INJURIES ASSOCIATED With PITCHING
Historically, it has been reported that as many as 50% of professional pitchers will experience shoulder or elbow pain that prohibits throwing at some point in their career.It is also estimated that 57% of pitchers suffer some form of shoulder injury during the playing season. It is the notion that the extreme joint range of motion and torques applied during pitching are causes of certain injuries to pitchers. Overuse injuries are the most common type with the cause as cumulative microtrauma associated with the high-magnitude, repetitive stresses of pitching. Mechanisms contributing to degenerative injuries observed in the baseball athlete are believed to be initiated during the athlete's early playing years. Injuries to the throwing shoulder and elbow are most common in baseball pitchers.
elbow injuries
Injuries can occur at any area of the joint: anterior, lateral, posterior, or medial compartment.
The repetitious overhead throwing motion can produce incomplete elbow extension due to:
Incomplete elbow flexion frequently indicates posterior elbow problems in the athlete which is susceptible to injury during the arm deceleration phase.
Valgus Extension Overload (VEO) is a throwing related syndrome which is a common cause of posterior elbow pain and causes elbow tension and bony compression.
-UCL rupture ("Tommy John"): to resist valgus stress, high tension is developed in the ulnar collateral ligament at the end of the arm cocking phase and this tension is near the ligament's ultimate tensile strength.
-Little League Elbow: used to describe injury to the growth plate on medial epicondyle and results in inner elbow pain. During pitching, muscles that originate here pull at the grpwth plate causing separation as well as small muscle tears causing inflammation.
Common Origins of Medial-Sided Elbow Pain
The repetitious overhead throwing motion can produce incomplete elbow extension due to:
- anterior capsule sprains (cause: traumatic hyperextension of elbow)
- flexor-pronator strains
- bicipital tendinitis
- presence of intra-articular/loose bodies
- avascualr necrosis
- osteochondritis dissecans
- osteochondral chip fracture
Incomplete elbow flexion frequently indicates posterior elbow problems in the athlete which is susceptible to injury during the arm deceleration phase.
Valgus Extension Overload (VEO) is a throwing related syndrome which is a common cause of posterior elbow pain and causes elbow tension and bony compression.
-UCL rupture ("Tommy John"): to resist valgus stress, high tension is developed in the ulnar collateral ligament at the end of the arm cocking phase and this tension is near the ligament's ultimate tensile strength.
-Little League Elbow: used to describe injury to the growth plate on medial epicondyle and results in inner elbow pain. During pitching, muscles that originate here pull at the grpwth plate causing separation as well as small muscle tears causing inflammation.
Common Origins of Medial-Sided Elbow Pain
- medial epicondylitis
- UCL sprain
- flexor-pronator mass strain
- ulnar nerve neuritis
Medial-sided elbow injuries
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Lateral-sided elbow injuries
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SHOULDER INJURIES
A delicate balance exists between mobility and stability at the shoulder and a fine line separates optimal athletic performance and unwanted injury. Due to the extreme motions at the shoulder needed to throw a ball, baseball pitchers acquire increased laxity of static stabilizers of the shoulder joint. While laxity is necessary for performance, the repetition of throwing can further stretch the capsulolabral complex which makes the dynamic stabilizers of the shoulder work harder, including the rotator cuff and generates more stress on these muscles.
-Rotator cuff tears are caused by the high forces generated along with shoulder motions during arm deceleration. Most tears located in area from mid-supraspinatus posterior to mid-infraspinatus
-Labral tearing can result from translation, subluxation, and compression of humeral head which induces entrapment of the labrum between humeral head and glenoid rim
-Humeral translation is possible due to large torques and forces produced at the shoulder during throwing. Capsular laxity, muscle weakness and fatigue affect the ability to maintain joint stability and increase potential damage caused by humeral translation
-Repetitive translation and subluxation of humeral head during arm acceleration and deceleration can result in labrum degeneration
-The extreme external rotation during throwing also makes the shoulder prone to injury. During ER of the abducted arm, humeral head translates anteriorly and the posterior rotator cuff becomes impinged between the glenoid labrum and humeral head. Impingement can cause degeneration of both superior labrum and rotator cuff called "over rotation" injury
-Due to the motions of arm deceleration, the inability to generate sufficient muscle force and torque can lead to humeral head translation which generates high tensile force on the capsule. Superior translation of humerus causes:
-Pain in follow-through phase may indicate posterior shoulder instability
-Rotator cuff tears are caused by the high forces generated along with shoulder motions during arm deceleration. Most tears located in area from mid-supraspinatus posterior to mid-infraspinatus
-Labral tearing can result from translation, subluxation, and compression of humeral head which induces entrapment of the labrum between humeral head and glenoid rim
-Humeral translation is possible due to large torques and forces produced at the shoulder during throwing. Capsular laxity, muscle weakness and fatigue affect the ability to maintain joint stability and increase potential damage caused by humeral translation
-Repetitive translation and subluxation of humeral head during arm acceleration and deceleration can result in labrum degeneration
-The extreme external rotation during throwing also makes the shoulder prone to injury. During ER of the abducted arm, humeral head translates anteriorly and the posterior rotator cuff becomes impinged between the glenoid labrum and humeral head. Impingement can cause degeneration of both superior labrum and rotator cuff called "over rotation" injury
-Due to the motions of arm deceleration, the inability to generate sufficient muscle force and torque can lead to humeral head translation which generates high tensile force on the capsule. Superior translation of humerus causes:
- impingement of greater tuberosity, rotator cuff muscles, or biceps against inferior acromion surface or coracoacromial ligament
- Supraspinatus, infraspinatus, bicipital tendinitis or abrasion
- results from repetitive overuse not trauma
- forces imparted by long head of biceps brachii during arm deceleration tear labrum away from the glenoid
-Pain in follow-through phase may indicate posterior shoulder instability
shoulder injuries during cocking/acceleration
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SHOULDER INJURIES DURING DECELERATION PHASE
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CORRELATION OF TORQUE AND INJURY
- There is a significant trend toward elbow injury with higher levels of both elbow valgus torque and shoulder external rotation torque. Higher levels of EV and SER torque during the late cocking phase of the pitch cycle can result in pitchers suffering elbow injury
- Humeral torque generated near time of maximum external rotation is likely to be related to pitcher's risk of suffering a humeral shaft fracture. Torsional loads result in high shear forces being generated in a plane 45 degrees from axis about which torque is produced. When the shear stress exceeds the shear strength of a bone, the result is a spiral fracture
- If all humeral torque is translated to the humeral shaft, a professional baseball player uses approximately 48% of his bone's shear strength capacity during each pitch