Andrew J. Schoenfeld

Risk Factors for Immediate Postoperative Complications and Mortality Following Spine Surgery: A Study of 3475 Patients from the National Surgical Quality Improvement Program

BACKGROUND This investigation sought to identify risk factors for immediate postoperative morbidity and mortality among a large series of patients undergoing spine surgery who were prospectively entered into a national registry. METHODS The database of the National Surgical Quality Improvement Program was queried to identify all patients undergoing spine surgery in the years 2005 to 2008. Demographic data, comorbidities, medical history, body-mass index, and the type of procedure performed were obtained for all patients. Postoperative complications and mortality within thirty days after the spinal procedure were also documented. The chi-square test and univariate and multivariate logistic regression analyses were used to evaluate the effect of individual risk factors on mortality, as well as the probability of the development of complications. RESULTS From 2005 to 2008, 3475 patients undergoing spine surgery were registered in the database. The average age of patients was 55.5 years (range, sixteen to ninety years), and 54% of the cohort were men. Ten patients (0.3%) died after surgery, and there were 407 complications in 263 patients (7.6%). Increased patient age and contaminated or infected wounds were identified as independent predictors of mortality. Increased patient age, cardiac disease, preoperative neurologic abnormalities, prior wound infection, corticosteroid use, history of sepsis, American Society of Anesthesiologists classification of >2, and prolonged operative times were independent predictors for the development of one or more complications. CONCLUSIONS Patient age, female sex, longer procedural times, and several types of medical comorbidities influenced the risk of postoperative complications or mortality. This information enhances estimates of morbidity and mortality following spine surgery and may improve patient selection for spine surgery as well as preoperative discussions related to the risks of spine surgery.

Thirty-day postoperative complications and mortality following total knee arthroplasty: incidence and risk factors among a national sample of 15,321 patients.

BACKGROUND The purpose of this investigation was to determine the incidence rates of, and identify risk factors for, thirty-day postoperative mortality and complications among more than 15,000 patients who underwent a primary unilateral total knee arthroplasty as documented in the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP). METHODS The NSQIP database was queried to identify patients who had undergone primary unilateral total knee arthroplasty between 2006 and 2010. Patient demographics, medical history, and surgical characteristics were recorded, as were thirty-day postoperative complications, mortality, and length of hospital stay. Complications were divided into categories, which included major systemic complications (complications requiring complex medical intervention) and major local complications (including deep wound infection and peripheral nerve injury). Univariate testing and multivariate logistic regression analysis were used to identify significant independent predictors of the outcome measures. RESULTS A total of 15,321 individuals underwent primary unilateral total knee arthroplasty. The mean age (and standard deviation) of the patients was 67.3 ± 10.2 years. Obesity (a body mass index [BMI] of ≥30 kg/m²) was documented in 61.2% of cases, 18.2% of patients had diabetes, and 50% were graded as Class 3 or higher on the basis of the American Society of Anesthesiologists (ASA) classification system. The thirty-day mortality rate was 0.18%, and 5.6% of the patients experienced complications. Patient age (odds ratio [OR] = 1.12; 95% confidence interval [CI] = 1.06 to 1.17) and diabetes (OR = 2.99; 95% CI = 1.35 to 6.62) were independent predictors of mortality. A BMI of ≥40 kg/m² was an independent predictor of postoperative complications (OR = 1.47; 95% CI = 1.09 to 1.98). Patient age of eighty years or older, an ASA classification of ≥3, and an operative time of >135 minutes influenced the development of any postoperative complication as well as major and minor systemic complications. Cardiac disease (OR = 4.32; 95% CI = 1.01 to 18.45) and a BMI of ≥40 kg/m² (OR = 2.01; 95% CI = 1.02 to 3.97) were associated with minor local complications. CONCLUSIONS Patient age and diabetes increased the risk of mortality after primary total unilateral knee arthroplasty. Predictive factors impacting the development of postoperative complications included an ASA classification of ≥3, increased operative time, increased age, and greater body mass.

Low back pain in the United States: incidence and risk factors for presentation in the emergency setting

BACKGROUND CONTEXT Low back pain is prevalent in the United States. At the present time, no large longitudinal study is available characterizing the incidence of this condition in the US population or identifying potential risk factors for its development. PURPOSE To characterize the incidence of acute low back pain requiring medical evaluation in the emergency department and establish risk factors for its development. STUDY DESIGN Cross-sectional study. PATIENT SAMPLE United States population estimates. OUTCOME MEASURES Incidence rate ratios were calculated to determine the influence of age, sex, and race on the development of low back pain requiring emergent medical evaluation. METHODS The National Electronic Injury Surveillance System was queried for all cases of low back pain presenting to emergency departments between 2004 and 2008. Incidence rate ratios were then calculated with respect to age, sex, and race. The chi-square statistic was used to identify statistically significant differences in the incidence of low back pain requiring emergent medical evaluation between subgroups. RESULTS An estimated 2.06 million episodes of low back pain occurred among a population at risk of over 1.48 billion person-years for an incidence rate of 1.39 per 1,000 person-years in the United States. Low back pain accounted for 3.15% of all emergency visits. Injuries sustained at home (65%) accounted for most patients presenting with low back pain. Low back pain demonstrates a bimodal distribution with peaks between 25 and 29 years of age (2.58/1,000 person-years) and 95 to 99 years of age (1.47/1,000) without differentiation by underlying etiology. When compared with females, males showed no significant differences in the rates of low back pain. However, when analyzed by 5-year age group, males aged 10 to 49 years and females aged 65 to 94 years had increased risk of low back pain than their opposite sex counterparts. When compared with Asian race, patients of black and white race were found to have significantly higher rates of low back pain. Older patients were found to be at a greater risk of hospital admission for low back pain. CONCLUSION Age, sex, and race are significant risk factors for the development of low back pain necessitating treatment in an emergency department.

Combat wounds in Iraq and Afghanistan from 2005 to 2009.

BACKGROUND There have been no large cohort studies examining the wounding patterns and injury mechanisms in Iraq and Afghanistan from 2005 to 2009. This investigation sought to characterize the incidence and epidemiology of combat-related injuries for this period. METHODS Using the Joint Theater Trauma Registry, a detailed description of the combat casualty care statistics, distribution of wounds, and injury mechanisms sustained by all US service members for wounds (DRG International Classification of Diseases—9th Rev. codes 800–960) during the Iraq and Afghanistan Wars from 2005 to 2009 was performed. RESULTS Among the 1,992,232 military service members who were deployed, there were 29,624 distinct combat wounds in 7,877 combat casualties. The mean age of the combat casualty cohort was 26.0 years old. The combat casualties were predominantly male (98·8%), Army (77·5%), and junior enlisted (59·0%). The distribution of combat wounds was as follows: head/neck, 28·1%; thorax, 9·9%; abdomen, 10·1%; and extremities, 51·9%. Explosive injury mechanisms accounted for 74·4% of all combat casualties, which was significantly higher than those caused by gunshot wounds (19·9%) (p < 0.0001). From 2005 to 2007, explosive mechanisms of injury were significantly more common in Iraq than in Afghanistan (p < 0.001). The percentage of explosive mechanisms increased significantly in Afghanistan between the years 2007 (59·5%) and 2008 (73·6%) (p < 0.0003). CONCLUSION The wounding patterns observed in Iraq and Afghanistan from 2005 to 2009 differ from previous conflicts. Explosive mechanisms accounted for 74·4% of combat casualties, which is a higher percentage than in previous US conflicts. A progressive increase in the use of explosive mechanisms in Afghanistan, eventually equaling that in Iraq, was observed during the study period. (J Trauma Acute Care Surg. 2012;73: 3–12. Copyright

Clinical Outcome of Metastatic Spinal Cord Compression Treated with Surgical Excision ± Radiation Versus Radiation Therapy Alone: A Systematic Review of Literature

Study Design. Systematic literature review from 1970 to 2007. Objective. This study reports the results of a systematic review comparing surgical decompression ± radiation to radiation therapy alone among patients with metastatic spinal cord compression. Summary of Background Data. Currently, the optimal treatment of metastatic spine lesions is not well defined and is inconsistent. Radiation and surgical excision are both accepted and effective. There appears to be a favorable trend for improved neurological outcome with surgical excision and stabilization as part of the management. Methods. A review of the English literature from 1970 to 2007 was performed in the Medline database using general MeSH terms. Relevant outcome studies for the treatment of metastatic spinal cord compression were selected through criteria defined a priori. The primary outcome was ambulatory capacity. A random effects model was built to compare results between treatment groups, based on calculated proportions from each study. Results. Of the 1595 articles screened, 33 studies (2495 patients) were selected based on our inclusion and exclusion criteria. Sixty-four percent of the patients who underwent surgical decompression, tumor excision, and stabilization had neurological improvement from nonambulatory to ambulatory status. Twenty-nine percent of the radiation therapy group regained the ability to ambulate after treatment (P < 0.001). Paraplegic patients had a 4-fold greater recovery rate to functional ambulation with surgical intervention than with radiation therapy alone (42% vs. 10%, P < 0.001). Pain relief was noted in 88% of the patients in the surgical studies and in 74% of the patients in studies of radiation therapy (P < 0.001). The overall surgical complication rate was 29%. Conclusion. This systematic review suggests that surgical excision of tumor and instrumented stabilization may improve clinical outcomes compared with radiation therapy alone, with regard to neurological function and pain. However, most data in the current literature are from observational studies, where variations in patient population and treatments cannot be controlled. This compromised our ability to compare the results of both treatments directly.

Arthroscopic Basic Task Performance in Shoulder Simulator Model Correlates with Similar Task Performance in Cadavers

BACKGROUND Attainment of the technical skill necessary to safely perform arthroscopic procedures requires the instruction of orthopaedic surgery residents in basic arthroscopic skills. Although previous studies involving shoulder arthroscopy simulators have demonstrated a correlation between task performance and the level of prior arthroscopic experience, data demonstrating the correlation of simulator performance with arthroscopic skill in a surgical setting are scarce. Our goal was to evaluate the correlation between timed task performance in an arthroscopic shoulder simulator and timed task performance in a cadaveric shoulder arthroscopy model. METHODS Subjects were recruited from among residents and attending surgeons in an orthopaedic surgery residency program. Each subject was tested on an arthroscopic shoulder simulator and objectively scored on the basis of the time taken to complete a standardized object selection program. After an interval of at least two weeks, each subject was then tested on a cadaveric shoulder arthroscopy model designed to replicate the shoulder arthroscopy simulator testing protocol, and the time to completion was again recorded. Both testing protocols involved the simple task of placing a probe on a series of assigned locations in the glenohumeral joint. Spearman rank correlation analysis was performed, and regression analysis was used to determine the predictive ability of the simulator score. RESULTS The performance time on the simulation program was strongly correlated with the performance time on the cadaveric model (r = 0.736, p < 0.001). The time required to complete the simulator task was a significant predictor of the time required to complete the cadaveric task (t = 4.48, p < 0.001). CONCLUSIONS These results demonstrated a strong correlation between performance of basic arthroscopic tasks in a simulator model and performance of the same tasks in a cadaveric model.

Distal Femoral Fixation : A Biomechanical Comparison of Trigen Retrograde Intramedullary (I.M.) Nail, Dynamic Condylar Screw (DCS), and Locking Compression Plate (LCP) Condylar Plate

BACKGROUND The purpose of this study was to establish if there are biomechanical differences between implants in stiffness of construct, microdisplacement, and fatigue failure in a supracondylar femoral fracture model. METHODS A retrograde intramedullary (i.m.) nail, dynamic condylar screw (DCS), and locked condylar plate (LCP) were tested using 33-cm long synthetic femurs. A standardized supracondylar medial segmental defect was created in the distal femur bone models. A gap away from the distal joint axis and parallel to the knee axis was created for axial testing of the specimens (Arbeitsgemeinschaft fur Osteosynthesefragen [AO] type 33-A) and a T-fracture (33-C) was created for the fatigue testing of the specimens. Peak displacements were measured, and analysis was done to determine construct stiffness and gap micromotion in axial loading. Cyclic loading was performed for fatigue testing. RESULTS It was observed that there were statistically significant differences in micromotion across the fracture gap and overall stiffness of various implant constructs. The stiffness of the i.m. nail, DCS, and LCP were 1,106, 750, and 625 N/mm, respectively. The average total micromotion across the fracture gap for the i.m. nail, DCS, and LCP were 1.96, 10.55, and 17.74 mm, respectively. In fatigue testing, the i.m. nail distal screws failed at 9,000 cycles, the DCS did not fail (80,000 cycles completed), and the LCP failed at 19,000 and 23,500 cycles. CONCLUSIONS When considering micromotion and construct stiffness, the i.m. nail had statistically significant higher stiffness and significantly lower micromotion across the fracture gap with axial compression. Hence, the i.m. nail tested had the greatest stability for type 33-A fractures. However, the nail demonstrated the least amount of resistance to fatigue failure with type 33-C fractures, whereas the DCS did not fail with testing in any pattern.

Type II Odontoid Fractures of the Cervical Spine: Do Treatment Type and Medical Comorbidities Affect Mortality in Elderly Patients?

Study Design. Retrospective cohort study. Objective. To determine the influence of age, comorbidities, and treatment type on mortality in elderly patients with acute Type II odontoid fractures. Summary of Background Data. Prior studies have documented increased morbidity and mortality among geriatric patients sustaining odontoid fractures. However, there is limited data regarding the effect of patient age, medical comorbidities, and treatment selection on mortality after Type II odontoid (C2) fractures in the elderly. Methods. An institutional registry was used to identify all Type II odontoid fractures sustained by patients aged 65 and older from 1991 to 2006. Demographic information, date of injury, associated injuries, treatment type, and comorbidities were abstracted from medical records. Mortality was ascertained using the National Death Index. Risks of mortality and their associated 95% confidence intervals (CIs) were calculated at 3 months, 1 year, 2 years, and 3 years. Multivariable Cox proportional hazard regression was used to evaluate independent factors affecting mortality stratified by age (65–74 years, 75–84 years, ≥85 years) and treatment type (operative or nonoperative treatment, and halo or collar immobilization). Results. Of 156 patients identified with Type II odontoid fracture, the average age was 82 years (SD = 7.8; Range: 65–101). One hundred and twelve patients (72%) were treated nonoperatively. At 3 years postinjury, there was a 39% (95% CI: 32–47) mortality rate for the entire cohort. Mortality for the operative group was 11% (95% CI: 2–21) at 3 months and 21% (95% CI: 9–32) at 1 year compared with 25% (95% CI: 17–33) at 3 months and 36% (95% CI: 27–45) at 1 year in the nonoperative group. The Cox regression model showed that the protective effect of surgery was seen in patients aged 65 to 74 years, in whom the hazard ratio associated with surgery for mortality after odontoid fracture was 0.4 (95% CI: 0.1–1.5). Those aged 75 to 84 years had a hazard ratio of 0.8 (95% CI: 0.3–2.3), and patients 85 years or older had a hazard ratio of 1.9 (95% CI: 0.6–6.1; P value for interaction between age and treatment = 0.09) with operative treatment having a protective effect in patients aged 65 to 74 years. Conclusion. In a cohort of elderly patients, Type II odontoid fractures were associated with a high rate of mortality, regardless of intervention.

Morbidity and Mortality in the Thirty-Day Period Following Total Hip Arthroplasty: Risk Factors and Incidence

The study sought to ascertain the incidence rates and risk factors for 30-day post-operative complications after primary total hip arthroplasty (THA). Complications were categorized as systemic or local and subcategorized as major or minor. There were 17,640 individuals who received primary THA identified from the 2006-2011 ACS NSQIP. The mortality rate was 0.35% and complications occurred in 4.9%. Age groups ≥ 80 years (P <0.001) and 70-79 years old (P = 0.003), and renal insufficiency (P = 0.02) best predicted mortality. Age ≥80 years (P <0.001) and cardiac disease (P = 0.01) were the strongest predictors of developing any postoperative complication. Morbid obesity (P <0.001) and operative time > 141 minutes (P <0.001) were strongly associated with the development of major local complications.

Thirty-day morbidity and mortality after elective total shoulder arthroplasty: patient-based and surgical risk factors

BACKGROUND Total shoulder arthroplasty (TSA) is an effective treatment for painful glenohumeral arthritis, but its morbidity has not been thoroughly documented. METHODS The National Surgical Quality Improvement Program database was queried to identify all patients undergoing primary TSA between 2006 and 2011, with extraction of selected patient-based or surgical variables and 30-day clinical course. Postoperative complications were stratified as major systemic, minor systemic, major local, and minor local, and mortality was recorded. Odds ratios (ORs) with 95% confidence intervals (95% CIs) were derived from bivariate and multivariable analysis to express the association between risk factors and clinical outcomes. RESULTS Among the 2004 patients identified, the average age was 69 years, and 57% were women. Obesity was present in 46%, and 48% had an American Society of Anesthesiologists classification of ≥3. The 30-day mortality and total complication rates were 0.25% and 3.64%, respectively. Comorbid cardiac disease (OR, 85.31; 95% CI, 8.15, 892.84) and increasing chronologic age (OR, 1.19; 95% CI, 1.06, 1.33) were independent predictors of mortality, whereas peripheral vascular disease was associated with statistically significant increase in any complication (OR, 6.25; 95% CI, 1.24, 31.40). Operative time >174 minutes was an independent predictor for development of a major local complication (OR, 4.05; 95% CI, 1.45, 11.30). Obesity was not associated with any specified complication after controlling for other variables. CONCLUSIONS Whereas TSA has low short-term rates of perioperative complications and mortality, careful perioperative medical optimization and efficient surgical technique should be emphasized to decrease morbidity and mortality.