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What is the Growth Plate?


Growth plates, referred to as physis or physeal plates, can be found at the ends of long bones in children and teenagers. These specialized regions of cartilage play a crucial role in the longitudinal growth and maturation of bones.

Throughout childhood and adolescence, the lengthening of long bones occurs primarily through a gradual transformation process. Over the course of several years during adolescent growth, these cartilaginous regions undergo a gradual conversion into solid bone tissue, signifying the completion of the growth phase.

The growth plate is composed of multiple layers of specialized cartilage cells. These cells undergo division and multiplication, resulting in the generation of new cartilage. Simultaneously, as the new cartilage develops, the older cartilage cells at the plate’s end progressively transition into bone tissue. It is this transformative process that facilitates bone lengthening. It is worth noting that during the initial stages and throughout the years of adolescent growth spurts, the cartilage cells are at their softest, weakest, and consequently most susceptible to injury.

In the event of an injury to a growth plate, the regular growth process can be disrupted, possibly resulting in growth abnormalities or deformities. Consequently, it is crucial to safeguard these regions during activities that pose a risk of harm, such as sports or physically demanding pursuits. By taking appropriate precautions, we can help minimize the chances of injury and maintain the healthy progression of growth in children and adolescents.

Upon reaching the conclusion of puberty, known as skeletal maturity, the growth plates undergo closure and are substituted with solid bone, signifying the cessation of longitudinal bone growth. At this stage, the bones have attained their maximum length, and any additional growth is not possible. The closure of the growth plates is influenced by various factors, such as genetics, hormones, and overall health, all playing a role in determining the timing and extent of this process.

Young athletes who are still in the process of skeletal development place significant stress on various parts of their bodies, whether it be through throwing, running, jumping, participating in contact sports, or engaging in strength training. It is often said that any chain is only as strong as its weakest link. In adults, the weak link tends to be the tendons and ligaments, meaning that these structures absorb the maximum stress, resulting in conditions like tendinitis or ligament sprains. However, in growing children, the stress is absorbed by the weakest parts of the bones, namely the cartilage at the ends of the bones. The cartilage in the growth plates is considerably weaker compared to the surrounding ligaments and muscles that attach to it. Consequently, skeletally immature athletes are more prone to injuries in their growth plates, as opposed to ligament and tendon injuries seen in adults. Once the growth plates have fused, athletes are more likely to experience injuries in their ligaments and tendons instead.

Mechanisms of Injury

There are two primary mechanisms through which the growth plate can sustain injuries: 1) Traction tensile stress and 2) Crushing compression stress.

Tensile stress predominantly arises from repetitive overuse, commonly observed in athletes involved in throwing activities. These injuries commonly affect the shoulder or elbow joints of throwing athletes. The intensive and repetitive nature of throwing can lead to a range of injuries, ranging from microtrauma and cartilage cell damage to more severe cases where the growth plate separates and fractures due to the forces exerted by the attached ligaments and tendons.

Compression or crush injuries can occur due to acute falls, direct impacts, or repetitive compressive forces that surpass the threshold of cartilage cell health over time. In throwing activities, repetitive compressive forces are often exerted on the outer aspect of the elbow during the cocking and acceleration phases, potentially leading to growth plate damage in that region. However, it is a common misconception regarding heavy weight strength training and its impact on growth plates. Fortunately, there is no evidence to suggest that weight lifting affects the growth plates through compressive crushing forces.

Among the two mechanisms of growth plate injuries, tensile traction stress is the primary concern for skeletally immature athletes, barring falls or direct injuries. The population most affected by this type of injury are baseball pitchers, although any competitive throwing athletes, gymnasts, and tennis players are also susceptible. Shoulder injuries, known as Little League Shoulder, typically occur between the ages of 11 and 16 due to varying vulnerability periods for growth plates. Elbow injuries, referred to as Little League Elbow, usually manifest between the ages of 9 and 14. However, it is important to note that these injuries can theoretically occur at any age before the closure of the growth plates, which typically takes place between the ages of 16 and 20 for the shoulder and elbow.

Signs, Symptoms, and Diagnosis

The typical symptoms of Little League Shoulder or Little League Elbow involve a gradual onset of generalized pain in the shoulder or elbow during throwing activities. Initially, symptoms tend to improve with rest. However, as the condition progresses, the pain may persist even during simple arm movements and may be present even at rest. Other accompanying symptoms include a decline in throwing accuracy and/or velocity. It is worth noting that approximately ten to fifteen percent of patients may experience concurrent pain in both the shoulder and elbow.

During physical examination, tenderness is observed when pressure is applied to the affected area. While there may be slight swelling, visual inspection and palpation generally appear normal. The severity of the condition can lead to a decrease in range of motion and muscle weakness. The weakness is often attributed to protective guarding mechanisms triggered by pain during movement.

The diagnosis of Little League Shoulder or elbow primarily relies on a high level of clinical suspicion. In most instances, routine X-rays may appear normal, displaying no abnormalities in the growth plate. However, a definitive diagnosis can be reached when the affected shoulder or elbow shows widened growth plates on X-ray imaging. In more chronic and advanced cases, X-rays may also reveal signs of sclerosis, demineralization, and fragmentation. In some situations, ultrasound can be utilized to assist in the diagnosis. While often unnecessary, an MRI scan can be employed if X-rays do not yield conclusive results. MRI scans would exhibit edema around the growth plate, providing confirmation of the diagnosis.

Management and Prevention

Taking early action by discontinuing activities that induce pain can aid in preventing a complete stress fracture of the growth plate. With prompt treatment and sufficient rest, pain typically resolves within approximately four weeks. However, once a stress fracture has occurred, the treatment duration can extend from three to six months, necessitating the complete cessation of overhead activities. Once the pain subsides at rest, treatment can progress with the guidance of a physical therapist.

The progressive rehabilitation process aims to restore normal levels of range of motion, strength, and scapular motion. Once these aspects are successfully rehabilitated, a structured throwing program is initiated, gradually reintroducing throwing activities. It is crucial to achieve these milestones before contemplating a return to competitive play. The entire treatment and recovery journey can extend up to one year, underscoring the importance of preventive measures. These include maintaining proper throwing mechanics, monitoring pitch count, regulating throwing intensity, and promptly addressing any complaints or symptoms expressed by the child.

In the majority of cases, Little League Elbow does not require surgical treatment, however in more severely involved cases with a fracture to a part of the elbow, surgery may be necessary. Likewise, it is rare for Little League Shoulder to require surgery, unless the affected growth plates are severely injured.

Prevention plays a pivotal role in effectively managing Little League Shoulder or elbow. It is important to pay close attention to the number of pitches thrown and the specific types of pitches utilized by the pitcher. Higher stress pitches, such as curveballs or breaking balls, should be avoided until the pitcher reaches the appropriate age of skeletal maturity. By implementing these preventive measures, the risk of growth plate injuries can be significantly reduced, thereby promoting the long-term health and well-being of young athletes.

It is strongly advisable to follow the guidelines provided by reputable organizations such as Little League® Baseball, the world’s largest organized youth sports program, or the American Academy of Orthopedic Surgeons’ Guide to Safety for Young Athletes. These resources offer valuable recommendations and safety measures that should be adhered to in order to protect the well-being of young athletes. By following these guidelines, we can ensure a safer and more secure sports environment for our youth.

Safeguard the well-being of young throwing athletes. Prioritize injury prevention!