Article

Clavicle malunion affects the biomechanics of the shoulder joint. The
purpose of this study is to establish the abduction, flexion, and internal
(medial) rotation biomechanics
of the shoulder after clavicle malunion. METHODS:
A computational study was performed utilizing a three-dimensional, validated
computational model of the upper extremity. Sequential shortening of the clavicle
up to 20% was simulated.
Muscle forces, moment arms,
and moments were calculated
for the surrounding musculature through a range of flexion, abduction, and
internal rotation during the simulated shortening. FINDINGS: Shortening of the
clavicle decreases the shoulder elevation moments of the upper extremity muscles
during abduction. Internal rotation moments are also decreased with shortening.
Flexion moments were affected less through physiologic range of motion. The
observed effects are due to a combination of changes in moment arms of the
individual muscles as well as a decrease in the force generating capacity of the
muscles. Additionally, shortening of the clavicle increases coronal angulation of
the clavicle at the sternoclavicular joint. INTERPRETATION:
Shortening causes a
decrease in the moment generating capacity as well as the total force generating
capacity of the shoulder girdle muscles. The clinical significance of these
computational results, which are consistent with recent clinical studies, is
validation of the proposed functional deficit caused by clavicle malunion.
CI - Copyright (c) 2011 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS