45. A prospective, in-depth analysis of perioperative anterior thigh symptoms associated with a direct lateral access approach for lumbar interbody fusion

BACKGROUND CONTEXT Anterior thigh symptoms post-transpsoas lateral approach for lumbar interbody arthrodesis are well documented. Symptoms may be transient ( PURPOSE The aim of this analysis was to prospectively characterize adverse perioperative neurological changes associated with a direct lateral transpsoas retroperitoneal closed tubular retractor system. Further, provider-reported changes were compared vs subject-reported changes. STUDY DESIGN/SETTING This investigation is a prospective, multicenter, single-arm, IRB approved post-market study. PATIENT SAMPLE One hundred fifteen subjects (115), 71 females (61.7%), with a mean age of 64.0 and mean BMI of 30.8 presenting with degenerative disc disease at one or two adjacent levels from L2 to L5 were included for analysis. OUTCOME MEASURES Subjects self-reported thigh pain, hip flexion weakness, and knee extension weakness on a 100mm Visual Analog Scale. Clinical assessments including muscle strength, Achilles reflexes, patellar reflexes, and sensory testing were performed at the same time points. Multiple questions specific to lateral access not typically collected in lumbar fusion studies were included in the analysis. METHODS All outcome measures were prospectively collected at the preoperative visit, prior to hospital discharge, and at the two-week, six-week, three-month, six-month, and twelve-month postoperative visits. Data were descriptively analyzed. RESULTS Objective neurological exam showed 17 (14.8%) subjects with access-sided adverse changes from baseline at hospital discharge. These 17 included 5 (4.4%) with changes in strength, 5 (4.4%) with sensation changes, and 11 (9.6%) with reflex changes. Of these, 2 subjects had changes in both strength and reflexes; 2 had changes in both sensation and reflexes. All strength and sensation changes were resolved by 6 weeks. All reflex changes resolved by 3 months. Twenty-two subjects (19.1%) reported increased thigh pain (\u003e20mm) at discharge. All were resolved by 3 months. Forty-four (44) subjects (38.3%) reported increased hip flexion or extension weakness (\u003e20mm) with 29 (65.9%) resolved by 6 weeks, 37 (84.1%) resolved by 3 months, 41/45 (93.2%) resolved by 6 months, and 3 have additional follow-up pending. Of the 17 subjects with objectively identified changes, 7 also reported subjective changes. Only 2 subjects’ (11.8%) reported symptoms (weakness) correlated with objectively reported results (strength). CONCLUSIONS This unique prospective study is the first to our knowledge that captures in-depth subjective and objective thigh symptom data specific to lateral access transpsoas surgery. The perioperative results provide a rare illustration of adverse changes and their almost complete resolution within 3 months. Further research to understand the differences in clinician reported vs subject reported changes is warranted. FDA DEVICE/DRUG STATUS Duo Interbody Fusion System (Approved for this indication)