Incidental Dural Tears During Lumbar Spine Surgery: A Retrospective Case Study of 84 Degenerative Lumbar Spine Patients

STUDY DESIGN: A retrospective case study. PURPOSE: To retrospectively review all incidental dural tears (DTs) that occurred at a single institution, classify them anatomically and evaluate the clinical significance of each subgroup. OVERVIEW OF LITERATURE: Dural tears are considered the most commonly encountered complication during lumbar spine surgery. In contrast to the high frequency of DTs, reports on the characteristic location and mechanism are sparse. METHODS: We retrospectively retrieved all cases of degenerative lumbar spine surgery performed over a 9-year period and classified all identified DTs according to two independent planes. The coronal plane was divided into lower, middle and upper surgical fields, and the sagittal plane into posterior, lateral and ventral occurring tears. Demographic and clinical variables were retrieved and analyzed to search for significant associations. RESULTS: From 2003 to 2011, 1,235 cases of degenerative lumbar spine conditions were treated surgically at our institution. In 84 operations (6.8%), an incidental DT was either identified intraoperatively or suspected retrospectively. The most commonly involved location was the lower surgical field (n=39, 46.4%; p=0.002), followed equally by the middle and upper fields (n=16, 19%). In the sagittal plane, the most commonly involved locations were those in close proximity to the nerve root (n=35, 41.6%), followed by the dorsal aspect of the dural sac (n=24, 28.6%). None of the variables recorded was found to be associated with a particular location. CONCLUSIONS: In our series, incidental DTs were found to occur most commonly in the lower surgical field. We hypothesize that local anatomic feature, such as the lordotic and broadening lumbar dura, may play a role in the observed DT tendency to occur in the lower surgical field. In light of the high frequency and potentially substantial resulting morbidity of incidental DTs, a better characterization of its location and mechanism may optimize both prevention and management.