title: The fifth metatarsal base: anatomic evaluation regarding fracture mechanism and treatment algorithms.
abstract: Fractures occurring within the 1.5-cm proximal portion of the fifth metatarsal are commonly considered avulsion fractures. The exact mechanisms of such fractures are controversial. The present study focused on determining the likely mechanism of fracture according to the exact anatomy to allow for more successful treatment. The research sample included 10 frozen cadaveric specimens. The lateral band of the plantar fascia, peroneus brevis, and articular surface were identified and separated from their attachments, thereby splitting the fifth metatarsal base into zones A, B, and C. In zone A, the attachment of the plantar fascia was 6.6 ± 2.2 mm from the inferior aspect, 9.5 ± 2.9 mm from the proximal aspect, and 11.5 ± 0.9 mm from the lateral aspect. In zone B, the attachment of the peroneus brevis was 12.0 ± 2.2 mm from the inferior aspect, 10.2 ± 2.2 mm from the proximal aspect, and 11.5 ± 0.9 mm from the lateral aspect. Zone C was measured from the border of zone B and encompassed the articulation of the fifth metatarsal to the cuboid. We propose that fractures occurring in the most proximal end of the fifth metatarsal, zone A, are caused by a lateral band of plantar fascia and might be able to be treated conservatively by immobilization with weightbearing. We also propose that fractures occurring in zones B and C result from traumatic tension on peroneus brevis and might need to be treated with strict immobilization and non-weightbearing or open reduction internal fixation.
authors.affiliation: Attending Physician, BayCare Clinic, Orthopedic and Sports Medicine, Manitowoc, WI. Electronic address: ofacresearch@orthofootankle.com.
authors.forename: J George
authors.initials: JG
authors.lastname: DeVries
authors.affiliation: Student, Ripon College, Ripon, WI.
authors.forename: Erfan
authors.initials: E
authors.lastname: Taefi
authors.affiliation: Attending Physician, Professional Foot and Ankle, Iowa City, IA.
authors.forename: Bradly W
authors.initials: BW
authors.lastname: Bussewitz
authors.affiliation: Fellowship Director, Advanced Foot and Ankle Surgical Fellowship, Orthopedic Foot and Ankle Center, Westerville, OH.
authors.forename: Christopher F
authors.initials: CF
authors.lastname: Hyer
authors.affiliation: Attending Physician, Orthopedic Foot and Ankle Center, Westerville, OH.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Lee
mesh_terms: D000465:Algorithms; D002102:Cadaver; D050723:Fractures, Bone / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D008682:Metatarsal Bones / Q000033:anatomy & histology* / Q000293:injuries / Q000503:physiopathology*
keywords: Jones fracture; avulsion fracture; diaphyseal stress; fifth metatarsal; injury; trauma