Ultrasound measurement of stable and unstable shoulders

This companion study to the shoulder taping trial is the first step: understanding the basic differences between a stable shoulder and an unstable one using ultrasound imaging. The shoulder is a highly mobile joint that relies heavily on soft tissues (muscles, tendons, ligaments) to stay in place. When these structures are weak or loose, the arm bone (humerus) can drift out of its ideal position — something researchers believe they can detect on ultrasound. Participants fall into two groups: those with symptomatic shoulder instability (with a confirmed positive sulcus test) and those with healthy, stable shoulders (negative sulcus test, no symptoms). By comparing ultrasound measurements between these two groups, researchers hope to identify reliable markers of shoulder instability that could one day guide diagnosis and treatment. Eligible participants are adults aged 18–35 with either confirmed shoulder instability or a symptom-free shoulder. People who have had significant trauma or surgery to the shoulder, known neurological conditions, connective tissue disorders (such as Marfan syndrome or Ehlers-Danlos), or cervical radiculopathy (nerve pain from the neck) are not eligible.