Long-term outcomes after non-instrumented lumbar arthrodesis

Non-instrumented lumbar fusion is an accepted technique for the treatment of various spinal degenerative pathologies. The purpose of this study is to report long-term outcomes of patients undergoing in situ fusion. A retrospective review was performed at a single institution over a 20 year period. The main outcome variables were symptom resolution at last follow-up, development of adjacent segment disease (ASD) and overall need for re-operation. A total of 376 patients were identified, with a mean age of 61.1 ± standard deviation of 13.54 years. The most common presenting symptom was back pain in 344 (91.5%) patients, followed by radiculopathy in 304 (80.9%) patients. The most common pre-operative diagnosis was multi-level spinal stenosis with claudication in 211 (56.1%) patients. At last follow-up, the prevalence of back pain (60.64%; p < 0.001) and radiculopathy (57.71%; p < 0.001) were significantly lower. The cumulative rate of ASD was 18.35% (69 patients). In total, the rate of re-operation due to non-improvement or worsening of symptoms was 30.59% (115 patients). In this manuscript, we present one of the largest cohorts of patients undergoing in situ fusion for degenerative lumbar spine disease with a median follow-up time of 92 (range 24-154) months. Although the prevalence of both back pain and radiculopathy was significantly reduced at last follow-up, a significant portion of patients still experienced continued symptoms. Notably, while 18.35% of patients developed ASD, 30.6% of patients required re-operation due to recurrent or worsening symptoms during the follow-up period, highlighting the need for additional stabilization techniques.