Avulsion Fracture of the Fifth Metatarsal Tuberosity [Diagnostic Radiology]

Author: Bow Wang, M.D.

Bow Wang, M.D. suffered ankle inversion and plantar flexion due to a misstep on the stairs. After taking an X-ray, Bow Wang, M.D. was diagnosed with an avulsion fracture of the 5th metatarsal tuberosity.

Bow Wang, M.D. went to the Debang Clinic on Wusheng Road, where Dr. Huang Mingdong scanned ultrasound's foot and ankle to assess the damage to surrounding joints and soft tissues. The image above shows that besides the fracture site, there is damage to multiple joints in the foot and ankle.

In addition to diagnosis, Dr. Huang used an elastic bandage to immobilize the injured ankle and foot, and provided medication, instructions on using forefoot decompression shoes and crutches, and the recovery period of six to eight weeks.

Avulsion fracture of the 5th metatarsal tuberosity is a relatively common avulsion injury of the foot, also known as a Pseudo-Jones fracture. The fracture occurs at the base of the fifth metatarsal and extends to the articular surface.

Patients with avulsion fracture of the 5th metatarsal tuberosity (Pseudo-Jones fracture) usually have a history of ankle twisting and injury, involving inversion of the ankle and foot and plantar flexion. This is due to the lateral band of the plantar aponeurosis attaching to the plantar surface of the trochanter, with the peroneus brevis tendon attaching laterally; both may contribute to the detachment injury caused by forefoot plantar flexion and excessive hindfoot inversion. This condition usually occurs when running on uneven surfaces or during improper landing.

[Avulsion fracture of the 5th metatarsal tuberosity/Pseudo Jones fracture] This type of fracture, if without displacement, is usually treated conservatively and heals well due to good blood supply. In contrast, Jones fractures are more likely to result in delayed healing or nonunion due to poor blood supply. Elastic bandages can be used for immobilization, along with hard-soled shoes for functional weight-bearing. Delayed healing may occur in the elderly, patients who do not follow medical advice, and patients with diabetes or peripheral vascular disease. If there is displacement in the fracture, a physician must assess whether surgical fixation is necessary.

Depending on the location of the fifth metatarsal fracture and the patient's age, different differential diagnoses may be made, including those involving normal structures such as: [Jones fracture], [stress fracture of the fifth metatarsal], [normal apophysis of the proximal 5th metatarsal, between 10-16 years/year], and [apophysitis].The physician will then evaluate and diagnose based on the patient's history and medical imaging, and provide appropriate treatment and management.