Brief Outline of Hip Avulsion Fracture
An avulsion fracture occurs when a tendon or ligament pulls away from the bone at its attachment, pulling a piece of the bone away with it. This usually results from a forceful twisting muscular contraction, or powerful hyperextension or hyperflexion. This injury is more prevalent in children than in adult. The tendon or ligament tends to tear before the bone is involved in adults, but the softer bones tend to become involved in children. Most commonly seen in boys between 13 and 17, although the ligament-bone junction is a common site of injury in middle-aged people.
Anatomy and physiology
Although any tendon or ligament in the body can be involved in an avulsion fracture, it is more common in those around the pelvis. Avulsion fractures most commonly occur at apophyses, sites where a major tendon attaches onto a growing bone prominence. In children, the growth plate is a weaker site where the bone is continuously forming, and is an area where avulsion fractures often occur. The anterior superior iliac spine, the anterior inferior iliac spine, and the ischial tuberosity are the bony prominences most commonly involved. The corresponding muscles affected are the sartorius, the resctus femoris and the hamstrings, respectively. If a musculo-tendinous unit is involved, muscle function will be limited.
Cause of Hip Avulsion Fracture
Forceful twisting, extending, or flexing causing extra stress on the ligaments or tendons. Direct impact on a joint causing forceful stretching of the ligaments.
Signs and symptoms
Pain, swelling, and tenderness at the injury site. Sudden localised pain that may radiate down the muscle.
Complications if left unattended
When left untreated, an avulsion fracture will lead to long-term disablity in the muscles and joints involved. Incomplete, or incorrect healing may result as well, leading to future injuries to other muscles.
Seek immediate medical help to rule out major consequence.
- Immobilisation of the joint involved.
- Platelet Rich Plasma Injection
Rehabilitation and prevention
Rest for the injured muscles and joints, and then strengthening of the muscles and supporting ligaments, will help rehabilitate and prevent future fractures. Gradual re-entry into full activity is important to prevent re-injuring the weakened area.
With proper treatment, most simple avulsion fractures will heal completely with no limitations. In rare cases surgery may be needed to repair the avulsed bone, especially in children when the avulsion involves a growth plate.