Microsurgical Foraminotomy via Wiltse Paraspinal Approach for Foraminal or Extraforaminal Stenosis at L5-S1 Level : Risk Factor Analysis for Poor Outcome

ABSTRACT

OBJECTIVE: The purpose of this study was to present the outcome of the microsurgical foraminotomy via Wiltse paraspinal approach for foraminal or extraforaminal (FEF) stenosis at L5–S1 level. We investigated risk factors associated with poor outcome of microsurgical foraminotomy at L5–S1 level. METHODS: We analyzed 21 patients who underwent the microsurgical foraminotomy for FEF stenosis at L5–S1 level. To investigate risk factors associated with poor outcome, patients were classified into two groups (success and failure in foraminotomy). Clinical outcomes were assessed by the visual analogue scale (VAS) scores of back and leg pain and Oswestry disability index (ODI). Radiographic parameters including existence of spondylolisthesis, existence and degree of coronal wedging, disc height, foramen height, segmental lordotic angle (SLA) on neutral and dynamic view, segmental range of motion, and global lumbar lordotic angle were investigated. RESULTS: Postoperative VAS score and ODI improved after foraminotomy. However, there were 7 patients (33%) who had persistent or recurrent leg pain. SLA on neutral and extension radiographic films were significantly associated with the failure in foraminotomy (p17.3°) and extension radiographic films (>24°).