The Journal of Bone and Joint Surgery, Vol 76, Issue 9 1371-1375, Copyright © 1994 by Journal of Bone and Joint Surgery, Inc
Anatomical restraints to dislocation of the second metatarsophalangeal joint and assessment of a repair technique
D Bhatia, MS Myerson, MJ Curtis, BW Cunningham and RH Jinnah
Department of Orthopaedic Surgery, Union Memorial Hospital, Baltimore, Maryland 21218-2869.
The aim of this study was to determine the anatomical restraints to
dislocation of the second metatarsophalangeal joint and to assess the
biomechanical efficacy of a technique that is commonly used to stabilize
this joint. Cadaveric feet were disarticulated at the ankle, with
preservation of the long flexor tendons at the medial malleolus. The
hindfoot was transfixed to an aluminum jig, and a contoured nylon block was
secured to the dorsum of the second metatarsal. A Kirschner wire was passed
transversely through the proximal phalanx and was attached to a wire loop
through which a constant vertical displacement was applied with a universal
testing machine. A preload of five newtons was applied, followed by a
constant displacement of two millimeters per minute, and the
load-displacement curves were measured. The volar plate and the collateral
ligaments were divided in five feet each. In another ten feet, both of
these structures were divided simultaneously. Each load cycle was repeated
four times. The force required to dislocate the joint, in the position in
which testing was performed, was reduced by a mean of 30 per cent when the
volar plate was divided and by a mean of 46 per cent when the collateral
ligaments were divided. Division of both of these structures created an
unstable joint, which dislocated at an applied load of five to ten newtons.
The metatarsophalangeal joint was then repaired with use of a flexor tendon
transfer in all twenty feet. This repair technique restored the
load-displacement curves to that of the normal toe.
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