SAN DIEGO — Addressing anterior shoulder instability at an earlier age may prevent shoulder osteoarthritis. However, other factors, such as increased BMI, smoking, and manual labor, may increase a patient’s risk of osteoarthritis.
Two studies presented at the 2021 meeting of the American Association of Orthopaedic Surgeons suggest that patients who develop anterior shoulder instability at an older age are at a higher risk of developing shoulder arthritis.
In one of the largest studies of a US population with anterior shoulder instability, researchers from the Mayo Clinic identified 154 patients from a regional database.
“While some work has been done on the long-term risk for osteoarthritis after glenohumeral joint instability, most of this work has been done in Europe,” said Christopher Camp, MD, one of the Mayo Clinic study authors. “The long-term outcomes in a US population were not as well understood.”
With an average of 15.2 years of follow-up, 22.7% of the patients in the Mayo Clinic cohort developed clinically symptomatic shoulder arthritis without shoulder stabilization surgery.
Univariate analysis revealed that patients with symptomatic osteoarthritis were more likely to be a current or former smoker (relative risk [RR], 2.46; 95% CI, 1.37 – 4.42; P = .003), to have an occupation as a manual laborer (RR, 2.14; 95% CI, 1.14 – 4.01; P = .040), and to be of increased age at the initial instability event (odds ratio, 1.09 per year; 95% CI; 1.03 – 1.17).
In a complementary study, researchers from Walter Reed Medical Center presented the largest series published to date of a young, high-demand population with shoulder instability.
Of the 287 active duty US service members within the Military Heath System with shoulder instability, only 23 (8%) treated surgically went on to develop arthritis at a median follow-up of 9 years.
After adjusting for potential confounders in a multivariable Cox regression model, risk factors for the development of glenohumeral arthritis included age at the time of surgery (HR, 1.85; 95% CI, 1.34 – 2.55), the number of anchors with the initial surgery (HR, 1.54; 95% CI, 1.11 – 2.14), and revision surgery (HR, 2.83; 95% CI, 1.15 – 6.95).
Ashley Bee Anderson, MD, an author on the study from Walter Reed National Military Medical Center, noted that the study didn’t specifically focus on reducing the risk of developing arthritis. What it did demonstrate is that several factors contributed to the development of arthritis, most notably age at the time of surgery.
Like the Mayo clinic study, older patients were still at greater risk for developing shoulder osteoarthritis. “These results may advocate for early surgical intervention for a young patient presenting with shoulder instability,” Anderson told Medscape Medical News.
She said it’s important for primary care physicians, athletic trainers, and coaches to recognize and diagnose shoulder instability early on. “It may be important to have an orthopedic evaluation sooner rather than later for surgical counseling.”
Camp also offered his own advice on preventing osteoarthritis. “The main takeaways are to counsel patients with anterior shoulder instability on their risk for long-term arthritis and to discuss the modifiable risk factors that may impact that risk. Specifically, if they are able to stop smoking, lower their BMI, and minimize heavy labor at work, this may improve their long term risk.”
Mark Schickendantz, MD, program director of orthopedic surgery for the Cleveland Clinic Sports Health Center, Cleveland, Ohio, agrees with the authors that education and early intervention are important in preventing osteoarthritis.
“These concerns should be addressed by physicians with good patient education; these patients — overweight patients, laborers, and smokers — should be counseled that they have a greater risk of developing osteoarthritis and should be offered programs to help them modify those risk factors,” said Schickendantz, who was not involved with either study.
Schickendantz also pointed to the finding that an increasing number of repair anchors resulted in an increased risk factor for developing osteoarthritis. “The fact that more anchors correlates with more osteoarthritis might result in surgeons recommending earlier surgery to prevent extension of a labral tear” that occurred with the initial shoulder dislocation.
Of the risk factors studied, the most challenging to address may be a manual labor occupation because it isn’t something that is easily modifiable. “The laborer issue is a tough one,” Schickendantz said. “Other than education, I can’t think really of anything practical. Most people who do physical labor do so because they can’t do anything else.”
Anderson and Camp have disclosed no relevant financial relationships. Schickendantz is a consultant for Arthrex but reports no financial relationships relevant to the study.
American Association of Orthopaedic Surgeons (AAOS) 2021 Annual Meeting. August 31-September 3, 2021.