Apophysitis refers to irritation and inflammation of the apophysis, a secondary ossification center which acts as an insertion site for a tendon. It is a common overuse injury in young athletes. In a growing athlete the apophysis is susceptible to injury because of repetitive stress or an acute avulsion injury. An avulsion fracture usually occurs with sudden muscle contractions where a small piece of bone is torn away from its origin.
During rapid growth period, the ability of the muscle tendon unit to stretch decreases compared to bone growth resulting in increased tension at the attachment site. In the young athlete, because of training and participation in multiple sports a traction force at the apophysis is exaggerated. Certain conditions such as pronation of the foot or genu valgum may aggravate abnormal forces at the apophysis and result is apophysitis.
Apophysitis can occur at the hip and pelvis, knee, and foot. Pelvic or hip apophysitis is often seen in individuals aged between 14 and 18 years. Risk of pelvis/hip apophysitis is more in individuals having excessively tight hip and thigh muscles. Pelvic bone has many apophyses and any of these may affected. However apophysitis of anterior superior iliac spine, anterior inferior iliac spine and iliac crest apophyses is more common.
Apophysitis of the knee is known as Osgood-Schlatter disease. Osgood-Schlatter disease is characterized by swelling, pain and tenderness just below the knee, over the shin bone (tibia). It is commonly seen in young adolescent boys who participate in certain sports, such as soccer, gymnastics, basketball, and distance running.
Apophysitis of the foot is known as server’s disease. Severs disease, also called as calcaneal apophysitis is a condition that affects growing adolescents causing inflammation of the growth plate of calcaneus bone, a bone at the back of the heel. The condition can affect both heels and most commonly occurs in boys between the ages 8 and 13.
Children with apophysitis may complain of pain that may occur gradually without a particular history of injury. The symptom tends to worsen after a single traumatic event. These symptoms decrease once growth at the apophysis is complete.
Your doctor will diagnose apophysitis based on history and physical examination. X-rays may be needed to rule out other conditions such as infection or tumor. The goal of the treatment is to relieve the pain and to treat the underlying factors. Avoid activities that worsen the pain and protect the apophysis from further injury. Participating in sports is not allowed as long as limping is present during walking or during activities. An open growth plate is more susceptible to injury and hence lack of protection of the apophysis can result in an avulsion fracture. A rehabilitation program that includes home exercise program and physical therapy may be recommended to improve strength and flexibility.