The shoulder joint is subject to a great deal of motion, more so than other large joints in the body. This makes the shoulder susceptible to dislocation. Anyone who has experienced a dislocated shoulder knows how painful it can be. In fact, a dislocation can lead to a condition called multidirectional instability of the shoulder (MDI). The joint dislocation can result in an excessive forward, backward or downward motion relative to its normal position. MDI is often seen as a result of a sports-related injury, but it can develop over time with repetitive use of the shoulder joint.
Surrounding soft tissues are also affected. Ligaments and muscles in the arm and shoulder region can become stretched or torn. At times, a genetic abnormality of the joint can be an underlying cause. Repetitive motions, shoulder sprains and sudden muscle contractions can result in MDI. Individuals with below average fitness levels and 'loose joints' are also at risk.
Multidirectional instability leads to weakness in the rotator cuff muscles, which become fatigued and overworked. The surrounding bursa (fluid filled protective sacs), tendons and nerves may also get affected.
Pain in the shoulder at rest and with motion is a common symptom. MDI may be associated with numbness, paralysis and weakness in the shoulder. Some patients report a crackling feeling or sound in the shoulder area during motion.