Association Between Serum Relaxin and Subsequent Shoulder Instability.

Area of Science:

• Orthopedics
• Sports Medicine
• Endocrinology

Background:

• Ligamentous laxity is a known risk factor for joint instability.
• Relaxin, a hormone, has been associated with knee laxity and anterior cruciate ligament (ACL) injuries.

Purpose of the Study:

• To prospectively evaluate the association between preinjury serum relaxin concentration and the likelihood of acute shoulder instability in young athletes.

Main Methods:

• A prospective cohort study of 1050 young athletes was conducted.
• A nested case-control analysis compared 53 athletes with shoulder instability to 53 matched controls.
• Serum relaxin levels were measured using enzyme-linked immunosorbent assay (ELISA).

Main Results:

• Mean serum relaxin concentration was significantly higher in athletes with shoulder instability (3.69 pg/mL) compared to controls (2.20 pg/mL).
• A 1-pg/mL increase in baseline serum relaxin was associated with a 2.18-fold increased odds of developing acute shoulder instability.
• While detectable relaxin was found in 25% of unstable cases versus 17% of controls, the difference was not statistically significant (P=.34).

Conclusions:

• Preinjury serum relaxin concentration is associated with an increased risk of subsequent acute shoulder instability in young athletes.
• Relaxin may serve as a potential biomarker for predicting shoulder instability risk.
• Further research is recommended to elucidate the role of relaxin in shoulder instability.