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Eccentric exercises are commonly used as a treatment for various muscle and tendon injuries. During complex motions such as the forward lunge, however, it is not always clear which muscles may be contracting eccentrically and at what time. Because this exercise is used during rehabilitation, the purpose of this investigation was to determine what type of contractions take place during two differen
Introduction Knee muscles are commonly labeled as flexors or extensors and aptly stabilize the knee against sagittal plane loads. However, how these muscles stabilize the knee against adduction-abduction and rotational loads remains unclear. Our study sought 1) to classify muscle roles as they relate to joint stability by quantifying the relationship between individual muscle activation patterns a
Background: There is a lack of objective dynamic knee joint control measures that can be related to the status of the anterior cruciate ligament (ACL). The purpose of this study was to introduce two novel measures and apply a third to determine how dynamic knee joint control changes in relation to ACL status during dynamic movements. Methods: Twenty patients (13 male) were tested pre- (ACLd) and 1
Knee joint functional deficits are common after anterior cruciate ligament (ACL) injury, but different assessment methods of joint function seem to provide contradicting information complicating recovery monitoring. We previously reported improved perceived knee function and functional performance (forward lunge ground contact time) in patients with an ACL injury from pre to 10 months post ACL rec
BACKGROUND: The rates of anterior cruciate ligament (ACL) graft failure or contralateral ACL rupture range from 17% to 30% in pediatric patients after ACL reconstruction (ACLR). A contributing factor to the high reinjury rate in this population may be the limited evidence regarding appropriate criteria for allowing unrestricted return to activity (RTA) postoperatively.PURPOSE: To review the litera
Background: The hip joint is generally considered a ball-and-socket joint, the center of which is used as an anatomic landmark in functional analyses and by surgical navigation systems. The location of the hip center has been estimated using functional techniques using various limb motions. However, it is not clear which specific motions best predicted the functional center. Purpose: This study ai
The complexity of human tibiofemoral joint motion is now better understood with the advancement of new methodologies to measure tibiofemoral kinematics in vivo. Marker clusters anchored to stainless steel bone pins inserted directly into the femur and tibia provide the most sensitive and accurate means for directly measuring skeletal tibiofemoral joint motion. Despite its invasiveness, this techni
The mechanism of anterior cruciate ligament (ACL) injury is still unclear. To gain this insight, knowledge of the mechanical behaviour of the healthy ACL during activities that may stress the ligament must be investigated in vivo. The goal of this research was to measure ACL strain in vivo during rapid deceleration, a sport type movement that has been previously shown to precede injuries to the AC
The insertion of a silent period (or gap) in a frequently occurring standard stimulus elicits a negative-going event-related potential (ERP), called the Deviant-Related Negativity (DRN). This is often studied using a single-deviant paradigm. To study the effects of gaps with multiple durations, a different sequence would be required for each gap. A more time-efficient multi-deviant paradigm has be
Purpose: Although basic objective measures (e.g., knee laxity, strength, and hop tests) have been related to subjective measures of function, associations between knee-specific objective and subjective measures have yet to be completed. The objective was to determine if knee joint contact and ligament forces differ between pre- and post-anterior cruciate ligament (ACL) reconstructed states and if
Musculoskeletal modeling and simulations have vast potential in clinical and research fields, but face various challenges in representing the complexities of the human body. Soft tissue artifact from skin-mounted markers may lead to non-physiological representation of joint motions being used as inputs to models in simulations. To address this, we have developed adaptive joint constraints on five
Eight healthy male subjects had intra-cortical bone-pins inserted into the proximal tibia and distal femur. Three reflective markers were attached to each bone-pin and four reflective markers were mounted on the skin of the tibia and thigh, respectively. Roentgen-stereophotogrammetric analysis (RSA) was used to determine the anatomical reference frame of the tibia and femur. Knee joint motion was
We developed a novel approach that requires subjects to produce and finely tune ground reaction forces (GRFs) while standing. The aim of this study was to examine the reliability of electromyographic data recorded during these tasks. Healthy young adults stood with their dominant leg in a boot fixed to a force platform. A target matching protocol required subjects to control both the direction and
We investigated the accuracy of a linear soft tissue artefact (STA) model in human movement analysis. Simultaneously recorded bone-mounted pin and skin marker data for the thigh and shank during walking, cutting and hopping were used to measure and model the motion of the skin marker clusters within anatomical reference frames (ARFs). This linear model allows skin marker movements relative to the
The forward lunge (FL) may be a promising movement to assess functional outcome after ACL reconstruction. Thus, we aimed to investigate the FL movement pattern before and after ACL reconstruction with a comparison to healthy controls to determine if differences were present. Twenty-eight ACL injured participants and 28 matched healthy controls were included. They performed FL movements while sagit
Previous investigations have identified the roles of knee joint muscles in supporting external loads during non-weight-bearing tasks and found these to depend on moment arm orientation (MAO). However, during weight-bearing tasks ground reaction forces (GRF) are transferred up through the knee, subjecting it to large multi-directional forces and stability is dependent on articular geometry, loading
Objective: Externally applied abduction and rotational loads are major contributors to the knee joint injury mechanism; yet, how muscles work together to stabilize the knee against these loads remains unclear. Our study sought to evaluate lower limb functional muscle synergies in healthy young adults such that muscle activation can be directly related to internal knee joint moments. Methods: Conca
When recording human movement with stereophotogrammetry, skin deformation and displacement (soft tissue artefact; STA) inhibits surface markers' ability to validly represent the movement of the underlying bone. To resolve this issue, the components of marker motions which contribute to STA must be understood. The purpose of this study is to describe and quantify which components of this marker mot
This study provides a forward-muscular inverse-skeletal dynamics framework for musculoskeletal simulations. The simulation framework works based on solving the muscle redundancy problem forward in time parallel to a torque tracking between the musculotendon net torques and joint moments from inverse dynamics. The proposed framework can be used by any musculoskeletal modeling software package; howe
The ideal timing to implement anterior cruciate ligament injury prevention programs with respect to maturation is unclear. The purpose of this study was to investigate the effects of an injury prevention program on knee mechanics in early-, late-, and post-pubertal females. In the study, 178 adolescent female basketball players were assigned to six groups: early-pubertal training, early-pubertal c
