HSS Ultrasound of the Month Case #100

Clinical History An 18 year old male presents with right thigh pain and weakness without recollection of a specific injury.

On exam, there is tenderness over the anterior right hip with weakened right hip flexion.

A right hip ultrasound was ordered.

Ultrasound of the Month – Case 100

1

Ultrasound of the Month – Case 100

2

Ultrasound of the Month – Case 100

Diagnosis: Anterior Inferior Iliac Spine (AIIS) Avulsion Avulsion of the apophysis at the direct head of the rectus femoris

Discussion Epidemiology • 14-17 years of age • Males > Females • Athletic activities that require kicking a ball Pathophysiology • Eccentric contraction of the rectus femoris, which results in sudden hip joint extension with a flexed knee joint Clinical Presentation • Sudden pop • Anterior hip pain • Hip flexion weakness • Antalgic gait

Ultrasound of the Month – Case 100

4

Discussion - continued Imaging Radiographs: • Can identify an avulsed osseous fragment; however, radiographs may be negative prior to apophyseal ossification or in the setting of a nondisplaced apophyseal avulsion injury • Marked callus formation may be seen radiographically, which may be misinterpreted as an infectious or neoplastic process MRI: • Allows for demonstration of a retracted coiled tendon attached to an avulsed apophysis Treatment - Conservative nonoperative management Bed rest, ice, and activity modification • Two weeks of hip flexion to minimize extending the involved muscle and apophysis • Four subsequent weeks of guarded weight bearing

Ultrasound of the Month – Case 100

5