Apophyseal stress injury is a chronic overuse injury of the apophysis and a relatively common type of injury in young athletes.
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Terminology
This entity has often been termed 'apophysitis'. However, as the suffix '-itis' is usually used in inflammatory-mediated conditions, it is regarded by many authors as misleading and inaccurate. Instead, they advocate the use of the term 'apophyseal stress injury' in order to emphasise the overuse aetiology, or 'apophysiolysis', which indicates incomplete apophyseal fusion 4.
Epidemiology
Apophyseal stress injuries occur in skeletally immature patients, usually in the 2nd decade of life, but they may affect younger children as well. It is postulated that physeal closure may be delayed in female athletes due to low oestrogen levels - in such cases apophyseal injury may occur in a slightly older age group.
Clinical presentation
Patients present with tenderness and gradual-onset chronic pain in the affected area, worsening with impact activity, and no history of trauma. A recent increase in training frequency or intensity may be reported.
Most of the injuries occur in the pelvic region, mostly due to the presence of numerous apophyses and strength of the attaching muscles. Other locations include the tibial tuberosity, inferior patellar pole, calcaneal tuberosity, 5th metatarsal base, acromion, proximal humerus, radial medial epicondyle, and distal radius.
Pathology
Chronic traction microinjuries to the apophysis, especially in sports that require rapid muscle contractions and in gymnastics.
injuries of the pelvic region and lower limb occur mostly in runners, soccer players and in sports that involve jumping
injuries of the upper limb occur usually in throwers, e.g. basketball players
Radiographic features
Plain radiograph
Radiographs may be normal or show subtle apophyseal irregularities, bony remodelling or subtle physeal widening.
MRI
MRI is the most sensitive modality for detecting apophyseal stress injuries, showing:
physeal widening without displacement
increased signal of the physis on fluid-sensitive sequences
bone marrow oedema of the apophysis
soft-tissue oedema
Treatment and prognosis
Apophyseal stress injuries are treated conservatively with NSAIDs, activity modification and physiotherapy. The outcome is generally favourable. If not diagnosed and treated early, the injury may progress to apophyseal fragmentation or result in deformities.