The Journal of Bone and Joint Surgery, Vol 71, Issue 10 1548-1555, Copyright © 1989 by Journal of Bone and Joint Surgery, Inc
Mechanical considerations for the syndesmosis screw. A cadaver study
SD Boden, PA Labropoulos, P McCowin, WF Lestini and SR Hurwitz
Department of Orthopaedic Surgery, George Washington University School of Medicine, Washington, D.C. 20037.
The purpose of this study was to examine the mechanical necessity of using
a syndesmosis screw to supplement rigid internal fixation of the fibula and
medial malleolus in the treatment of pronation-external rotation fractures.
The legs of thirty embalmed and five fresh cadavera were dissected and
mounted through the tibia to a frame so that multiple radiographs could be
made with a constant relationship between the specimen and the x-ray
apparatus. A standardized pronation-external rotation load was applied to
the foot, and widening of the syndesmosis was studied on mortise
radiographs that were made after each experimental step. On the basis of
previous investigations, we developed a model for pronation-external
rotation injuries that included disruption of the syndesmosis and
interosseous membrane up to the level of the fibular fracture. Accordingly,
multiple repaired fibular fractures could be simulated at several levels in
the same specimen by incremental proximal division of the interosseous
membrane. Specimens were separated into two groups. Group I consisted of
thirteen specimens in which the deltoid ligament, syndesmosis, and
interosseous membrane were serially sectioned in 1.5-centimeter increments.
Group II (ten sections) was subjected to the same protocol, except that the
deltoid ligament was kept intact until the final step. The five fresh
specimens were sectioned in the same way as those in Group I. In Group I,
since the simulated pronation-external rotation injury included a deltoid
tear, rigid medial fixation was not possible; accordingly, there was rigid
fibular fixation only.(ABSTRACT TRUNCATED AT 250 WORDS)