Shoulder Injuries in the Throwing Athlete

The shoulder is a ball-and-socket joint formed by the humeral head (ball) and the glenoid cavity (socket) of the scapula (shoulder blade). This shallow socket allows for an extraordinary range of motion, critical for throwing but inherently less stable than deeper joints like the hip.

Stability depends on a combination of static and dynamic structures. The labrum, a cartilage rim, deepens the socket, cushions and stabilizes the joint, and helps keep the ball in the socket. The rotator cuff muscles (supraspinatus, infraspinatus, teres minor, and subscapularis) provide dynamic stability, working to keep the ball centered in the socket throughout movement.

SLAP tears (Superior Labrum Anterior to Posterior)

A SLAP tear refers to damage to the upper part of the labrum where the biceps tendon anchors into the shoulder socket. In throwers, this area is vulnerable during the late cocking phase of the throw when extreme external rotation places strain on the biceps-labrum complex.

Symptoms of SLAP tears may include deep shoulder pain, clicking or catching with motion, and reduced throwing velocity. Diagnosis is based on a detailed clinical history, provocative shoulder maneuvers, and imaging. MRI arthrograms are often used to visualize labral damage more clearly.

Biceps tendonitis and tendon tears

The long head of the biceps tendon travels through the bicipital groove of the humerus and attaches to the superior glenoid. Repetitive overhead activity can lead to irritation or inflammation of this tendon, known as biceps tendonitis.

Athletes with biceps tendon involvement may report pain in the front of the shoulder, especially with lifting or deceleration. Physical examination often reveals tenderness over the bicipital groove. Advanced cases may result in partial or full-thickness tendon tears, detectable on imaging such as ultrasound or MRI.

Rotator cuff tendonitis and tears

The rotator cuff stabilizes the shoulder during dynamic movement. In throwing athletes, repetitive use and high-velocity arm motions can lead to inflammation (tendonitis) or degeneration and tearing of the rotator cuff tendons.

Symptoms may include pain during or after throwing reduced strength, and limited overhead function. Physical exam tests can help localize which tendon is involved. MRI provides detailed visualization of tendon quality and can identify partial or complete tears.

Internal impingement

Internal impingement occurs during maximal external rotation when the rotator cuff and posterior labrum become pinched between the humeral head and glenoid rim. This typically occurs during the late cocking phase of the throw.

Throwers with internal impingement often describe posterior shoulder pain and decreased control during high-velocity motion. Diagnosis is based on history, selective impingement tests, and imaging that may reveal posterior labral wear or undersurface cuff fraying.

Instability

Shoulder instability occurs when the humeral head moves excessively within the glenoid socket, often due to capsular laxity or previous subluxation events. In throwing athletes, repetitive stress can stretch the joint capsule, especially in the anterior direction.

Symptoms of instability include a sense of looseness, slipping, or dead arm during throwing. Clinical tests evaluate for translation of the joint and apprehension. MRI can assess for capsular redundancy or associated labral damage.

GIRD (Glenohumeral Internal Rotation Deficit)

GIRD is a loss of internal rotation range of motion in the throwing shoulder compared to the non-dominant side. It occurs as an adaptive change in throwers but can, if excessive, contribute to abnormal mechanics and increased injury risk.

Diagnosis involves comparing internal rotation side-to-side with the shoulder abducted. GIRD is typically associated with posterior capsular tightness and can be measured in degrees using a goniometer.

Scapular rotation dysfunction (SICK scapula)

SICK scapula is a syndrome involving scapular malposition, inferior medial border prominence, coracoid pain, and scapular dyskinesis. It results from abnormal scapular motion patterns that disrupt shoulder mechanics during throwing.

Athletes may complain of fatigue, tightness, or shoulder pain during the throwing cycle. Observation often reveals winging or asymmetry in scapular positioning. Diagnosis relies on physical examination and dynamic assessment of scapular motion during shoulder activity.

Diagnosing shoulder injuries in throwing athletes begins with a comprehensive history and physical exam. Understanding the athlete’s training volume, mechanics, prior injuries, and symptoms offers key insights. Specific physical exam maneuvers can isolate pain patterns and test for instability, impingement, or labral involvement.

Advanced imaging plays an important role. MRI, particularly with intra-articular contrast (MR arthrogram), is often used to visualize soft tissue structures such as the labrum and rotator cuff. In some cases, diagnostic ultrasound or dynamic fluoroscopic studies may be helpful in real-time assessment.

At Wake Forest’s integrated sports medicine facilities, including the Wake Forest Pitching Lab, advanced motion capture and biomechanics evaluations can help identify flawed mechanics contributing to injury—allowing for a more personalized and preventative approach to care.