Mark S. Hsiao

Incidence of Acute Traumatic Patellar Dislocation among Active-Duty United States Military Service Members

Background Although some studies have reported an increased incidence of patellar dislocations within active populations, few studies have reported incidence rates and examined risk factors for this injury. Purpose To examine the incidence of patellar dislocation injuries and the influence of demographic and occupational risk factors associated with injury among active-duty United States (US) service members between 1998 and 2007. Study Design Cohort study; Level of evidence, 3. Methods Using the Defense Medical Surveillance System, a search was performed for International Classification of Disease, 9th Revision (ICD-9) code 836.3 among all US service members on active duty during the study period. Multivariable Poisson regression analysis was used to estimate the rate of patellar dislocation per 1000 person-years at risk to injury. Incidence rates (IRs) and incidence rate ratios (IRRs) for patellar dislocation along with 95% confidence intervals (CIs) were estimated by gender, age, race, branch of military service, and rank while controlling for the other variables in the model. Results There were a total of 9299 individuals with documented patellar dislocation injuries among a population at risk of 13 443 448 person-years. The IR was 0.69 per 1000 person-years at risk. Women were 61% more likely (IRR, 1.61; 95% CI, 1.53-1.69) to sustain a patellar dislocation injury than men. Rates were highest in the youngest age group and decreased with increasing age. Service members aged <20 years were 84% more likely (IRR, 1.84; 95% CI, 1.61-2.10) to sustain a patellar dislocation injury as service members aged ≥40 years. Differences were also noted by race, service, and rank. Conclusion The incidence of patellar dislocation injuries among US service members was an order of magnitude greater than that previously reported in civilian population studies. Gender, age, race, rank, and branch of military service are important risk factors related to the incidence of patellar dislocation injuries in this population.

The nature and incidence of musculoskeletal combat wounds in Iraq and Afghanistan (2005-2009)

Objectives: This investigation sought to describe orthopaedic wounds sustained by service members deployed to Iraq or Afghanistan from 2005 to 2009. Design: Retrospective review of prospective data. Setting: Joint Theater Trauma Registry (JTTR). Patients: The 6092 musculoskeletal casualties contained in the JTTR. Intervention: The JTTR was queried to identify all personnel sustaining musculoskeletal injuries in the period 2005–2009. Demographic information, injury mechanism, and nature of wounds were determined for all individuals. Deployment data for all service members were obtained through the Defense Manpower Data Center and the incidence of orthopaedic injuries and wounding patterns was assessed. Main Outcome Measurements: Pairwise comparisons were made to identify statistically significant differences in incidence, and significant associations, between injury mechanism and injuries/wounding patterns. Results: The JTTR contained data on 6092 musculoskeletal casualties with 17,177 wounds. Seventy-seven percent of all casualties sustained a musculoskeletal wound. The incidence of musculoskeletal combat casualties was 3.06 per 1000 deployed personnel per year, with fractures occurring in 3.41 per 1000 and soft-tissue wounds most commonly encountered (4.04 per 1000). Amputations represented 6% of all combat wounds. Most musculoskeletal wounds were caused by explosive blast (P < 0.001), as were nearly all traumatic amputations. Conclusions: This study represents the most complete description of the scope of orthopaedic war trauma. It also presents injury-specific incidences that have not previously been described for musculoskeletal combat casualties. Musculoskeletal casualties may occur in 3 of every 1000 personnel deployed per year. Level of Evidence: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Incidence and epidemiology of spinal cord injury within a closed American population: the United States military (2000-2009).

Study design:Cohort studyObjectives:The objective of this study was to characterize the incidence of spinal cord injury (SCI) within the population of the United States military from 2000–2009. This investigation also sought to define potential risk factors for the development of SCI.Setting:The population of the United States military from 2000–2009.Methods:The Defense Medical Epidemiology Database was queried for the years 2000–2009 using the International Classification of Diseases, Ninth Revision, Clinical Modification codes for SCI (806.0, 806.1, 806.2, 806.3, 806.4, 806.5, 806.8, 806.9, 952.0, 952.1, 952.2, 952.8, 952.9). The raw incidence of SCI was calculated and unadjusted incidence rates were generated for the risk factors of age, sex, race, military rank and branch of service. Adjusted incidence rate ratios were subsequently determined via multivariate Poisson regression analysis that controlled for other factors in the model and identified significant independent risk factors for SCI.Results:Between 2000 and 2009, there were 5928 cases of SCI among a population at-risk of 13 813 333. The raw incidence of SCI within the population was 429 per million person-years. Male sex, white race, enlisted personnel and service in the Army, Navy or Marine Corps were found to be significant independent risk factors for SCI. The age groups 20–24, 25–29 and >40 were also found to be at significantly greater risk of developing the condition.Conclusions:This study is one of the few investigations to characterize the incidence, epidemiology and risk factors for SCI within the United States. Results presented here may represent the best-available evidence for risk factors of SCI in a large and diverse American cohort.

Clavicle Fractures in the United States Military: Incidence and Characteristics

BACKGROUND Although it is generally known that clavicle fractures represent a common injury of the shoulder girdle in the general population, the true incidence in the active duty military population is unknown. Given the implications for such injuries on the ability to perform occupation-specific tasks, determining the incidence in the U.S. military population is worthwhile. The purpose of this study was to determine the incidence of clavicle fractures in the U.S. military and to identify any demographic risk factors for injury. METHODS We performed a query of the Defense Medical Epidemiology Database with the code from the International Classification of Diseases, Ninth Revision, for clavicle fractures for the years 1999 through 2008. An overall injury incidence was calculated, in addition to multivariate analysis, to determine independent risk factors among the following demographic considerations: sex, race, branch of military service, rank, and age. RESULTS During the study period, a total of 12,514 clavicle fractures were documented among an at-risk population of 13,770,767 person-years for an incidence rate (IR) of 0.91 per 1,000 person-years in the U.S. Military. Males, when compared with females, were more than twice as likely to sustain a clavicle fracture (IR ratios [IRR], 2.30; 95% confidence intervals [CI], 2.12-2.49). The peak incidence of clavicle fractures occurred in the age groups of <20 and 20 to 24. Compared to black service members, the white service members were associated with significantly higher rate of clavicle fractures (IRR, 2.45; 95% CI, 2.28-2.63). The service members serving in the Marine Corps were associated with a higher IR of clavicle fractures when compared to those in the Navy (IRR, 1.44; 95% CI, 1.35-1.53). Junior enlisted service members were 34% as likely to sustain a clavicle fracture when compared to senior officers (IRR, 1.46; 95% CI, 1.34-1.60 and IRR, 1.12; 95% CI, 0.99-1.28, respectively). CONCLUSIONS The incidence of clavicle fractures among U.S. military personnel (0.908 per 1,000 person-years) is higher than previous epidemiological reports.

Use of an Irrigation Pump System in Arthroscopic Procedures

Since its inception, arthroscopic surgery has become widely adopted among orthopedic surgeons. It is therefore important to have an understanding of the basic principles of arthroscopy. Compared with open techniques, arthroscopic procedures are associated with smaller incisions, less structural damage, improved intra-articular visualization, less pain in the immediate postoperative period, and faster recovery for patients. Pump systems used for arthroscopic surgery have evolved over the years to provide improved intraoperative visualization. Gravity flow systems were described first and are still commonly used today. More recently, automated pump systems with pressure or dual pressure and volume control have been developed. The advantages of automated irrigation systems over gravity irrigation include a more consistent flow, a greater degree of joint distention, improved visualization especially with motorized instrumentation, decreased need for tourniquet use, a tamponade effect on bleeding, and decreased operative time. Disadvantages include the need for additional equipment with increased cost and maintenance, the initial learning curve for the surgical team, and increased risk of extra-articular fluid dissection and associated complications such as compartment syndrome. As image quality and pump systems improve, so does the list of indications including diagnostic and treatment modalities to address intra-articular pathology of the knee, shoulder, hip, wrist, elbow, and ankle joints. This article reviews the current literature and presents the history of arthroscopy, basic science of pressure and flow, types of irrigation pumps and their functions, settings, applications, and complications. [Orthopedics. 2016; 39(3):e474-e478.].

Functional outcomes of hip arthroplasty in active duty military service members.

There are few reports on outcomes after hip arthroplasty in the military population despite increases among young, active patients. U.S. Army service members with coded hip arthroplasty between 2004 and 2010 were reviewed. Patient demographic variables were correlated with occupational outcomes. Of 183 patients, the occupational outcomes at a minimum 2 years postoperatively for service members undergoing primary hip arthroplasty were medically separated (n = 44, 24%), retired (n = 82, 45%), and returned to active duty (n = 57, 31%). Multivariate analysis identified that age less than 40 years [odds ratio (OR), 3.41; 95% confidence interval (CI), 1.14, 10.12] and enlisted rank (OR, 3.63; 95% CI, 1.29, 10.20) as major independent risk factors for medical separation. Univariate analysis revealed that officer rank had an increased likelihood of postoperative combat deployment than enlisted rank (OR, 3.39; 95% CI, 1.50, 7.94). Despite encouraging results in the civilian literature, this study documents modest retention rates on active duty at a minimum of 2 years after primary hip arthroplasty.