Differential Diagnosis
- Avulsion fracture of the anterior inferior iliac spine
- Extra-articular femoroacetabular impingement
- Muscle strain
- Rectus femoris muscle tear
Diagnosis
The x-ray shows a displaced fracture of the anterior inferior iliac spine, with separation by 5 mm. There is also a rectus femoris muscle tear at the insertion site.
Rectus femoris is a hip flexor muscle and has two origins from the anterior inferior iliac spine and the supra acetabular ilium. Distally, it inserts on the patella and patellar ligament. Avulsion tear of the muscle and accompanying fracture of the anterior inferior iliac spine are common in boys 14-to-17 years of age, when the ratio of muscular strength to the physical strength is greatest. Rectus femoris tears are usually associated with athletic activity, including sprinting and competitive kicking sports. A sudden forceful pull of the rectus femoris muscle during a forceful extension of the hip and flexion of the knee is the mechanism of the injury. A loud popping sound followed by severe groin pain and inability to move the limb are common clinical presenting features. Clinical findings include localized groin tenderness, painful active flexion and forceful extension.
MRI findings include a displace fracture, soft tissue edema, hemorrhage and retracted rectus femoris muscle.
Learnings/What to Look for
- Diagnosis is usually made on plain x-rays, CT, or MRI
- Plain x-rays and CT reveal a displaced fracture of the anterior inferior iliac spine, with accompanying soft tissue swelling and hemorrhage
Pearls for Urgent Care Management and Considerations for Transfer
- Usual treatment is conservative with rest, analgesia, and physical therapy. Lack of treatment results in chronically painful groin which could be career limiting for the athletes
- Surgical repair/internal fixation is usually reserved for fractures with more than 2 cm separation, failed conservative treatment, and nonunion of fracture and in athletes to facilitate early recovery
Acknowledgment: Images and case provided by Experity Teleradiology.