Evaluation of retraction time as a predictor of postoperative motor dysfunction after minimally invasive transpsoas interbody fusion at L4-L5.

BACKGROUND

Complications associated with the lateral lumbar transpsoas approach largely comprise various nerve-related syndromes particularly at L4-5. Quadriceps weakness can occur from stretch injury to the femoral nerve during retraction.

OBJECTIVE

The purpose of this study is to evaluate the role of retraction time in the development of postoperative neuropathic motor weakness at the L4-5 level.

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

50% of patients had leg weakness after surgery (13/26). All postoperative motor deficits were at least antigravity strength (>3/5) and all deficits resolved. The mean RT for the motor dysfunction cohort was 29 min (14-51) compared to 27.5 min for the cohort without postoperative weakness (19-37) (p = 0.685).

CONCLUSION

The results of this study suggest that longer retraction time (within a range of 14-51 min) 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. Motor deficits resolved quickly after surgery.