The shoulder joint offers tremendous range of motion. Athletes can generate immense torque with circular shoulder motion. This is why great baseball pitchers can throw the ball 100 mph, football quarterbacks can throw the ball 70 yards and a tennis player can hammer a 130 mph serve. But the joint relies on relatively weak soft-tissue stabilizers -- muscles, ligaments and cartilage -- to hold things together. So tennis players are vulnerable to repetitive stress injuries.
Shoulder Instability
Young players are especially prone to shoulder instability. Ligament looseness often develops during their growth spurts. Also, muscular development often lags behind skeletal development. The ball-like top of the humerus bone can begin slipping out of the glenoid socket. This overtaxes the four muscles that make up the rotation cuff, leading to further slippage and a "dead arm" sensation.
Rotator Cuff Impingement
A primary consequence of shoulder instability is the impingement of the rotator cuff tendons. Fatigued rotator cuff muscles allow the deltoid muscles to contract unopposed, causing the humerus to migrate upward in the socket. That migration causes the rotator cuff tendons to become pinched under the acromion bone on top of the shoulder. Chronic impingement can lead to tendon inflammation and pain. It can also cause bone spurs to form on the underside of the acromion, exacerbating the injury.
Rotator Cuff Inflammation, Strains and Tears
Repetitive stress can lead to rotator cuff tendon inflammation and relatively minor tendon strains. But acromion spurs and other structural breakdowns can lead to partial tears of the rotator cuff tendons -- and even full tears away from the bones in older players.
Shoulder Injury Treatments
Sports medicine professionals may treat rotator cuff strains with anti-inflammatory medicine, rest, therapy, steroid injections and rehabilitative exercise. But spurs may require arthroscopic removal. Complete tendon tears from the bone may require tendon reattachment surgery.
