Throwers Elbow

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Elbow Anatomy
Throwing Motion


Overhand throwing places multiple stresses on the elbow joint. These stresses place demands on vulnerable immature elbows that can cause numerous injuries. Persistent elbow soreness, stiffness, and discomfort can lead not only poor performance but can be significant indicators of debilitating injuries.

Baseball is one of the most popular participation sports for children in the USA, but repeated throwing, in skeletally immature athletes, can produce elbow injuries that threaten proper growth. It is estimated that 40% of 9 - 12 year old throwing athletes sustain elbow injuries requiring medical intervention. Athletic Trainers, physicians, and parents should be aware that persistent elbow pain after throwing can be a sign of a significant injury.

The skeletally immature elbow has secondary growth centers at the distal humerus (lower arm) radial head (thumb side of the forearm) and olecranon (tip of the elbow). When these structures are subjected to the stress of overhand throwing, the growth plates (physes) are vulnerable to injuries more than the adjacent muscles and tendons. The act of throwing places compressive forces on the lateral elbow, specifically the radial head and capitellum of the humerus. It also places distractive forces on the ulnar collateral ligament (MCL). Both of these forces can result in debilitating injuries that have lifelong implications.

These stresses are felt during the acceleration and follow-through phases of pitching. These phases place a valgus stress on the elbow, resulting in distraction forces on the medial joint complex and compressive forces on the radiocapitellar joint. Repeated overuse, exacerbated by poor mechanics, will result in failure of the tissues on either side of the elbow.


The distractive forces on the medial elbow can result in damage to the growth plates in skeletally immature athletes and disruption of the MCL in the mature athlete. Both of these injuries are potential career ending injuries.

The skeletally mature athlete will often times tear the ligament rather than avulsing it from the bone. These injuries result in a reconstructive surgery referred to as “Tommy John Surgery.” This is named for the first athlete that successfully returned to professional baseball following an MCL reconstruction.

The skeletally immature athlete is at potential risk for an avulsion fracture of the MCL from the medial epicondyle of the humerus. This type of injury may not be due to a one-time injury, but rather the result of repetitive stress. Due to this coaches and parents must be aware of soreness after throwing that does not resolve within 24 hours. Post exercise soreness should resolve with in one day of the activity, pain that lingers longer may be a sign of significant injury.

Signs and symptoms of a medial compartment injury are: medial joint tenderness, pain with a valgus stress test, diffuse medial pain while palpating the flexor muscle wad, and pain with resisted pronation. The medial musculature becomes symptomatic while acting as a secondary restraint for the injured MCL.

In the event of persistent medial elbow pain, a physician should be consulted to rule out ligamentous injury. Bilateral x-rays should be performed to compare the amount of medial apophyseal separation at the distal humerus. A separation of greater than 3 mm is an indication for a surgical repair.

Treatment for the non-surgical cases should include rest and rehabilitation exercises. The athlete should not throw a ball until the elbow is completely pain free and full strength has returned. Rehabilitation exercises should focus on wrist flexors and extensors, forearm pronators and supinators, as well as the shoulder musculature. After the athlete is pain free he/she should begin an interval throwing program, gradually returning to full throwing activities. Any pain during the interval throwing program should be evaluated and the throwing progression adjusted to compensate.


The same valgus stress that can lead to medial compartment injuries also place compressive forces on the lateral compartment that can result in damage. These compressive forces cause the radial head to impinge on the capitellum of the humerus. The capitellum has a tenuous vascular supply that makes this area predisposed to bony necrosis or osteochondritis dissecans (OCD). Some researchers feel there may also be a genetic predisposition for the formation of an OCD.

The repetitive forces of throwing cause subchondral (below the joint surface cartilage) bone fatigue that results in microfractures. Repeated trauma and the limited blood supply to the area, does not allow these fractures to heal. This results in bone resorption and separation of an osteochondral fragment from its underlying bed. Without the osseous structural support, this separated fragment becomes avascular resulting a partial or complete loose body.

The resulting loose body can then impinge on other areas in the joint causing further damage. X-rays may also show radial head hypertorphy. This is a result of the increased surface contact with the capitellum.

Signs and symptoms of this type of injury include: loss of full range of motion, most commonly in a loss of extension; pain with throwing that does not resolve after rest; swelling; grinding with elbow motion; and a decrease in performance.

This injury usually results in surgical intervention to correct the damage. If this injury is not treated appropriately the damage to the joint surfaces may result in permanent loss of normal joint function. Many athletes who have dealt with this injury have complications that include: lack of full extension, loss of normal pronation and supination, and incontractable pain.



©2000 - 2009 David Edell

Information on this site is not a substitute for physician directed care.

Please consult your personal physician for more detailed information

concerning specific injuries or illnesses.

Last Update for 10/24/2009 12:09:35 AM