P48. The use of motion metrics parameters to predict postoperative patient reported outcomes in patients with lumbar stenosis and spondylolisthesis

BACKGROUND CONTEXT Lumbar stenosis is a common spinal pathology and studies have shown that surgical treatment is often more effective than nonoperative management. Surgical options for the treatment of lumbar stenosis include decompression alone or decompression with fusion. Patients are often chosen for decompression with fusion when there is perceived instability; however, it is often unclear which radiographic parameters indicate instability requiring fusion. PURPOSE To evaluate the potential of motion metrics in predicting postop Patient Reported Outcomes (PROs) in patients with lumbar stenosis undergoing decompression with fusion or decompression alone. We hypothesize that patients with abnormal preoperative motion parameters will achieve better outcomes with decompression with fusion, and that patients with normal preop motion metrics will achieve better outcomes with decompression alone. STUDY DESIGN/SETTING Retrospective single center cohort study. PATIENT SAMPLE Patients treated for single level lumbar stenosis with spondylolisthesis by either decompression only or decompression plus fusion. OUTCOME MEASURES PROs (ODI, VAS and NRS), Angular Motion, Intervertebral Translation, Sagittal Plane Shear Index (SPSI), Spondylolisthesis Index, Anterior and Posterior Disc Integrity Index, Global ROM. METHODS This preliminary analysis includes 16/40 patients. Preop and 1-year postop flexion/extension X-ray images were analyzed with previously validated motion analysis software. Since the mechanical integrity of soft-tissues cannot be assessed unless the soft-tissues are sufficiently stressed, patients with RESULTS Of the 16 patients, 12 (75%) were female and 4 (25%) were male. Ages ranged from 33 to 77 years old with an average of 64 at the time of surgery. Two patients had surgery at L3-L4 (12%) and 14 had surgery at L4-L5 (88%). All 16 patients received decompression with fusion. The 95% confidence interval of a dataset that includes 384 radiographically normal asymptomatic volunteers was used to define normal limits of motion. SPSI > 2 indicates that the translation per degree of rotation was beyond the upper limit of normal. Preop SPSI was measured at 16 treatment levels and 50 non-treatment levels. Preop SPSI at the treatment level was 1.4±2.5 [-4.1 to 6.4] with 7 patients having SPSI>2 and 9 subjects having SPSI CONCLUSIONS SPSI is an objective measure of sagittal plane instability that may inform physicians of the need for fusion. In this preliminary analysis, the mean preop SPSI at the treatment level approached the upper limit of normal, while the mean at non-treatment levels was near the center of normal. There were 43.8% of patients who had abnormal preop SPSI values at the treatment level. Upon review of the PROs we will determine if preop SPSI is predictive of clinical outcome success, and if other novel metrics can be used along with SPSI to inform the optimal treatment pathway. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.