Thrower's Shoulder

Why throwing stresses the shoulder

During a pitch, the shoulder rotates at extremely high speeds, among the fastest movements in sport. Forces pull on the front of the shoulder as the arm cocks back and on the back of the shoulder as it decelerates after release. Over years of throwing:

• the front ligaments and capsule stretch, increasing external rotation (useful for velocity)
• the back of the capsule tightens, reducing internal rotation
• the shoulder blade may lose its normal control and position

These adaptations can be normal up to a point, but excess changes lead to injury.

Common conditions in thrower's shoulder

Dead arm syndrome

Athletes describe a sudden sharp pain and the arm going "dead" or weak when throwing, with loss of velocity and control. It is often linked to a SLAP tear with GIRD.

Symptoms

• pain at the back or front of the shoulder during the late cocking or acceleration phase of throwing
• reduced velocity, control or endurance
• stiffness, especially at the back of the shoulder
• clicking, catching or popping
• a dead arm sensation
• pain at night in more advanced cases
• elbow pain from altered mechanics (ulnar collateral ligament strain)

Risk factors

• high pitch counts and pitching on consecutive days
• pitching year-round without a rest period
• playing for multiple teams at the same time
• pitching while fatigued, and continuing to throw with pain
• poor mechanics, including weak core and leg drive
• pitching as a catcher on the same days
• throwing curveballs or sliders before mechanics are mature, in some studies

Diagnosis

A sports medicine doctor or orthopedic surgeon will:

• compare internal and external rotation of both shoulders
• check shoulder blade movement and posture
• test rotator cuff strength, stability and labral signs
• assess the elbow and core and lower body mechanics

Imaging:

• MRI arthrogram (MRI with contrast in the joint) is the best test for labral and partial rotator cuff tears
• X-rays for growth plate injuries in young athletes and bone changes
• ultrasound for dynamic assessment of the rotator cuff

Treatment

Non-surgical (first line for most)

• rest from throwing, often 2 to 6 weeks or more, while staying fit in other ways
• posterior capsule stretching, such as the sleeper stretch and cross-body stretch, to restore internal rotation
• rotator cuff strengthening, especially external rotators
• scapular stabilization exercises
• core and lower body strengthening, since much throwing power comes from the legs and trunk
• mechanics assessment with a coach or biomechanics specialist
• pain relief with ice and short-term NSAIDs if needed
• a structured interval throwing program to return gradually, increasing distance and intensity over weeks

Surgery

Considered when symptoms persist despite a full rehab program, or for chronic shoulder pain with a confirmed structural tear:

• arthroscopic SLAP or labral repair, or biceps tenodesis in some cases
• debridement or repair of partial rotator cuff tears
• capsular procedures for instability

Return to the same level of throwing after shoulder surgery is less predictable than after rehab alone, particularly for pitchers, which is why surgery is a last resort.

Prevention

Following pitch count and rest guidelines such as MLB and USA Baseball's Pitch Smart reduces injuries in young athletes:

• respect age-based pitch count limits and required rest days
• avoid pitching more than one game in a day or on consecutive days
• take at least 2 to 3 months off from overhead throwing each year, and 4 months total from competitive pitching
• do not play for multiple teams with overlapping seasons
• never pitch with arm pain or fatigue
• avoid serving as catcher on days off from pitching
• include year-round shoulder, scapular and core conditioning and a daily posterior stretching routine

Frequently asked questions

What is thrower's shoulder?

Thrower's shoulder is a group of overuse injuries in athletes who throw or move the arm overhead repeatedly. It includes posterior tightness (GIRD), internal impingement, labral SLAP tears, rotator cuff damage and poor shoulder blade control.

What is dead arm syndrome?

Dead arm syndrome is a sudden sharp pain with weakness or a "dead" feeling in the arm during throwing, with loss of velocity and control. It is often associated with a SLAP tear and tightness at the back of the shoulder.

How is thrower's shoulder treated?

Most cases are treated with rest from throwing, stretching the back of the shoulder, strengthening the rotator cuff, shoulder blade and core, and a gradual return-to-throw program. Surgery is reserved for persistent symptoms or significant tears.

What is GIRD in the shoulder?

GIRD stands for glenohumeral internal rotation deficit. It is a loss of internal rotation in the throwing shoulder compared with the other side, caused by tightness at the back of the shoulder. It increases the risk of labral and rotator cuff injuries.

How can young pitchers prevent shoulder injuries?

Follow age-based pitch count and rest guidelines, take several months off from throwing each year, avoid pitching on multiple teams or with fatigue, stop throwing when the arm hurts, and keep the shoulder, shoulder blade and core strong.