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Overhand throwing places extremely high stresses on the elbow. In baseball pitchers and other throwing athletes, these high stresses are repeated many times and can lead to serious overuse injury.
Unlike an acute injury that results from a fall or collision with another player, an overuse injury occurs gradually over time. In many cases, overuse injuries develop when an athletic movement is repeated often during single periods of play, and when these periods of play — games, practices — are so frequent that the body does not have enough time to rest and heal.
Although throwing injuries in the elbow most commonly occur in pitchers, they can be seen in any athlete who participates in repetitive overhand throwing.
Common Throwing Injuries of the Elbow
When athletes throw repeatedly at high speed, the repetitive stresses can lead to a wide range of overuse injuries. Problems most often occur at the inside of the elbow because considerable force is concentrated over the inner elbow during throwing.
Repetitive throwing can irritate and inflame the flexor/pronator tendons where they attach to the humerus bone on the inner side of the elbow. Athletes will have pain on the inside of the elbow when throwing, and if the tendinitis is severe, pain will also occur during rest.
The ulnar collateral ligament (UCL) is the most commonly injured ligament in throwers. Injuries of the UCL can range from minor damage and inflammation to a complete tear of the ligament. Athletes will have pain on the inside of the elbow, and frequently notice decreased throwing velocity.
During the throwing motion, the olecranon and humerus bones are twisted and forced against each other. Over time, this can lead to valgus extension overload (VEO), a condition in which the protective cartilage on the olecranon is worn away and abnormal overgrowth of bone — called bone spurs or osteophytes — develop. Athletes with VEO experience swelling and pain at the site of maximum contact between the bones.
Stress fractures occur when muscles become fatigued and are unable to absorb added shock. Eventually, the fatigued muscle transfers the overload of stress to the bone, causing a tiny crack called a stress fracture.
The olecranon is the most common location for stress fractures in throwers. Athletes will notice aching pain over the surface of the olecranon on the underside of the elbow. This pain is worst during throwing or other strenuous activity, and occasionally occurs during rest.
When the elbow is bent, the ulnar nerve stretches around the bony bump at the end of the humerus. In throwing athletes, the ulnar nerve is stretched repeatedly, and can even slip out of place, causing painful snapping. This stretching or snapping leads to irritation of the nerve, a condition called ulnar neuritis.
Throwers with ulnar neuritis will notice pain that resembles electric shocks starting at the inner elbow (often called the "funny bone") and running along the nerve as it passes into the forearm. Numbness, tingling, or pain in the small and ring fingers may occur during or immediately after throwing and may also persist during periods of rest.
Ulnar neuritis can also occur in non-throwers, who frequently notice these same symptoms when first waking up in the morning, or when holding the elbow in a bent position for prolonged periods.
Elbow injuries in throwers are usually the result of overuse and repetitive high stresses. In many cases, pain will resolve when the athlete stops throwing. It is uncommon for many of these injuries to occur in non-throwers.
In baseball pitchers, rate of injury is highly related to the number of pitches thrown, the number of innings pitched, and the number of months spent pitching each year. Taller and heavier pitchers, pitchers who throw with higher velocity, and those who participate in showcases are also at higher risk of injury. Pitchers who throw with arm pain or while fatigued have the highest rate of injury.
Most of these conditions initially cause pain during or after throwing. They will often limit the ability to throw or decrease throwing velocity. In the case of ulnar neuritis, the athlete will frequently experience numbness and tingling of the elbow, forearm, or hand as described above.
During an examination, the doctor will check the range of motion, strength, and stability of the elbow. The doctor will ask the athlete to identify the area of greatest pain and will frequently use direct pressure over several distinct areas to try to pinpoint the exact location of the pain.
The doctor may perform the valgus stress test to determine if the elbow is loose. The results of these tests help the doctor decide if additional testing or imaging of the elbow is necessary.