Fractures of proximal portion of fifth metatarsal bone: anatomic and imaging evidence of a pathogenesis of avulsion of the plantar aponeurosis and the short peroneal muscle tendon.
OBJECTIVE
To evaluate the normal anatomy of the structures supporting the proximal portion of the fifth metatarsal bone and investigate the pathogenesis of fractures in this region.


METHODS
In two cadaveric feet, the region of the lateral component of the plantar aponeurosis (PAL), short peroneal muscle (SPM) tendon, and third peroneal muscle (TPM) tendon was dissected. These two foot specimens and four nondissected foot specimens were studied at magnetic resonance (MR) imaging. Two of the six specimens were studied at computed tomography (CT). Sectioning the nondissected foot specimens enabled anatomic correlation. In two additional specimens, simulation of the presumed mechanism of fifth metatarsal bone fracture was attempted. The radiographic, CT, and MR images obtained in 13 patients with fractures of the proximal portion of the fifth metatarsal bone were evaluated.


RESULTS
Anatomic, CT, and MR imaging studies revealed broad insertion of the PAL into the plantar aspect of the proximal portion of the fifth metatarsal bone in all specimens. The SPM tendon was consistently attached more distally and to the lateral side of the tuberosity, blending with the PAL fibers. The TPM tendon was inconsistently identified inserting anteriorly to the SPM tendon. No fracture was created in the specimens subjected to attempted injury. Frequent attachment of the PAL and the SPM tendon to the avulsed fragment was confirmed in clinical cases.


CONCLUSIONS
The pathogenesis of fractures of the proximal portion of the fifth metatarsal bone appears to be related to avulsion injury of PAL and SPM tendon fibers.
Theodorou
Daphne J
DJ
Department of Radiology, School of Medicine, University of California, San Diego Medical Center, CA, USA. rjtheodorou@hotmail.com
Theodorou
Stavroula J
SJ
Kakitsubata
Yousuke
Y
Botte
Michael J
MJ
Resnick
Donald
D
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D005260:Female; D005528:Foot / Q000033:anatomy & histology*; D050723:Fractures, Bone / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008682:Metatarsal Bones / Q000293:injuries*; D008875:Middle Aged; D011446:Prospective Studies; D013708:Tendon Injuries / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed