Proximal Fifth Metatarsal Fractures

There are three types of fractures at the proximal fifth metatarsal
1-Avulsion fracture
2-Jones fracture
3-Stress fracture

Zone I injury = avulsion fracture

•Relative incidence =93%
•An avulsion fracture at the base of the fifth metatarsal . due to sudden hindfoot inversion resulting in tension along the lateral band of plantar aponeurosis which inserts into the proximal base of the fifth metatarsal.

Treatment

•Weight bearing as tolerated with hard sole shoe.
Zone II injury = Jones fracture
•Relative incidence = 4%
•An area of limited blood supply.

Fracture at the proximal metaphyseal-diaphyseal junction.

•Fracture extends from the lateral aspect of the fifth metatarsal toward the fourth and fifth metatarsal articular surface.
•Result from tensile stress along the lateral border of the fifth metatarsal. Chronic injuries have a high incidence of nonunion.

Treatment
•Conservative non-weight bearing for 6-8 weeks. 2/3 healing in acute fracture.
•In athletes percutaneous screw fixation allows faster healing and return of function.

Zone III injury = stress fracture
•Relative incidence = 3%
•Proximal diaphyseal stress fracture.
•Seen mainly in athletes.
•Occur in the proximal 1.5 cm of the shaft in the fifth metatarsal and results from repetitive cycling loading.
•Can occur in cavovarus foot.

Treatment
•Conservative non-weight bearing cast with 50% nonunion.
•Surgical internal compressive fixation and possibly bone grafting. Surgery is performed in athletes and in non-union.
•Nonunion is defined by patients who have pain with lucency around the fracture and/or intramedullary sclerosis.

Complication

•Higher fracture rate if returned to sports prior to radiographic union.
Blood supply is multiple metaphyseal arteries. Nutrient artery with intramedullary branches provide retrograde blood flow to proximal fifth metatarsal.

Courtesy: Prof Nabil Ebraheim, University of Toledo, Ohio, USA