Article

The purpose of this study was to use magnetic resonance imaging to
measure the moment arm of the flexor digitorum superficialis tendon about the
metacarpophalangeal joint of the index, middle, ring, and little fingers when the
position and force production level of the index finger was altered. A secondary
goal was to create regression models using anthropometric data to predict moment
arms of the flexor digitorum superficialis about the metacarpophalangeal joint of
each finger. METHODS: The hands of subjects were scanned using a 3.0T magnetic
resonance imaging scanner. The metacarpophalangeal joint of the index finger was
placed in: flexion, neutral, and extension. For each joint configuration subjects
produced no active force (passive condition) and exerted a flexion force to
resist a load at the fingertip (active condition). RESULTS: The following was
found: (1) The moment arm of the flexor digitorum superficialis at the
metacarpophalangeal joint of the index finger (a) increased with the joint
flexion and stayed unchanged with finger extension; and (b) decreased with the
increase of force at the neutral and extended finger postures and did not change
at the flexed posture. (2) The moment arms of the flexor digitorum superficialis
tendon of the middle, ring, and little fingers (a) did not change when the index
metacarpophalangeal joint position changed (P>0.20); and (b) The moment arms of
the middle and little fingers increased when the index finger actively produced
force at the flexed metacarpophalangeal joint posture. (4) The moment arms showed
a high correlation with anthropometric measurements. INTERPRETATION: Moment arms
of the flexor digitorum superficialis change due to both changes in joint angle
and muscle activation; they scale with various anthropometric measures.
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Langue : ANGLAIS