UC San Diego

The shoulder is the most unstable joint in the body.1 Decreased stability causes the shoulder to dislocate easily, stretching the joint capsule and glenohumeral ligaments. This increases the likelihood of redislocation. Recurrent dislocations can cause the ligaments and joint capsule to pull on the labrum and create a lesion. Once a lesion is formed the joint is chronically unstable, and must be repaired surgically. The standard method of repair is to arthroscopically implant a suture anchor into the bone, which is then used to secure the soft tissue back onto the bone. This reintroduces tension to the capsule and glenohumeral ligaments, therefore restoring stability to the joint. There are several different types of suture anchors currently available on the market: the rigid knotted anchor, the rigid knotless anchor, and the soft anchor.

This study defines the anatomical and mechanical design constraints of shoulder instability repair by researching the injury mechanism, and benefits and downfalls of the current repair methods. Once these design constraints are well defined, two new suture anchor prototype designs are then proposed. Design 1 is a hybrid between a rigid and soft anchor, starting with the design for the current soft anchor, but creating wings from Nitinol, rather than using the sleeve to anchor the device. Design 2 starts with the soft anchor design, but adds a bone barrier to protect the bone from the micro-motion of the anchor.