13-Year-Old With Inversion Injury

Published on June 1, 2025

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Differential Diagnosis

• Left midfoot sprain
• 5^th metatarsal avulsion fracture
• 5^th metatarsal shaft fracture

Diagnosis

The correct diagnosis is an avulsion fracture of the base of the 5th metatarsal adjacent to the oblique apophysis. It does not involve the diaphysis, and there is no skin tenting or rotation. As seen in the image, normal apophysis is noted at the base of the 5th metatarsal as well as a transverse lucency at base of 5th metatarsal. Avulsion fracture is among the more common fractures of the foot and is predisposed to poor healing due to the limited blood supply to the specific areas of the 5th metatarsal base.

What To Look For

• On x-ray, a normal apophysis may be seen at the base of the 5^th metatarsal
• Tenderness to palpation, erythema, or swelling at the base of the 5^th metatarsal may be present

Pearls For Urgent Care Management

• Subtle avulsion fractures may require anterior posterior view or anterior posterior oblique (mortise) view of ankle to visualize
• Symptoms may last 2-6 months
• Nonoperative treatment includes protective weight bearing in a stiff soled boot or cast
• Follow-up with orthopedics or podiatry may be indicated for evaluation of operative management in cases of non-union