Apophyseal Injuries

Avulsion injuries are common among skeletally immature athletes because of the inherent weakness across the open apophysis [1]. The incidence of avulsion fractures is increasing, especially among 14 to 17 year olds, as a result of the growth in competitive sports participation.

Avulsion fractures results from indirect trauma caused by sudden, violent, or unbalanced muscle contraction, and are most commonly associated with sports such as soccer, rugby, ice hockey, gymnastics, and sprinting, that involve kicking, rapid acceleration and deceleration, and jumping. Whereas in adults this mechanism of injury typically causes a muscle or tendon strain, in skeletally immature athletes the consequences are more serious, because of the inherent biomechanical weakness and subsequent separation of the apophyseal region. Intensive training exposes the epiphyseal plate to repetitive tensile stress while simultaneously enhancing muscle contractility and power. The inherent weakness at the epiphyseal plate, combined with the increased functional demands placed on the musculature, may predispose athletes to subsequent avulsion injury. Once the injury has occurred, the degree of bony displacement is restricted by the periosteum and surrounding fascia.

Although avulsion fractures can occur at any major muscle attachment, the three most common sites of avulsion injuries include the anterior superior iliac

* Corresponding author. E-mail address: [email protected] (M.S. Kocher).

0278-5919/06/$ - see front matter © 2006 Elsevier Inc. All rights reserved.

doi:10.1016/j.csm.2006.01.001 sportsmed.theclinics.com

Fig. 1. Anterior superior iliac spine (ASIS) avulsion fracture in an adolescent athlete.

spine (ASIS) (Fig. 1), the anterior inferior iliac spine (AIIS) and the ischial tuberosity (Fig. 2), because of violent contraction of the sartorius, rectus femoris, and hamstring muscles, respectively. In addition, avulsion fractures of the lesser trochanter can also occur (Fig. 3).

Clinical presentation typically follows a traumatic incident or strenuous exercise, and is characterized by acute onset of localized pain and swelling that is exacerbated on palpation and by passive stretching of the involved muscle. Patients will characteristically assume a position that places the least amount of tension on the involved muscle. Although clinical presentation is often diagnostic, radiological imaging is useful in determining the size of the avulsed fragment and degree of bony displacement.

Fig. 2. Ischial tuberosity avulsion fracture in an adolescent athlete.

Fig. 3. Lesser trochanteric avulsion fracture in an adolescent athlete.

Controversy exists regarding the optimal management of avulsion fractures, particularly those involving the ischial tuberosity [1]. Typically, initial management will be conservative, including rest and ice, followed by protected weight-bearing with crutches until symptoms resolve. Thereafter, progression to light isometric stretching and full weight bearing is indicated, and return to full sports participation can occur once full strength and a pain-free range of motion is achieved. The need for surgical intervention is rare, and is typically based on ongoing symptoms and the degree of bony displacement. As a general rule, large displaced fragments greater than 2 cm may require surgical fixation; however, the optimal timing of surgical intervention remains unclear.

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