Automatic Segmentation of Quadriceps Femoris Cross-Sectional Area in Ultrasound Images: Development and Validation of Convolutional Neural Networks in People With Anterior Cruciate Ligament Injury and Surgery.

Objective: Deep learning approaches such as DeepACSA enable automated segmentation of muscle ultrasound cross-sectional area (CSA). Although they provide fast and accurate results, most are developed using data from healthy populations. The changes in muscle size and quality following anterior cruciate ligament (ACL) injury challenges the validity of these automated approaches in the ACL population.

Associations Between Body Mass Index, Gait Biomechanics, and In Vivo Cartilage Function After Exercise in Those With Anterior Cruciate Ligament Reconstruction.

Background: Both high body mass index (BMI) and anterior cruciate ligament reconstruction (ACLR) independently influence knee osteoarthritis risk. Preliminary evidence shows the combination of these risk factors leads to poorer recovery and altered biomechanical outcomes after ACLR, but few studies have directly evaluated early changes in cartilage health between normal-BMI and high-BMI groups in this population.

Purpose: To evaluate ultrasound-based measures of cartilage strain and compositional changes (via echo-intensity [EI]) in response to an incline walking stress test between normal-BMI and high-BMI individuals with ACLR.

The relationship between knee joint effusion and quadriceps strength and activation after anterior cruciate ligament (ACL) injury and reconstruction.

Context: Knee joint effusion and quadriceps strength and activation deficits are common consequences of anterior cruciate ligament (ACL) injury and reconstruction. The presence of an effusion may initiate or worsen the quadriceps dysfunction present after ACL trauma. In simulated effusion studies, evidence indicates an inverse relationship between effusion size and quadriceps dysfunction.

Number of conditioning trials, but not stimulus intensity, influences operant conditioning of brain responses after total knee arthroplasty.

Purpose: The primary purpose of this randomized, cross-sectional study was to determine whether operant conditioning of motor evoked torque (MEP) in individuals with total knee arthroplasty (TKA) increases quadriceps MEP responses within a single session and induces acute corticospinal adaptations by producing sustained increases in MEP after training. A secondary purpose was to determine if these changes were affected by the stimulus intensity and number of training trials.

Methods: Thirty participants were block-randomized into one of three groups based on the participant's active motor threshold (100%, 120%, and 140%) to evaluate the effect of stimulus intensity.

Chronic Adaptions in Quadriceps Fascicle Mechanics Are Related to Altered Knee Biomechanics After Anterior Cruciate Ligament Reconstruction.

Following anterior cruciate ligament reconstruction (ACLR), patients exhibit abnormal walking mechanics and quadriceps dysfunction. Quadriceps dysfunction has been largely attributed to muscle atrophy and weakness. While important, these factors do not capture intrinsic properties of muscle that govern its ability to generate force and withstand load.

Conditioning of Motor Evoked Responses After Anterior Cruciate Ligament Reconstruction: Effects of Stimulus Intensity.

Background: Operant conditioning of motor evoked torque (MEP) can directly target the corticospinal pathway in patients with anterior cruciate ligament (ACL) reconstruction. However, it remains unclear whether operant conditioning can elicit short-term improvements in corticospinal excitability and whether these improvements are influenced by stimulus intensity.

Hypothesis: Quadriceps MEP responses can be upconditioned in a single session and will elicit short-term adaptations in corticospinal excitability, with higher stimulus intensities eliciting greater effects.

Beyond weakness: Exploring intramuscular fat and quadriceps atrophy in ACLR recovery.

Muscle weakness following anterior cruciate ligament reconstruction (ACLR) increases the risk of posttraumatic osteoarthritis (OA). However, focusing solely on muscle weakness overlooks other aspects like muscle composition, which could hinder strength recovery. Intramuscular fat is a non-contractile element linked to joint degeneration in idiopathic OA, but its role post-ACLR has not been thoroughly investigated.

Associations between Body Mass Index, Gait Mechanics and Trochlear Cartilage Thickness in Those with ACL Reconstruction.

Purpose: High body mass index (BMI) is a strong predictor of posttraumatic osteoarthritis (OA) after anterior cruciate ligament reconstruction (ACLR). Altered gait mechanics are independently affected by BMI and ACLR, and influence OA risk. Yet, evidence directly assessing the impact of high BMI on gait or cartilage characteristics after ACLR are limited.

Changes in Quadriceps Rate of Torque Development After Anterior Cruciate Ligament Reconstruction and Association to Single-Leg Hop Distance.

Background: Quadriceps neuromuscular function is negatively affected after anterior cruciate ligament reconstruction (ACLR). The specific effect that the ACLR has on the quadriceps femoris rate of force production and its impact on functional recovery is unknown.

Hypothesis: The anterior cruciate ligament (ACL) limb would present persistent deficits in the rate of torque development (RTD), when compared with the non-ACL limb before ACLR until 9 months (9M) post-ACLR.

Quadriceps torque complexity before and after anterior cruciate ligament reconstruction.

Objectives: The purpose of this project was to longitudinally examine quadriceps torque complexity in a group of individuals who tore their ACL and underwent ACL reconstruction.

Design: Cohort analysis.

Methods: Thirty-four individuals completed maximal effort bilateral isometric strength testing after ACL injury but pre-surgery, five months' post-surgery (mid-point of rehabilitation), and when cleared to return to activity.

Walking speed differentially affects lower extremity biomechanics in individuals with anterior cruciate ligament reconstruction compared to uninjured controls.

Background: Walking biomechanics are commonly affected after anterior cruciate ligament reconstruction and differ compared to uninjured controls. Manipulating task difficulty has been shown to affect the magnitude of walking impairments in those early after knee surgery but it is unclear if patients in later phases post-op are similarly affected by differing task demands. Here, we evaluated the effects of manipulating walking speed on between-limb differences in ground reaction force and knee biomechanics in those with and without anterior cruciate ligament reconstruction.

Joint and Limb Loading during Gait in Adults with ACL Reconstruction: Comparison between Single-Step and Cumulative Load Metrics.

Purpose: Individuals with anterior cruciate ligament reconstruction (ACLR) generally exhibit limb underloading behaviors during walking, but most research focuses on per-step comparisons. Cumulative loading metrics offer unique insight into joint loading as magnitude, duration, and total steps are considered, but few studies have evaluated if cumulative loads are altered post-ACLR. Here, we evaluated if underloading behaviors are apparent in ACLR limbs when using cumulative load metrics and how load metrics change in response to walking speed modifications.

Biomechanical Effects of Manipulating Preferred Cadence During Treadmill Walking in Patients With ACL Reconstruction.

Background: Abnormal gait is common after anterior cruciate ligament reconstruction (ACLR) which may influence osteoarthritis risk in this population. Yet few gait retraining options currently exist in ACLR rehabilitation. Cueing cadence changes is a simple, low-cost method that can alter walking mechanics in healthy adults, but few studies have tested its effectiveness in an ACLR population.

Open-sourced semi-automatic program for ultrasound assessments of femoral trochlea cartilage health.

We developed an open-sourced program that accounts for the current limitations of B-mode ultrasound and extends the clinical utility of ultrasound for assessing femoral trochlear cartilage thickness. Images were collected on 18 patients with a history of knee surgery. By failing to account for ultrasound acoustics and beam refraction, cartilage thickness was underestimated by 26% and overestimated by 0-4%, respectively ( < 0.

Dynamic knee stiffness during walking is increased in individuals with anterior cruciate ligament reconstruction.

Individuals with anterior cruciate ligament (ACL) reconstruction often display abnormal gait mechanics reflective of a "stiff-knee" gait (i.e., reduced knee flexion angles and moments).

Quadriceps motor evoked torque is a reliable measure of corticospinal excitability in individuals with anterior cruciate ligament reconstruction.

This study comprehensively evaluated the test-retest reliability of raw and normalized quadriceps motor evoked responses elicited by transcranial magnetic stimulation (TMS) in individuals with anterior cruciate ligament (ACL) reconstruction. Fifteen participants were tested on three different days that were separated at least by 24 h. Motor evoked responses were collected during a small background contraction on the reconstructed leg across a range of TMS intensities using torque (MEP) and electromyographic (MEP) responses.

Electrically Evoked Torque at Rest is Strongly Related to Quadriceps Muscle Size in Individuals with Anterior Cruciate Ligament Reconstruction.

Electrically evoked torque at rest (i.e., the torque produced from supramaximal stimul applied to a resting muscle) has been shown to be related to muscle size in healthy adults, but this relationship has not been evaluated in pathological populations where atrophy is present.

Mechanical Factors Contributing to Altered Knee Extension Moment during Gait after ACL Reconstruction: A Longitudinal Analysis.

Purpose: This study aimed to comprehensively examine the extent to which knee flexion angle at initial contact, peak knee flexion angle, and vertical ground reaction force (vGRF) contribute to knee extension moments during gait in individuals with anterior cruciate ligament (ACL) reconstruction.

Methods: Overground gait biomechanics were evaluated in 26 participants with ACL reconstruction at three time points (about 2, 4, and 6 months after the surgery). Knee flexion angle at initial contact, peak knee flexion angle, peak vGRF, and peak knee extension moment were calculated for each limb during the early stance phase of gait for all three time points.

Functional Resistance Training Differentially Alters Gait Kinetics After Anterior Cruciate Ligament Reconstruction: A Pilot Study.

Background: Quadriceps weakness is common after anterior cruciate ligament (ACL) reconstruction and can alter gait mechanics. Functional resistance training (FRT) is a novel approach to retraining strength after injury, but it is unclear how it alters gait mechanics. Therefore, we tested how 3 different types of FRT devices: a knee brace resisting extension (unidirectional brace), a knee brace resisting extension and flexion (bidirectional brace), and an elastic band pulling backwards on the ankle (elastic band)-acutely alter gait kinetics in this population.

Functional Resistance Training After Anterior Cruciate Ligament Reconstruction Improves Knee Angle and Moment Symmetry During Gait: A Randomized Controlled Clinical Trial.

Purpose: The purpose of this study was to determine 1) whether progressive functional resistance training (FRT) during walking would improve knee biomechanical symmetry after anterior cruciate ligament (ACL) reconstruction and 2) whether the mode of delivery of FRT would have a differential effect on symmetry.

Methods: Thirty individuals who underwent primary ACL reconstruction at a single institution volunteered for this study. Participants were randomized into one of three groups: 1) BRACE, 2) BAND, or 3) CONTROL.

Functional Resistance Training Improves Thigh Muscle Strength after ACL Reconstruction: A Randomized Clinical Trial.

Purpose: Quadriceps weakness is common after anterior cruciate ligament (ACL) reconstruction, resulting in prolonged disability and increased risk for reinjury and osteoarthritis. Functional resistance training (FRT) combines resistance training with task-specific training and may prove beneficial in restoring quadriceps strength. The primary purpose of this study was to determine if a walking-specific FRT program (e.

Muscle Synergies in People With Chronic Ankle Instability During Anticipated and Unanticipated Landing-Cutting Tasks.

Context: Although neuromuscular deficits in people with chronic ankle instability (CAI) have been identified, previous researchers have mostly investigated the activation of multiple muscles in isolation. Investigating muscle synergies in people with CAI would provide information about the coordination and control of neuromuscular activation strategies and could supply important information for understanding and rehabilitating neuromuscular deficits in this population.

Objective: To assess and compare muscle synergies using nonnegative matrix factorization in people with CAI and healthy control individuals as they performed different landing-cutting tasks.

The Influence of Sex, Body Mass Index, and Age on Cartilage Metabolism Biomarkers in Patients After Anterior Cruciate Ligament Injury and Reconstruction.

Context: Serum biomarkers may allow for the early identification of posttraumatic osteoarthritis after anterior cruciate ligament (ACL) injury and reconstruction. Homeostasis of matrix-metalloproteinase-3 (MMP-3) and type II collagen turnover biomarkers (C2C:CPII ratio) is believed to be compromised in individuals with ACL injury, yet the influence of sex, body mass index (BMI), and age on these biomarkers before and after ACL reconstruction remains unknown.

Objective: To determine the relationship of sex, BMI, and age with serum levels of MMP-3 and C2C:CPII before and after ACL reconstruction.

Muscle force contributions to ankle joint contact forces during an unanticipated cutting task in people with chronic ankle instability.

The purpose of this study was to compare muscle force contributions to ankle joint compression and anteroposterior shear forces between people with chronic ankle instability (CAI) and healthy controls (CON) during an unanticipated cutting task. Eleven people with CAI and 11 CON performed an unanticipated cutting task as three-dimensional motion capture, ground reaction force (GRF), and muscle activation data were collected. A musculoskeletal modeling was used to calculate talocrural joint compression and anteroposterior shear forces and parse out the contributions to these forces from ankle-spanning muscles and from GRF.