scholarly journals The Effect of Three Foot Types on the Achilles Tendon Lever Arm

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0020
Author(s):  
Manja Deforth ◽  
Lukas Zwicky ◽  
Tamara Horn Lang ◽  
Beat Hintermann
Keyword(s):  
Achilles Tendon ◽  
The Body ◽  
Triceps Surae ◽  
Horizontal Line ◽  
Neutral Position ◽  
Moment Arm ◽  
Pes Cavus ◽  
Pes Planus ◽  
Lever Arm ◽  
The Moment

Category: Hindfoot Introduction/Purpose: During locomotion, propulsion of the body is created by the force of the triceps surae complex as it is transmitted to the metatarsal heads. The amount and pattern of the resulting propulsion force highly depends on the moment arm of the Achilles tendon. To our knowledge, no data exists on how and to which extent position and morphology of the foot affects the moment arm of the Achilles tendon. The aim of this study was 1) to develop a method to determine the Achilles tendon moment arm, and 2) to calculate the Achilles tendon moment arm with the foot in different degrees of dorsi- and plantarflexion for 3 foot types (normal arched foot, pes planus, and pes cavus). Methods: 99 study participants with a healthy ankle joint (males, 40; females, 59; mean age 49 [range, 14 – 78] years) were included. Participants’ foot type was classified as a normal arched foot (n = 33), as pes planus (n = 33), or as pes cavus (n = 33) based on the calcaneal inclination angle (CI) (Figure 1). Besides the foot type, the foot length (FL), the calcaneal insertion of the Achilles tendon (ATI), the angle (a) between the line (L) connecting ATI with the center of rotation of the ankle (COR) and the horizontal line (L’) were measured on the lateral radiographs. The interrater reliabilities of measuring a on radiographs and on MRIs were compared. The lever arm of the Achilles tendon (L’calculated) was calculated as following (foot and tibia were regarded as two rigid segments; the influences of other muscles were neglected): L’calculated = cos(a - plantarflexion)*L Results: The interrater reliability of a was higher on radiographs (ICC = 0.84, [0.73 – 0.91]) than on MRIs (ICC = 0.61, [0.27 – 0.81]). The ICC comparing a measured on MRIs and radiographs was 0.63 [0.50-0.74]. There was no difference in FL between the three foot types (p = 0.199). However, the average a was significantly different (normal arched foot 31°, pes planus 24°, pes cavus 36°, p = 0.021), resulting in a statistically significant shorter Achilles tendon lever arm for pes cavus than for pes planus (p < 0.0001) and normal arched feet (p = 0.006) in neutral position. The maximum lever arm for the three different foot types was reached at different degrees of plantarflexion (Figure 2). Conclusion: The assessment of the Achilles tendon lever arm using radiographs is reliable. The foot configuration determines the lever arm of the Achilles tendon for a given flexion position of the foot. It also determines the plantarflexion position where the Achilles tendon reaches the maximum of its lever arm. This has to be taken into consideration when planning surgeries that change a or L, as they may also result in changes of plantarflexion power.

scholarly journals Effects of Achilles Tendon Moment Arm Length on Insertional Achilles Tendinopathy

2020 ◽  
Vol 10 (19) ◽  
pp. 6631
Author(s):  
Takuma Miyamoto ◽  
Yasushi Shinohara ◽  
Tomohiro Matsui ◽  
Hiroaki Kurokawa ◽  
Akira Taniguchi ◽  
...  
Keyword(s):  
Achilles Tendon ◽  
Achilles Tendinopathy ◽  
Control Group ◽  
Moment Arm ◽  
Healthy Individuals ◽  
Suture Bridge ◽  
Significant Difference ◽  
The Moment ◽  
Insertional Achilles Tendinopathy ◽  
Suture Bridge Technique

Insertional Achilles tendinopathy (IAT) is caused by traction force of the tendon. The effectiveness of the suture bridge technique in correcting it is unknown. We examined the moment arm in patients with IAT before and after surgery using the suture bridge technique, in comparison to that of healthy individuals. We hypothesized that the suture bridge method influences the moment arm length. An IAT group comprising 10 feet belonging to 8 patients requiring surgical treatment for IAT were followed up postoperatively and compared with a control group comprising 15 feet of 15 healthy individuals with no ankle complaints or history of trauma or surgery. The ratio of the moment arm (MA) length/foot length was found to be statistically significant between the control group, the IAT group preoperatively and the IAT group postoperatively (p < 0.01). Despite no significant difference in the force between the control and preoperative IAT groups, a significantly higher force to the Achilles tendon was observed in the IAT group postoperatively compared to the other groups (p < 0.05). This study demonstrates that a long moment arm may be one of the causes of IAT, and the suture bridge technique may reduce the Achilles tendon moment arm.

scholarly journals Considerations on the human Achilles tendon moment arm for in vivo triceps surae muscle–tendon unit force estimates

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Denis Holzer ◽  
Florian Kurt Paternoster ◽  
Daniel Hahn ◽  
Tobias Siebert ◽  
Wolfgang Seiberl
Keyword(s):  
Achilles Tendon ◽  
Triceps Surae ◽  
Muscle Forces ◽  
Moment Arm ◽  
Unit Force ◽  
Plateau Region ◽  
Triceps Muscle ◽  
Triceps Surae Muscle ◽  
The Individual

Abstract Moment arm-angle functions (MA-a-functions) are commonly used to estimate in vivo muscle forces in humans. However, different MA-a-functions might not only influence the magnitude of the estimated muscle forces but also change the shape of the muscle’s estimated force-angle relationship (F-a-r). Therefore, we investigated the influence of different literature based Achilles tendon MA-a-functions on the triceps surae muscle–tendon unit F-a-r. The individual in vivo triceps torque–angle relationship was determined in 14 participants performing maximum voluntary fixed-end plantarflexion contractions from 18.3° ± 3.2° plantarflexion to 24.2° ± 5.1° dorsiflexion on a dynamometer. The resulting F-a-r were calculated using 15 literature-based in vivo Achilles tendon MA-a-functions. MA-a-functions affected the F-a-r shape and magnitude of estimated peak active triceps muscle–tendon unit force. Depending on the MA-a-function used, the triceps was solely operating on the ascending limb (n = 2), on the ascending limb and plateau region (n = 12), or on the ascending limb, plateau region and descending limb of the F-a-r (n = 1). According to our findings, the estimated triceps muscle–tendon unit forces and the shape of the F-a-r are highly dependent on the MA-a-function used. As these functions are affected by many variables, we recommend using individual Achilles tendon MA-a-functions, ideally accounting for contraction intensity-related changes in moment arm magnitude.

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 Orthotic Heel Wedges Do Not Alter Hindfoot Kinematics and Achilles Tendon Force During Level and Inclined Walking in Healthy Individuals

2016 ◽  
Vol 32 (2) ◽  
pp. 160-170 ◽  
Author(s):  
Robert A. Weinert-Aplin ◽  
Anthony M.J. Bull ◽  
Alison H. McGregor
Keyword(s):  
Achilles Tendon ◽  
Plantar Flexion ◽  
Force Plate ◽  
The Body ◽  
Triceps Surae ◽  
Tibialis Posterior ◽  
Muscle Forces ◽  
Flexor Muscle ◽  
Optical Motion ◽  
Tendon Force

Conservative treatments such as in-shoe orthotic heel wedges to treat musculoskeletal injuries are not new. However, weak evidence supporting their use in the management of Achilles tendonitis suggests the mechanism by which these heel wedges works remains poorly understood. It was the aim of this study to test the underlying hypothesis that heel wedges can reduce Achilles tendon load. A musculoskeletal modeling approach was used to quantify changes in lower limb mechanics when walking due to the introduction of 12-mm orthotic heel wedges. Nineteen healthy volunteers walked on an inclinable walkway while optical motion, force plate, and plantar pressure data were recorded. Walking with heel wedges increased ankle dorsiflexion moments and reduced plantar flexion moments; this resulted in increased peak ankle dorsiflexor muscle forces during early stance and reduced tibialis posterior and toe flexor muscle forces during late stance. Heel wedges did not reduce overall Achilles tendon force during any walking condition, but did redistribute load from the medial to lateral triceps surae during inclined walking. These results add to the body of clinical evidence confirming that heel wedges do not reduce Achilles tendon load and our findings provide an explanation as to why this may be the case.

scholarly journals Longer Achilles tendon moment arm results in better running economy

2021 ◽  
Vol 107 (4) ◽  
pp. 527-541
Author(s):  
B. Kovács ◽  
I. Kóbor ◽  
Ö. Sebestyén ◽  
J. Tihanyi
Keyword(s):  
Electrical Activity ◽  
Achilles Tendon ◽  
Body Height ◽  
The Body ◽  
Running Economy ◽  
Medial Gastrocnemius ◽  
Moment Arm ◽  
Marathon Runners ◽  
The Right ◽  
Leg Kinematics

AbstractBased on the current literature, the link between Achilles tendon moment arm length and running economy is not well understood. Therefore, the aim of this study was to further investigate the connection between Achilles tendon moment arm and running economy and the influence of Achilles tendon moment arm on the function of the plantarflexor muscle-tendon unit during running.Ten male competitive marathon runners volunteered for this study. The participants ran on a treadmill at two running speeds: 3 and 3.5 m s−1. During running the oxygen consumption, lower leg kinematics, electrical activity of plantar flexor muscles, and fascicle behavior of the lateral gastrocnemius were measured simultaneously. On the second occasion, an MRI scan of the right leg was taken and used to estimate the Achilles tendon moment arm length.There was a negative correlation between running economy and the body height normalized moment arm length at both selected speeds (r = −0.68, P = 0.014 and r = −0.70, P = 0.01). In addition, Achilles tendon moment arm length correlated with the amplitude of the ankle flexion at both speeds (r = −0.59, P = 0.03 and r = −0.60, P = 0.03) and with the electrical activity of the medial gastrocnemius muscle at 3 m s−1 speed (r = −0.62, P = 0.02). Our finding supports the concept that a longer moment arm could be beneficial for distance runners.

Achilles Tendon Ruptures—Peroneus Brevis Transfer

Foot & Ankle ◽  
1987 ◽  
Vol 7 (4) ◽  
pp. 253-259 ◽  
Author(s):  
Vincent J. Turco ◽  
Anthony J. Spinella
Keyword(s):  
Achilles Tendon ◽  
Tendon Transfer ◽  
Triceps Surae ◽  
Proximal Fragment ◽  
Neutral Position ◽  
Peroneal Tendon ◽  
Calcaneal Tendon ◽  
Musculotendinous Junction ◽  
Tendon Ruptures ◽  
Peroneus Brevis

Peroneus brevis tendon transfer has been utilized in 40 individuals during the last 13 years. All cases consisted of complete Achilles tendon ruptures. In 34 cases the rupture was in the distal one-third of the tendon substance, in four cases bony avulsion of the calcaneal tuberosity occurred, and in two cases there was a diffuse tear in the proximal two-thirds of the tendon near the musculotendinous junction. The middle-aged athlete sustained the majority of these injuries during sports. Eleven patients were less than 30 years old, 23 patients were 30 to 40 years old, and six were over 40 years old. Five patients had reruptures that involved prior nonoperative treatment of cast immobilization, and one had undergone simple direct suture. This repair has been used in acute, chronic, and recurrent ruptures of the tendoachillis. Thirty-three patients presented within 1 week of injury, and seven after more than 1 week. A. Perez Teuffer personally described the preferred technique in 1971 and subsequently published in 1978. The transfer of the peroneus brevis is combined with a direct end-to-end suture of the triceps surae tendon that allows a secure reconstruction with the foot at a right angle. The peroneus brevis tendon is detached from the base of the fifth metatarsal and then tunnelled through the distal Achilles tendon stump. The distal portion of the tendon transfer is then drawn proximally along the medial calcaneal tendon border. The proximal triceps surae tendon is pulled distally and secured to the peroneal tendon. The ruptured ends of the Achilles tendon are sandwiched between the U-shaped peroneal tendon transfer, which acts as a biologic scaffold for the reparitive process. Several advantages are apparent when compared to nonoperative care and other operative techniques including simple Achilles tendon repair, plantaris tendon transfers, reconstructive fascial flaps, and synthetic substitutes. A strong repair with the foot at the neutral position is possible even when the Achilles tendon is shredded. The transfer provides an active motor, adds some power to the damaged triceps, and avoids the danger of rerupture. No reruptures have occurred after this surgical procedure. Calf weakness is minimized because the proximal fragment of the damaged Achilles tendon is sutured securely under physiologic tension into the peroneus brevis. Immobilization postoperatively in a short leg cast at a right angle and early weightbearing facilitate the rehabilitation period and avoid the many months necessary to regain dorsiflexion after 6 to 8 weeks of casting in plantarflexion. The bulk and profile of the repaired Achilles tendon is restored. A healthy tendon transfer is an additional benefit. Strength after the peroneus brevis U-shaped tendon transfer is superior to other methods of treatment and is particularly advantageous in the sports-oriented individual.

scholarly journals The Effect of Achilles Tendon Loading on Ankle Joint Contact Area and Peak Pressure

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0030
Author(s):  
L. Daniel Latt ◽  
Alfonso Ayala ◽  
Samuel Kim ◽  
Jesus Lopez
Keyword(s):  
Achilles Tendon ◽  
Ankle Joint ◽  
Contact Area ◽  
Axial Load ◽  
Peak Pressure ◽  
The Body ◽  
Neutral Position ◽  
Joint Contact ◽  
Axially Loaded ◽  
The Impact

Category: Ankle Introduction/Purpose: Increased tibiotalar peak pressure (PP) and decreased contact area (CA) following ankle fracture are associated with the development of post-traumatic osteoarthtritis. Lateral talar translation of just 1 mm has been shown to decrease CA by 42%. The impact of talar malalignment in other directions on ankle joint contact pressures (AJCP) are not well understood. The majority of research on AJCP has utilized cadaveric models in which body weight is simulated with an axial load applied through the tibia. This model does not account for Achilles tendon - which transmits the largest tendon force in the body during weight bearing. This study aimed to determine the effects of Achilles tendon loading on tibiotalar CA and PP in an axially loaded cadaver model at different ankle flexion angles. Methods: Ten fresh frozen cadaveric lower extremity specimens transected mid-tibia were dissected free of soft tissues surrounding the ankle, sparing the ligaments. The proximal tibia and fibula were potted in quick drying cement for rigid mounting on a MTS machine. A pressure sensing element (TekScan KScan model 5033) was inserted into the tibiotalar joint and used to measure CA (cm2) and PP (MPa). An axial load of 686 N was applied through the tibia and fibula, followed by a 350 N load via the Achilles tendon to simulate mid-stance conditions. Measurements were taken at neutral position, 15 degrees of dorsiflexion and 15 degrees of plantarflexion, with and without Achilles load. The effects of Achilles load and ankle flexion angle on CA and PP were analyzed using a 2x3 ANOVA. Bonferroni post-hoc adjustments were used for multiple comparisons. Level of statistical significance was set at p < 0.05. Results: ANOVA revealed significant main effects of ankle flexion on contact area and peak pressures (Table 1). Contact area was significantly lower for 15 degrees of plantarflexion than neutral and 15 degrees of dorsiflexion (p < 0.001). In addition, peak pressure was significantly higher for 15 degrees of plantarflexion than neutral and 15 degrees of dorsiflexion. ANOVA also indicated that contact area and peak pressure were significantly higher with Achilles load than without (p < 0.001). No interaction effects were found. Conclusion: The applied Achilles tendon load significantly altered tibiotalar PP in an axially loaded cadaver model. On the other hand, changes in CA with Achilles load were found to be minimal (~1.8%). We also found that the greatest PP and smallest CA occured during plantar flexion. This observation can be explained by a difference in width between the anterior and posterior talus. While the results of this study demonstrate the importance of Achilles tendon load on tibiotalar measurements, further studies investigating the effects of additional factors such as loading techniques are warranted to improve the physiological accuracy of cadaver models.

scholarly journals Achilles tendon moment arm in humans is not affected by inversion/eversion of the foot: a short report

2018 ◽  
Vol 5 (1) ◽  
pp. 171358 ◽  
Author(s):  
Susann Wolfram ◽  
Christopher I. Morse ◽  
Keith L. Winwood ◽  
Emma Hodson-Tole ◽  
Islay M. McEwan
Keyword(s):  
Achilles Tendon ◽  
Magnetic Resonance Images ◽  
Triceps Surae ◽  
Short Report ◽  
Moment Arm ◽  
Moment Arms ◽  
Musculoskeletal Models ◽  
Rotation Method ◽  
Centre Of Rotation ◽  
Foot Position

The triceps surae primarily acts as plantarflexor of the ankle joint. However, the group also causes inversion and eversion at the subtalar joint. Despite this, the Achilles tendon moment arm is generally measured without considering the potential influence of inversion/eversion of the foot during plantarflexion. This study investigated the effect of foot inversion and eversion on the plantarflexion Achilles tendon moment arm. Achilles tendon moment arms were determined using the centre-of-rotation method in magnetic resonance images of the left ankle of 11 participants. The foot was positioned at 15° dorsiflexion, 0° or 15° plantarflexion using a Styrofoam wedge. In each of these positions, the foot was either 10° inverted, neutral or 10° everted using an additional Styrofoam wedge. Achilles tendon moment arm in neutral foot position was 47.93 ± 4.54 mm and did not differ significantly when the foot was positioned in 10° inversion and 10° eversion. Hence, inversion/eversion position of the foot may not considerably affect the length of the Achilles tendon moment arm. This information could be useful in musculoskeletal models of the human lower leg and foot and when estimating Achilles tendon forces during plantarflexion with the foot positioned in inversion or eversion.

Optimal Design of a Mechatronic Lever Arm for Pneumatic Exoskeleton: Design and Validation

2020 ◽  
Author(s):  
Donald Ward ◽  
Brian Epstein ◽  
Lucas Tiziani ◽  
Frank L. Hammond
Keyword(s):  
Artificial Muscle ◽  
Pressure Control ◽  
The Body ◽  
Pneumatic Actuators ◽  
Lever Arm ◽  
Expected Performance ◽  
Metabolic Performance ◽  
The Moment ◽  
The Impact ◽  
Exoskeleton Design

Abstract Pneumatically powered, lower limb exoskeletons provide high levels of compliant assistance to a user and add little on-body mass when the power source is located off the body. Such tethered systems are useful to testing the impact of control methods on a user’s metabolic performance and benefit from the pneumatic actuators’ simplicity of control. However, the pneumatic artificial muscle (PAM), a popular lightweight actuator, suffers from a nonlinear relationship between its contraction force, length and actuation pressure, reducing its output capabilities and complicating the design of exoskeletons that implement these actuators. This work describes a mechatronic lever arm system that extends the capabilities of a PAM actuated exoskeleton by configuring the moment arm, joint angle profile to create a torque profile specific to the designers’ requirements. A design optimization shows how the proposed system can tailor the exoskeleton performance without changing the simplistic, on-off pressure control. The specifications and the expected performance of the detailed design is described.

Rationale for a Modified Crutch Use Methodology for Individuals With Weak or Paralyzed Hip Abductor Muscles

2013 ◽  
Author(s):  
James Borrelli ◽  
Henry W. Haslach
Keyword(s):  
Three Dimensional ◽  
Frontal Plane ◽  
The Body ◽  
Moment Arm ◽  
Gait Kinematics ◽  
Hip Abductor ◽  
Pathological Gait ◽  
The Moment ◽  
Positive Effect ◽  
Traditional Manner

Individuals with weak or paralyzed hip abductors may make use of two methods to reduce pathological gait kinematics as a result of their disability; reducing the need for the hip abductors or developing an equivalent torque on the body. Compensatory motions such as torso tilting or hip hiking “balance” the body reducing the need for the torque that would be developed by the hip abductors. A contralateral crutch develops a body torque that is equivalent to that developed by the hip abductors. Individuals with weak or paralyzed hip abductors intuitively adopt a wide crutch stance, contrary to the prescribed method where the crutches are vertical in the frontal plane. Using a wide stance angle in the frontal plane is hypothesized to improve gait with weak or paralyzed hip abductors more so than when using crutches in the traditional manner. Crutches develop a torque on the body that is equivalent to what would be developed by the hip abductors while standing still. A wide stance angle increases the moment arm that the crutch force acts through while standing still, increasing the torque developed, potentially increasing the positive effect of the crutch which may reduce the need for compensatory motions. However, a similar effect has not been characterized during gait. The hypothesis is that a wide crutch stance angle improves a gait with paralyzed hip abductors more so than a crutch used vertically in the frontal plane. The assumption is that this is accomplished by decreasing energy expenditure and/or reducing the need for compensatory motions more so than a crutch used vertically in the frontal plane. A three-dimensional dynamic model is used to test the hypothesis. The model predicts that excessive pelvis depression and decreased pelvic rotation result when the hip abductors are paralyzed. Compensatory motions, hip hiking and torso tilting, and crutch use are shown to decrease the prevalence of pathological kinematics. Crutch use with a wide stance angle improves gait kinematics more than a vertical crutch with the same body weight supported on it. This study provides evidence that the need for compensatory motions and the prevalence of pathological gait kinematics may be reduced when using a wide crutch stance angle compared to a vertical crutch stance angle.

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