Review Question - QID 216769

The patient sustained an avulsion fracture of the anterior superior iliac spine (ASIS) due to the sartorius muscle (Figure B, Label A).

Adolescent children are at risk for avulsion fractures due to disproportionately strong muscles compared to the weaker physes near their attachments and insertions. Multiple muscles with pelvic attachments can cause avulsion fractures. This patient presents with injury of the ASIS which was likely caused by a combination of direct trauma and eccentric contraction of the sartorius muscle while getting checked. Nonsurgical treatment is usually attempted first with protected weight-bearing. Displacement greater than 2-3cm may benefit from open reduction and internal fixation.

Yeager et al. reviewed pelvic avulsion injuries in adolescent athletes. In their review article, they discuss the etiology, presentation, and management of common avulsion fracture to include ASIS, AIIS, ischial tuberosity, and iliac crest avulsions. They discuss operative and nonoperative treatment, and they state that most patients are able to return to the same level of activity with appropriate treatment.

Schiller et al. performed a review on lower extremity avulsion fractures in pediatric and adolescent athletes. They report that these fractures can be misdiagnosed and require proper imaging or clinical suspicion. When these injuries are identified, non-operative treatment is usually successful. If these injuries are misdiagnosed and treated with an early range of motion, nonunion or further displacement may occur.

Figure A is an AP pelvis radiograph demonstrating an avulsion fracture of the left ASIS. Figure B is a cross-sectional artistic rendering of the thigh. Illustration A is a diagram demonstrating common pelvic avulsion fractures and their associated muscles.

Incorrect Answers:
Answer 2: This is pointed to rectus femoris, which can cause avulsion fractures of the anterior inferior iliac spine (AIIS)
Answer 3: This is pointed to the vastus lateralis, which does not have an associated avulsion fracture.
Answer 4: This is pointed to the long head of the biceps femoris muscle belly, which can cause avulsions off the ischium.
Answer 5: This is pointed to the adductor magnus, which can cause avulsions off the ischial tuberosity/pubis.