Introduction: Lateral Lumbar Interbody Fusion (LLIF) is an established technique for the treatment of degenerative conditions of the spine including degenerative disc disease, spondylolisthesis, and scoliosis. Complications associated with the transpsoas approach largely comprise various nerve-related syndromes as the lumbar contribution to the lumbosacral plexus lies within the substance of the psoas major muscle particularly at L4-5. Quadriceps weakness can occur from stretch injury to the femoral nerve during retraction. The purpose of this study is to evaluate the role of retraction time in the development of postoperative neuropathic motor weakness in patients undergoing LLIF at L4-5.
Methods: A retrospective review of a prospectively collected database at a single institution was reviewed over a two-year period (March 2014-2016) for a single surgeon. Twenty-six patients undergoing single level LLIF at L4-5 were identified. Pre- and postoperative data collection obtained included motor function grading (0-5/5) with a minimum of 3-month postoperative follow-up. Intraoperative data collection included retraction time (RT) defined as the time the retraction system was affixed to the spine and expanded to the time of closure and removal. Two-Tailed T-Test was used to determine clinical significance.
Results: Combined psoas and quadriceps weakness was seen in 9/26 (35%). No patients developed pure quadriceps weakness. Pure psoas weakness was seen in 4/26 (15%). All postoperative motor deficits were at least antigravity strength (>3/5). The mean RT for the total cohort was 26.8 minutes and was 27.9 minutes in those that developed quadriceps weakness (0.69). One patient had persistent mild quadriceps weakness three months after surgery, which eventually improved to full strength at six months.
Conclusions: The results of this study suggest that longer retraction time (within a range of 14-51 minutes) did not correlate with a greater risk of postoperative neuropathic quadriceps muscle dysfunction for lateral lumbar interbody fusions performed at L4-5. Other factors may contribute to postoperative neurologic dysfunction regardless of RT. A rapid resolution in any weakness as time increased from surgery was also seen.
Patient Care: Better understanding factors related to postoperative patient morbidity with lateral access approaches to the spine will aid surgeons improve patient care.
Learning Objectives: 1. Postoperative neuropathic quadriceps dysfunction after LLIF at L4-5 is not correlated with retraction time.
2. Other factors may be contributing to muscle weakness after LLIF.
3. In those that develop weakness, a rapid improvement in strength is seen over the following weeks.