Elbow and Forearm Overuse Injuries

Overuse injuries to the forearm and elbow are very common in throwing and racquet sports. ^{[5, 6, 7, 8, 9, 10, 11]} Any activity that entails repetitive flexion-extension of the elbow or pronation-supination of the wrist can lead to overuse injuries.

Among high school athletes, sport specialization is associated with upper-extremity overuse injuries. A study by Post et al found that high school athletes who played baseball for more than 8 months per year and those who were pitchers were more likely to have a history of upper-extremity overuse injury. ^[12]

As the number of recreational athletes increases, the incidence of overuse injuries increases. ^[13] The physician must obtain a very comprehensive history when dealing with these injuries because a subtle finding often can determine the proper diagnosis. ^{[8, 9, 11, 14, 15, 16]} Obtaining a vocational history is also very important because many skilled laborers or assembly line workers perform the same offending motion at work.

Related Medscape Reference topics

Biceps Tendinopathy

Little League Elbow Syndrome

Nerve Entrapment Syndromes

Related Medscape resources

Resource Center Exercise and Sports Medicine

Resource Center Trauma

Causes of elbow and forearm overuse injuries are as follows:

• Biceps tendinosis

  • This injury is caused by repetitive microtrauma in most cases. Occasionally, biceps tendinosis can be caused by an intense bout of exercise that produces tendon injury, which is never allowed to heal and perpetuates into a tendinosis.

  • This overuse syndrome is caused by repetitive elbow flexion against resistance or repetitive forearm supination.

• Anterior capsule strain: Either a single event or repetitive hyperextension of the elbow causes anterior capsule strain.

• Pronator syndrome

  • Pronator syndrome is a nerve entrapment syndrome and can occur at multiple sites along the course of the median nerve through the forearm.

  • The most common site of entrapment is under the hypertrophied head of the pronator muscle.

  • Entrapment can also occur under the lacertus fibrosus, or bicipital aponeurosis, at the elbow or under the flexor digitorum superficialis.

• Radial tunnel syndrome

  • This condition is another nerve entrapment syndrome; the radial nerve is most commonly entrapped at the arcade of Frohse.

  • The entrapment can also occur distally at the supinator muscle.

  • There have been case reports of nerve entrapment at the margin of the extensor carpi radialis brevis and under the fibrous band in front of the radial head.

• Triceps tendinosis: This tendinosis is an overuse syndrome caused by repetitive elbow extension against resistance.

• Olecranon impingement syndrome

  • Olecranon impingement syndrome is caused by repetitive elbow extension, in which a valgus stress is applied to the elbow.

  • This syndrome often occurs with overhead throwing and tennis strokes.

• Olecranon stress fractures

  • These stress fractures result from an explosive varus and valgus force that is put on the elbow during throwing.

  • These motions often occur in baseball pitchers and javelin throwers and cause the olecranon to be forced against the medial or posterior walls of the olecranon fossa.

• Radiocapitellar chondromalacia

  • This condition is caused by repetitive valgus stress, which compresses the radial head into the capitellum.

  • Radiocapitellar chondromalacia can result in bone bruises, osteochondral injury, or even loose-body formation.

• Posterolateral rotatory instability: This instability is a direct result of a posterior elbow dislocation and results in a laxity of the ulnar portion of the lateral collateral ligaments of the elbow.

United States data

The frequency of elbow and forearm overuse injuries is difficult to determine because of the multiple comorbid states and diagnoses that are possible (see Differentials and Other Problems to Be Considered). Some of these are covered in this article.

Bunstine et al reported that most overuse injuries that occurred among US high school baseball and softball players were to an upper extremity (72.5% of such injuries among male athletes and 53.7% among female athletes). ^[17]

International data

A study by Lau and Mukherjee found that the prevalence of elbow overuse injuries was 9.2% among competitive overhead athletes aged 12-18 years in Singapore. ^[18]

The elbow is a complex joint that consists of 3 true joints that function as 1 joint. ^{[1, 2]} The humeroulnar joint is a modified hinge joint and allows flexion and extension. The humeroradial joint functions not only as a hinge joint to allow flexion and extension, but also as a pivot joint that allows rotation of the radial head on the capitellum. The proximal radioulnar joint allows supination and pronation to occur. The combined motion of these joints allows a range of motion from 5-150º of flexion-extension and 75º of pronation to 80º of supination. Remember that the olecranon process of the ulna sits in the humeral olecranon fossa in 20º or less of flexion.

The ligamentous structures can be divided into the lateral and medial structures. ^{[1, 2]} These ligaments are better described as thickenings of the capsule, rather than true ligaments. Of the 3 medial structures, the anterior medial collateral ligament (AMCL) is the most important, providing approximately 70% of the valgus stability of the elbow. On the lateral side, the lateral ulnar collateral ligament (LUCL) is the strongest of the 4 branches, providing varus support.

The annular ligament maintains the radial head position in the radial notch of the humerus. Dynamic stability is provided by 4 muscle groups that transverse the elbow. The biceps brachii, brachioradialis, and brachialis muscles are the major flexors of the elbow joint. The triceps and anconeus muscles achieve extension. The supinator and biceps brachii muscles provide supination. Pronation is achieved through the pronator quadratus, pronator teres, and flexor carpi radialis muscles.

Understanding where the 3 major nerves cross the elbow is also very important. Overuse injuries or direct trauma can affect these nerves. The median nerve crosses the joint medially between the 2 heads of the pronator muscle and consists of fibers from the C5-T1 spinal nerves. The ulnar nerve travels posterior to the medial epicondyle in the cubital tunnel, down the posterior medial side of the forearm and crosses the wrist in the Guyon canal. This nerve is composed of fibers from C8 and T1 spinal nerves. ^[19] The radial nerve crosses the elbow laterally and branches into the superficial (sensory) and posterior interosseous nerve, which is purely motor in innervation. This branch goes deep through the arcade of Frohse, which is a common site of entrapment. The radial nerve is made up of branches from the C5-C7 spinal nerves.

Repetitive elbow flexion can cause biceps tendinosis or anterior capsule strain. Activity that involves forceful elbow extension can cause triceps tendinosis or posterior impingement syndrome. In addition, any activity that causes increased valgus stress on the elbow can also cause ulnar nerve injury, posterior impingement syndrome, or olecranon stress fractures. These injuries are common in throwing sports and overhead racquet sports. Sports that require a great deal of wrist flexion-extension or pronation-supination can lead to pronator syndrome or radial tunnel syndrome. Posterolateral rotatory instability is seen only after a posterior elbow dislocation.

Related Medscape Reference topics

Biceps Tendinopathy

Imaging of Elbow Fractures and Dislocations in Adults

Little League Elbow Syndrome

Nerve Entrapment Syndromes

Ulnar Nerve Entrapment

Related Medscape resources

Resource Center Exercise and Sports Medicine

Resource Center Trauma

The prognosis of most overuse injuries is very good, as long as the athlete completes a thorough rehabilitation program. The correction of any training or biomechanical errors that caused the original overload is also very important.

Complications

The major complication of overuse syndromes is the individual returning to the same poor habits that caused the original insult. Care must be taken when correcting the biomechanics of an injury, in order not to cause overuse injuries at another point in the kinetic chain. Very rarely, permanent nerve damage can result from nerve entrapment syndromes.