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Study Design: A retrospective review of instrumented spine registry from an integrated US healthcare system., Objective: Investigate the 30-day readmission rate and risk factors after instrumented spine surgery., Summary of Background Data: Published readmission rates range from 2% to over 20%. We were interested in learning which patients were at greatest risk, when did readmissions occur, and why., Method: 30-day readmission rates were determined for 14,939 patients after an index spine procedure between 1/2009 and 3/2013. Data were analyzed with descriptive statistics, univariate, and multivariate logistic regression analysis., Result: The average age of the cohort was 59 (SD = 13.4) and 52% were female. The 30-day readmission rate was 5.5% (821/14,939). The temporal pattern for readmission was: 17% (140) at week 1, 48% (394) at week 2, 72% (591) at week 3, and 100% (821) at week 4. The leading causes were wound complications (infection, hematoma, dehiscence, seroma), sepsis, pain management, pneumonia, and pulmonary emboli/deep venous thrombosis. In a multivariate model, readmission risk factors were: malignancy (OR 2.99, 95% CI: 1.56, 5.73), operative time more than 400 minutes (OR 2.59, 95% CI: 1.66, 4.02), operative time 300-399 minutes (OR 2.33, 95% CI: 1.54-3.52), hospital stay 6-10 days (OR 2.03, 95% CI: 1.31-3.14), hospital stay more than 10 days (OR 1.85, 95% CI: 1.1, -3.08), surgical complications (OR 1.67, 95% CI: 1.18, 2.36), operative time 200-299 (OR 1.52, 95% CI: 1.04, 2.22), depression (OR 1.48, 95% CI: 1.14, 1.93), rheumatoid arthritis (OR 1.45, 95% CI: 1.05, 2.01), deficiency anemia (OR 1.30, 95% CI: 1.05, 1.61), and hypothyroidism (OR 1.29, 95% CI: 1.01, 1.64)., Conclusion: Surgical complications (dural tear, deep infections, superficial infections, epidural hematoma), malignancy, lengthy operative times, and lengthy initial hospitalizations are all risk factors for 30-day readmission. These findings should be considered during preoperative assessment and surgical planning., Level of Evidence: 3.

Study Design: A retrospective cohort study with medical record review., Objective: To determine if there is difference in the operative nonunion rates with and without the use of bone morphogenetic protein (BMP) after spinal fusions by analyzing data from an integrated health care system's spine registry., Summary of Background Data: BMP was first approved in 2002 for use in single-level anterior lumbar fusions. Follow-up studies have advocated its use in reducing the need for reoperations for nonunions. Recent studies, however, have questioned these conclusions and the usefulness of BMP in spinal fusions has been highly debated., Methods: We identified 9425 spinal fusion cases between 2009 and 2011 from a spine registry in a large integrated health care organization. Patient characteristics, diagnosis, operative times, length of stay, and reoperations were extracted from the registry. Reoperations for nonunions were adjudicated via medical record review. Cox regression models were used to evaluate the risk of reoperation while adjusting for confounders., Results: In our cohort, there were 5456 BMP cases and 3969 non-BMP cases. The mean age was 60.4 years (standard deviation: 12.9 yr), with the majority being females (53%). The median follow-up time was 1.2 years (interquartile range: 0.6-2.0 yr). Reoperation rates for BMP versus non-BMP nonunions for all fusion cases with follow-up of 1 year or more (1.9% vs. 2.2%) and follow-up of 2 years or more (2.3% vs. 2.6%) were not statistically significantly different. Operative nonunion rates did not reach statistical significance for different spine regions and for different fused columns (anterior only, posterior only, or combined). After controlling for differences in patient characteristics, operative times, levels fused, and spinal regions, the risk of reoperation in the BMP versus non-BMP groups was 0.67 (95% CI: 0.42-1.06)., Conclusion: In this large cohort of spinal fusions at all spine regions involving all fused columns with and without BMP, we found no statistically significant difference in operative nonunion rates., Level of Evidence: 3.

Objectives: To assess if hydroxyapatite (HA)-coated titanium pedicle screws exhibit the same electroconductive characteristics as non-HA-coated screws., Methods: Resistance measurements were obtained from a random sampling of 10 HA-coated pedicle screws and 10 non-HA-coated screws, and surgical conditions simulated. Surface resistivity measurements were taken for each screw to determine voltage drop over its entire length., Results: The non-HA-coated screws tested showed low resistive properties and proved to be an ideal conductor of electrical current. The resistive properties associated with the HA-coated pedicle screws were found to be similar to those of commonly used insulators removing the effectiveness of triggered electromyographic responses., Conclusions: Based on test results, these data suggest that the resistance value of the HA-coated screw is large enough to prevent modern Intra-Operative Monitoring (IOM) equipment from delivering the necessary current through the shank of the screw to create a diagnostic electromyographic response. Any response that would be produced would be because of shunting of electric current from the non-coated head of the screw into adjacent tissue and not through the shank of the screw. These study results suggest that HA-coated screws cannot be stimulated to assist in determining the accuracy of pedicle screw placement.