Search results for "Achilles tendon"
showing 10 items of 101 documents
Individual muscle contributions to the in vivo achilles tendon force
1998
OBJECTIVE: To ascertain the possibility of non-uniform stress within the achilles tendon due to individual force contributions of the triceps surae. DESIGN: Calculation of non-uniform stress through discrepancies in moments about the ankle joint. BACKGROUND: Non-uniform stress over the cross-sectional area have been implied in the etiology of achilles tendon injury and may influence functional aspects. However, this has not been empirically demonstrated. METHODS: In vivo achilles tendon forces were measured with an optic fibre technique during isometric plantarflexions at systematically varied knee angles and contraction intensities. A comparison to the plantar force measured underneath the…
EFFECTS OF STRIKING STRATEGY ON LOWER EXTREMITY LOADING DURING RUNNING
2013
Backround It is expected that every second runner has a running-related overuse injury each year. The knee joint and Achilles tendon are the most commonly injured sites covering both about one fifth of all running related injuries. 1 Runners can be categorized into rearfoot strikers, mid-foot strikers or forefoot strikers based on the landing strategy at the instant of initial ground contact. Forefoot or mid-foot striking has been shown to reduce impact peak and loading rate of the ground reaction force during early stance phase. 2 Furthermore, the finding of the recent study suggest that forefoot striking may potentially decrease the risk of running-related injuries. 3 However, the effect …
Surgical repair of acute Achilles tendon rupture with an end-to-end tendon suture and tendon flap.
2015
Abstract Background Achilles tendon ruptures are becoming more common. Complications after open or minimally invasive surgery are: recurrent rupture (2–8%), wound breakdown, deep infections, granuloma, and fistulas. The authors expose their experience with a personal technique. Materials In 8 patients with acute rupture of Achilles tendon the surgery was performed at least 25 days after trauma. Clinical exam and MR demonstrated in all case a total lesion of tendon. After a posterolateral skin incision the tendon stumps were debrided and suture in end-to-end fashion. A tendon flap was harvested from the proximal part of the tendon, in order to protect and reinforce the suture itself. A plast…
Micromechanical Properties and Collagen Composition of Ruptured Human Achilles Tendon
2012
Background:The Achilles tendon is one of the strongest tendons in the human body, and yet it frequently ruptures, which is a substantial clinical problem. However, the cause of ruptures remains elusive.Hypothesis:Ruptured human Achilles tendon displays inferior biomechanical properties and altered collagen composition compared with noninjured tendon.Study Design:Controlled laboratory study.Methods:Biopsy specimens were obtained at the rupture site and the noninjured part of the tendon (internal controls) in 17 patients with acute Achilles tendon rupture. Age- and weight-matched human cadaveric Achilles tendons (external controls) were also obtained. Tendon samples were tested micromechanica…
Comparison between the directly measured achilles tendon force and the tendon force calculated from the ankle joint moment during vertical jumps.
1988
Summary The purpose of this study was to compare the relationship between the achilles tendon force and the tendon force estimated from the ankle joint moment (EATF) during vertical jump. A healthy male subject performed the following jumps on the force platform: (a) maximal vertical jump from a squat position without counter-movement; (b) maximal vertical jump from an erect standing position with a preliminary counter-movement; (c) repetitive submaximal hopping on the spot with preferred frequency. The achilles tendon force was measured directly with an implanted tendon transducer in all jumping conditions. In addition the joint moment obtained from the film and ground reaction force was u…
Viewpoint: On the hysteresis in the human Achilles tendon.
2012
This viewpoint was stimulated by two observations: 1) the statistical skewness whereby numerous articles have reported tendon stiffness and Young9s modulus, but far fewer have reported tendon hysteresis; 2) in vivo human studies seem very often to report hysteresis values greater than 10%, suggesting either that there are methodological differences between human and animal studies, or that human tendons have a much poorer capacity to store and reutilize elastic energy. In this article we focus on the healthy human Achilles/gastrocnemius tendon (AT) since it has an important locomotor function and clearly a low AT hysteresis would allow elastic recoil for efficient locomotion. We discuss tha…
Gastrocnemius tendon length and strain are different when assessed using straight or curved tendon model
2011
The present study investigated the effects of tendon curvature on measurements of tendon length using 3D-kinematic analysis. Curved and straight tendon models were employed for assessing medial gastrocnemius tendon length and strain during hopping (N = 8). Tendon curvature was identified using small reflective markers placed on the skin surface along the length of the tendon and a sum of vectors between the markers from the calcaneous up to the marker at the origin of tendon was calculated. The straight tendon was defined as a length of vector from the calcaneous to the marker at the origin of tendon. The curved tendon method yielded 5.0 ± 1.3 mm longer tendon (p < 0.001) than the straight …
Effect of Training-Induced Changes in Achilles Tendon Stiffness on Muscle–Tendon Behavior During Landing
2018
During rapid deceleration of the body, tendons buffer part of the elongation of the muscle–tendon unit (MTU), enabling safe energy dissipation via eccentric muscle contraction. Yet, the influence of changes in tendon stiffness within the physiological range upon these lengthening contractions is unknown. This study aimed to examine the effect of training-induced stiffening of the Achilles tendon on triceps surae muscle–tendon behavior during a landing task. Twenty-one male subjects were assigned to either a 10-week resistance-training program consisting of single-leg isometric plantarflexion (n = 11) or to a non-training control group (n = 10). Before and after the training period, plantarf…
Training-induced increase in Achilles tendon stiffness affects tendon strain pattern during running
2019
Background During the stance phase of running, the elasticity of the Achilles tendon enables the utilisation of elastic energy and allows beneficial contractile conditions for the triceps surae muscles. However, the effect of changes in tendon mechanical properties induced by chronic loading is still poorly understood. We tested the hypothesis that a training-induced increase in Achilles tendon stiffness would result in reduced tendon strain during the stance phase of running, which would reduce fascicle strains in the triceps surae muscles, particularly in the mono-articular soleus. Methods Eleven subjects were assigned to a training group performing isometric single-leg plantarflexion co…
Focal lesions of the Achilles tendon: real-time variation of lesion grading during ultrasound-guided platelet-concentrate injection.
2009
INTRODUCTION: Achillodynia (Achilles tendon pain) is a significant source of disability for many sport people. Achilles tendon (AT) tear is the third most frequent major tendon disruption after those of the rotator cuff and knee extensor mechanism. The incidence of the AT tears is 11–18% overall. Unlike acute AT tear, chronic tear diagnosis is more difficult to make particularly when the chronic tear involves the AT only partially. Over the last 10 years, real time ultrasound has been used increasingly to diagnose Achilles tendon tears, thanks to its ability to perform dynamic study, in passive and active muscle contraction. Furthermore, ultrasound-guided procedures are increasingly used fo…