Ultrasound-based speckle-tracking in tendons: a critical analysis for the technician and the clinician.

Ultrasound has risen to the forefront as one of the primary tools in tendon research, with benefits including its relatively low cost, ease of use, and high safety. Moreover, it has been shown that cine ultrasound can be used to evaluate tendon deformation by tracking the motion of anatomical landmarks during physical movement. Estimates from landmark tracking, however, are typically limited to global tissue properties, such that clinically relevant regional nonuniformities may be missed.

Patellar tendon buckling in post-operative total knee arthroplasty patients is more prominent than in healthy controls.

Recent evidence suggests the patellar tendon undergoes buckling during normal knee flexion, which likely contributes to the functioning of the extensor mechanism. Thus, evaluating buckling in patients following total knee arthroplasty (TKA), where extensor mechanism dysfunction remains a common complication, may be relevant. The study goals were to identify whether post-TKA patients exhibit differences in patellar tendon buckling from healthy, similarly-aged adults and whether such buckling correlates with knee and patellar tendon health.

Non-uniformity in the healthy patellar tendon is greater in males and similar in different age groups.

There is increasing evidence that tendons are heterogeneous and take advantage of structural mechanisms to enhance performance and reduce injury. Fascicle-sliding, for example, is used by energy-storing tendons to enable them to undergo large extensions while protecting the fascicles from damage. Reductions in fascicle-sliding capacity may thus predispose certain populations to tendinopathy.

Patellar tendon buckling is altered with age.

Recent evidence has revealed that the patellar tendon exhibits buckling during passive knee extension, wherein the tendon folds back onto itself. The clinical relevance of such buckling is unclear, but it has been suggested that it serves to protect the patellar tendon from rupture when subjected to a sudden extreme contraction. Although prior evidence suggests buckling occurs universally, it is poorly understood, and may be influenced by age and sex.

Evidence of Generalized Muscle Stiffness in the Presence of Latent Trigger Points Within Infraspinatus.

Objective: To evaluate stiffness of infraspinatus muscle tissue, both with and without latent trigger points, using ultrasound shear wave elastography (SWE). The primary hypothesis is that muscle with a latent trigger point will demonstrate a discrete region of increased shear wave speed. The secondary hypothesis is that shear wave speed (SWS) in the region with the trigger point will be higher in patients compared with controls, and will be similar between the two groups in the uninvolved regions.

The challenges of measuring in vivo knee collateral ligament strains using ultrasound.

Ultrasound-based methods have shown promise in their ability to characterize non-uniform deformations in large energy-storing tendons such as the Achilles and patellar tendons, yet applications to other areas of the body have been largely unexplored. The noninvasive quantification of collateral ligament strain could provide an important clinical metric of knee frontal plane stability, which is relevant in ligament injury and for measuring outcomes following total knee arthroplasty. In this pilot cadaveric experiment, we investigated the possibility of measuring collateral ligament strain with our previously validated speckle-tracking approach, but encountered a number of challenges during both data acquisition and processing.

Nonuniform Deformation of the Patellar Tendon During Passive Knee Flexion.

The purpose of this study was to evaluate localized patterns of patellar tendon deformation during passive knee flexion. Ultrasound radiofrequency data were collected from the patellar tendons of 20 healthy young adults during knee flexion over a range of motion of 50°-90° of flexion. A speckle tracking approach was used to compute proximal and distal tendon displacements and elongations.

The measurement of medial knee gap width using ultrasound.

Introduction: Medial knee instability is a key clinical parameter for assessing ligament injury and arthroplasty success, but current methods for measuring stability are typically either qualitative or involve ionizing radiation. The purpose of this study was to perform a preliminary analysis of whether ultrasound (US) could be used as an alternate approach for quantifying medial instability by comparing an US method with an approach mimicking the current gold standard fluoroscopy method.

Materials And Methods: US data from the medial knee were collected, while cadaveric lower limbs (n = 8) were loaded in valgus (10 Nm).

A 3D model of the Achilles tendon to determine the mechanisms underlying nonuniform tendon displacements.

The Achilles is the thickest tendon in the body and is the primary elastic energy-storing component during running. The form and function of the human Achilles is complex: twisted structure, intratendinous interactions, and differential motor control from the triceps surae muscles make Achilles behavior difficult to intuit. Recent in vivo imaging of the Achilles has revealed nonuniform displacement patterns that are not fully understood and may result from complex architecture and musculotendon interactions.

Evidence of patellar tendon buckling during passive knee extension.

Purpose: The purpose of this study was to investigate and describe buckling of the patellar tendon.

Methods: Healthy young adults (28±4years, 10F/10M) underwent passive knee flexion/extension during the simultaneous measurement of knee angle and collection of cine ultrasound from the patellar tendon. Patellar tendon buckling was observed visually in ultrasound images, and the corresponding knee angle at which evidence of buckling disappeared was identified.

Quantitative ultrasound mapping of regional variations in shear wave speeds of the aging Achilles tendon.

Objectives: Evaluate the effects of aging on healthy Achilles tendon and aponeurosis shear wave speed (SWS), a quantitative metric which reflects tissue elasticity.

Methods: Shear wave elastography was used to measure spatial variations in Achilles tendon SWS in healthy young (n = 15, 25 ± 4 years), middle-aged (n = 10, 49 ± 4 years) and older (n = 10, 68 ± 5 years) adults. SWS was separately measured in the free Achilles tendon, soleus aponeurosis and gastrocnemius aponeurosis in resting (R), stretched (dorsiflexed 15° from R) and slack (plantarflexed 15° from R) postures.

Middle-aged adults exhibit altered spatial variations in Achilles tendon wave speed.

The purpose of this study was to investigate spatial variations in measured wave speed in the relaxed and stretched Achilles tendons of young and middle-aged adults. Wave speed was measured from the distal Achilles tendon, soleus aponeurosis, medial gastrocnemius aponeurosis and medial gastrocnemius muscle in healthy young (n = 15, aged 25   ±   4 years) and middle-aged (n = 10, aged 49   ±   4 years) adults in resting, dorsiflexed and plantarflexed postures. In both age groups, Achilles tendon wave speed decreased proximally, with the lowest wave speed measured in the gastrocnemius aponeurosis.

Achilles tendon displacement patterns during passive stretch and eccentric loading are altered in middle-aged adults.

The purpose of this study was to investigate middle-age effects on Achilles displacement patterns under passive stretch and eccentric loading. Healthy young (24.1 ± 1.

Non-uniform in vivo deformations of the human Achilles tendon during walking.

The free Achilles tendon (AT) consists of distinct fascicles arising from each of the triceps surae muscles that may give rise to non-uniform behavior during functional tasks such as walking. Here, we estimated in vivo deformations of the human AT during walking using simultaneous ultrasound and motion capture measurements. Ten subjects walked at three speeds (0.

Non-uniform displacements within the Achilles tendon observed during passive and eccentric loading.

The goal of this study was to investigate Achilles tendon tissue displacement patterns under passive and eccentric loading conditions. Nine healthy young adults were positioned prone on an examination table with their foot secured to a rotating footplate aligned with the ankle. Subjects cyclically rotated their ankle over a 25° range of motion at 0.

Spatial variations in Achilles tendon shear wave speed.

Supersonic shear imaging (SSI) is an ultrasound imaging modality that can provide insight into tissue mechanics by measuring shear wave propagation speed, a property that depends on tissue elasticity. SSI has previously been used to characterize the increase in Achilles tendon shear wave speed that occurs with loading, an effect attributable to the strain-stiffening behavior of the tissue. However, little is known about how shear wave speed varies spatially, which is important, given the anatomical variation that occurs between the calcaneus insertion and the gastrocnemius musculotendon junction.