Effects of Hormone Therapy on Regional Surface Strain as a Function of Applied Strain in the Macaque Inferior Glenohumeral Ligament

Hormones such as estrogen are known to have an effect on the biomechanical properties of certain ligaments such as the anterior cruciate ligament in the knee; however, relatively little is known about its effect on the ligaments of the shoulder. The inferior glenohumeral ligament (IGHL) is a static stabilizer of the shoulder that prevents anterior translation of the humeral head. Alterations to the properties of this ligament can result in capsular stretching, increased laxity, and ultimately instability. The cynomolgus macaque (Macaca fascicularis) shares many hormonal similarities with humans including a 28-day menstrual cycle and is a commonly used model for hormone replacement therapy studies. This study uses the female cynomolgus monkey as a model of the human shoulder to determine if estrogen has an effect on the regional surface strain behavior of the inferior glenohumeral ligament.