Estimates of Achilles Tendon Moment Arm Length at Different Ankle Joint Angles: Effect of Passive Moment

2018 ◽  
Vol 34 (3) ◽  
pp. 220-225 ◽  
Author(s):  
Jared R. Fletcher ◽  
Brian R. MacIntosh
Keyword(s):  
Achilles Tendon ◽  
Passive Force ◽  
Moment Arm ◽  
Joint Angles ◽  
Joint Rotation ◽  
Male And Female ◽  
Moment Arms ◽  
Passive Rotation ◽  
Ankle Angle ◽  
Tendon Excursion

The length of a muscle’s moment arm can be estimated noninvasively using ultrasound and the tendon excursion method. The main assumption with the tendon excursion method is that the force acting on the tendon during passive rotation is constant. However, passive force changes through the range of motion, and thus moment arm is underestimated. The authors attempted to account for passive force on the measurement of Achilles tendon moment arm using the tendon excursion method in 8 male and female runners. Tendon excursion was measured using ultrasound while the ankle was passively rotated at 0.17 rad·s−1. Moment arm was calculated at 5° intervals as the ratio of tendon displacement to joint rotation from 70° to 115°. Passive moment (MP) was measured using a dynamometer. The displacement attributable to MP was calculated by monitoring tendon displacement during a ramp isometric maximum contraction. MP was 5.7 (2.1) N·m at 70° and decreased exponentially from 70° to 90°. This resulted in MP-corrected moment arms that were significantly larger than uncorrected moment arms at joint angles where MP was present. Furthermore, MP-corrected moment arms did not change with ankle angle, which was not the case for uncorrected moment arms.

Estimates of Achilles Tendon Moment Arm Length at Different Ankle Joint Angles: Effect of Passive Moment

2018 ◽  
pp. 1-22 ◽  
Author(s):  
Jared R. Fletcher ◽  
Brian R. MacIntosh
Keyword(s):  
Achilles Tendon ◽  
Passive Force ◽  
Moment Arm ◽  
Joint Angles ◽  
Joint Rotation ◽  
Male And Female ◽  
Moment Arms ◽  
Passive Rotation ◽  
Ankle Angle ◽  
Tendon Excursion

The length of a muscle’s moment arm can be estimated non-invasively using ultrasound, and the tendon excursion method. The main assumption with the tendon excursion method, however, is that the force acting on the tendon during passive rotation is constant. However, passive force changes through the range of motion, and moment arm is underestimated. We attempted to account for passive force on the measurement of Achilles tendon moment arm using the tendon excursion method in 8 male and female runners. Tendon excursion was measured using ultrasound while the ankle was passively rotated at 0.17 rad•s-1. Moment arm was calculated at 5° intervals as the ratio of tendon displacement to joint rotation from 70° to 115°. Passive moment (MP) was measured by a dynamometer. The displacement attributable to MP was calculated by monitoring tendon displacement during a ramp isometric maximum contraction. MP was 5.7±2.1 Nm at 70° and decreased exponentially from 70°-90°. °. This resulted in MP-corrected moment arms that were significantly larger than uncorrected moment arms at joint angles where MP was present. Further, MP-corrected moment arms did not change with ankle angle, which was not the case for uncorrected moment arms.

Estimation of Achilles Tendon Moment Arms In Vivo: A Novel Hybrid Method Using Ultrasound and Motion Analysis

2008 ◽  
Author(s):  
Justin D. Cowder ◽  
Nicole J. Chimera ◽  
Thomas S. Buchanan ◽  
Kurt T. Manal
Keyword(s):  
Achilles Tendon ◽  
Motion Capture ◽  
Moment Arm ◽  
Measurement Instruments ◽  
Center Of Rotation ◽  
Moment Arms ◽  
Rotation Methods ◽  
Hybrid Methodology ◽  
Tendon Excursion

The musculotendon moment arm (MA) is the perpendicular distance from a muscle’s line of action to the rotational center of a joint. Moment arms are important in muscle modeling [1], and thus their accuracy is of great importance. Current in vivo techniques for computing MAs include the center of rotation and tendon excursion methods [1, 2]. The tendon excursion (TE) method relates the change in musculotendon length to an angular change in joint position [3]. This requires two measurements of musculotendon length for each MA computed. Similarly, the center of rotation method requires multiple image-based geometry measurements to compute the MA for a specific joint angle. The TE and center of rotation methods are both prone to measurement error, and thus it is difficult to ascertain the accuracy of the resulting MA. In this paper we present a novel hybrid methodology combining ultrasound (US) and video-based motion capture to compute the Achilles tendon moment arm. An advantage of this approach is that data used to derive the MA are acquired using highly accurate and reliable measurement instruments (i.e, US & motion capture), which may improve the accuracy of the MA estimate. The purpose of this paper is to present the hybrid methodology and validation results based on testing the method using an animal model.

Direct comparison of in vivo Achilles tendon moment arms obtained from ultrasound and MR scans

2010 ◽  
Vol 109 (6) ◽  
pp. 1644-1652 ◽  
Author(s):  
Florian Fath ◽  
Anthony J. Blazevich ◽  
Charlie M. Waugh ◽  
Stuart C. Miller ◽  
Thomas Korff
Keyword(s):  
Achilles Tendon ◽  
Strong Relationship ◽  
Coefficient Of Determination ◽  
Moment Arm ◽  
Mr Images ◽  
Moment Arms ◽  
Musculoskeletal Models ◽  
Tendon Excursion ◽  
Differentiation Technique

Accurate and reliable estimation of muscle moment arms is a prerequisite for the development of musculoskeletal models. Numerous techniques are available to estimate the Achilles tendon moment arm in vivo. The purposes of this study were 1) to compare in vivo Achilles tendon moment arms obtained using the center of rotation (COR) and tendon excursion (TE) methods and 2) to assess the reliability of each method. For the COR method, magnetic resonance (MR) images from nine participants were obtained at ankle angles of −15°, 0°, and +15° and analyzed using Reuleaux' method. For the TE method, the movement of the gastrocnemius medialis-Achilles tendon junction was recorded using ultrasonography as the ankle was passively rotated through its range of motion. The Achilles tendon moment arm was obtained by differentiation of tendon displacement with respect to ankle angular excursion using seven different differentiation techniques. Moment arms obtained using the COR method were significantly greater than those obtained using the TE method ( P < 0.01), but results from both methods were well correlated. The coefficient of determination between moment arms derived from the COR and TE methods was highest when tendon displacement was linearly differentiated over a ±10° interval ( R2 = 0.94). The between-measurement coefficient of variation was 3.9% for the COR method and 4.5–9.7% for the TE method, depending on the differentiation technique. The high reliabilities and strong relationship between methods demonstrate that both methods are robust against their limitations. The large absolute between-method differences (∼25–30%) in moment arms have significant implications for their use in musculoskeletal models.

Analysis of the mero-carpopodite joint of the American lobster and snow crab. II. Kinematics, morphometrics and moment arms

2003 ◽  
Vol 83 (6) ◽  
pp. 1249-1259 ◽  
Author(s):  
S.C. Mitchell ◽  
M.E. DeMont
Keyword(s):  
Joint Angle ◽  
Snow Crab ◽  
Moment Arm ◽  
Scaling Effects ◽  
Joint Angles ◽  
Positive Allometry ◽  
Moment Arms ◽  
Arm Reaching ◽  
Flexion Extension ◽  
The Moment

This research reports on the kinematics of lobster and snow crab walking, documents changes in the moment arms of the mero-carpopodite joint during rotation, and examines scaling effects of morphological and mechanical variables in these crustacean species. Forward walking lobsters and lateral walking crabs were recorded and images analysed to describe the kinematics of these animals, and subsequently morphometric and moment arm measurements made. During forward walking the lobster maintains fixed mero-carpopodite joint angles during both the power and recovery strokes, though each of the walking legs maintains different joint angles. Legs 3 and 5 are maintained at angles which appear to equalize the flexor and extensor moment arms, and leg 4 joint angle appears to maximize the extensor moment arm. The snow crab has a joint excursion angle of between approximately 50° to 150° and, during flat bed walking, the leading and trailing legs move through similar excursion angles. The length of the meropodite for both species are longer for the anterior two leg pairs relative to the posterior two pairs and the rate of growth of the meropodite is largely isometric for the lobster while consistently increases with positive allometry in the crab. The flexor and extensor moment arms generated as the joint undergoes flexion/extension show two distinct patterns with the extensor moment arm being maximized at relatively low joint angles (55°–115°) and the flexor moment arm reaching a plateau at joint extension with angles between 95° and 155°. The flexor apodeme possesses the largest moment arms in all legs for both species, suggesting the flexors are able to generate greater torques. It appears that, mechanically, these laterally moving animals may be ‘pulling’ with the leading legs to a greater extent than ‘pushing’ with the trailing legs.

Achilles Tendon Moment Arms Computed Using Ultrasound and Motion Analysis: In Vivo Estimates for Male Subjects

2008 ◽  
Author(s):  
Justin D. Cowder ◽  
Thomas S. Buchanan ◽  
Kurt T. Manal
Keyword(s):  
Achilles Tendon ◽  
Motion Capture ◽  
Hybrid Method ◽  
Lower Limb ◽  
Muscle Force ◽  
Average Weight ◽  
Moment Arm ◽  
Moment Arms ◽  
Male Subjects

Accurate estimates for Achilles tendon moment arm (MA) are essential when computing gastroc-soleus force from the net plantarflexion moment. Errors in approximating the Achilles tendon MA will adversely affect the muscle force estimate. We have noted that Achilles tendon MAs reported by Maganaris [1] and others are significantly greater (> 1 cm) than values used by Delp et al. computed using SIMM [2]. It is important to note that the stature of Delp’s lower limb model was almost identical to the average weight and height of the subjects in a study by Maganaris. This led us to question which MA profiles were more anatomically meaningful. To address this, we calculated Achilles tendon MAs for 10 male subjects using a previously described method. The method combines ultrasound and video-based motion capture, and referred to as the hybrid method. Subjects in our study were chosen to ensure they were of a similar stature to those tested by Maganaris, thereby minimizing confounding effects of subject anthropometrics.

scholarly journals A Hybrid Method for Computing Achilles Tendon Moment Arm Using Ultrasound and Motion Analysis

2010 ◽  
Vol 26 (2) ◽  
pp. 224-228 ◽  
Author(s):  
Kurt Manal ◽  
Justin D. Cowder ◽  
Thomas S. Buchanan
Keyword(s):  
Achilles Tendon ◽  
Motion Capture ◽  
Hybrid Method ◽  
Moment Arm ◽  
Measurement Instruments ◽  
Moment Arms ◽  
Perpendicular Distance ◽  
The Moment ◽  
Joint Center

In this article, we outline a method for computing Achilles tendon moment arm. The moment arm is computed from data collected using two reliable measurement instruments: ultrasound and video-based motion capture. Ultrasound is used to measure the perpendicular distance from the surface of the skin to the midline of the tendon. Motion capture is used to determine the perpendicular distance from the bottom of the probe to the ankle joint center. The difference between these two measures is the Achilles tendon moment arm. Unlike other methods, which require an angular change in joint position to approximate the moment arm, the hybrid method can be used to compute the moment arm directly at a specific joint angle. As a result, the hybrid method involves fewer error-prone measurements and the moment arm can be computed at the limits of the joint range of motion. The method is easy to implement and uses modalities that are less costly and more accessible than MRI. Preliminary testing using a lamb shank as a surrogate for a human ankle revealed good accuracy (3.3% error). We believe the hybrid method outlined here can be used to measure subject-specific moment arms in vivo and thus will potentially benefit research projects investigating ankle mechanics.

scholarly journals Interactive Effects of Joint Angle, Contraction State and Method on Estimates of Achilles Tendon Moment Arms

2013 ◽  
Vol 29 (2) ◽  
pp. 241-244 ◽  
Author(s):  
Florian Fath ◽  
Anthony J. Blazevich ◽  
Charlie M. Waugh ◽  
Stuart C. Miller ◽  
Thomas Korff
Keyword(s):  
Achilles Tendon ◽  
Joint Angle ◽  
Input Parameter ◽  
Maximum Voluntary Contraction ◽  
Muscular Contraction ◽  
Voluntary Contraction ◽  
Interactive Effects ◽  
Moment Arm ◽  
Moment Arms ◽  
Musculoskeletal Models

The muscle-tendon moment arm is an important input parameter for musculoskeletal models. Moment arms change as a function of joint angle and contraction state and depend on the method being employed. The overall purpose was to gain insights into the interactive effects of joint angle, contraction state and method on the Achilles tendon moment arm using the center of rotation (COR) and the tendon excursion method (TE). Achilles tendon moment arms were obtained at rest (TErest, CORrest) and during a maximum voluntary contraction (CORMVC) at four angles. We found strong correlations between TErest and CORMVC for all angles (.72 ≤ r ≤ .93) with Achilles tendon moment arms using CORMVC being 33–36% greater than those obtained from TErest. The relationship between Achilles tendon moment arms and angle was similar across both methods and both levels of muscular contraction. Finally, Achilles tendon moment arms for CORMVC were 1–8% greater than for CORrest.

scholarly journals Plantar flexor moment arm and muscle volume predict torque-generating capacity in young men

2014 ◽  
Vol 116 (5) ◽  
pp. 538-544 ◽  
Author(s):  
Josh R. Baxter ◽  
Stephen J. Piazza
Keyword(s):  
Plantar Flexion ◽  
Young Men ◽  
Knee Extensor ◽  
Muscle Volume ◽  
Joint Torque ◽  
Muscle Size ◽  
Plantar Flexor ◽  
Moment Arm ◽  
Joint Rotation ◽  
Moment Arms

Muscle volume is known to correlate with maximal joint torque in humans, but the role of muscle moment arm in determining maximal torque is less clear. Moderate correlations have been reported between maximal isometric knee extensor torque and knee extensor moment arm, but no such observations have been made for the ankle joint. It has been suggested that smaller muscle moment arms may enhance force generation at high rates of joint rotation, but this has not yet been observed for ankle muscles in vivo. The purpose of the present study was to correlate plantar flexor moment arm and plantar flexor muscle volume with maximal plantar flexor torque measured at different rates of plantar flexion. Magnetic resonance imaging was used to quantify the plantar flexor moment arm and muscle volume of the posterior compartment in 20 healthy young men. Maximal plantar flexor torque was measured isometrically and at three plantar flexion speeds using an isokinetic dynamometer. Plantar flexor torque was significantly correlated with muscle volume (0.222 < R2 < 0.322) and with muscle moment arm at each speed (0.323 < R2 < 0.494). While muscle volume was strongly correlated with body mass and stature, moment arm was not. The slope of the torque-moment arm regression line decreased as the rate of joint rotation increased, indicating that subjects with small moment arms experienced smaller reductions in torque at high speeds. The findings of this study suggest that plantar flexor moment arm is a determinant of joint strength that is at least as important as muscle size.

scholarly journals A Forefoot Strike Requires the Highest Forces Applied to the Foot Among Foot Strike Patterns

2017 ◽  
Vol 01 (02) ◽  
pp. E37-E42 ◽  
Author(s):  
Satoru Hashizume ◽  
Toshio Yanagiya
Keyword(s):  
Achilles Tendon ◽  
Ground Reaction Force ◽  
Reaction Force ◽  
Moment Arm ◽  
Moment Arms ◽  
Joint Reaction Forces ◽  
Force Moment ◽  
Foot Strike ◽  
Reaction Forces ◽  
Joint Reaction

AbstractGround reaction force is often used to predict the potential risk of injuries but may not coincide with the forces applied to commonly injured regions of the foot. This study examined the forces applied to the foot, and the associated moment arms made by three foot strike patterns. 10 male runners ran barefoot along a runway at 3.3 m/s using forefoot, midfoot, and rearfoot strikes. The Achilles tendon and ground reaction force moment arms represented the shortest distance between the ankle joint axis and the line of action of each force. The Achilles tendon and joint reaction forces were calculated by solving equations of foot motion. The Achilles tendon and joint reaction forces were greatest for the forefoot strike (2 194 and 3 137 N), followed by the midfoot strike (1 929 and 2 853 N), and the rearfoot strike (1 526 and 2 394 N). The ground reaction force moment arm was greater for the forefoot strike than for the other foot strikes, and was greater for the midfoot strike than for the rearfoot strike. Meanwhile, there were no differences in the Achilles tendon moment arm among all foot strikes. These differences were attributed mainly to differences in the ground reaction force moment arm among the three foot strike patterns.

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