Page 41 - JSOM Spring 2023

The study was approved by the Institutional Review Board using the Fisher’s exact test for categorical variables and the
of the University of Pittsburgh (IRB0604091—NSW Injury independent samples t test for continuous variables. Statistical
Prevention and Human Performance Initiative) and required significance was set a priori at α = 0.05, two-sided. Statistical
military entities. Data were collected from study participants analyses were conducted using SPSS version 26 (IBM, https://
at Naval Special Warfare Center, Coronado, CA, and John C. www.ibm.com/analytics/spss-statistics-software).
Stennis Space Center, Stennis, MS. All participants understood
and signed a written informed consent document prior to un- Cost of MSIs
dergoing any research procedures. The cost of MSIs that occurred during a one-year period in
this sample of SWCC Operators and CQT students was esti-
Obtaining Self-Reported MSI Data mated using the Centers for Disease Control and Prevention
The MSI data presented in this manuscript were obtained by web-based Injury Statistics Query and Reporting System Cost
12
self-report from the volunteers using an investigator-guided of Injury Reports. Reports were generated by specifying the
questionnaire. This questionnaire has been utilized before MSI location and type, age of the injured study participant,
as a research data management tool in other military pop- year of MSI, and whether or not the MSI resulted in hospi-
ulations. 10,11 The questions in the questionnaire followed a talization. The lifetime cost of each MSI, which is the sum of
predetermined flowchart, so that questions presented to the lifetime medical and work-loss costs, was calculated for each
study participants depended on their response to the previous MSI. Costs were indexed to the year 2017, and these costs
question. The anatomic locations included in the questionnaire were converted into year 2021 costs by using the Bureau of
were lower extremity, upper extremity, spine, torso, head/face, Labor Statistics Consumer Price Index Inflation Calculator. 13
and other. The anatomic sub-locations listed under lower ex-
tremity were hip, knee, ankle, thigh, lower leg, and foot and Results
toes. The anatomic sub-locations listed under upper extremity
were shoulder, elbow, wrist, arm, forearm, and hand and fin- A total of 142 SWCC Operators (age: 26.9 ± 5.9 years, height:
gers. Spine injuries were classified as those affecting the cervi- 1.8 ± 0.1 m, body mass: 85.6 ± 9.5 kg) and 187 CQT students
cal, thoracic, or lumbopelvic spine. Sub-locations under torso (22.8 ± 3.2 years, 1.8 ± 0.2 m, 81.8 ± 8.3 kg) participated
included chest and abdomen. The option “other” was allowed in the study. SWCC Operators were significantly older (p <
as a response for questions, followed by a free text box, to 0.001) and had significantly greater body mass (p < 0.001)
enter participants’ responses that did not conform to the pre- than the CQT students. Height was not significantly different
determined flowchart. between the two groups.

Data about musculoskeletal injuries in the past was collected. Of the 142 SWCC Operators, 22 (15.5% of SWCC Opera-
The questionnaire was administered by trained certified ath- tors) reported one MSI each, eight (5.6%) reported two MSIs
letic trainers, and de-identified MSI data were stored in a cus- each, and 112 (78.9%) did not report any MSIs during a one-
tomized database. year period. Of the 187 CQT students, 45 (24.1% of CQT
students) reported one MSI each, 22 (11.8%) reported two
Operational Definitions MSIs each, three (1.6%) reported three MSIs each, and 117
A MSI was defined as an injury to the musculoskeletal sys- (62.6%) did not report any MSIs during a one-year period.
tem (bones, ligaments, muscles, tendons, etc.) that, if occur- The frequency of MSIs was 26.8 MSIs/100 subjects/year
ring after enlistment, resulted in alteration of tactical activities, among SWCC Operators and 52.4 MSIs/100 subjects/year
tactical training, or physical training for a minimum of one among CQT students. The one-year cumulative MSI incidence
day, regardless of medical attention sought. Contact MSIs was significantly lower among SWCC Operators compared to
were defined as those caused by direct contact (e.g., a distal CQT students (21.1% versus 37.4%, respectively; p = 0.002).
radial fracture caused by blunt force trauma) or indirect con-
tact (e.g., fall on the outstretched hand leading to a distal ra- Among SWCC Operators as well as CQT students, the pre-
dial fracture). Overuse MSIs were defined as MSIs caused by dominant anatomic location was the lower extremity (SWCC
excessive repeated activity that were exacerbated by activity Operators: 50.0% of MSIs, CQT students: 66.3%), followed
and relieved by rest. In addition, MSIs were classified as either by the upper extremity (SWCC Operators: 28.9%, CQT stu-
non-contact or contact MSIs. Non-contact MSIs were defined dents: 24.5%), and spine (SWCC Operators: 13.2%, CQT
as those that did not involve either direct or indirect contact. students: 9.2%). Among SWCC Operators, 5.3% and 2.6%
of the MSIs affected the head/face and torso, respectively. No
Statistical Analysis head/face or torso MSIs were reported among CQT students.
MSIs that occurred during a one-year period prior to the date The percentage of CQT students with at least one lower ex-
of administration of the self-reported questionnaire for each tremity injury (52/187 = 27.8%) was significantly higher than
participant were included in this analysis. MSI frequency was the percentage of SWCC Operators with at least one lower
calculated as the number of MSIs/100 participants/year. The extremity injury (16/142 = 11.3%; p < 0.001).
one-year cumulative incidence of MSI was calculated as the
number of injured participants/100 participants/year. Table 1 lists the anatomic sub-locations of MSIs. There was
a distinct pattern of distribution of MSIs by anatomic sub-
Statistical analysis included categorization of MSIs by ana- locations between the two groups. Among SWCC Operators,
tomic location and sub-location; cause (e.g., lifting, fall, run- the most common sub-location was the knee (28.9% of MSIs)
ning, etc.); activity at the time of MSI; MSI type; mechanism followed by the shoulder (21.1%) and the lumbo-pelvic re-
(contact or non-contact); and overuse. Absolute frequency gion of the spine (13.2%). Among CQT students, the most
(count) and relative frequency (percent) of MSIs were calcu- common sub-location was the lower leg (20.4%) followed by
lated in each category. Group comparisons were conducted the shoulder (16.3%) and knee (15.3%). The percentage of

Musculoskeletal Injuries in Naval Special Warfare | 39