Back

Mapping Stress Points in Injured Shoulders

When the shoulder is injured, the head of the humerus can shift in the socket. This may lead to changes in pressure points inside the joint. In this study, scientists from Munich, Germany, took a closer look at what happens after shoulder injury.

The authors used CT scans and computer programs to measure and map the thickness (density) of bone in the shoulder joint. Two groups were compared. The first group had minor or major trauma to the shoulder leading to forward (anterior) dislocation. All patients had surgery to repair the shoulder. The second group was the same age with healthy shoulders and no sign of trauma or injury. A special CT scan called osteoabsorptiometry was used to measure bone density. The shape of the shoulder socket was also mapped.

The researchers found a change in bone density for the injured shoulders. They report a shift forward of maximum joint contact for patients with major trauma. There was a downward shift for patients with minor trauma. This suggests that stress occurs in a different part of the joint. Where the joint surfaces make contact depends on the force, size, and position of the load. The load pattern changes from normal when injury occurs.

The authors conclude that CT osteoabsorptiometry can be used as a tool to measure and monitor joints. It shows the stress pattern and load of unstable joints by using mineral content of the bone. Differences in joint shape don't seem to affect the contact area or load pattern. This information may help doctors and surgeons choose the best treatment option for each patient.

References: Christoph Udo Schulz, MD, et al. Anterior Shoulder Instability Modifies Glenoid Subchondral Bone Density. In Clinical Orthopaedics and Related Research. June 2004. Vol. 423. Pp. 259-263.

Back