The overall incidence rate for joint replacements among US active component service members increased during an 11-year surveillance period, according to a report published in the May issue of the Medical Surveillance Monthly Report. The report also found that service members in their 30s and early 40s are having the procedures more often and are remaining in the military longer after rehabilitation.
During the surveillance period, overall incidence rates increased 10.5% during 2004 through 2009 and 61.9% during 2009 through 2014. Knee and hip joint replacements accounted for a majority of cases. In 2014, the rates of knee and hip replacements were identical (1.6 per 10,000 person-years) and were the highest for each during the 11-year surveillance period.
The report suggested that service members and their clinicians may be electing to have joint replacements at earlier ages amid improvements in surgical techniques and increased durability and longevity of prosthetic joints.
Service members are at risk for joint replacement for several reasons, the report noted. Military training and operational activities are often physically demanding, and sometimes traumatic. Some occupations are more stressful for bones and joints, and have been associated with higher frequencies of musculoskeletal disorders among service members during wartime and repeated deployments. In addition, recent increases in the incidence of overweight and obesity in service members can contribute to an increase in osteoarthritis and joint and back disorders among service members.
The report documents 3,905 joint replacements among 3,805 active component members of the Army, Navy, Air Force, Marine Corps, and Coast Guard during 2004 through 2014. Knee and hip joint replacements numbered 1,825 and 1,694, respectively.
Among the 2,902 service members who had a joint replaced during 2004 through 2012, 18.2% had retired, 5.2% had been medically disqualified from service, 6.3% had otherwise left service, and 70.3% were still in service 1 year after joint replacement. By 2 years post-joint replacement, 30.2% had retired, 13.0% had been medically disqualified, 10.0% had otherwise left service, and 46.8% were still in service.
The Army and Coast Guard had the highest overall rates of joint replacement (2.89 and 2.88 per 10,000 person-years, respectively). The Coast Guard had the highest rate of hip replacement (1.54 per 10,000 person-years) and the Army had the highest rate of knee replacement (1.46 per 10,000 person-years). The Army and Coast Guard had the highest rates of shoulder replacement (0.16 per 10,000 person-years for each). The study authors noted that these findings may, in part, be accounted for by differences in age and occupational distributions between the services.
Among racial and ethnic groups, black, non-Hispanic service members had the highest rates of joint replacement and in the 2 largest joint replacement categories, hip and knee. Previous surveillance has documented that osteoarthritis is diagnosed at higher rates among active component service members who are black, non-Hispanic. Among black, non-Hispanic service members ages 40 years or older, rates of osteoarthritis were 57% higher than rates among white, non-Hispanic counterparts.
In civilian settings, rates of joint replacement are reportedly higher among white, non-Hispanics than among all other racial and ethnic groups.