Multiple High-Risk Features for Stage II Colon Carcinoma Portends Worse Survival Than Stage III Disease

BACKGROUND

High-risk features in stage II colon cancer worsen survival and serve as an impetus for adjuvant chemotherapy. Limited data exist on the effect of multiple high-risk features on survival.

OBJECTIVE

The study aimed to compare the survival of 0, 1, or multiple high-risk features in stage II to stage III colon cancer.

DESIGN

Patients with stage II and III colon cancer diagnosed between 2010 and 2016 were identified using the Survival, Epidemiology, and End Results database. Patients with stage II colon cancer were then classified according to the presence of 0, 1, or 2 or more of the following high-risk features: pathologic T4, perineural invasion, fewer than 12 lymph nodes assessed, or poor histologic differentiation. Overall survival and cause-specific survival were calculated. Each group was then stratified on the basis of whether chemotherapy was given.

SETTINGS

This study used the Survival, Epidemiology, and End Results database (2010-2016).

PATIENTS

Patients who had stage II or III colon cancer were included.

MAIN OUTCOME MEASURES

The primary outcome measures were 5-year overall survival and cause-specific survival.

RESULTS

A total of 65,831 patients were studied. Of these, 18,056 patients with stage II cancer had 0 high-risk features, 9426 had 1 high-risk feature, and 3503 had 2 or more high-risk features. There were 34,842 patients diagnosed with stage III disease. The 5-year overall survival and cause-specific survival for patients with stage II cancer with 2 or more high-risk features (49.2%, 59.5%) were lower than those without high-risk features (74.9%, 90.7%), with 1 high-risk feature (67.1%, 82.4%), or stage III disease (59.1%, 68.1%; p < 0.05). Although chemotherapy is associated with improved cause-specific survival in stage III disease, it is associated with worse cause-specific survival in patients with stage II disease.

LIMITATIONS

This study being a retrospective database analysis is the main limitation. Also, lymphovascular invasion, margin status, and clinical obstruction or perforation were absent from the dataset.

CONCLUSIONS

Multiple high-risk features in stage II colon cancer predict worse survival than lymph node metastasis. Chemotherapy is associated with adverse cause-specific survival in patients with stage II disease. Further study into this group should focus on the type and duration of adjuvant therapy and biological features of these tumors. See Video Abstract at http://links.lww.com/DCR/B929 .

MLTIPLES CARACTERSTICAS DE ALTO RIESGO PARA EL CARCINOMA DE COLON EN ESTADIO II PRESAGIAN PEOR SUPERVIVENCIA QUE LA ENFERMEDAD EN ESTADIO III

ANTECEDENTES:Las características de alto riesgo en el cáncer de colon en estadio II empeoran la supervivencia y sirven como impulso para la quimioterapia adyuvante. Existen datos limitados sobre el efecto de múltiples características de alto riesgo en la supervivencia.OBJETIVO:Comparar la supervivencia de cero, una o múltiples características de alto riesgo en el cáncer de colon en estadio II con la enfermedad en estadio III.DISEÑO:Los pacientes con cáncer de colon en estadio II y III diagnosticados entre 2010 y 2016 se identificaron mediante la base de datos de supervivencia, epidemiología y resultados finales. Luego, los pacientes en etapa II se clasificaron según la presencia de cero, 1 o 2+ de las siguientes características de alto riesgo: T4 patológico, invasión perineural, menos de 12 ganglios linfáticos evaluados (< 12 ganglios linfáticos) o mala diferenciación histológica. Se calculó la supervivencia observada y específica de la causa. Luego, cada grupo se estratificó en función de si se administró quimioterapia.ESCENARIO:Este estudio utilizó la base de datos de supervivencia, epidemiología y resultados finales, 2010-2016.PACIENTES:Los pacientes tenían cáncer de colon en estadio II o III.PRINCIPALES MEDIDAS DE RESULTADO:La medida principal fue la supervivencia observada a 5 años y la supervivencia por causa específica.RESULTADOS:Se estudiaron un total de 65,831 pacientes. 18,056 pacientes estaban en estadio II sin características de alto riesgo, 9.426 con 1 característica de alto riesgo y 3.503 con 2+ características de alto riesgo. Hubo 34.842 pacientes a los que se les diagnosticó enfermedad en estadio III. La supervivencia observada a los 5 años y la supervivencia específica de la causa para los pacientes con cáncer en estadio II con 2+ características de alto riesgo (49.2 %, 59.5 %) fueron más bajas, en comparación con aquellos sin características de alto riesgo (74.9 %, 90.7 %), con 1 característica de alto riesgo (67.1 %, 82.4 %) o enfermedad en estadio III (59.1 %, 68.1 %) (p < 0.05). Si bien la quimioterapia se asocia con una mejor supervivencia por causa específica en la enfermedad en estadio III, se asocia con una peor supervivencia por causa específica en pacientes con enfermedad en estadio II.LIMITACIONES:Este es un análisis de base de datos retrospectivo. La invasión linfovascular, el estado de los márgenes y la obstrucción o perforación clínicas estaban ausentes en la base de datos.CONCLUSIONES:Múltiples características de alto riesgo en el cáncer de colon en estadio II predicen una peor supervivencia que la metástasis en los ganglios linfáticos. La quimioterapia se asocia con una supervivencia específica de causa adversa en pacientes con enfermedad en estadio II. El estudio adicional de este grupo deberá centrarse en el tipo y la duración de la terapia adyuvante y las características biológicas de estos tumores. Consulte Video Resumen en http://links.lww.com/DCR/B929 . (Traducción-Dr. Jorge Silva Velazco ).

Morbid Obesity Not a Risk for Serious Complications Following Outpatient Surgery

Patients with class III obesity are often excluded from surgery in ambulatory surgery centers (ASCs). We hypothesize that class III obesity is not a risk factor for serious post-operative complications following outpatient operations. ACS-NSQIP database from 2012 to 2018 was queried. Patients undergoing outpatient inguinal hernia repair (IHR) and laparoscopic cholecystectomy (LC) were grouped by BMI. Baseline characteristics and 30-day outcomes were compared using univariate and multivariate analyses. Of these, 79,916 patients underwent IHR and 107,471 patients underwent LC. Multivariable analysis in IHR showed increased odds of superficial SSIs in all classes of obesity compared to normal weight (P < .0001). In the LC group, there were higher rates of SSIs with obesity (P < .0001). For both surgeries, a higher rate of readmissions to the hospital were observed in class II and IIIa obesity (both P < .0001), although rates were relatively low (<3%). Class III obesity demonstrates a statistically significant increase in SSI following IHR and LC. Severe complications requiring readmission are not mirrored, suggesting the morbidly obese patients should be considered for routine surgical procedures in outpatient settings.

Abstract 6315: Are a subset of patients at higher risk for mortality in stage III colon cancer: An analysis of the SEER database

Background: High-risk features (HRF) increase mortality for Stage II colon cancer (CC). These HRF include pathologic T4 disease, perineural invasion (PNI), lymphovascular invasion (LVI), an inadequate lymphadenectomy (less than 12 lymph nodes harvested) and poorly differentiated tumors. The presence of two or more HRF has an additive impact on survival for patients with Stage II CC. While T4 and disease greater than N1a raise the risk of mortality in Stage III CC, the effect of the other accepted HRF in patients with Stage III CC has not been studied.

Materials and Methods: Surveillance, Epidemiology and End Results (SEER) (2010 - 2017) was used to identify patients with Stage III and IV CC. Patients with Stage III CC were then further classified by the presence of zero, 1, or 2 or more of the following HRF: pathologic T4, PNI, inadequate lymphadenectomy, or poor differentiation. Overall (OS) and cause-specific (CS) survival were calculated.

Results: 57,640 patients with Stage III or IV CC were identified. 35,760 (62%) patients had Stage III disease and 21,880 (38%) had Stage IV disease. Among patients with Stage III disease, 16,733 (46.8%) had no HRF, 12,703 (35.5%) had 1 HRF and 6,324 (17.7%) had 2 or more HRF. For patients with 1 HRF, 4,610 (36.3%) had poor differentiation, 2,339 (18.4%) had PNI, 3,673 (28.9%) had T4 disease, and 2,078 (16.4%) had an inadequate nodal harvest. Patients with Stage III CC without HRF had the best OS (73.3%) and CS (81.4%,). This was followed by Stage III with 1 HRF (OS 63.7%, CS 71.6%) and Stage III with 2 or more HRF (OS 44%, CS 51%). Patients with Stage IV disease had the worst OS (18.1%) and CS (20.4%) (p&lt;0.05). For patients with 1 HRF, pathologic T4 conferred worse OS (57.2%) and CS (63.2%), compared to PNI (OS 66.4%, CS 73.7%), inadequate lymphadenectomy (OS 64.6%, CS 74.9%) and poor differentiation (OS 66.6%, CS 75.4%) (p&lt;0.01).

Conclusion: HRF have a cumulative influence on OS and CS in patients with Stage III CC. The presence of multiple HRF should be considered higher risk for patients with Stage III disease.

Citation Format: Luv N. Hajirawala, Yong Yi, Michelle A. Bergeron, Danielle A. Dooley, Guy R. Orangio, Elyse R. Bevier-Rawls, Kurt G. Davis, Jeffrey S. Barton. Are a subset of patients at higher risk for mortality in stage III colon cancer: An analysis of the SEER database [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6315.

Minimally Invasive Surgery is Associated with Improved Outcomes Following Urgent Inpatient Colectomy

Objectives

The use of minimally invasive techniques for urgent colectomies remains understudied. This study compares short-term outcomes following urgent minimally invasive colectomies to those following open colectomies.

Methods & Procedures

The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) colectomy database was queried between January 1, 2013 and December 31, 2018. Patients who underwent elective and emergency colectomies, based on the respective NSQIP variables, were excluded. The remaining patients were divided into two groups, minimally invasive surgery (MIS) and open. MIS colectomies with unplanned conversion to open were included in the MIS group. Baseline characteristics and 30-day outcomes were compared using univariable and multivariable regression analyses.

Results

A total of 29,345 patients were included in the study; 12,721 (43.3%) underwent MIS colectomy, while 16,624 (56.7%) underwent open colectomy. Patients undergoing MIS colectomy were younger (60.6 vs 63.8 years) and had a lower prevalence of either American Society of Anesthesiology (ASA) IV (9.9 vs 15.5%) or ASA V (0.08% vs 2%). After multivariable analysis, MIS colectomy was associated with lower odds of mortality (odds ratio = 0.75, 95% confidence interval: 0.61, 0.91 95% confidence interval), and most short-term complications recorded in the ACS NSQIP. While MIS colectomies took longer to perform (161 vs 140 min), the length of stay was shorter (12.2 vs 14.1 days).

Conclusions

MIS colectomy affords better short-term complication rates and a reduced length of stay compared to open colectomy for patients requiring urgent surgery. If feasible, minimally invasive colectomy should be offered to patients necessitating urgent colon resection.

Buschke-Lowenstein Tumors: A Review and Proposed Classification System

ABSTRACT

Buschke-Lowenstein (B-L) tumors or giant condylomata are large fungating lesions that are caused by human papillomavirus (HPV) and develop in the anogenital region. Although uncommon, physicians and surgeons who treat sexually transmitted diseases or other diseases involving the anogenital area will encounter these patients. The purpose of this study is to review the current literature regarding these lesions. We evaluated every published study in PubMed and Embase from 1925 to 2020, concentrating on the clinical data included in each report, such as presentation and treatment. We also evaluated each work for any definition used and found that there is no accepted definition for these lesions. As such, we provide an inclusive, workable definition. In addition, there are many misconceptions about B-L that continue to be propogated as more case reports are published every year. After evaluating every published case, we refute the fact that these lesions have a high mortality or a high malignancy rate. Furthermore, we refute that these lesions are synonymous with verrucous carcinoma. In addition to a definition, we also propose a simple grading system that we hope can be used to assist in the study and management of these patients moving forward. Although the literature is very heterogenous regarding B-L, they are caused by HPV and are distinct from verrucous carcinoma. Because of the majority of information is based on case reports, the literature concentrates on treatment, but more work is clearly needed to delineate the association with specific HPV types and optimal management of this disease.

Laparoscopic Colectomy for Acute Diverticulitis in the Urgent Setting is Associated with Similar Outcomes to Open

PURPOSE/BACKGROUND

The role of minimally invasive surgery (MIS) for the surgical treatment of diverticular disease is evolving. The aim of this study is to compare the outcomes of MIS colectomy to those of open surgery for patients with acute diverticulitis requiring urgent surgery.

METHODS

The American college of Surgeons National Surgical Quality Improvement Project database was queried for all patients undergoing an urgent colectomy for acute diverticulitis between 2013 and 2018. The patients were then divided into 2 groups: MIS and open. Baseline characteristics and short-term outcomes were compared using univariable and multivariable regression analyses.

RESULTS/OUTCOMES

3487 patients were included in the analysis. Of these, 1272 (36.5%) underwent MIS colectomy and 2215 (63.5%) underwent open colectomy. Patients undergoing MIS colectomy were younger (58.7 vs 61.9 years) and less likely to be American Society of Anesthesiologists Classification (ASA) III (52.5 vs 57.9%) or IV (6.3 vs 10.5%). After adjusting for baseline differences, the odds of mortality for MIS and open groups were similar. While there was no difference in short-term complications between groups, the odds of developing an ileus were lower following MIS colectomy (OR .61, 95% CI: .49, .76). Both total length of stay (LOS) (12.3 vs 13.9 days) and post-operative LOS (7.6 days vs 9.5 days) were shorter for MIS colectomy. Minimally invasive surgery colectomy added an additional 40 minutes of operative time (202.2 vs 160.1 min).

CONCLUSION/DISCUSSION

Minimally invasive surgery colectomy appears to be safe for patients requiring urgent surgical management for acute diverticulitis. Decreased incidence of ileus and shorter LOS may justify any additional operative time for MIS colectomy in suitable candidates.

Trends in Open, Laparoscopic, and Robotic Approaches to Colorectal Operations

The use of robotic approach has gained momentum in colorectal surgery. We analyzed the trends in the adoption of robotic-assisted platform (RAP) for colorectal surgery over a 6-year period (2013-2018) using the American College of Surgeons National Surgical Quality Improvement Project. We assessed yearly prevalence of robotic, laparoscopic, and open approaches, and evaluated trends in the adoption of RAP across age, gender, BMI, and American Society of Anesthesiology (ASA) subgroups. Overall, the frequency of open, laparoscopic, and robotic approach was 36%, 46.8%, and 7.8%, respectively. While the use of laparoscopic cases remained stable over the study period, the prevalence of RAP increased from 2.8% to 11.4%. This was accompanied by a concomitant decline in the use of open approach, from 40.8% to 33%. The use of RAP also increased across all age, gender, BMI, and ASA subgroups. Robotic-assisted platform is increasingly utilized for higher risk, older, and obese patients, allowing more patients to receive minimally invasive colorectal surgery.

Delayed Surgery Does Not Increase Risk in Urgent Colectomy for Ulcerative Colitis

BACKGROUND

Medical management is the cornerstone of therapy for ulcerative colitis (UC). In the setting of fulminant disease, hospitalized patients may undergo medical rescue therapy (MRT) or urgent surgery. We hypothesized that delayed attempts at MRT result in increased morbidity and mortality following urgent surgery for UC.

OBJECTIVE

The aim is to assess the outcomes for patients requiring urgent, inpatient surgery for UC in a prompt or delayed fashion.

DESIGN

The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) general and colectomy-specific databases from 2013 to 2016 were queried. Urgent surgery was defined as nonelective, nonemergency surgery. Patients were divided into prompt and delayed groups based on time from admission to surgery of <48 hours or >48 hours. Baseline characteristics and 30-day outcomes were compared using univariate and multivariate analyses.

SETTING

The ACS NSQIP database from 2013 to 2016 was evaluated.

PATIENTS

Adult patients undergoing nonelective, nonemergency colectomy for UC.

MAIN OUTCOME MEASURES

30-day morbidity and mortality.

RESULTS

921 patients underwent urgent inpatient surgery for UC. In univariate analysis, there was no significant difference between prompt and delayed surgery for wound infection, sepsis, return to operating room, or readmission.

LIMITATIONS

Retrospective study of a quality improvement database. Patients who underwent successful MRT did not receive surgery, so are not included in the database.

CONCLUSIONS

Delaying surgery to further attempt MRT does not alter short-term outcomes and may allow conversion to elective future surgery. Contrarily, medical optimization does not improve short-term outcomes.

The Impact of a Colorectal Care Bundle for Surgical Site Infections at an Academic Disproportionate Share Hospital With a Level I Trauma Center

OBJECTIVES

Colorectal care bundles for surgical site infections (CRCB-SSIs) have been shown to reduce SSIs following elective colorectal surgery (CRS). There are limited data evaluating the effect of CRCB-SSI at Academic Disproportionate Share Hospitals (ADSH) with significant rates of urgent and emergent cases.

METHODS

A CRCB-SSI was implemented in April 2016. We reviewed medical records of all patients undergoing colon resections between August 2015 and December 2017. Patients were divided into preimplementation and postimplementation groups. The primary endpoint was the SSI rate, and the secondary endpoint included types of SSI (superficial, deep, organ space). Univariable and multivariable analyses were performed. A subset analysis was performed in elective cases.

RESULTS

We analyzed a total of 417 patients. Of these, 116 (28%) and 301 (72%) patients were in the preimplementation and postimplementation groups, respectively. The rate of SSI decreased from 30.1% to 15.9% in the postimplementation group (P = .0012); however, it was not statistically significant after adjusting for baseline differences (relative risk [RR] 0.65; 95% CI 0.41-1.02).The elective subset included 219 patients. The rate of SSI in this cohort decreased from 25% to 10.5% in the postimplementation group (P = .0012) and remained significant following multivariable analysis (RR 0.41, 95% CI 0.19- 0.88). There were no differences in the subtypes of SSI.

DISCUSSION

While the CRCB-SSI was effective in decreasing the postoperative SSI rate for elective cases, its effect on the overall patient population was limited. CRCB-SSIs are not enough to bring SSI rates to accepted rates in high-risk patients such as those seen at ADSH.

Basic Science, Epidemiology, and Screening for Anal Intraepithelial Neoplasia and Its Relationship to Anal Squamous Cell Cancer

Despite the progress made in the reduction of squamous cell carcinoma of the cervix, the incidence of anal squamous cell carcinoma (ASCC) has been increasing since 1992. While it remains an uncommon disease, the prevalence is climbing steadily. Among human immunodeficiency virus (HIV)-infected adults, especially men who have sex with men, ASCC is one of the more common non-AIDS-defining malignancies. The precursor lesion, anal intraepithelial neoplasia (AIN), is prevalent in the HIV-infected population. More than 90% of ASCCs are related to human papilloma virus (HPV), oncogenic types (HPV 16, 18). While the biology of HPV-related intraepithelial neoplasia is consistent in the anogenital area, the natural history of AIN is poorly understood and is not identical to cervical intraepithelial neoplasia (CIN). CIN is also considered an AIDS-defining malignancy, and the methods for screening and prevention of AIN are derived from the CIN literature. This article will discuss the epidemiology of ASCC and its association with HPV and the life cycle of the HPV, and the molecular changes that lead to clearance, productive infection, latency, and persistence. The immunology of HPV infection will discuss natural immunity, humoral and cellular immunity, and how the HPV virus evades and interferes with these mechanisms. We will also discuss high-risk factors for developing AIN in high-risk patient populations with relation to infections (HIV, HPV, and chlamydia infections), prolonged immunocompromised people, and sexual behavior and tobacco abuse. We will also discuss the pre- and post-HAART era and its effect on AINs and ASCC. Finally, we will discuss the importance of anal cytology and high-resolution anoscopy with and without biopsy in this high-risk population.

Professionalism: A Core Competency, but What Does it Mean? A Survey of Surgery Residents

OBJECTIVE

Professionalism is 1 of the 6 core competencies of the Accreditation Council of Graduate Medical Education. Despite its obvious importance, it is poorly defined in the literature and an understanding of its meaning has not been evaluated on surgical trainees. The American College of Surgeons (ACS) has previously published tenets of surgical professionalism. However, surgery residents may not share similar views on professionalism as those of the ACS.

DESIGN

Surgical residents of all levels at 2 surgery residencies located in the same city were interviewed regarding their personal definitions, thoughts, and experiences regarding professionalism during their training. They were then queried regarding 20 points of professionalism as outlined by the ACS tenets of professionalism.

SETTING

The study utilized the surgery residencies at William Beaumont Army Medical Center and Texas Tech University Health Science Center in El Paso, Texas.

PARTICIPANTS

All general surgery residents at each program were invited to participate in the study. Eighteen residents volunteered to take the survey and be interviewed.

RESULTS

The definitions of professionalism centered on clinical competence. Surgery residents conveyed experiences with both professional and unprofessional behavior. Seven of the 20 ACS tenets of professionalism were unanimously agreed upon. There were key differences between resident definitions and those as outlined by the ACS. The least agreed upon ACS tenets of professionalism include professionalism education, public education, and public health.

CONCLUSIONS

Surgical trainees express personal experiences in both professional and unprofessional behavior. Their definitions of professionalism are not as expansive as those of the ACS and seem to focus on patient and colleague interaction. Due to the lack of congruency, a tailored curriculum for professionalism based upon ACS tenets appears warranted.

A short-duration restrictive diet reduces visceral adiposity in the morbidly obese surgical patient

BACKGROUND

This study aims to determine if visceral obesity can be reduced after a brief preoperative diet in obese patients.

METHODS

Forty morbidly obese patients were placed on a 1,000 kCal per day diet for 14 days before bariatric surgery. Patients had weight measurements and an abdominal ultrasound performed on days 1 and 14. The ultrasound measured visceral obesity using the distance between the abdominal muscle and the aorta, the fat thickness of the perinephric space, and the distance between the abdominal muscle and splenic vein. Mesenteric fat burden was calculated and compared.

RESULTS

Thirty-eight patients (95%) lost weight on the diet, with a mean loss of 5.2 lbs. Twenty-five patients (63%) had a reduction in mesenteric fat. The average visceral obesity lost was 7.76 cm³ or 3% of the visceral adiposity of the average obese patient (250 cm³).

CONCLUSIONS

A short preoperative calorie restricting diet is well tolerated and results in a reduction in visceral obesity.

Crohn's Disease of the Foregut

Crohn's disease of the foregut is more common than previously recognized, with up to 40% of patients with Crohn's disease in the distal intestine also having evidence of foregut disease. Esophageal disease is best managed medically with proton pump inhibition, steroids, thiopurines, methotrexate, and anti-tumor necrosis factor-α biologic medications. Esophageal strictures are dealt with using endoscopic dilation. Surgery is generally reserved of resistant strictures or esophageal fistulas. Patients with gastroduodenal disease more commonly come to surgery. The most commonly performed operations for gastroduodenal Crohn's disease are intestinal bypass or strictureplasty. The concomitant use of vagotomy remains controversial.

Equivalence in colonoscopy results between gastroenterologists and general surgery residents following an endoscopy simulation curriculum

BACKGROUND

In 2011, multiple gastroenterology societies published a position statement expressing concern over the American Board of Surgery guidelines regarding endoscopy education. Their position asserted that the American Board of Surgery's guidelines were inadequate to produce competency and the requirements should be similar to those adopted by the American Society for Gastrointestinal Endoscopy. This assertion failed to take into account the increasing use of simulation in surgical and endoscopic education.

METHODS

Surgery residents were required to complete a self-paced endoscopy simulation curriculum. A retrospective review of all patients undergoing colonoscopy at a single institution over a 6-month period was then undertaken. Specifically, the quality measures associated with colonoscopy including the cecal intubation rate and the adenoma detection rate (ADR) were compared between those colonoscopies that were performed by faculty gastroenterologists and general surgery residents.

RESULTS

In total, 818 colonoscopies were performed during the study period-598 were performed by the gastroenterology service (GI) and 220 were performed by general surgery residents on the surgery service (GS). Baseline characteristics of the groups were similar. Cecal intubation rates for GI and GS were 98.4% and 93.5% respectively. ADRs were similar between the groups (GI-29.8% in men and 15.3% in women; GS-26.8% in men and 18.7% in women). GI was found to perform biopsies at a higher rate than GS: 0.92 vs 0.62 (not significant, NS). GS had a higher rate of adenomas biopsied: 0.42 vs 0.32 (NS).

CONCLUSIONS

Following endoscopy simulation training, general surgery residents, under the supervision of surgical staff, are capable of achieving quality measures equivalent to those of staff gastroenterologists at a single institution. The ADRs and cecal intubation rates seen in this study are consistent with those previously identified in the literature.

Evaluating Alternatives to Traditional Cotton Laparotomy Sponges for Blood Absorption in the Austere and Mobile Surgical Environment

BACKGROUND

The operative control of noncompressible hemorrhage is the single largest impact that could be addressed in reducing the mortality on the battlefield. Laprotomy pads, traditionally used for hemorrhage evacuation, are made of woven cotton, and, while effective, their use requires a substantial amount of space and adds weight. This poses no concern in traditional operating rooms but is a hindrance for mobile providers and providers in austere environments. We sought to compare different absorptive compunds to ascertain their utility as alternatives for traditional laparotomy pads.

METHODS

Samples of cotton laparotomy pads, pure rayon sheets, rayon-polypropylene composite sheets, and non-polyester composite "microfiber" sheets were weighed and submerged in heparinized whole bovine blood. After saturation, the favrics were weighed, wrung dry, reweighed, and resubmerged. This process was performed for a total of three sequential submersions. The saturated weights and dry weights of each fabric were used to calculate how much blood each fabric could absorb initially and after multiple repeated uses. The initial densities of the four fabrics was calculated and compared.

RESULTS

The initial submersions demonstrated that 1g each of cotton, rayon, rayon-polypropylene, and nylon-polyester were able to absorb 7.58 g, 12.98 g, 10.16 g, and 9.73 g of blood respectively. The second and third sequential trials, which were statistically similar, demonstrated that 1g of cotton, rayon, rayon-polypropolyene, and nylon-polyester were able to absorb 1.73 g, 2.83 g, 2.3g, and 2.3g of blood, respectively. The calculated densities of cotton, rayon, rayon-polypropylene, and nylon-polyester were 0.087 g/cm³, .012 g/cm³, 0.098 g/cm³, and 0.093 g/cm³, respectively.

CONCLUSION

Per gram, rayon absorbed approximately 1.7 times more blood thancotton and three-quarters the amount of the storage space. Rayon also retained its superior absorption abilites on repeated uses, demonstrating the potential for re-use in remote and austere environments. Thus, rayon could serve as a viable alternative to traditional cotton laparotomy pads in the austere environments.

Cellular changes of the colon after mechanical bowel preparation

BACKGROUND

The purpose of this study was to evaluate the effect of mechanical bowel preparation (MBP) on the intracellular environment, specifically evaluating butyrate transport, within the colon of the Sprague-Dawley rat.

METHODS

Sixty-eight Sprague-Dawley rats were randomized to either an MBP group (n = 34) or a control group (n = 34). Twenty-four hours after the completion of the MBP, both groups were euthanized, and the colons were harvested. The level of cellular apoptosis was investigated after DNA fragmentation, poly(ADP-ribose) polymerase cleavage, and caspase assays. Western blot analysis was performed to measure the expression of the butyrate transporter protein, monocarboxylate transporters 1, and proliferating cell nuclear antigen (a marker for tissue proliferation). Immunohistochemical staining was performed to further investigate cellular proliferation. Statistical significance (P < 0.05) was determined using two-tailed t-test.

RESULTS

Apoptosis was detected without significant differences in both groups. Western Blot analysis demonstrated that the expression of the monocarboxylate transporters 1 protein is downregulated in the MBP group (10.18 ± 3.09) compared with the control group (16.73 ± 7.39, P = 0.001), and proliferating cell nuclear antigen levels showed a decrease in cellular proliferation in the MBP group (13.35 ± 5.88) compared with the control (20.07 ± 7.55, P = 0.018). Immunohistochemistry confirmed a decrease in cellular proliferation after MBP with 23.4 ± 7.8% of the cells staining positive for Ki-67 in the MBP group versus 28.6 ± 7.9% in the control group (P = 0.006).

CONCLUSIONS

MBP has a negative impact on cellular proliferation and intracellular transport of butyrate within the rat colon, not related to apoptosis. This is the first study to demonstrate the intracellular effects that MBP has on the rat colon.

Surgical management and associated complications of penetrating rectal injuries sustained in Iraq and Afghanistan

PURPOSE

The aim of this study was to analyze the surgical management and associated complications of penetrating rectal injuries sustained in Operation Iraqi Freedom and Operation Enduring Freedom.

METHODS

A retrospective review was performed using the Joint Theater Trauma Registry. U.S. military personnel injured in Iraq and Afghanistan from October 2003 to November 2008 were included. The surgical management of rectal injuries was evaluated, specifically looking at the utilization of diversion with ostomy, distal washout, and presacral drainage. Complications were compared between the treatment groups.

RESULTS

57 patients who sustained a penetrating rectal injury were included in this study. Surgical management included diversion and ostomy alone in 34 patients (60%), diversion and distal washout in 11 patients (19%), diversion and drainage in 8 patients (14%), and diversion, distal washout, and drainage in 4 patients (7%). Complications were identified in 21% of patients. There were no deaths in the study group. Logistical regression failed to show a correlation between postoperative complications with either distal washout (p = 0.33) or presacral drainage (p = 0.9).

CONCLUSIONS

The majority of patients were successfully managed with fecal diversion alone, suggesting that drainage and distal washout may be unnecessary steps in the management of high-velocity, penetrating rectal injuries.

Controversies in the care of the enterocutaneous fistula

Enterocutaneous fistula and its variations are some of the most difficult problems encountered in the practice of general surgery. Reliable evidence that can be used to direct the care of patients afflicted with this malady is limited. There are controversies in several areas of care. This article addresses some of the gray areas of care for the patient with enterocutaneous fistula. There is particular attention directed toward the phenomenon of enteroatmospheric fistula, as well as prevention and abdominal wall reconstruction, which is often required in these individuals.

Perirectal abscess infections related to MRSA: a prevalent and underrecognized pathogen

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is not a commonly recognized pathogen isolated from perirectal abscesses. Complex perirectal abscesses of MRSA origin may present a significant challenge to the physician and result in treatment failure. The aim of our study was to determine the prevalence of MRSA in our patient population with perirectal abscesses and whether antibiotics coverage, if given, was adequate.

METHODS

We conducted a retrospective study of all adult patients who presented with a perirectal abscess. The bacteriology of the cultures taken from more than 100 patients during an 8-year period was examined. The prevalence of MRSA was specifically analyzed, and the sensitivities of the organisms isolated were then compared with any antibiotics prescribed to determine the adequacy of coverage.

RESULTS

In all, 124 patients were treated for perirectal abscess during the 8-year period. Fifty-nine percent of patients were taken to the operating room for incision and drainage, 52% of the patients had cultures taken of the abscess, and 35% of patients were given antibiotics coupled with incision and drainage. The antibiotics offered adequate coverage when compared with the sensitivities of the organisms 73% of the time. The prevalence of MRSA in our patient population was 19%, and when this organism was cultured, the patient only received adequate coverage 33% of the time.

CONCLUSION

The presence of MRSA in perirectal abscesses is underrecognized. Recent data has shown that incision and drainage combined with antibiotics offers a superior outcome in soft tissue abscesses caused by this organism. If cultures are not routinely taken at the time of incision and drainage, the institutional incidents of MRSA will remain unknown. Physicians must recognize that MRSA is a potential organism present in perirectal abscesses when considering antimicrobial therapy for complex abscesses.

Lymph node evaluation of colon cancer and its association with improved staging and survival in the Department of Defense Health Care System

BACKGROUND

Improved survival is associated with an increased number of lymph nodes (LNs) examined. The aim of this study was to assess whether the examination of >or=12 LNs is associated with more accurate colon cancer staging.

METHODS

We queried the Department of Defense Automated Central Tumor Registry database for stage I-III colon cancer patients. Logistic regression analysis was performed to determine whether the examination of >or=12 LNs is associated with increased rates of LN-positive colon cancer. Kaplan-Meier and Cox proportional hazard analysis was performed to evaluate the effect of number of LNs examined on survival.

RESULTS

The rate of LN-positive colon cancer is significantly higher with increasing number of LNs examined (1-3 LNs examined: 31% vs. >12 LNs examined: 41%, P<.001). Logistic regression analysis adjusting for patients, tumor, and hospital characteristics showed that examination of >or=12 LNs is associated with a >30% increase in detecting a LN-positive colon cancer (odds ratio, 1.350; 95% confidence interval, 1.175-1.511). The evaluation of >or=12 LNs is associated with improved survival in LN-negative colon cancer patients (P<.001).

CONCLUSIONS

Our study demonstrates that the proportion of LN-positive colon cancer is far higher when >or=12 LNs are examined. Examination of >or=12 LNs may improve staging accuracy and outcome with optimal use of systemic chemotherapy.

Can a transitional work grant program in a workers' compensation system reduce cost and facilitate return to work?

Although previous research has shown returning the injured worker to work as soon as possible is important to the long-term prospects of the worker remaining in the work force, there is limited economic support for implementing such programs. Thus, the purpose of this case control study was to determine the cost savings of the implementation of a Transitional Work Grant (TWG) program, which consisted of several components including job analyses, education, communication and transitional work (TW). Companies that enrolled in the TWG program were matched to nonparticipating companies (NTW) based on employer size, type of industry, number of overall claims, and number of claims with > 7 days lost time (LT claims) submitted the year prior to enrollment. The study analyzed economic data: number of claims, number of LT claims, indemnity costs, medical costs, and days lost (days away from the workplace). An additional outcome was the ratio of LT claims (> 7 days lost work) to medical only (MO) claims (LT/MO ratio). Overall, participation in the TWG program was associated with decreased indemnity cost and decreased LT/MO ratio. However, effectiveness of the program varied by employer size and industry. In terms of the state of Ohio, these costs translate into substantial savings: more than $2.3 million per year. Although the cost savings and reduction in lost time claims is encouraging, the true benefit of TW has yet to be completely quantified. Future work must account for other potential co-factors and programs that could also contribute to the savings as well as document further the indirect benefits associated with a TWG program, such as improved employee morale and increased productivity and product quality that could be four times greater than the direct savings. In summary, programs such as this one adopted by several companies in Ohio can reduce the cost burden of injuries.

Prevalence of teaching sentinel lymph node biopsy for breast cancer in general surgery residency programs

PURPOSE

Sentinel lymphadenectomy (SLNB) for the evaluation of clinically negative lymph nodes in women with invasive breast cancer is rapidly gaining acceptance within the surgical community. The purpose of this study was to document the prevalence of teaching SLNB to residents in general surgery training programs in the United States.

METHODS

The Fellowship and Residency Electronic Interactive Database (FREIDA) was searched for a listing of all general surgery residency programs. A short questionnaire was mailed to the program director of each residency program listed. The program directors were asked whether general surgery residents are taught the technique of performing SLNB for breast cancer, and how the procedure is performed at their institutions.

RESULTS

Of the 255 surgical programs listed in FREIDA, 191 or 75% responded to the survey. Of responding programs, 92% are currently teaching surgical residents SLNB, whereas 4% plan on adding SLNB to the curriculum within the next academic year. A total of 74% of programs are performing SLNB as part of an organized hospital protocol, whereas 40% routinely follow SLNB with an axillary node dissection. A total of 89% of the programs use both sulfur colloid radioisotope and isosulfan blue dye, whereas 7% use dye alone, and 4% use only radioisotope.

CONCLUSIONS

The practice of performing SLNB for the purpose of detecting occult nodal metastases in breast cancer is being taught at most surgery training programs in this country. In the less than 6 years since the modification of this technique for the treatment of breast disease, it has become the standard of care for treating women with invasive breast cancer with clinically negative axillary lymph nodes at training hospitals in the United States.

Subcutaneous fissurotomy: a novel procedure for chronic fissure-in-ano. a review of 109 cases

PURPOSE

The constant presence of a narrow subcutaneous tract extending caudad to chronic fissures-in-ano is reported. The efficacy of surgically unroofing this tract (subcutaneous fissurotomy) without sphincterotomy was evaluated.

METHODS

By using a narrow-gauge, hooked probe, a constant, midline subcutaneous tract was identified extending from the caudad aspect of chronic anal fissures. These tracts are present within the sentinel tag, when present, and extend up to 1 cm caudad to the fissure in the subcutaneous plane. A proximal connection with the dentate line in the submucous plane also was identified. Surgically unroofing the tract (subcutaneous fissurotomy) resulted in significant widening of the distal anal canal, rendering internal sphincterotomy unnecessary. A 32-month prospective evaluation of this new technique was performed. Inclusion criteria included patients with chronic anal fissures that had failed conservative therapy, including topical agents. In each case, the tract was identified and surgically laid open along its entire length. No internal sphincterotomy was performed in any patient. Postoperatively, patients were instructed to apply topical 10 percent metronidazole t.i.d. The need for repeat surgery and/or subsequent internal sphincterotomy was recorded.

RESULTS

A total of 109 patients were enrolled during the study period. Median follow-up was 12 months. During the study period, two patients (1.8 percent) required repeat surgery for persistent symptoms at 3 and 12 months postoperatively. No change in continence was reported in any patient.

CONCLUSIONS

Laying open the subcutaneous tract has a very high success rate and a low incidence of repeat surgery. This finding introduces a new debate relating to the etiology of fissure-in-ano and makes routine internal sphincterotomy unnecessary.

Combined colonoscopy and three-quadrant hemorrhoidal ligation: 500 consecutive cases

PURPOSE

This study was designed to evaluate the safety and efficacy of combining outpatient colonoscopy with simultaneous three-quadrant hemorrhoidal ligation in patients with symptomatic internal hemorrhoidal disease.

METHODS

A four-year analysis of patients undergoing combined colonoscopy and synchronous three-quadrant hemorrhoidal ligation was performed. Indications for the procedure were patients with symptomatic internal hemorrhoids who had failed conservative management and who also required colonoscopy. Conventional colonoscopy was performed under moderate sedation, immediately followed by synchronous three-quadrant hemorrhoidal ligation, using a TriView anoscope and Short-Shot hemorrhoidal ligator. Patients undergoing this procedure were entered in a computer database, and outcomes were tracked. Patients requiring repeat ligation, surgical intervention, or readmission within 30 days were identified and further analyzed.

RESULTS

Five hundred patients underwent colonoscopy with simultaneous three-quadrant internal hemorrhoid ligation during the study period. Four hundred sixty-seven patients (93.4 percent) had complete resolution of their symptoms and required no further treatment. Thirty-three patients (6.6 percent) required repeat ligation, and 11 (2.2 percent) required completion surgical hemorrhoidectomy for persistent symptoms. Fifty-two patients (10.4 percent) required incidental biopsy/polypectomy during the colonoscopy. Two incidental colon carcinomas were identified, and ligation was deferred. No patients required admission for bleeding after the procedure. There were no cases of pelvic sepsis, and no patients required emergent surgical intervention.

CONCLUSIONS

Combining colonoscopy with three-quadrant hemorrhoidal ligation is a safe and effective method of treating symptomatic internal hemorrhoids. The procedure is convenient for both physician and patient and makes more efficient use of time and resources.

The use of simvastatin for the prevention of gallstones in the lithogenic prairie dog model

BACKGROUND

Surgery for morbid obesity is rapidly increasing. Patients undergoing bariatric surgery are prone to gallstone development during the rapid weight loss. These patients are often given medications such as ursodeoxycholic acid to prevent gallstone formation; however, these medications are often poorly tolerated by patients, who subsequently discontinue them. We performed a study in a lithogenic animal model to assess the effectiveness of a potential alternate medication for gallstone prevention.

METHODS

20 male prairie dogs were randomly separated into 2 groups and fed a lithogenic diet for 28 days. The study group animals were given 2.5 mg of the HMG-CoA reductase inhibitor simvastatin. Total cholesterol and triglycerides were measured and an open cholecystectomy was performed on each animal at the conclusion of the study period. The gallbladder was visually inspected for gallstones and microscopic biliary cholesterol crystal formation.

RESULTS

There was a decrease of 36% in the total cholesterol of the study animals compared to controls. The animals treated with simvastatin showed gallstone formation in 5/10 (50%) of animals, compared with 6/10 (60%) of control animals. The study animals demonstrated microscopic cholesterol crystal formation in 80%, identical to the number found in the control animals.

CONCLUSION

Despite a reduction in cholesterol, simvastatin prevented neither gallstone formation nor biliary cholesterol crystals in this animal model. Given the rapid increase in the number of bariatric surgical procedures coupled with the poor tolerance of ursodeoxycholic acid, viable alternatives should continue to be sought for these patients.

Subject-specific compressive tolerance estimates

Spinal load models have become an increasingly valuable tool for the evaluation of the stress placed on the spine. In order to get an accurate representation of these spinal loads, they must be compared to known tolerance values. Bone mineral content and density of the lumbar spine of 23 males and 21 females was measured using a dual energy x-ray absorptiometry. Compression tolerance values were predicted by previously published studies based upon bone mineral levels. Anthropometric measurements were recorded and related to the compression tolerance values through the use of multivariate linear regression techniques. Compression tolerance values based on the bone mineral content or density explains more of the individual variability than solely age-based estimates. Several anthropometric variable regression models were developed that resulted in moderate to good predictive power (R(2) = 0.62 to 0.81). The current study describes a useful alternative to traditional tolerance estimates that accounts for individual differences requiring non-invasive and time-efficient procedures.

Implementation of sentinel lymph node biopsy for breast cancer by surgeons in the Department of Defense

BACKGROUND

Sentinel lymph node biopsy (SLNB) for the evaluation of women with invasive breast cancer is rapidly gaining acceptance. The purpose of this study was to assess how surgeons in the Department of Defense (DOD) are incorporating SLNB into practice.

METHODS

Surgeons at all DOD hospitals were telephonically surveyed regarding their current practices with SLNB.

RESULTS

Of 66 DOD hospitals 23 (35%) are currently performing SLNB. Eleven hospitals (11 of 23, 48%) are academic centers, while 12 (12 of 23, 52%) are not teaching facilities. Seventeen (17 of 23, 77%) are in the learning phase of SLNB and follow SLNB with an axillary dissection. Eighteen (18 of 23, 78%) of facilities have surgeons who learned the procedure in residency/fellowship training. Sixteen (16 of 23, 70%) use a combination of isosulfan blue dye and sulfur colloid radioisotope. Surgeons performing SLNB are not aware of the method of examination of the sentinel node at their institution at 6 of 23 (26%) of hospitals.

CONCLUSIONS

Increasing numbers of surgeons in the DOD Healthcare System are performing SLNB. The majority learned the procedure in residency or fellowship and are using a combination of blue dye and radioisotope for the performance of SLNB.

Spinal loading when lifting from industrial storage bins

The study documented three-dimensional spinal loading during lifting from an industrial bin. Two lifting styles and two bin design factors were examined in Phase I. The lifting style measures in Phase I were one hand versus two hand and standing on one foot versus two feet. The bin design variables were region of load in the bin and bin height. The Phase II study examined one-handed lifting styles with and without supporting body weight with the free hand on the bin as well as region and the number of feet. Twelve male and 12 female subjects lifted an 11.3 kg box from the bin. Spinal compression, lateral shear and anterior - posterior shear forces were estimated using a validated EMG-assisted biomechanical model. Phase I results indicated that the bin design factor of region had the greatest impact on spinal loading. The upper front region minimized spinal loading for all lifting styles. Furthermore, the lifting style of two hands and two feet minimized spinal loading. However, comparing Phase I two-handed lifting with Phase II one-handed supported lifting, the one-handed supported lifting techniques had lower compressive and anterior - posterior shear loads in the lower regions as well as the upper back region of the bin. A bin design that facilitates lifting from the upper front region of the bin reduces spinal loading more effectively than specific lifting styles. Furthermore, a bin design with a hand hold may facilitate workers using a supported lifting style that reduces spinal loading.

Acute management of white phosphorus burn

White phosphorus is a combustible solid that is used in many of the smoke devices that are prevalent throughout the military arsenal. Exposure to phosphorus-containing compounds causes serious, often fatal, burns and can be the source of significant morbidity and lengthy hospital stays. I present the case of an individual with serious cutaneous phosphorus burns suffered at a munitions manufacturing plant. The purpose of this paper is to discuss the emergent treatments necessary in such patients and to discuss decontamination in the phosphorus-burned patient. Phosphorus-containing munitions are prevalent throughout the military arsenal, and all military physicians should be aware of these treatments.

Spine loading characteristics of patients with low back pain compared with asymptomatic individuals

STUDY DESIGN

Patients with low back pain and asymptomatic individuals were evaluated while performing controlled and free-dynamic lifting tasks in a laboratory setting.

OBJECTIVE

To evaluate how low back pain influences spine loading during lifting tasks.

SUMMARY OF BACKGROUND DATA

An important, yet unresolved, issue associated with low back pain is whether patients with low back pain experience spine loading that differs from that of individuals who are asymptomatic for low back pain. This is important to understand because excessive spine loading is suspected of accelerating disc degeneration in those whose spines are damaged already.

METHODS

In this study, 22 patients with low back pain and 22 asymptomatic individuals performed controlled and free-dynamic exertions. Trunk muscle activity, trunk kinematics, and trunk kinetics were used to evaluate three- dimensional spine loading using an electromyography- assisted model in conjunction with a new electromyographic calibration procedure.

RESULTS

Patients with low back pain experienced 26% greater spine compression and 75% greater lateral shear (normalized to moment) than the asymptomatic group during the controlled exertions. The increased spine loading resulted from muscle coactivation. When permitted to move freely, the patients with low back pain compensated kinematically in an attempt to minimize external moment exposure. Increased muscle coactivation and greater body mass resulted in significantly increased absolute spine loading for the patients with low back pain, especially when lifting from low vertical heights.

CONCLUSIONS

The findings suggest a significant mechanical spine loading cost is associated with low back pain resulting from trunk muscle coactivation. This loading is further exacerbated by the increases in body weight that often accompany low back pain. Patient weight control and proper workplace design can minimize the additional spine loading associated with low back pain.

Crystallohydrodynamics for solving the hydration problem for multi-domain proteins: open physiological conformations for human IgG

Hydrodynamic methods provide a route for studying the low-resolution conformation--in terms of time-averaged spatial orientation of the Fab' and Fc domains relative to each other--of the human IgG subclasses, IgG1, IgG2, IgG3 and IgG4 in the environment in which many exist naturally---a solution. Representative modelling strategies are now available using 'shell-bead' or 'shell' modelling of the surface of the molecules with the size-independent programme SOLPRO [J. Garcia de la Torre, S.E. Harding, B. Carrasco, Eur. Biophys. J. 28 (1999) 119-132]. The shell model fits to the equivalent inertial surface ellipsoids of the published crystal structures for the Fab' and Fc domains of IgG are made and an apparent hydration delta(app) of 0.51g/g for Fab' and 0.70 g/g for the glycoprotein Fc are obtained, which yield an average value of (0.59+/-0.07) g/g for the intact antibody (2 Fab'+1 Fc). The relative orientations of these domains for each of the IgG subclasses is then found (using where appropriate a cylindrical hinge) from SOLPRO by modelling the Perrin function, P (i.e. 'frictional ratio due to shape') using this delta(app) and experimentally measured sedimentation coefficients. All the IgG subclasses appear as open, rather than compact structures with the degree of openness IgG3>IgG1>(IgG2, IgG4), with IgG3 and IgG1 non-coplanar. The hingeless mutant IgGMcg, with s degrees (20,w) approximately 6.8 S yields a coplanar structure rather similar to IgG2 and IgG4 and consistent with its crystallographic structure. The extension of this procedure for representing solution conformations of other antibody classes and other multi-domain proteins is indicated.

Exposure to liquid sulfur mustard

Chemical weapons continue to pose a serious threat to humanity. With the use of chemical weapons by terrorists in Tokyo, and the projected disarming of the chemical weapon stockpile in this country, the possibility that emergency physicians will encounter patients contaminated by chemical munitions, such as sulfur mustard, exists. Mustard is a vesicating agent with a long latency between exposure and symptoms. Exposure can cause burns, conjunctivitis, pneumonia, and death. We describe 3 workers exposed to mustard at a chemical weapon storage facility. This article reports the first case of an exposure to mustard at a storage facility, as well as the first documented incident occurring in the United States. All physicians who manage patients in an acute care setting should be aware of the presentation and emergency treatments involving patients contaminated with mustard.

A non-MVC EMG normalization technique for the trunk musculature: Part 1. Method development

Normalization of muscle activity has been commonly used to determine the amount of force exerted by a muscle. The most widely used reference point for normalization is the maximum voluntary contraction (MVC). However, MVCs are often subjective, and potentially limited by sensation of pain in injured individuals. The objective of the current study was to develop a normalization technique that predicts an electromyographic (EMG) reference point from sub-maximal exertions. Regression equations predicting maximum exerted trunk moments were developed from anthropometric measurements of 120 subjects. In addition, 20 subjects performed sub-maximal and maximal exertions to determine the necessary characteristic exertions needed for normalization purposes. For most of the trunk muscles, a highly linear relationship was found between EMG muscle activity and trunk moment exerted. This analysis determined that an EMG-moment reference point can be obtained via a set of sub-maximal exertions in combination with a predicted maximal exertion (expected maximum contraction or EMC) based upon anthropometric measurements. This normalization technique overcomes the limitations of the subjective nature for the MVC method providing a viable assessment method of individuals with a low back injury or those unwilling to exert an MVC as well as could be extended to other joints/muscles.

A non-MVC EMG normalization technique for the trunk musculature: Part 2. Validation and use to predict spinal loads

Estimates of the amount of force exerted by a muscle using electromyography (EMG) rely partially upon the accuracy of the reference point used in the normalization technique. Accurate representations of muscle activities are essential for use in EMG-driven spinal loading models. The expected maximum contraction (EMC) normalization method was evaluated to explore whether it could be used to assess individuals who are not capable of performing a maximum exertion such as a person with a low back injury. Hence, this study evaluated the utility of an EMG normalization method (Marras and Davis, A non-MVC EMG normalization technique, Part 1, method development. Journal of Electromyography and Kinesiology 2000) that draws upon sub-maximal exertions to determine the reference points needed for normalization of the muscle activities. The EMC normalization technique was compared to traditional MVC-based EMG normalization by evaluating the spinal loads for 20 subjects (10 males and 10 females) performing dynamic lifts. The spinal loads (estimated via an EMG-assisted model) for the two normalization techniques were very similar with differences being <8%. The model performance variables indicated that both normalization techniques performed well (r(2)>0.9 and average error below 6%) with only the muscle gain being affected by normalization method as a result in different reference points. Based on these results, the proposed normalization technique was considered to be a viable method for EMG normalization and for use in EMG-assisted models. This technique should permit the quantitative evaluation of muscle activity for subjects unable to produce maximum exertions.

The effects of motion on trunk biomechanics

OBJECTIVE

To review the literature that evaluates the influence of trunk motion on trunk strength and structural loading.

BACKGROUND

In recent years, trunk dynamics have been identified as potential risk factors for developing low-back disorders. Consequently, a better understanding of the underlying mechanisms involved in trunk motion is needed.

METHODS

This review summarizes the results of 53 studies that have evaluated trunk motion and its impact on several biomechanical outcome measures. The biomechanical measures consisted of trunk strength, intra-abdominal pressure, muscle activity, imposed trunk moments, and spinal loads. Each of these biomechanical measures was discussed in relation to the existing knowledge within each plane of motion (extension, flexion, lateral flexion, twisting, and asymmetric extension).

RESULTS

Trunk strength was drastically reduced as dynamic motion increased, and males were impacted more than females. Intra-abdominal pressure seemed to only be affected by trunk dynamics at high levels of force. Trunk moments were found to increase monotonically with increased trunk motion. Both agonistic and antagonistic muscle activities were greater as dynamic characteristics increased. As a result, the three-dimensional spinal loads increase significantly for dynamic exertions as compared to isometric conditions.

CONCLUSIONS

Trunk motion has a dramatic affect on the muscle coactivity, which seems to be the underlying source for the decrease strength capability as well as the increased muscle force, IAP, and spinal loads. This review suggests that the ability of the individual to perform a task "safely" might be significantly compromised by the muscle coactivity that accompanies dynamic exertions. It is also important to consider various workplace and individual factors when attempting to reduce the impact of trunk motions during dynamic exertions. Relevance This review provides insight as to why trunk motions are important risk factors to consider when attempting to control low-back disorders in the workplace. It is apparent that trunk motion increases the risk of low-back disorders. To better control low-back disorders in industry, more comprehensive knowledge about the impact of trunk motion is needed. A better understanding of muscle coactivity may ultimately lead to reducing the risk associated with dynamic exertions.

The influence of psychosocial stress, gender, and personality on mechanical loading of the lumbar spine

STUDY DESIGN

The effects of psychosocial stress on muscle activity and spinal loading were evaluated in a laboratory setting.

OBJECTIVE

To evaluate the influence of psychosocial stress, gender, and personality traits on the functioning of the biomechanical system and subsequent spine loading.

SUMMARY OF BACKGROUND DATA

Physical, psychosocial, and individual factors all have been identified as potential causal factors of low back disorders. How these factors interact to alter the loading of the spine has not been investigated.

METHODS

Twenty-five subjects performed sagittally symmetric lifts under stressful and nonstressful conditions. Trunk muscle activity, kinematics, and kinetics were used to evaluate three-dimensional spine loading using an electromyographic-assisted biomechanical model. A personality inventory characterized the subject's personality traits. Anxiety inventories and blood pressure confirmed reactions to stress.

RESULTS

Psychosocial stress increased spine compression and lateral shear, but not in all subjects. Differences in muscle coactivation accounted for these stress reactions. Gender also influenced spine loading; Women's anterior-posterior shear forces increased in response to stress, whereas men's decreased. Certain personality traits were associated with increased spine loading compared with those with an opposing personality trait and explained loading differences between subjects.

CONCLUSIONS

A potential pathway between psychosocial stress and spine loading has been identified that may explain how psychosocial stress increases risk of low back disorders. Psychosocially stressful environments solicited more of a coactivity response in people with certain personality traits, making them more susceptible to spine loading increases and suspected low back disorder risk.

The relationship between psychosocial work characteristics and low back pain: underlying methodological issues

OBJECTIVE

To evaluate the current epidemiological evidence linking psychosocial work characteristics with low back pain.

BACKGROUND

Psychosocial work characteristics have been widely evaluated as potential risk factors for low back injury. However, studies with different study populations and using various types of measures have had conflicting results.

METHODS

This review is the most extensive to date, reviewing 66 articles that have provided empirical evidence about the relationship between psychosocial work characteristics and initial reporting of lower back pain. The studies are reviewed with an emphasis on certain methodological issues: controlling for potential confounding; timing of the data collection; and measurement of the exposures and outcomes.

RESULTS

The results of this review suggest that controlling for potential confounding from occupational biomechanical demands had a large influence on the associations found between psychosocial work characteristics and lower back pain. In addition, the use of accurate and reliable measures for the occupational exposures (biomechanical and psychosocial) and the lower back pain outcomes appears to influence the strength of the associations found between psychosocial work characteristics and lower back pain.

CONCLUSION

Given the methodological concerns discussed in this review, it is difficult to draw strong causal inferences from this literature. However, it does appear that psychosocial characteristics are related to some lower back pain outcomes, and that employees' reactions to psychosocial work characteristics (e.g., job dissatisfaction and job stress) are more consistently related to lower back pain than are the psychosocial work characteristics themselves (e.g., work overload, lack of influence over work, quality of relationships with coworkers).

RELEVANCE

This review attempts to identify and address methodological issues in the literature evaluating the relationship between psychosocial work characteristics and lower back pain. Implications for future research are presented.

Effect of foot movement and an elastic lumbar back support on spinal loading during free-dynamic symmetric and asymmetric lifting exertions

The aim of this study was to assess the effect of an elastic lumbar back support on spinal loading and trunk, hip and knee kinematics while allowing subjects to move their feet during lifting exertions. Predicted spinal forces and moments about the L5/S1 intervertebral disc from a three-dimensional EMG-assisted biomechanical model, trunk position, velocities and accelerations, and hip and knee angles were evaluated as a function of wearing an elastic lumbar back support, while lifting two different box weights (13.6 and 22.7 kg) from two different heights (knee and 10 cm above knee height), and from two different asymmetries at the start of the lift (sagittally symmetric and 60 degrees asymmetry). Subjects were allowed to lift using any lifting style they preferred, and were allowed to move their feet during the lifting exertion. Wearing a lumbar back support resulted in no significant differences for any measure of spinal loading as compared with the no-back support condition. However, wearing a lumbar back support resulted in a modest but significant decrease in the maximum sagittal flexion angle (36.5 to 32.7 degrees), as well as reduction in the sagittal trunk extension velocity (47.2 to 40.2 degrees s(-1)). Thus, the use of the elastic lumbar back support provided no protective effect regarding spinal loading when individuals were allowed to move their feet during a lifting exertion.

An investigation of perceived exertion via whole body exertion and direct muscle force indicators during the determination of the maximum acceptable weight of lift

The objective of this study was to identify the perceived exertion mechanisms (direct muscle force and whole body exertion) associated with the decision to change the weight of lift during the determination of the maximum acceptable weight of lift (MAWL). Fifteen males lifted a box of unknown weight at a rate of 4.3 lifts/min, and adjusted the weight until their MAWL was reached. Variables such as the predicted muscle forces and heart rate were measured during the lifting exertion, as well as the predicted spinal loading in three dimensions using an EMG-assisted biomechanical model. Multiple logistic regression techniques were used to identify variables that were associated with the decision to change the weights up and down prior to a subsequent lift. Results indicated that the force in the left erector spinae, right internal oblique, and left latissimus dorsi muscles as well as heart rate were associated with decreases in the weight prior to the next lift. It appears that a combination of local factors (muscle force) and whole body exertion factors (heart rate) provide the feedback for the perceived exertion when decreasing the weight. The up-change model indicated that the forces of the right erector spinae, left internal oblique, and the right latissimus dorsi muscles were associated with the decision to increase the weight prior to the next lift. Thus, local factors provide feedback during the decision to increase the weight when starting from light weights. Collectively, these findings indicate that psychophysically determined weight limits may be more sensitive to muscular strain rather than spinal loading.