Review Question - QID 4421

The clinical scenario is consistent with an avulsion fracture of the anterior superior iliac spine (ASIS). The ASIS is the origin of sartorius and tensor fascia lata (TFL). Sartorius inserts on the pes anserinus which is a common location of painful bursitis.

Avulsion fractures of the ASIS are usually due to sudden forceful contraction of the sartorius and/or the TFL in young athletes. Treatment is almost always symptomatic with partial weight bearing and physical therapy. Rarely ORIF is required when there is > 3cm of displacement.

Holden et al. reviewed pediatric pelvic fractures including avulsion fractures of the pelvis. They report most low energy pelvic avulsion injuries in children are treated nonsurgically, with protected weight bearing and gradual return to activity. Open reduction and internal fixation is usually required for higher energy acetabular fractures with >2 mm of intra-articular or triradiate cartilage fracture displacement.

Figure A shows an avulsion of the right ASIS. Illustration A shows the origins of the muscles of the pelvis that are the most common causes of avulsion fractures. Illustration B is a radiograph of an AIIS avulsion.

Incorrect Responses:
Answer 1: Describes the femoris biceps tendon, which originates on the ischial tuberosity.
Answer 2: Describes the popliteus tendon, which originates on the posteromedial proximal tibia.
Answer 4: Describes the gracilis and semitendinosis tendons, which originate on the inferior pubic ramus, and ischial tuberosity respectively. They both insert in the pes anserinus along with sartorius.
Answer 5: Describes the hamstring muscles.