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- Author or Editor: Liduin S. Meershoek x
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Abstract
Objective—To test the sensitivity to measurement and modeling errors of a method for noninvasive calculation of flexor tendon forces in the equine forelimb and to calculate tendon forces for Dutch Warmblood horses during trotting.
Sample Population—A normative set of kinematic and ground-reaction force (GRF) data obtained from horses during trotting in another study.
Procedure—Forces in the flexor tendons were calculated from the data set before and after addition of fixed relative and absolute errors. Amount of error was based on normal accuracy of the variables. A similar analysis was performed for a measure of strain of the accessory ligament of the deep digital flexor tendon.
Results—The only errors that had a substantial influence on accuracy were modeling errors in the mechanical properties of the suspensory ligament and measurement errors in the point of application of the GRF and position of the marker on the distal interphalangeal joint. Influence of the measurement errors could be minimized by applying usual correction methods.
Conclusion and Clinical Relevance—After correction of measurement errors, the method can be used to calculate mean tendon forces for a group of horses and to evaluate the influence of factors such as surface properties, type of shoe, speed, and fatigue on tendon forces. The method could become an important tool for use in research on the cause, prevention, and treatment of tendon injuries in horses. (Am J Vet Res 2001;62:1594–1598)
Abstract
Objective—To describe a method to calculate flexor tendon forces on the basis of inverse dynamic analysis and an in vitro model of the equine forelimb and to quantify parameters for the model.
Sample Population—38 forelimbs of 23 horses that each had an estimated body mass of ≥ 500 kg.
Procedure—Longitudinal limb sections were used to determine the lines of action of the tendons. Additionally, limb and tendon loading experiments were performed to determine mechanical properties of the flexor tendons.
Results—The study quantified the parameters for a pulley model to describe the lines of action. Furthermore, relationships between force and strain of the flexor tendons and between fetlock joint angle and suspensory ligament strain were determined, and the ultimate strength of the tendons was measured.
Conclusion and Clinical Relevance—The model enables noninvasive determination of forces in the suspensory ligament, superficial digital flexor tendon, and distal part of the deep digital flexor (DDF) tendon. In addition, it provides a noninvasive measure of loading of the accessory ligament of the DDF tendon for within-subject comparisons. However, before application, the method should be validated. The model could become an important tool for use in research of the cause, prevention, and treatment of tendon injuries in horses. (Am J Vet Res 2001;62:1585–1593)
Abstract
Objective—To calculate forces in the flexor tendons and the influence of heel wedges in affected and contralateral (compensating) forelimbs of horses with experimentally induced unilateral tendinitis of the superficial digital flexor (SDF) tendon.
Animals—5 Warmblood horses.
Procedure—Ground reaction force and kinematic data were obtained during a previous study while horses were trotting before and after induction of tendinitis in 1 forelimb SDF and after application of 6° heel wedges to both forehooves. Forces in the SDF, deep digital flexor (DDF), and the suspensory ligament (SL) and strain in the accessory ligament (AL) of the DDF were calculated, using an in vitro model of the distal region of the forelimb.
Results—After induction of tendinitis, trotting speed slowed, and forces decreased in most tendons. In the affected limb, SL force decreased more than SDF and DDF forces. In the compensating limb, SDF force increased, and the other forces decreased. After application of heel wedges, SDF force in both limbs increased but not significantly. Furthermore, there was a decrease in DDF force and AL strain.
Conclusions and Clinical Relevance—The increase in SDF force in the compensating forelimb of horses with unilateral SDF tendinitis may explain the high secondary injury rate in this tendon. The lack of decrease of SDF force in either limb after application of heel wedges suggests that heel wedges are not beneficial in horses with SDF tendinitis. Instead, heel wedges may exacerbate the existing lesion. (Am J Vet Res 2002;63:432–437)
Abstract
Objective—To determine the effects of exercise on biomechanical properties of the superficial digital flexor tendon (SDFT) in foals.
Animals—43 Dutch Warmblood foals.
Procedure—From 1 week until 5 months of age, 14 foals were housed in stalls and not exercised, 14 foals were housed in stalls and exercised daily, and 15 foals were maintained at pasture. Eight foals in each group were euthanatized at 5 months, and remaining foals were housed together in a stall and paddock until euthanatized at 11 months. After euthanasia, SDFT were isolated and fit in a material testing system. Mean cross-sectional area (CSA) was measured and traction forces recorded. Normalized force at rupture (forcerup), normalized force at 4% strain, strain at rupture, stress at 4% strain (stress4%strain), and stress at rupture were compared among and within groups.
Results—At 5 months, mean CSA and normalized forcerup were significantly greater and stress4%strain significantly less in the pastured group, compared with the other groups. At 11 months, CSA and normalized forcerup were not significantly different among groups, because forcerup increased significantly from 5 to 11 months in the nonexercised group and decreased significantly in the pastured group.
Conclusions and Clinical Relevance—Exercise significantly affected the biomechanical properties of the SDFT in foals. Evenly distributed moderate- and low-intensity exercise at a young age may be more effective for development of strong, flexible tendons in horses than single episodes of high-intensity exercise superimposed on stall rest. This effect may impact later susceptibility to SDFT injury. (Am J Vet Res 2001;62:1859–1864)
