Risk Factors for Postoperative Ileus in Patients Undergoing Spine Surgery.

STUDY DESIGN: Retrospective Cohort Study. OBJECTIVES: Postoperative ileus (POI) is a common complication following elective spinal surgeries. The aim of this study was to determine the incidence of POI and identify demographic and surgical risk factors for developing POI after elective instrumented fusion of the thoracolumbar spine. METHODS: The University of Utah Institutional Review Board (IRB) approved this retrospective study. The study does not require informed consent given the data reviewed was deidentified and collected in accordance with the institution's standard of care. A designated IRB committee determined that study is exempt under exemption category 7. IRB approval number 00069703. Patients undergoing instrumented thoracolumbar fusion for one or more levels were retrospectively identified from an internal spine surgery database. Cases performed for trauma, infection, or tumors were excluded. Demographics, medical comorbidities, surgical variables, and opioid medication administration (morphine milligram equivalents, MME) were abstracted from the electronic medical record. Univariate analysis was used to identify variables associated with POI. These variables were then tested for independent association with POI using multivariate logistic regression. RESULTS: 418 patients were included in the current study. The incidence of POI was 9.3% in this cohort. There was no significant relationship between development of POI and patient age, gender, BMI, diabetes mellitus, thyroid dysfunction, lung disease, CKD, GERD, smoking status, alcohol abuse, anemia, or prior abdominal surgery. Univariate analysis demonstrated significant association between POI and fusion ≥7 levels compared to fusions of fewer levels (P = .001), as well as intraoperative sufentanil compared to other opioids (35.9% vs 20.1%, P = .02). POI was not significantly associated with total intraoperative MME, approach, use of interbody cage, or osteotomy. Multivariate logistic regression confirmed total 24-hour postoperative MME as an independent risk factor for POI (OR 1.004, P = .04), however, intraoperative sufentanil administration was not an independent risk factor for POI when controlling for other variables. CONCLUSIONS: This retrospective cohort study demonstrates that greater postoperative MME is an independent risk factor for POI after thoracolumbar spine fusion when accounting for demographic, medical, and surgical variables with multiple logistic regression. Prospective studies are warranted to evaluate clinical measures to decrease the risk of POI among patients undergoing instrumented thoracolumbar spinal fusions.

Oswestry Disability Index: a psychometric analysis with 1,610 patients.

BACKGROUND: One-fourth of the adult US population has or will experience back pain and has undergone one of a myriad of treatments. Understanding the outcomes of these many treatments from pharmacologic to surgical, from manipulation to modality, allows for a better understanding and value-driven decision making. Patient-reported outcome measures are the current standard and include general and disease-specific measures. The Oswestry Disability Index (ODI) is the most commonly used disease-specific patient-reported outcome tool to measure functional disability related to back pain. Few studies have evaluated its psychometric properties in a large patient sample using a modern tool such as the Rasch analysis model. This study aims to identify the benefits and deficiencies of the ODI as an outcome tool for assessing patients with back pain. PURPOSE: This study aimed to investigate the psychometric properties, performance, and applicability of the ODI in patients with back pain who visited a university-based outpatient clinic. STUDY DESIGN: This study used a secondary analysis-assessment of diagnostic tool on consecutive patients. PATIENT SAMPLE: The sample comprised 1,610 patients visiting an academic spine center. OUTCOME MEASURES: The ODI was the outcome measure. METHODS: Detailed Rasch analysis of the ODI was performed. Standard descriptive statistics were also assessed. RESULTS: The ODI performed well overall. It demonstrated suboptimal unidimensionality (ie, unexplained variance after accounting for the first dimension) of 8.3%. Person reliability was good, at 0.85, and item reliability was excellent, at 1.00. The overall item fit for the ODI was good with an outfit mean square of 1.02. The ODI had a floor effect of 29.9% and ceiling effect of 3.9%. The raw score to measure correlation of the ODI was excellent, at 0.944. CONCLUSIONS: The ODI performed relatively well overall, with some problematic findings. It had good person and item reliability, although it did not demonstrate strong evidence of unidimensionality. The ODI has moderately poor coverage, with a very large floor effect and small ceiling effect, which could present a challenge in interpreting results of scores at the end of the spectrum.

Fixed-Angle, Posteriorly Connected Anterior Cage Reconstruction Improves Stiffness and Decreases Cancellous Subsidence in a Spondylectomy Model.

STUDY DESIGN: An idealized biomechanical model. OBJECTIVE: The aim of this study was to evaluate the biomechanical properties of a construct designed to minimize intervertebral cage subsidence and maximize stiffness. SUMMARY OF BACKGROUND DATA: Reconstruction after vertebral resection typically involves posterior segmental fixation and anterior interbody support. However, poor bone density, adjuvant radiation, or the oncologic need for endplate resection make interbody device subsidence and resultant instrumentation failure a significant concern. METHODS: An idealized thoracolumbar spondylectomy reconstruction model was constructed using titanium segmental instrumentation and Delrin plastic. In vivo mechanical stress was simulated on a custom multi-axis spine simulator. Rigid body position in space was measured using an optical motion-capture system. Cancellous subsidence was modeled using a 1 cm thick wafer of number 3 closed-cell Sawbones foam at one endplate. Ten foam specimens were tested in a control state consisting of posterior segmental fixation with a free interbody cage. Ten additional foam specimens were tested in the test state, with the Delrin interbody cage "connected" to the posterior rods using two additional pedicle screws placed into the cage. Foam indentation was quantified using a precision digital surface-mapping device, and subsidence volume calculated using geometric integration. RESULTS: The control group exhibited significantly greater foam indentation after cycling, with a mean subsidence volume of 1906 mm [95% confidence interval (95% CI) 1810-2001] than the connected cage group subsidence volume of 977 mm (95% CI 928-1026 mm; P < 0.001]. Construct stiffness was greater in the connected cage group (3.1 Nm/degree, 95% CI 3.1-3.2) than in the control group (2.3 Nm/degree, 95% CI 2.2-2.4; P < 0.001). CONCLUSION: In an idealized spondylectomy model, connecting the anterior column cage to the posterior instrumentation using additional pedicle screws results in a construct that is nearly 40% stiffer and exhibits 50% less cancellous subsidence compared with a traditional unconnected cage. LEVEL OF EVIDENCE: N/A.