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Little League Shoulder

Little League Shoulder, also known as “proximal humeral epiphysiolysis” in medical terms, refers to a stress injury that affects the growth plate of the shoulder in athletes who are still in the process of skeletal maturation. The closure of the shoulder’s growth plate usually takes place between the ages of 18 and 21. Little League Shoulder primarily affects young baseball players, especially pitchers between the ages of 11 and 16, when the growth plate is most vulnerable to injury. However, in theory, this injury can occur at any age until the growth plate closes. Although this condition is commonly associated with youth baseball players and throwing athletes, competitive gymnasts and tennis players are also susceptible to experiencing this type of injury.

Little League Shoulder develops as a consequence of repetitive overhead throwing, which subjects the shoulder to excessive rotational and distractional forces. The repetitive microtrauma caused by these forces leads to cartilage damage in the proximal humeral epiphysis. Notably, the rotational forces exerted on the shoulder are believed to play a more significant role than the distractional force in the development of this condition.

The growth plate, known as the epiphyseal plate, is a specialized region of developing tissue found near the ends of long bones such as the legs, arms, and fingers. It plays a crucial role in bone development during childhood and adolescence, enabling bone growth and elongation. Over time, as an individual’s skeleton matures, the growth plate transforms from a soft cartilage area into solid bone. Interestingly, during the shoulder’s growth phase, the adjacent rotator cuff tendons and ligaments are stronger compared to the soft cartilage of the growth plate. This leads to a higher susceptibility to growth plate injuries rather than tendon injuries in young athletes with open growth plates. In contrast, individuals with fully matured skeletons are more prone to tendon injuries. Recognizing these distinctions is essential for effectively managing and preventing injuries in young athletes.

The throwing motion consists of two distinct phases: the arm-cocking phase and the acceleration phase. Towards the end of the arm-cocking phase, just before the forward arm acceleration, significant external rotational torque is applied to the shoulder growth plate, resulting in shear stress across the plate. The growth plate is more vulnerable to torsional stress rather than tensile distraction stress. Therefore, the primary stress that leads to Little League Shoulder occurs during the final stage of arm-cocking.

In the subsequent acceleration phase, the rotator cuff muscles contract to maintain the stability of the glenohumeral joint. These muscles exert a tensile distraction force on the proximal humerus because their attachment site is located proximal to the proximal humeral epiphysis. However, the tensile distraction force during the acceleration phase has a lesser impact on the growth plate compared to the twisting rotational force experienced during the arm-cocking phase.

Having a previous elbow injury in the same arm can heighten the chances of developing Little League Shoulder. This is because experiencing discomfort in the elbow may cause a child to consciously or unconsciously modify their throwing mechanics to alleviate the prior pain in the elbow. By altering their mechanics, the child may inadvertently increase the risk of injury by redistributing forces across the humerus in a different manner.

Furthermore, a recent growth spurt further amplifies the vulnerability of the growing child to proximal humeral epiphysiolysis. During periods of rapid growth, the cartilage in the growth plate is at its weakest and most susceptible to injury. As a result, the combination of altered throwing mechanics and the weakened state of the growth plate due to rapid growth significantly increases the risk of developing Little League Shoulder.

Common symptoms of Little League Shoulder usually involve a gradual onset of generalized shoulder pain during throwing, which tends to improve with rest. As the condition progresses, the pain may arise even with simple arm lifting and could be present even at rest. Other symptoms can manifest as a decline in throwing accuracy and/or velocity. Additionally, approximately ten to fifteen percent of patients may experience elbow pain in the same arm, in addition to shoulder pain.

During a physical examination, patients with Little League Shoulder often exhibit tenderness when pressure is applied to the outer aspect of the shoulder. There might be slight swelling, but overall visual inspection and palpation appear normal. The severity of the condition can result in reduced shoulder range of motion and weakness. Weakness is typically attributed to protective guarding mechanisms in response to pain.

The diagnosis of Little League Shoulder primarily relies on clinical suspicion. In most cases, routine X-rays may appear normal, showing no abnormalities in the growth plate. However, a definitive diagnosis can be made by comparing X-rays of the affected shoulder with those of the opposite asymptomatic shoulder. This comparison may reveal a widened growth plate in the affected shoulder. In more chronic and advanced cases, X-rays may also show signs of sclerosis, demineralization, and fragmentation. In some instances, ultrasound can assist in the diagnosis when performed skillfully. Although often unnecessary, an MRI can be used if X-rays do not provide conclusive results. MRI scans would reveal edema around the growth plate, confirming the diagnosis.

Early intervention by discontinuing activities that cause pain can help prevent a full stress fracture of the growth plate in Little League Shoulder. When caught early, pain typically resolves within four weeks with adequate rest. However, once a stress fracture occurs, treatment for Little League Shoulder can extend to three to six months, requiring complete cessation of overhead activities. Once the pain has subsided at rest, treatment can progress with the assistance of a physical therapist.

Gradual rehabilitation includes restoring range of motion, strength, and scapular motion to normal levels. Following this, a structured throwing program can be implemented, gradually reintroducing throwing activities. Only after these milestones are achieved should a return to competitive play be considered. The entire treatment and recovery process can last up to one year, highlighting the significance of preventive measures such as maintaining proper throwing mechanics, monitoring pitch count, regulating throwing intensity, and promptly addressing any complaints or symptoms expressed by the child.