The skeletal system of children is unique and makes them more susceptible than adults to certain types of injuries. One example is the presence of apophyses on certain bones. An apophysis is an area of growth cartilage found throughout a child's body and serves as an attachment site for muscles and their tendons. When your child is diagnosed with apophysitis it means they have an irritation of this area of growth cartilage. It typically occurs in athletes as a consequence of repetitive use. An apophyseal injury can occur after a traumatic injury.

With apophysitis, there is a repetitive pulling of the muscle on the bone at its insertion site. This results in irritation and the growth cartilage partially pulls away from where it anchors into the bone. There are several apophyses that are located in the hip and pelvic region. Some of the more commonly injured apophyses include:

  • Iliac crest
  • Ischial tuberosity
  • Lesser trochanter

The iliac apophysis is located on the iliac crest on the upper pelvis. Muscles of the back, abdomen, and sides of the trunk connect onto this iliac apophysis. Athletes who participate in activities that involve repetitive twisting and bending of the trunk, such as a long distance runner, are at risk of developing iliac apophysitis. Symptoms of iliac apophysitis include pain and tenderness over the iliac crest. The tenderness is often on both sides, and bending at the trunk often makes the pain worse. X-rays are typically normal. Treatment is similar to most overuse injuries – rest, avoidance of painful activities, application of ice, and use of anti-inflammatory medications (such as motrin or ibuprofen). Your physician may also prescribe physical therapy to help with recovery.

The anterior superior iliac spine (ASIS) is located on the front part of the pelvis bone. It can be felt as a large prominence just underneath the iliac crest, and roughly in line with the kneecap. The sartorius muscle originates at the ASIS and functions to bend the hip up (flex). When this muscle is suddenly stretched beyond its limits, such as when the hip is extended straight and the knee is bent, the ASIS apophysis may pull off the bone, resulting in an acute apophyseal injury. This is a common occurrence in sprinters and hurdlers.

When an athlete has an avulsion fracture of the ASIS, they typically experience pain and may experience a sudden popping sensation. The pain can make walking difficult. There is typically tenderness directly over the bony prominence of the front part of the pelvis.

The ischial tuberosity is the portion of the pelvis bone that one sits on. The hamstring muscles originate in this area. Hamstring muscles function to extend the hip backwards. If the muscle is forcefully stretched suddenly beyond its limits, this may result in an avulsion fracture of this portion of the bone. The muscle in its most stretched position would occur when the hip is flexed up and the knee is straight, such as when performing a hurdle or a split. Symptoms due to an ischial tuberosity avulsion fracture include pain and tenderness of the inferior buttock, difficulty walking due to pain, and pain with stretching of the hamstring muscles.

The lesser trochanter is another area at risk for injury. This is a prominence located on the top inside portion of the femur bone. A strong muscle named the iliopsoas inserts on this bony prominence. The iliopsoas is the most powerful flexor of the hip. An avulsion of the lesser trochanter (Figure 4) may occur during activities such as kicking, sprinting, and jumping, when the muscle is stretched beyond its limits. Symptoms of an avulsion of the lesser trochanter include pain in the groin and difficulty walking or bending at the hip when seated.

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