Psoas Avulsion Fracture in a Baseball Player

During a baseball game, a 29-year-old man had taken a lead off first base. He then did a half pivot to rapidly plant his foot back on the base before he ran and slid into second base. Immediately after sliding into the base, he felt pain in the right groin and required assistance to walk.

He had no previous injury to the groin area. Seven years earlier, he had sustained a traumatic fracture of the ankle. He had no family history of metabolic bone or connective-tissue disorders.

The patient's right leg was warm, with normal reflexes and sensation, good pulses, and soft compartments.The skin was intact. Active range of motion was preserved in the knee and ankle of the right leg but was limited in the right hip, secondary to pain. He complained of pain with hip flexion and of discomfort with adduction and rotation of the right hip.

A radiograph of the pelvis showed avulsion of the lesser trochanter.

In avulsion fractures of the pelvis, the involved muscle may be identified by the location of the fracture and, when the patient can tolerate a muscular strength evaluation, certain resistance testing clues:

• Pain with hip flexion and rotation: iliopsoas muscle has pulled off part of the lesser trochanter, as in this patient.
• Worsening pain with hip flexion and abduction: sartorius muscle has pulled off part of the anterior superior iliac spine.
• Worsening pain with hip flexion: rectus femoris muscle has pulled off part of the anterior inferior iliac spine.
• Worsening pain with hip extension: hamstring muscle has pulled off part of the ischial tuberosity.
• Pain with abduction and external rotation: piriformis muscle has pulled off part of the greater trochanter.
• Pain with adduction: hip abductor has pulled off part of the ischiopubic ramus.

Avulsion fractures of the pelvis are most common in patients between the ages of 11 and 15 years. The differential diagnosis includes muscle strain and periostitis. Consider osteomyelitis or tumor in patients with groin pain who have asymmetric radiographic findings and no history of trauma.

Treatment consists of rest and the use of crutches, with toe-touch weight bearing, for up to 2 months in most patients. A gradual return to stretching and activity is determined by the patient's symptoms; consultation with an orthopedist is recommended. Injuries with either large fragments or more than 15 mm of displacement may require surgical fixation. Complications include nonunion and healing with a bony prominence that can affect future function.

This patient was referred to an orthopedist. He fully recovered in 6 months.

(Case and photograph courtesy of D. Brady Pregerson, MD, of Los Angeles.)