Section 6
SPORTS-SPECIFIC CONSIDERATIONS
76 BASEBALL
James R Morales, MD
Dennis A Cardone, DOOVERVIEW
- America’s pastime is one of the most popular sports
played today. It has been estimated that more than
19 million children are involved in youth baseball in
the United States (Janda et al, 1998). - Although classified as a “limited contact” sport, the
incidence of injury ranges between 2 and 8% of par-
ticipants per year (Roberts, 2001). - Serious injuries are associated with blunt chest impact
and head and eye trauma. Most injuries involve soft
tissue trauma or throwing injuries.
BACKGROUND
- Biomechanicsof overhand throwing depends on ade-
quate transfer of momentum. This kinetic energy is
produced from larger slower muscles and transferred
to smaller faster body parts (Newsham et al, 1998). - Anatomyof the shoulder includes the sternoclavicular
joint, acromioclavicular joint, glenohumeral joint, and
scapulothoracic joint. The glenohumeral joint is a
complex joint involving many stabilizers including,
the joint capsule, glenoid labrum, glenohumeral liga-
ments, and the rotator cuff. - Anatomyof the elbow includes the humeroulnar joint,
humeroradial joint, and the radioulnar joint. Further
components are the medial and lateral collateral liga-
ment complexes. Musculature of the elbow includes
biceps brachii, bracioradialis, brachialis, triceps,
aconeus, as well as the supinators and pronators.
•Five phases of throwing: (1) Windup begins with initial
movement of pitcher, the deltoid abducts arm, and ends
when hands come apart or ball leaves nondominant
hand. (2) Early cocking begins when hands come apart,
the deltoid abducts arm, infraspinatus and teres minor
externally rotate the shoulder, and ends when front leg
is extended and strikes ground. (3) Late cocking begins
when front foot strikes the ground, glenohumeral joint
externally rotates, and ends when shoulder is maxi-
mally externally rotated. (4) Acceleration begins with
ball moving forward, horizontal adduction and internal
rotation of shoulder, and ends when ball is released. (5)
Deceleration begins at ball release and ends when
motion stops.- Deliveriesinclude overhead, three quarters, and side-
arm, each with their own specific risks.
COMMON INJURIES- Rotator cuff injuriesvary from mild forms of tendinitis
and impingement to complete tears. It is often due to
overuse and/or joint instability. Examination findings
include positive Neer’s sign, positive Hawkin’s sign,
and pain and weakness with muscle testing. Treatment
varies from NSAIDs and physical therapy to surgery,
depending on severity. - Instabilityis often related to a rotator cuff injury and
can be due to trauma, poor mechanics and/or overuse.
Symptoms include pain with acceleration. Exami-
nation findings include positive relocation test, laxity,
and weakness with muscle testing. Treatment includes
rehabilitation and in some cases surgery. - Glenoid labrum injuriesmay occur due to trauma,
instability, poor mechanics and/or changes in throw-
ing and training. Symptoms include painful clicking,
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