Faculty Bibliography

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) performed as an outpatient has become increasingly common for treating cervical spine pathology. Few reports have attempted to assess readmissions following outpatient ACDF. This study was performed to address this issue using population-based databases. METHODS: The State Ambulatory Services Database (SASD) for New Jersey (NJ) from 2003-2012 was used for analysis. Patients receiving ACDF (defined as anterior cervical fusion (ICD-0 code=81.02) + excision of intervertebral disc (80.51)) were extracted; those with three or more levels fused (ICD-9 codes 81.63-81.64), cancer (ICD-9 codes 140-239), or trauma (ICD-9 codes=805.0-806.9) were excluded. A series of perioperative complications including durotomy, red blood cell transfusion, acute posthemorrhagic anemia, paraplegia (weakness), and mortality were examined. Propensity score matching (PSM) was used to adjust the analysis for patient age, race, sex, primary payer for care, and number of diagnoses. The NJ SASD defined readmission as admission to the same facility within seven days of initial discharge. RESULTS: Two thousand sixteen (2,016) patients were found, 1,528 of whom had readmission data. Of these 1,528 patients, 83 (5.4%) required readmission. PSM was performed prior to comparing readmission versus non-readmission. While there was no difference in perioperative complications between the two groups, the small sample size of the readmission cohort prevented this analysis from having sufficient power. No patient requiring readmission had an initial length of stay greater than one day. CONCLUSION: Based on a 10-year outpatient analysis, fewer than 6% of outpatient 1-2 level ACDFs require readmission. Future studies involving outpatients from several states will be necessary to determine whether these results of outpatient ACDF are applicable nationwide.

STUDY DESIGN: Retrospective review OBJECTIVE.: To evaluate preoperative variability in radiographic sagittal parameters in adult spinal deformity (ASD). SUMMARY OF BACKGROUND DATA: In ASD surgical planning, deformity magnitude is determined from pre-op radiographs. The are no studies evaluating the clinical relevance and timing to repeat radiographs during interval clinic visits and timing to repeat radiograph for preoperative planning. METHODS: 139 ASD patients with minimum two pre-operative full body spine x-rays were included. Cervical, thoracic, lumbar, pelvic, and hip/knee sagittal alignment parameters were analyzed using dedicated spine measurement software. Patients were grouped by time intervals between x-rays: A: /=21 weeks. Changes in sagittal parameters were correlated to age and deformity magnitude (T1 pelvic angle [TPA] or pelvic tilt [PT] >20 degrees ). RESULTS: The cohort had mean age 59 years, mean BMI 27, 30% males, 95 patients with no prior spine surgery and 44 patients at minimum nine months since prior spine surgery. There were 25 patients in Group A, 38 in B, and 71 in C. All radiographic measures showed good time-based consistency at intervals <21 weeks (Groups A and B). Group C had significant increases in PT (1.5 degrees ) and hip extension (2.1 degrees ) (p < 0.05). These changes were greater in Group C patients with previous surgery (PT 3.7 degrees ; p < .006, hip extension 3.2 degrees ; p < .025). Greater interval changes in parameters were also associated with higher magnitude of deformity and younger patient age. CONCLUSIONS: All sagittal radiographic parameters were statistically consistent at intervals < 21 weeks. In patients with >21 weeks between interval x-rays, change in PT was greater than the standard error of measurement for patients with prior surgery or severe deformity. Consideration should be made to obtain new x-rays for adult spinal deformity patients when the interval between clinical visits exceeds 5 months. LEVEL OF EVIDENCE: 4.

STUDY DESIGN: Retrospective cohortObjective. To investigate the cervical alignment necessary for the maintenance of horizontal gaze depends on underlying thoracolumbar alignment SUMMARY OF BACKGROUND DATA.: Cervical curvature (CC) is affected by thoracic and global alignment. Recent studies suggest large variability in normative CC ranging from lordotic to kyphotic alignment. No previous studies have assessed the effect of global spinal alignment on CC in maintenance of horizontal gaze. METHODS: Patients without previous history of spinal surgery and were able to maintain their horizontal gaze while undergoing full body imaging were included. Patients were stratified based on thoracic kyphosis (TK) into (<30, 30-40, 40-50 and >50) then by SRS-Schwab sagittal vertical axis (SVA) modifier into (posterior alignment SVA<0, aligned 0-50 and malaligned >50 mm). Cervical alignment was assessed among SVA grade in TK groups. Stepwise linear regression analysis was applied on random selection of 60% of the population. A simplified formula was developed and validated on the remaining 40%. RESULTS: In each TK group (n = 118, 137, 125, 197), lower cervical curvature (C2-C7) was significantly more lordotic by increased Schwab SVA grade. T1 slope and cervical SVA significantly increased with increased thoracolumbar (C7-S1) SVA. Upper cervical curvature (C0-C2) and mismatch between T1 slope and cervical curvature (T1-CL) were similar. Regression analysis revealed LL minus TK (LL-TK) as an independent predictor (r = 0.640, r2 = 0.410) with formula: CC = 10 - (LL-TK)/2. Validation revealed that the absolute difference between the predicted CC and the actual CC was 8.5 degrees . Moreover, 64.2% of patients had their predicted C2-C7 values were within 10 degrees of the actual CC. CONCLUSIONS: Cervical kyphosis may represent normal alignment in a significant number of patients. However, in patients with SVA >50 and greater thoracic curvatures, cervical lordosis is needed to maintain the gaze. Cervical alignment can be predicted from underlying TK and lumbar lordosis, which may be clinically relevant when considering correction for thoracolumbar or cervical deformityLevel of Evidence: 3.

STUDY OBJECTIVE: Perioperative thrombotic complications after orthopedic surgery are associated with significant morbidity and mortality. The use of aspirin to reduce perioperative cardiovascular complications in certain high-risk cohorts remains controversial. Few studies have addressed aspirin use, bleeding, and cardiovascular outcomes among high-risk patients undergoing joint and spine surgery. DESIGN/SETTING/PATIENTS: We performed a retrospective comparison of adults undergoing knee, hip, or spine surgery at a tertiary care center during 2 periods between November 2008 and December 2009 (reference period) and between April 2013 and December 2013 (contemporary period). MEASUREMENTS: Patient demographics, comorbidities, management, and outcomes were ascertained using hospital datasets. MAIN RESULTS: A total of 5690 participants underwent 3075 joint and spine surgeries in the reference period and 2791 surgeries in the contemporary period. Mean age was 61+/-13 years, and 59% were female. In the overall population, incidence of myocardial injury (3.1% vs 5.8%, P<.0001), hemorrhage (0.2% vs 0.8%, P=.0009), and red blood cell transfusion (17.2% vs 24.8%, P<.001) were lower in the contemporary period. Among 614 participants with a preoperative diagnosis of coronary artery disease (CAD), in-hospital aspirin use was significantly higher in the contemporary period (66% vs 30.7%, P<.0001); numerically, fewer participants developed myocardial injury (13.5% vs 19.3%, P=.05), had hemorrhage (0.3% vs 2.1%, P=.0009), and had red blood cell transfusion (37.2% vs 44.2%, P<.001) in the contemporary vs reference period. CONCLUSIONS: In a large tertiary care center, the incidence of perioperative bleeding and cardiovascular events decreased over time. In participants with CAD, perioperative aspirin use increased and appears to be safe.

STUDY DESIGN: Retrospective review of a prospective multicenter database evaluating surgical adult spinal deformity (ASD) patients. OBJECTIVE: This study aims to identify risk factors for medical complications in ASD patients undergoing surgery. SUMMARY OF BACKGROUND DATA: ASD surgery is known for its high complication rate. This study examines baseline patient characteristics for predictors of medical complications in surgical ASD patients. METHODS: Intra and perioperative medical complications were included. Medical complications were: infection, pneumonia, urinary tract infection, c-difficile, sepsis, stroke, delirium, deep venous thrombosis, pulmonary embolism, myocardial infarction, arrhythmia, congestive heart failure, pneumothorax, atelectasis, adult respiratory distress syndrome, bowel obstruction, ileus, and renal failure. Potential predictors were identified using univariate testing. Multivariate Poisson regression was used to determine independent predictors of medical complications. Health-related quality of life (HRQL) was measured using the Oswestry Disability Index and SF-36. Multivariate repeated measures mixed models were used to examine HRQL. RESULTS: Four hundred forty-eight patients were included. The incidence of patients with at least one medical complication was 26.8%. Potential predictors included: age, BMI, anemia, arthritis, depression, cardiac history, hypertension, lung disease, history of PVD, Charlson Comorbidity Index, ASA, smoking, sex, and the number of years with spine problems. Independent predictors identified on multivariate logistic regression modeling included hypertension (IRR 2.43 P = 0.0001), smoking (IRR 2.49 P = 0.0001), and number of years with spine problems (IRR 1.23 P = 0.03). Despite medical complications, patients experienced significant improvements in HRQL, as measured by the SF-36 (P = 0.0001) and oswestry disability index (P = 0.0001). The rate of improvement and overall improvement compared with baseline were not statistically different than that of patients who did not experience medical complications. CONCLUSION: Risk factors for the development of postoperative medical complications after correction of ASD include smoking, hypertension, and duration of symptoms. Patients who have one or more of these risk factors should be identified and informed during informed consent of their increased risks. They should be optimized preoperatively, and followed closely during the postoperative period. LEVEL OF EVIDENCE: 3.

BACKGROUND: Though previous studies have shown improved outcomes associated with higher volume surgeons and hospitals, this may not be replicated in ASDS due to case complexity variation. We hypothesized that high-volume surgeons perform more complex surgeries. Therefore, we defined an Operative Complexity Index (OCI), specifically for the National Inpatient Samples (NIS) data, which provides information on in-hospital postoperative complications, to assess rates of adult spine deformity surgery (ASDS) cases as they relate to surgeon and hospital operative volume. METHODS: The 2001 to 2010 NIS was queried for patients greater than 21 years of age with in-hospital stays, including a spine arthrodesis for a diagnosis of scoliosis. Surgeon and hospital identifiers were used to allocate records into volume quartiles by number of surgeries per year. The OCI was devised considering the number of fusion levels, surgical approach, revision status, and use of osteotomy. The index was validated using blood-loss-related diagnostic and procedural codes. One-way ANOVA assessed continuous measures. Chi-square assessed categorical measures. RESULTS: 141,357 ASDS cases met the inclusion criteria. High-volume surgeons performed a higher rate of longfusions (> 8 levels), revision surgeries, and surgeries requiring osteotomy. The OCI showed weak, but significant, correlation with blood loss values: acute blood loss anemia (r = 0.21) and treatment with blood products (r = 0.12) (p < 0.001). High OCI also was also associated with increased length of stay (r = 0.27) and total charges (r = 0.41) (p < 0.001). CONCLUSIONS: The operative complexity index (OCI) for ASDS increases with high-volume surgeons and centers, indicating it can be useful to adjust for surgical invasiveness in the NIS database. Operative complexity must be considered when evaluating patient safety and quality indices among hospitals and surgeons.