Apophysitis refers to irritation and inflammation of the apophysis, secondary ossification centers which act as insertion sites for tendons. In growing athletes the apophysis is susceptible to injury as a result of repetitive stress or acute avulsion fractures (an injury where a tendon or ligament tears away a small piece of bone).
- Pelvic or hip apophysitis is most often seen in individuals between the ages of 14 and 18 years. Individuals with excessively tight hip and thigh muscles are at higher risk of developing pelvic/hip apophysitis.
- Apophysitis of the knee is known as Osgood-Schlatter disease and 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 sports such as soccer, gymnastics, basketball, and distance running.
- Apophysitis of the foot is known as Sever’s disease or calcaneal apophysitis. This condition affects growing adolescents and causes inflammation of the growth plate of calcaneous 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.
During rapid growth periods, muscle tendons’ ability to stretch decreases in comparison to new bone growth resulting in increased tension at attachment sites. Individuals with conditions such as pronation of the foot or genu valgum (knock knees) and young athletes who train and participate in multiple sports may experience increased force at the apophysis which can cause injury.
Children with apophysitis may complain of pain that occurs gradually without a specific history of injury. However, symptoms tend to worsen after a single traumatic event and decrease once growth at the apophysis is complete.
Apophysitis is typically diagnosed based on history and physical examinations but x-rays may be needed to rule out other conditions such as infections or tumors.
Treatment typically consists of a rehabilitation program that includes a home exercise program and/or physical therapy to improve strength and flexibility. During treatment patients must avoid activities that intensify the pain and participation in sports should be restricted as long as a limp is present. An open growth plate is more susceptible to injury so care must be taken to protect the apophysis from further injury which could result in an avulsion fracture.