Musculoskeletal injuries in the young individual compared to the adult can be very different. The major reason is that younger, skeletally immature individuals have growth plates at the ends of their bones which are what makes the bone grow longer and larger as the person advances in age.
The growth plate is also known as the epiphyseal plate or physis; it is the area of growing cartilage near the ends of bones in children and adolescents. Each long bone has at least two growth plates at each end. The growth plate determines the future length and shape of the mature bone. When growth is complete, the growth plates close and are replaced by solid bone. As a definition, the epiphysis is at the end of a long bone, which is initially separated by cartilage from the shaft of the bone and develops separately. It eventually fuses with the shaft (diaphysis) of the bone to form a complete bone. Metaphysis is the growing portion of a long bone that lies between the ends of the bones (epiphyses) and the shaft (diaphysis). The physis or growth plate is the cartilage region between the epiphysis and the metaphysis. This is the area of concern in the growing individual.
Growth plate injuries are caused by many reasons but the most common injuries are usually due to an event, such as a fall or trauma to the limb. They can also result from overuse, especially in sports such as soccer, football, baseball, and gymnastics. Growth plate injuries are prevalent because the growth plate is the weakest part of the bone.
Many growth plate injuries can be seen in the young athlete. Little league shoulder and elbow are common in those who pitch or throw. These are traction injuries, which stress the growth plate of the shoulder and elbow respectively and require strict change in the amount, duration, and technique of throwing. Slipped capital epiphysis of the hip is another problem that is seen in the growing individual with hip or referred knee pain and asymmetry between motion of the two hips. Unlike traction injuries, this has to be treated surgically for stabilization of the hip femoral epiphysis. Sever’s disease, also called calcaneal apophysitis, is a painful bone disorder that results from inflammation of the growth plate in the heel. When there is pain and tenderness near the bottom of the kneecap, the problem might be from jumper’s knee. Sports that require a lot of kicking, jumping, or running can affect this part of the knee the most. Doing these actions over and over can lead to pain in the tendon that stretches over the front of the kneecap. Sometimes the bone growth center at the bottom tip of the kneecap is also affected. This condition is known as Sinding-Larsen-Johansson disorder. Disruption within the developing bone in the bottom tip of the kneecap may produce pain and tenderness in the front of the knee. Fortunately, this condition is not serious. It is usually only temporary and will improve with age. Traction at the tibial tuberosity can also be a reason for pain in the front of the knee but lower than the kneecap. This is called Osgood-Schlatter Syndrome and is characterized by proximal anterior tibia pain resulting from inflammation at the tendon-bone junction of the patellar tendon and its insertion on the anterior tibial tubercle.1 These are just a few examples where traction on the growth plate from repetitive activities can cause pain in the young athlete. Knowledge of the growth plates, especially in the long bones including the femur, tibia, and humerus, can raise the suspicion for possible injury and therefore provide appropriate treatment to the young individual.
Although many growth plate injuries are caused by accidents or overuse that occur during play or athletic activity, growth plates are also susceptible to other disorders. Bone infection can alter normal growth and should be aggressively treated. Injury from extreme cold can damage the growth plate in children and result in short, stubby fingers or premature degenerative arthritis. Radiation and medications may negatively affect bone growth. Prolonged use of steroids for inflammatory conditions such as juvenile idiopathic arthritis can also harm bone growth. Neurological disorders that result in sensory deficit or muscular imbalance are prone to growth plate fractures and abnormal biomechanical traction on the growth plate region. Genetics can affect growth plates proper growth. Child abuse should be considered in certain types of fracture configurations or multiple fractures at different phases of healing. Metabolic disease such as kidney failure and hormone disorders can also affect the growth plates and their function.
However, since sports overuse injuries are more common, this is where attention should be focused. The coach or trainer must have understanding of the importance of identifying the child who may have a growth plate injury. Any child who has persistent pain while involved in sports, or pain that affects their athletic performance or the ability to move should not be allowed or expected to “work through the pain.” Any change in function of the individual should be assessed, since in the growing individual the growth plate is the weakest link rather than the tendons or ligaments. Where an adult may have a ligament or tendon sprain/strain, a younger growing child will likely have a growth plate injury which is treated as a fracture rather than a sprain or strain. Very often the x-ray is negative, because the growth plate line is already there, and the fracture is nondisplaced but pain is a guide to suspicion. The doctor can still diagnose a growth plate fracture on clinical grounds because of tenderness over the plate. Many injuries are approached and treated based on clinical information rather than radiographic studies.
In comparison to overuse traction injuries to the growth plate, the other common type of growth plate injuries are fractures. There is a variation of the injury pattern to the growth plate called the Salter-Harris classification. This classification has classically been divided into five types based on the fracture configuration as seen radiographically.
Salter-Harris Classification of Injury to Growth Plates
|Type I Fracture|
|The epiphysis is separated from the end of the bone or the metaphysis, through the deep layer of the growth plate. The growth plate remains attached to the epiphysis.||Type I injuries generally require a cast to protect the growth plate as it heals.
Unless there is damage to the blood supply to the growth plate, the likelihood that the bone will grow normally is excellent.
|Type II Fracture|
|This fracture is through the growth plate and metaphysis, but the epiphysis is not involved in the injury.||Like Type I fractures, Type II fractures may need to be put back into place and immobilized. However, the growth plate fracture has excellent potential to heal, especially in the very young. If it is not too displaced, the doctor may not need to put it back into position since remodeling potential of the bone is also very good.|
|Type III Fracture|
|The fracture plane is through the growth plate and epiphysis. The fracture runs completely through the epiphysis and separates part of the epiphysis and growth plate from the metaphysis.||Surgery is sometimes necessary to restore the joint surface to normal.
The outlook or prognosis for growth is good if the blood supply to the separated portion of the epiphysis is still intact and if the joint surface heals in a normal position.
|Type IV Fracture|
|This fracture runs through the epiphysis, across the growth plate, and into the metaphysis.||Surgery is frequently needed to restore the joint surface to normal and to perfectly align the growth plate.
Unless perfect alignment is achieved and maintained during healing, prognosis for growth can be poor, and angulation of the bone may occur.
|Type V Fracture|
|Type V is a compression fracture through growth plate. This uncommon injury occurs when the end of the bone is crushed and the growth plate is compressed.||Prognosis may be poor, since premature stunting of growth is almost inevitable and the growth plate is damaged.|
There is also a newer classification, called the Peterson classification, which adds a type VI fracture in which a portion of the epiphysis, growth plate, and metaphysis is missing and generally occurs with significant open type of injuries associated with significant wounds. Bone abnormality usually occurs since growth of the bone is affected.2,3
In conclusion, growth plate injuries may be common in the young individual and careful attention to the young athlete is important since many of these injuries, when diagnosed early enough, can be treated nonsurgically and allow the individual to get back to sports within a reasonable amount of time. Overuse injuries and growth plate fractures are the most common type of growth plate injuries and should be kept in mind as part of the diagnosis in the young, skeletally immature individual.
- Lower Extremity Injuries in the Skeletally Immature Athlete. Frank JB, Jarit GJ, Bravman JT, Rosen JE. Journal Am Acad Orthop Surg. June 2007 ; 15:356-366.
- Fractures Around the Knee in Children. Zionts LE. Journal Am Acad Orthop Surg September/October 2002; 10:345-355.
- Lovell and Winter’s Pediatric Orthopaedics. Lovell WW, Winter RB, Morrissy RT, Weinstein SL. Lippincott Williams & Wilkins, 2006.