aug 2001;10(4):314-319. 4. Lee MJ, Dettori JR, Standaert CJ, Brodt ED, Chapman JR. The natural history of degeneration of the lumbar and cervical spines: a systematic review. Spine (Phila Pa 1976). Oct 15 2012;37(22 Suppl):S18-30. 5. Lund T, Oxland TR. Adjacent level disk disease--is it really a fusion disease? Orthop Clin North Am. Oct 2011;42(4):529-541, viii. 6. Park P, Garton HJ, Gala VC, Hoff JT, McGillicuddy JE. Adjacent segment disease after lumbar or lumbosacral fusion: review of the literature. Spine (Phila Pa 1976). Sep 1 2004;29(17):1938-1944. 7. Girardo M, Bettini N, Dema E, Cervellati S. Uninstrumented posterolateral spinal arthrodesis: is it the gold standard technique for I degrees and II degrees grade spondylolisthesis in adolescence? Eur Spine J. Jun 2009;18 Suppl 1:126-132.