Patrick B. Morrissey

Intraoperative pedicle screw navigation does not significantly affect complication rates after spine surgery

Various forms of intraoperative computer-assisted navigation technologies exist, and have consistently been shown to improve pedicle screw accuracy. However, the overall clinical effects of inaccurate pedicle screw placement have been debated. We examined the clinical effects of improved pedicle screw accuracy with computer navigation technology in reducing complication rates in patients undergoing multi-level spinal fusion. We retrospectively reviewed the ACS-NSQIP registry utilizing Current Procedural Terminology (CPT) codes 22843 + 22844 to identify patients undergoing spinal instrumentation of greater than 7 levels, as well as the CPT code 61783 to denote the use of intraoperative computer-assisted navigation. The data were then subdivided to into cohorts consisting of instrumentation cases with and without navigation. Demographic information, as well as intraoperative and postoperative complications, were compared between groups. A total of 3168 patients met our inclusion criteria. There were no statistically significant differences in preoperative population data. Surgical time was significantly longer in the navigation group (391.41 versus 350.3 min), but there were no significant improvements in complication rates with the use of navigation. We found that the mean operative time was significantly increased for patients undergoing spinal instrumentation with computer navigation. This increase in operative time was not associated with any increase in surgical or medical complications. However, in this large series, we were unable to show any clinical benefit to intraoperative navigation, and no reductions in short term complications or rates of return to surgery were observed.

Risk Factors for and Complications After Surgical Delay in Elective Single-level Lumbar Fusion

Study Design. Retrospective cohort. Objective. To assess the incidence of and risk factors for delay of elective lumbar fusion surgery, as well as medical and surgical complications associated with surgical delay. Summary of Background Data. Lumbar fusion is a well-established treatment for patients with degenerative spondylolisthesis with stenosis who have failed conservative management. Rarely, patients admitted for elective lumbar fusion may experience a delay in surgery past the day of admission. The incidence of, and risk factors for, delay of elective lumbar fusion surgery and the complications associated therewith have never been previously evaluated. Methods. We retrospectively reviewed the ACS-NSQIP registry utilizing Current Procedural Terminology (CPT) codes 22612, 22558, 22630, and 22633 to identify all patients undergoing a single level spinal fusion. The data were then subdivided into cohorts consisting of patients with and without surgical delay. Demographic information, preoperative risk factors for delay, as well as intraoperative and postoperative complications were compared between the groups. Results. We identified 2758 (5.46%) patients as experiencing a delay before lumbar fusion. Multivariate analysis was then performed and identified male sex, American Society of Anesthesiologists classes 3 and 4, and chronic steroid use as risk factors increasing the rate of surgical delay. Multiple complication rates were also significantly higher in the delayed group, including an almost 10-fold increase in mortality rate (0.2% vs. 1.9%, respectively, P < 0.001). Conclusion. Delays in elective surgery can affect medical system resource utilization, increasing costs and leading to worse patient outcomes. Patients with chronic steroid use and higher American Society of Anesthesiologists class may be at risk for surgical delay in lumbar fusion beyond the day of admission, and are at increased risk for significant complications postoperatively. Thorough medical evaluation and preoperative optimization may be indicated for these patients. Level of Evidence: 4

Severe Lumbar Disability Is Associated With Decreased Psoas Cross-Sectional Area in Degenerative Spondylolisthesis

Study Design: Retrospective cohort. Objectives: Alterations in lumbar paraspinal muscle cross-sectional area (CSA) may correlate with lumbar pathology. The purpose of this study was to compare paraspinal CSA in patients with degenerative spondylolisthesis and severe lumbar disability to those with mild or moderate lumbar disability, as determined by the Oswestry Disability Index (ODI). Methods: We retrospectively reviewed the medical records of 101 patients undergoing lumbar fusion for degenerative spondylolisthesis. Patients were divided into ODI score ≤40 (mild/moderate disability, MMD) and ODI score >40 (severe disability, SD) groups. The total CSA of the psoas and paraspinal muscles were measured on preoperative magnetic resonance imaging (MRI). Results: There were 37 patients in the SD group and 64 in the MMD group. Average age and body mass index were similar between groups. For the paraspinal muscles, we were unable to demonstrate any significant differences in total CSA between the groups. Psoas muscle CSA was significantly decreased in the SD group compared with the MMD group (1010.08 vs 1178.6 mm2, P = .041). Multivariate analysis found that psoas CSA in the upper quartile was significantly protective against severe disability (P = .013). Conclusions: We found that patients with severe lumbar disability had no significant differences in posterior lumbar paraspinal CSA when compared with those with mild/moderate disability. However, severely disabled patients had significantly decreased psoas CSA, and larger psoas CSA was strongly protective against severe disability, suggestive of a potential association with psoas atrophy and worsening severity of lumbar pathology.