The shoulder is one of the most complex joints in the human body and is relied upon extensively for day-to-day tasks and movements. Shoulder injury is a common and often debilitating result of sports mishaps, falls and automotive accidents, including side impacts. The more common shoulder injuries are soft tissue injuries including shoulder separation, shoulder dislocation and rotator cuff tear. These injuries do not pose a risk of serious injury and death but can cause long-term disability and have a negative impact on quality of life. A better understanding of the injury mechanism in lateral impacts to the shoulder is necessary in order to lower the risk of these debilitating types of injuries.

The biomechanical response of the shoulder has not been extensively studied;​ very little research has been done in this area. A greater understanding of the kinematics of the shoulder in lateral impacts as well as the tolerance and mechanisms of injury can lead to improvements in padding for sports equipment, automotive safety countermeasures, and advancements in side impact anthropomorphic test devices.

The objectives of this research were to:​ 1) Analyze the current body of literature available regarding injury to the shoulder in the automotive environment and in sports. 2) Understand the anatomy of the shoulder from a textbook perspective and a laboratory perspective through dissections. 3) Determine the extent and types of shoulder injuries occurring in the automotive environment by performing a NASS (National Accident Sampling Statistics) database study. Analyze the relationships that exist between various types of injuries and injury severity versus variables such as crash mode, seat belt usage, air bag deployment, age and gender. 4) Characterize the response and injury tolerance of the shoulder in lateral impacts. 5) Define the kinematics of the shoulder in lateral impacts.

To address objectives 4 and 5, twelve whole-body cadaver tests were conducted using a 23.4 kg, pneumatic impactor. Two impact speeds were used to assess the shoulder in lateral impacts, 4.5 m/s and 6.7 m/s. The cadavers were instrumented with accelerometers and target pins. The impacts were digitally recorded in three views on high-speed video. Acceleration, force and displacement data was analyzed to determine tolerance of the shoulder to injury. A kinematic analysis was also performed to define the movements of the shoulder during lateral impact.

Findings include the response of the shoulder to lateral impacts in terms of acceleration, force and displacement. Through film analysis, the kinematics of the shoulder were defined both qualitatively and quantitatively.

In addition, various injury criteria were explored. Regression analysis was used to demonstrate the significance of several variables as predictors of injury, including impact velocity, maximum impact force and percent compression of the shoulder.