Moment arms about the carpal and metacarpophalangeal joints for flexor and extensor muscles in equine forelimbs

Nicholas A.T. Brown, Marcus G. Pandy, William L. Buford, Christopher E. Kawcak, C. Wayne McIlwraith

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Objective: To determine whether muscle moment arms at the carpal and metacarpophalangeal joints can be modeled as fixed-radius pulleys for the range of motion associated with the stance phase of the gait in equine forelimbs. Sample Population: 4 cadaveric forelimbs from 2 healthy Thoroughbreds. Procedure: Thin wire cables were sutured at the musculotendinous junction of 9 forelimb muscles. The cables passed through eyelets at each muscle's origin, wrapped around single-turn potentiometers, and were loaded. Tendon excursions, measured as the changes in lengths of the cables, were recorded during manual rotation of the carpal (180° to 70°) and metacarpophalangeal (220° to 110°) joints. Extension of the metacarpophalangeal joint (180° and 220°) was forced with an independent loading frame. Joint angle was monitored with a calibrated potentiometer. Moment arms were calculated from the slopes of the muscle length versus joint angle curves. Results: At the metacarpophalangeal joint, digital flexor muscle moment arms changed in magnitude by ≤ 38% during metacarpophalangeal joint extension. Extensor muscle moment arms at the carpal and metacarpophalangeal joints also varied (≤ 41% at the carpus) over the range of joint motion associated with the stance phase of the gait. Conclusions and Clinical Relevance: Our findings suggest that, apart from the carpal flexor muscles, muscle moment arms in equine forelimbs cannot be modeled as fixed-radius pulleys. Assuming that muscle moment arms at the carpal and metacarpophalangeal joints have constant magnitudes may lead to erroneous estimates of muscle force in equine forelimbs.

Original languageEnglish
Pages (from-to)351-357
Number of pages7
JournalAmerican Journal of Veterinary Research
Volume64
Issue number3
DOIs
Publication statusPublished - 2003
Externally publishedYes

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Carpal Joints
Forelimb
forelimbs
joints (animal)
Horses
horses
Muscles
muscles
Metacarpophalangeal Joint
cables (equipment)
radius (bone)
Joints
gait
Articular Range of Motion
Wrist
Gait
carpus
tendons
wire
Tendons

Cite this

Brown, Nicholas A.T. ; Pandy, Marcus G. ; Buford, William L. ; Kawcak, Christopher E. ; McIlwraith, C. Wayne. / Moment arms about the carpal and metacarpophalangeal joints for flexor and extensor muscles in equine forelimbs. In: American Journal of Veterinary Research. 2003 ; Vol. 64, No. 3. pp. 351-357.
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title = "Moment arms about the carpal and metacarpophalangeal joints for flexor and extensor muscles in equine forelimbs",
abstract = "Objective: To determine whether muscle moment arms at the carpal and metacarpophalangeal joints can be modeled as fixed-radius pulleys for the range of motion associated with the stance phase of the gait in equine forelimbs. Sample Population: 4 cadaveric forelimbs from 2 healthy Thoroughbreds. Procedure: Thin wire cables were sutured at the musculotendinous junction of 9 forelimb muscles. The cables passed through eyelets at each muscle's origin, wrapped around single-turn potentiometers, and were loaded. Tendon excursions, measured as the changes in lengths of the cables, were recorded during manual rotation of the carpal (180° to 70°) and metacarpophalangeal (220° to 110°) joints. Extension of the metacarpophalangeal joint (180° and 220°) was forced with an independent loading frame. Joint angle was monitored with a calibrated potentiometer. Moment arms were calculated from the slopes of the muscle length versus joint angle curves. Results: At the metacarpophalangeal joint, digital flexor muscle moment arms changed in magnitude by ≤ 38{\%} during metacarpophalangeal joint extension. Extensor muscle moment arms at the carpal and metacarpophalangeal joints also varied (≤ 41{\%} at the carpus) over the range of joint motion associated with the stance phase of the gait. Conclusions and Clinical Relevance: Our findings suggest that, apart from the carpal flexor muscles, muscle moment arms in equine forelimbs cannot be modeled as fixed-radius pulleys. Assuming that muscle moment arms at the carpal and metacarpophalangeal joints have constant magnitudes may lead to erroneous estimates of muscle force in equine forelimbs.",
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Moment arms about the carpal and metacarpophalangeal joints for flexor and extensor muscles in equine forelimbs. / Brown, Nicholas A.T.; Pandy, Marcus G.; Buford, William L.; Kawcak, Christopher E.; McIlwraith, C. Wayne.

In: American Journal of Veterinary Research, Vol. 64, No. 3, 2003, p. 351-357.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Moment arms about the carpal and metacarpophalangeal joints for flexor and extensor muscles in equine forelimbs

AU - Brown, Nicholas A.T.

AU - Pandy, Marcus G.

AU - Buford, William L.

AU - Kawcak, Christopher E.

AU - McIlwraith, C. Wayne

PY - 2003

Y1 - 2003

N2 - Objective: To determine whether muscle moment arms at the carpal and metacarpophalangeal joints can be modeled as fixed-radius pulleys for the range of motion associated with the stance phase of the gait in equine forelimbs. Sample Population: 4 cadaveric forelimbs from 2 healthy Thoroughbreds. Procedure: Thin wire cables were sutured at the musculotendinous junction of 9 forelimb muscles. The cables passed through eyelets at each muscle's origin, wrapped around single-turn potentiometers, and were loaded. Tendon excursions, measured as the changes in lengths of the cables, were recorded during manual rotation of the carpal (180° to 70°) and metacarpophalangeal (220° to 110°) joints. Extension of the metacarpophalangeal joint (180° and 220°) was forced with an independent loading frame. Joint angle was monitored with a calibrated potentiometer. Moment arms were calculated from the slopes of the muscle length versus joint angle curves. Results: At the metacarpophalangeal joint, digital flexor muscle moment arms changed in magnitude by ≤ 38% during metacarpophalangeal joint extension. Extensor muscle moment arms at the carpal and metacarpophalangeal joints also varied (≤ 41% at the carpus) over the range of joint motion associated with the stance phase of the gait. Conclusions and Clinical Relevance: Our findings suggest that, apart from the carpal flexor muscles, muscle moment arms in equine forelimbs cannot be modeled as fixed-radius pulleys. Assuming that muscle moment arms at the carpal and metacarpophalangeal joints have constant magnitudes may lead to erroneous estimates of muscle force in equine forelimbs.

AB - Objective: To determine whether muscle moment arms at the carpal and metacarpophalangeal joints can be modeled as fixed-radius pulleys for the range of motion associated with the stance phase of the gait in equine forelimbs. Sample Population: 4 cadaveric forelimbs from 2 healthy Thoroughbreds. Procedure: Thin wire cables were sutured at the musculotendinous junction of 9 forelimb muscles. The cables passed through eyelets at each muscle's origin, wrapped around single-turn potentiometers, and were loaded. Tendon excursions, measured as the changes in lengths of the cables, were recorded during manual rotation of the carpal (180° to 70°) and metacarpophalangeal (220° to 110°) joints. Extension of the metacarpophalangeal joint (180° and 220°) was forced with an independent loading frame. Joint angle was monitored with a calibrated potentiometer. Moment arms were calculated from the slopes of the muscle length versus joint angle curves. Results: At the metacarpophalangeal joint, digital flexor muscle moment arms changed in magnitude by ≤ 38% during metacarpophalangeal joint extension. Extensor muscle moment arms at the carpal and metacarpophalangeal joints also varied (≤ 41% at the carpus) over the range of joint motion associated with the stance phase of the gait. Conclusions and Clinical Relevance: Our findings suggest that, apart from the carpal flexor muscles, muscle moment arms in equine forelimbs cannot be modeled as fixed-radius pulleys. Assuming that muscle moment arms at the carpal and metacarpophalangeal joints have constant magnitudes may lead to erroneous estimates of muscle force in equine forelimbs.

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U2 - 10.2460/ajvr.2003.64.351

DO - 10.2460/ajvr.2003.64.351

M3 - Article

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SP - 351

EP - 357

JO - American Journal of Veterinary Research

JF - American Journal of Veterinary Research

SN - 0002-9645

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ER -