The influence of lumbar vertebra and cage related factors on cage-endplate contact after lumbar interbody fusion: An in-vitro experimental study.

Lumbar interbody fusion (LIF) using interbody cages is an established treatment for lumbar degenerative disc disease, but fusion results are known to be affected by risk factors such as bone mineral density (BMD), endplate geometry and cage position. At present, direct measurement of endplate-cage contact variables that affect LIF have not been fully identified. The aim of this study was to use cadaveric experiments to investigate the dependency between BMD, endplate geometry, cage parameters like type, orientation, position, and contact variables like stress and area.

Gait balance recovery after tripping: The influence of walking speed and ground inclination on muscle and joint function.

Reactive lower limb muscle function during walking plays a key role in balance recovery following tripping, and ultimately fall prevention. The objective of this study was to evaluate muscle and joint function in the recovery limb during balance recovery after trip-based perturbations during walking. Twenty-four healthy participants underwent gait analysis while walking at slow, moderate and fast speeds over level, uphill and downhill inclines.

Recovering whole-body angular momentum and margin of stability after treadmill-induced perturbations during sloped walking in healthy young adults.

Although humans are well-adapted to negotiating sloped terrain, balance recovery after a disturbance on slopes is poorly understood. This study investigated how slope affects recovery from unanticipated simulated trips and slips. Eighteen healthy young adults walked on a split-belt treadmill at 1.

Lower extremity joint power and work during recovery following trip-induced perturbations.

Background: Successful recovery following a perturbation during walking depends on a quick well-coordinated response from the body. As such, lower limb joint power and work provide critical information characterizing the success of the recovery after a perturbation. Therefore, this study aimed to investigate lower-limb joint power and the relative contribution of each joint to the total leg work during the recovery following a trip-induced perturbation.

The role of the ankle plantar flexor muscles in trip recovery during walking: a computational modeling study.

Background: Reactive lower limb muscle function during walking plays a role in balance, stability, and ultimately fall prevention. The objective of this study was to evaluate muscle and joint function used to regain balance after trip-based perturbations during walking.

Research Question: How are lower limb muscles used to recover from external tripping during walking?

Method: The dominant legs of 20 healthy adult participants with similar athletic backgrounds were tripped using a split-belt instrumented treadmill.

Fixation of pelvic acetabular fractures using 3D-printed fracture plates: a cadaver study.

Open reduction and internal fixation of pelvic acetabular fractures are challenging due to the limited surgical exposure from surrounding abdominal tissue. There have been a number of recent trials using metallic 3D-printed pelvic fracture plates to simplify and improve various elements of these fracture fixation surgeries; however, the amount of time and accuracy involved in the design and implantation of customised plates have not been well characterised. This study recorded the amount of time related to the design, manufacture and implantation of six customised fracture plates for five cadaveric pelvic specimens with acetabular fracture, while manufacturing, and surgical accuracy was calculated from computed tomography imaging.

Effects of in vivo fatigue-induced microdamage on local subchondral bone strains.

Biomechanical strain is a major stimulus of subchondral bone (SCB) tissue adaptation in joints but may also lead to initiation and propagation of microcracks, highlighting the importance of quantifying the intratissue strain in subchondral bone. In the present study, we used micro computed tomography (μCT) imaging, mechanical testing, and digital image correlation (DIC) techniques to evaluate the biomechanical strains in equine SCB under impact compression applied through the articular surface. We aimed to investigate the effects of in vivo accumulated microdamage in equine SCB on the distribution of mechanical impact strain through the articular cartilage.

Biomechanical and Microstructural Properties of Subchondral Bone From Three Metacarpophalangeal Joint Sites in Thoroughbred Racehorses.

Fatigue-induced subchondral bone (SCB) injury is common in racehorses. Understanding how subchondral microstructure and microdamage influence mechanical properties is important for developing injury prevention strategies. Mechanical properties of the disto-palmar third metacarpal condyle (MCIII) correlate poorly with microstructure, and it is unknown whether the properties of other sites within the metacarpophalangeal (fetlock) joint are similarly complex.

Generation of hemipelvis surface geometry based on statistical shape modelling and contralateral mirroring.

Personalised fracture plates manufactured using 3D printing offer an improved treatment option for unstable pelvic ring fractures that may not be adequately secured using off-the-shelf components. To design fracture plates that secure the bone fragments in their pre-fracture positions, the fractures must be reduced virtually using medical imaging-based reconstructions, a time-consuming process involving segmentation and repositioning of fragments until surface congruency is achieved. This study compared statistical shape models (SSMs) and contralateral mirroring as automated methods to reconstruct the hemipelvis using varying amounts of bone surface geometry.

Glenohumeral joint reconstruction using statistical shape modeling.

Evaluation of the bony anatomy of the glenohumeral joint is frequently required for surgical planning and subject-specific computational modeling and simulation. The three-dimensional geometry of bones is traditionally obtained by segmenting medical image datasets, but this can be time-consuming and may not be practical in the clinical setting. The aims of this study were twofold.

Complications of Reverse Total Shoulder Arthroplasty: A Computational Modelling Perspective.

Reverse total shoulder arthroplasty (RTSA) is an established treatment for elderly patients with irreparable rotator cuff tears, complex proximal humerus fractures, and revision arthroplasty; however, with the increasing indications for RTSA over the last decade and younger implant recipients, post-operative complications have become more frequent, which has driven advances in computational modeling and simulation of reverse shoulder biomechanics. The objective of this study was to provide a review of previously published studies that employed computational modeling to investigate complications associated with RTSA. Models and applications were reviewed and categorized into four possible complications that included scapular notching, component loosening, glenohumeral joint instability, and acromial and scapular spine fracture, all of which remain a common cause of significant functional impairment and revision surgery.

Biomechanical and cognitive interactions during Visuo Motor Targeting Task.

Background: Biomechanical analyses primarily focus on physical aspects of human movement; however, it is not understood how walking is affected while simultaneously performing a demanding cognitive task - a form of Cognitive-Motor Interference (CMI). CMI occurs when performance of a primary task (e.g.

Specimen-specific fracture risk curves of lumbar vertebrae under dynamic axial compression.

Underbody blast attacks of military vehicles by improvised explosives have resulted in high incidence of lumbar spine fractures below the thorocolumbar junction in military combatants. Fracture risk curves related to vertical loading at individual lumbar spinal levels can be used to assess the protective ability of new injury mitigation equipment. The objectives of this study were to derive fracture risk curves for the lumbar spine under high rate compression and identify how specimen-specific attributes and lumbar spinal level may influence fracture risk.

Effect of Prophylactic Knee Bracing on Anterior Cruciate Ligament Agonist and Antagonist Muscle Forces During Perturbed Walking.

Background: Anterior cruciate ligament (ACL) injuries most commonly occur after a perturbation. Prophylactic knee braces (PKBs) are off-the-shelf braces designed to prevent and reduce the severity of knee injuries during sports, yet their effectiveness has been debated.

Purpose: To identify differences in ACL agonist and antagonist muscle forces, during braced and unbraced conditions, while walking with the application of unexpected perturbations.

Low-Profile Electromagnetic Field Sensors in the Measurement and Modelling of Three-Dimensional Jaw Kinematics and Occlusal Loading.

Dynamic occlusal loading during mastication is clinically relevant in the design and functional assessment of dental restorations and removable dentures, and in evaluating temporomandibular joint dysfunction. The aim of this study was to develop a modelling framework to evaluate subject-specific dynamic occlusal loading during chewing and biting over the entire dental arch. Measurements of jaw motion were performed on one healthy male adult using low-profile electromagnetic field sensors attached to the teeth, and occlusal anatomy quantified using an intra-oral scanner.

Anterior cruciate ligament agonist and antagonist muscle force differences between males and females during perturbed walking.

Anterior cruciate ligament (ACL) injuries most commonly occur following a perturbation. Perturbations make the athlete unbalanced or at loss of control, which ultimately can lead to injury. The purpose of this study was to identify differences in ACL agonist and antagonist muscle forces, between sexes, during unexpected perturbations.

Individual muscle contributions to hip joint-contact forces during walking in unilateral transfemoral amputees with osseointegrated prostheses.

Direct skeletal attachment of prostheses in transfemoral amputees circumvents skin-interface complications associated with conventional sockets; however, joint pain and musculoskeletal disease is known to occur postoperatively. This study quantified hip contact forces and the roles of individual muscles in producing hip contact forces during walking in transfemoral amputees with osseointegrated prostheses. Musculoskeletal models were developed for four transfemoral amputees.

Occlusion of the lumbar spine canal during high-rate axial compression.

Background Context: While burst fracture is a well-known cause of spinal canal occlusion with dynamic, axial spinal compression, it is unclear how such loading mechanisms might cause occlusion without fracture.

Purpose: To determine how spinal canal occlusion during dynamic compression of the lumbar spine is differentially caused by fracture or mechanisms without fracture and to examine the influence of spinal level on occlusion.

Study Design: A cadaveric biomechanical study.

Effect of sitting posture on pelvic injury risk under vertical loading.

Underbody blast (UBB) attacks on military vehicles can result in severe pelvic injuries to the vehicle occupants. The aim of this study was to evaluate the biomechanical responses of the pelvis to UBB-like vertical loading in different seated postures. High-rate axial loading were performed on six defleshed human cadaveric pelves, whilst a three-dimensional finite element model of a human pelvis was created and used to simulate the high-rate loading with the model responses validated against experimental measurements.

Effects of in vivo fatigue-induced subchondral bone microdamage on the mechanical response of cartilage-bone under a single impact compression.

Subchondral bone (SCB) microdamage is prevalent in the joints of human athletes and animals subjected to high rate and magnitude cyclic loading of the articular surface. Quantifying the effect of such focal in vivo fatigue-induced microdamage on the mechanical response of the tissue is critical for the understanding of joint surface injury and the development of osteoarthritis. Thus, we aimed to quantify the mechanical properties of cartilage-bone from equine third metacarpal (MC3) condyles, which is a common area of accumulated microdamage due to repetitive impact loading.

Gait compensatory mechanisms in unilateral transfemoral amputees.

Individuals with unilateral transfemoral amputation depend on compensatory muscle and joint function to generate motion of the lower limbs, which can produce gait asymmetry; however, the functional role of the intact and residual limb muscles of transfemoral amputees in generating progression, support, and mediolateral balance of the body during walking is not well understood. The aim of this study was to quantify the contributions of the intact and the residual limb's contralateral muscles to body center of mass (COM) acceleration during walking in transfemoral amputees. Three-dimensional subject-specific musculoskeletal models of 6 transfemoral amputees fitted with a socket-type prosthesis were developed and used to quantify muscle forces and muscle contributions to the fore-aft, vertical, and mediolateral body COM acceleration using a pseudo-inverse ground reaction force decomposition method during over-ground walking.

Bone Health in Rats With Temporal Lobe Epilepsy in the Absence of Anti-Epileptic Drugs.

Epilepsy patients often exhibit reduced bone mineral density and are at an increased risk of bone fracture. Whether these bone abnormalities are due to the use of anti-epileptic drugs (AED's) or the disease itself is unknown. For example, although decreased bone health in epilepsy patients is generally attributed to the use of AED's, seizures can also trigger a number of physiological processes that have the potential to affect bone.

Cortical and Trabecular Bone Fracture Characterisation in the Vertebral Body Using Acoustic Emission.

The ability to rapidly detect localised fractures of cortical and/or trabecular bone sustained by the vertebral body would enhance the analysis of vertebral fracture initiation and propagation during dynamic loading. In this study, high rate axial compression tests were performed on twenty sets of three-vertebra lumbar spine specimens. Acoustic Emission (AE) sensor measurements of sound wave pressure were used to classify isolated trabecular fractures and severe compressive fractures of vertebral body cortical and trabecular bone.