Report: Joint replacements increasing in service members older than 30July 1, 2015
Service members ages 40 years and older were at greater risk for all joint replacements overall and of each type during the surveillance period (Jan. 1, 2004, through Dec. 31, 2014), according to the report, which was released in the May issue of the Medical Surveillance Monthly Report published by the Armed Forces Health Surveillance Center. However, during 2009-14, incidence rates also increased in the following age groups: 30-34 years (45%); 35-39 years (107%); 40-44 years (130%); and 45 years and older (38%), the data showed.
Service members are at risk for joint replacement for several reasons, the report noted. Military training and operational activities often are 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. Recent increases in the incidence of overweight and obesity in service members also can contribute to an increase in osteoarthritis and joint and back disorders, the authors wrote.
The report documents a total of 3,905 joint replacements among 3,805 active-duty members of the Army, Navy, Air Force, Marine Corps and Coast Guard (an incidence rate of 2.43 per 10,000 person-years among service members) during 2004-14. During the surveillance period, there were 1,825 knee replacements and 1,694 hip replacements (with incidence rates of 1.16 and 1.08 per 10,000 person-years among service members, respectively), the data showed.
According to the report, overall incidence rates increased 10.5% during 2004-09, and then 61.9% during 2009-14. Knee and hip joint replacements accounted for a majority of cases throughout the 11-year period, findings showed. 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 surveillance period.
The report’s authors suggest service members and their clinicians might be electing to have joint replacements at earlier ages amid improvements in surgical techniques and increased durability and longevity of prosthetic joints.
“While more mid-career service members have had joint replacements, the procedures can prove beneficial to the health and readiness of the U.S. Armed Forces,” Army Col. Michael Bell, AFSHC’s director, said in a news release. “Each service member represents a precious resource for the Department of Defense. It takes years of training and experience to produce a seasoned NCO or officer. If joint replacement allows service members to remain on duty longer and continue being valuable contributors to the military, then it will be a good thing for the U.S. Armed Forces. Additional studies are needed to determine the full impact of joint replacement on operational readiness.”
Status one, two years postop
Among the 2,902 service members who had a joint replaced during 2004-12, one year after the procedure 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, according to the report. At two years postjoint replacement, 30.2% had retired, 13% had been medically disqualified, 10% had otherwise left service, and 46.8% were still in service.
Of the services, the U.S. 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), according to the report. The Army and Coast Guard also had the highest rates of shoulder replacement (0.16 and 0.16 per 10,000 person-years, respectively). These findings in part might be accounted for by differences in age and occupational distributions between the services, the authors wrote.
Among race/ethnicity groups, black, non-Hispanic service members had the highest rates of joint replacement overall and in the two largest joint replacement categories, hip and knee. Past surveillance has shown osteoarthritis is diagnosed at higher rates among black, non-Hispanic active component service members. For those ages 40 and older, rates of osteoarthritis were 57% higher among black, non-Hispanic service members than rates for white, non-Hispanic counterparts. The age and occupational distribution is not uniform across ethnic groups in the military and may contribute to the findings presented above.
In civilian settings, rates of joint replacement reportedly are higher among white, non-Hispanics than among all other race and ethnicity groups, the authors wrote. Differences in access to healthcare, which is at no cost to service members, might contribute to the relatively higher rates of joint replacement among black, non-Hispanics versus white, non-Hispanics in military versus civilian settings.