Elbow Injuries in the Athlete Christian Veillette M.D., M.Sc., FRCSC Assistant Professor, University of Toronto Shoulder & Elbow Reconstructive Surgery Toronto Western Hospital University Health Network Email: orthonet@gmail.com

Medial elbow problems in athletes Elbow is subjected to tremendous valgus stresses during overhead activities Specific injury patterns unique to the throwing athlete Forces generated with repetitive throwing are primarily concentrated on medial structures Medial elbow problems predominate in overhead athletes Majority of injuries are chronic, overuse injuries

Functional anatomy normal valgus carrying angle of 11 to 16o osseous configuration provides ~50% of the overall stability – varus stress + extension Remaining stability of the elbow provided by: anterior joint capsule ulnar collateral ligament (UCL) complex lateral collateral ligament complex

UCL Complex UCL complex composed of 3 portions Anterior bundle Anterior bundle – anterior/posterior bands Posterior bundle Oblique bundle (transverse ligament) Anterior bundle most important for valgus stability Eccentrically located Posterior band nearly isometric primary restraint to valgus stress with higher degrees of flexion

Musculotendinous anatomy flexor-pronator musculature provides dynamic functional resistance to valgus stress Proximal to distal pronator teres Flexor carpi radialis (FCR) palmaris longus flexor digitorum superficialis flexor carpi ulnaris (FCU)

Ulnar nerve

Cubital tunnel Floor – UCL Roof- Osborne/arcuate ligament Posterior – medial head triceps Anterior – medial epicondyle Lateral – olecranon

Biomechanics of throwing Stage I – windup initial preparation as the elbow is flexed and the forearm is slightly pronated Stage II – early cocking begins when the ball leaves the nondominant gloved hand and ends when the forward foot comes in contact with the ground The shoulder begins to abduct and externally rotate Stage III - late cocking further shoulder abduction and maximal external rotation, as well as elbow flexion between 90 and 120 degrees and increasing forearm pronation to 90 degrees. Stage IV - Rapid acceleration of the upper extremity generation of a large forward-directed force on the extremity by the shoulder musculature internal rotation and adduction of the humerus + rapid elbow extension terminates with ball release and occurs over a period of only 40 to 50 msec Elbow accelerates as much as 600,000 degrees/sec2 Stage V - follow-through dissipation of all excess kinetic energy as the elbow reaches full extension and ends when all motion is complete Rapid and forceful deceleration of the upper extremity occurs at a rate of almost 500,000 degrees/sec2 over a time span of 50 msec

Stage I - Windup

Stage II - Early cocking

Stage III - Late cocking

Stage IV - Acceleration

Stage V - Follow-through

Valgus instability Microtears of the UCL occur once the valgus forces generated during the cocking and acceleration phases of throwing exceed the intrinsic tensile strength of the UCL Improper throwing mechanics poor flexibility Inadequate conditioning attenuation and eventual rupture of UCL