Personalization of closed-chain shoulder models yields high kinematic accuracy for multiple motions.

Introduction: The shoulder joint complex is prone to musculoskeletal issues, such as rotator cuff-related pain, which affect two-thirds of adults and often result in suboptimal treatment outcomes. Current musculoskeletal models used to understand shoulder biomechanics are limited by challenges in personalization, inaccuracies in predicting joint and muscle loads, and an inability to simulate anatomically accurate motions. To address these deficiencies, we developed a novel, personalized modeling framework capable of calibrating subject-specific joint centers and functional axes for the shoulder complex.

Minimal Hip Flexion Increase During Gait After Femoroacetabular Impingement Surgery: A Systematic Review and Meta-Analysis of Pre- and Postoperative 3-Dimensional Motion Analysis.

Purpose: To evaluate the impact of surgical treatment on gait biomechanics in patients with femoroacetabular impingement syndrome (FAIS).

Methods: A comprehensive search of 6 databases (from inception to 2024) was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (CRD4202347397). Studies using 3-dimensional motion analysis to examine gait kinematics and/or kinetics in patients with FAIS before and after hip surgery were included.

Identifying gait subgroups in low back pain patients with artificial intelligence: implications for individualized interventions.

Purpose: The following study aimed to investigate the existence of different gait profiles in patients with low back pain (LBP) and assess their clinical characteristics.

Methods: This is a cross-sectional retrospective study that included individuals with chronic or acute LBP. Three-dimensional gait kinematics were assessed, including mean angles, range of motion (ROM), and coordination of the trunk and pelvis across three planes.

The Search for the Holy Grail in Running Biomechanics: Is There an Ideal Movement Profile for Minimizing Mechanical Overload?

Background: Running biomechanics can influence injury risk, but whether the combined effect of different biomechanical factors can be identified by individual running profiles remains unclear. Here, we identified distinct biomechanical profiles among healthy runners, examined lower limb mechanical load characteristics, and evaluated potential implications for injury risk.

Hypothesis: Multiple factors would serve as a common denominator allowing identification of specific patterns.

Squatting Biomechanics After Femoroacetabular Impingement Surgery: A Systematic Review and Meta-analysis.

Objective: Femoroacetabular impingement syndrome (FAIS) is a prevalent cause of hip pain, characterized by distinctive motion patterns. However, the impact of surgical intervention on squatting biomechanics remains underexplored. This review aims to evaluate the effects of surgical treatment on biomechanical outcomes during squatting in patients with FAIS.

Three-dimensional kinematics in patients with anterior shoulder instability - A systematic review with meta-analysis.

Anterior Shoulder Instability (ASI) is a common orthopedic condition often resulting in altered shoulder kinematics. Understanding the biomechanics of the unstable shoulder is critical to determine the most appropriate treatment. This study aims to conduct the first systematic review and meta-analysis of three-dimensional (3D) shoulder kinematic studies in ASI patients.

Personalization of Closed-Chain Shoulder Models Yields High Kinematic Accuracy for Multiple Motions.

The shoulder joint complex is prone to musculoskeletal issues, such as rotator cuff-related pain, which affect two-thirds of adults and often result in suboptimal treatment outcomes. Current musculoskeletal models used to understand shoulder biomechanics are limited by challenges in personalization, inaccuracies in predicting joint and muscle loads, and an inability to simulate anatomically accurate motions. To address these deficiencies, we developed a novel, personalized modeling framework capable of calibrating subject-specific joint centers and functional axes for the shoulder complex.

Changes in in vivo three dimensional shoulder kinematics following latissimus dorsi tendon transfer for irreparable posterosuperior rotator cuff tears: A systematic review with meta-analysis.

Background: Latissimus dorsi transfer is a surgical procedure that can be used for treating posterosuperior rotator cuff tears. The procedure leads to improved shoulder function via alterations in the force vector couple around the shoulder. However, there is still no consensus on the biomechanical changes resulting from latissimus dorsi transfer.

Effect of Femoral Head Material, Surgeon Experience, and Assembly Technique on Simulated Head-Neck Total Hip Arthroplasty Impaction Forces.

Background: There is no standard method for assembling the femoral head onto the femoral stem during total hip arthroplasty (THA). This study aimed to measure and record dynamic 3-dimensional (3D) THA head-neck assembly loads from residents, fellows, and attending surgeons, for metal and ceramic femoral heads.

Methods: An instrumented apparatus measured dynamic 3D forces applied through the femoral stem taper in vitro for 31 surgeons (11 attendings, 14 residents, 6 fellows) using their preferred technique (ie, number of hits or mallet strikes).

Biokinetic Evaluation of Hallux Valgus during Gait: A Systematic Review.

Background: Foot pathologies can affect the kinetic chain during gait, leading to altered loading at other joints that can lead to subsequent pathologies. Although hallux valgus is the most common foot disease, little has been discussed about the biokinetic effects of hallux valgus on the foot and lower limb. This systematic review evaluated the kinematic, kinetic, and pedobarographic changes of the hallux valgus foot compared to a healthy one.

Model validation for estimating taper microgroove deformation during total hip arthroplasty head-neck assembly.

Total hip arthroplasty (THA) failure and the need for revision surgery can result from fretting-corrosion damage of the head-neck modular taper junctions. Prior work has shown that implant geometry, such as microgrooves, influences damage on retrieved implants. Microgroove deformation within the modular taper junction occurs when the female head taper meets the male stem taper during THA surgical procedure.

Interaction of surface topography and taper mismatch on head-stem modular junction contact mechanics during assembly in modern total hip replacement.

Implant failure due to fretting corrosion at the head-stem modular junction is an increasing problem in modular total hip arthroplasty. The effect of varying microgroove topography on modular junction contact mechanics has not been well characterized. The aim of this study was to employ a novel, microgrooved finite element (FEA) model of the hip taper interface and assess the role of microgroove geometry and taper mismatch angle on the modular junction mechanics during assembly.

Combining advanced computational and imaging techniques as a quantitative tool to estimate patellofemoral joint stress during downhill gait: A feasibility study.

Background: The onset and progression of patellofemoral osteoarthritis (OA) has been linked to alterations in cartilage stress-a potential precursor to pain and subsequent cartilage degradation. A lack in quantitative tools for objectively evaluating patellofemoral joint contact stress limits our understanding of pathomechanics associated with OA.

Research Question: Could computational modeling and biplane fluoroscopy techniques be used to discriminate in-vivo, subject-specific patellofemoral stress profiles in individuals with and without patellofemoral OA?

Methods: The current study employed a discrete element modeling framework driven by in-vivo, subject-specific kinematics during downhill gait to discriminate unique patellofemoral stress profiles in individuals with patellofemoral OA (n = 5) as compared to older individuals without OA (n = 6).

Modelling changes in modular taper micromechanics due to surgeon assembly technique in total hip arthroplasty.

Aims: The aim of this study was to develop a novel computational model for estimating head/stem taper mechanics during different simulated assembly conditions.

Methods: Finite element models of generic cobalt-chromium (CoCr) heads on a titanium stem taper were developed and driven using dynamic assembly loads collected from clinicians. To verify contact mechanics at the taper interface, comparisons of deformed microgroove characteristics (height and width of microgrooves) were made between model estimates with those measured from five retrieved implants.

Contact conditions for total hip head-neck modular taper junctions with microgrooved stem tapers.

Implant failure due to fretting-corrosion of head-neck modular junctions is a rising problem in total hip arthroplasty. Fretting-corrosion initiates when micromotion leads to metal release; however, factors leading to micromotion, such as microgrooves on the stem taper, are not fully understood. The purpose of this study is to describe a finite element analysis technique to determine head-neck contact mechanics and investigate the effect of stem taper microgroove height during head-neck assembly.

Development and validation of a kinematically-driven discrete element model of the patellofemoral joint.

Quantifying the complex loads at the patellofemoral joint (PFJ) is vital to understanding the development of PFJ pain and osteoarthritis. Discrete element analysis (DEA) is a computationally efficient method to estimate cartilage contact stresses with potential application at the PFJ to better understand PFJ mechanics. The current study validated a DEA modeling framework driven by PFJ kinematics to predict experimentally-measured PFJ contact stress distributions.

Dynamic knee joint stiffness and contralateral knee joint loading during prolonged walking in patients with unilateral knee osteoarthritis.

Background: Long duration walking, a commonly recommended treatment option for knee osteoarthritis (OA), may lead to increased knee joint loading.

Research Question: To evaluate the effects of prolonged walking on dynamic knee joint stiffness and contralateral knee joint contact forces (KCFs) in individuals with unilateral symptomatic knee OA.

Methods: Twenty-six older adults with knee OA completed a 45-minute bout of walking on a treadmill.

A Stimulus-Response Framework to Investigate the Influence of Continuous Versus Interval Walking Exercise on Select Serum Biomarkers in Knee Osteoarthritis.

Objective: The aim of the study was to compare changes in the concentration of serum biomarkers in response to continuous versus interval walking exercise in participants with knee osteoarthritis.

Design: This study used a two-phase sequential design. Twenty-seven participants with unilateral knee osteoarthritis completed two separate treadmill walking sessions: (1) continuous 45-min walking exercise and (2) three 15-min bouts of walking exercise separated by 1-hr rest periods for a total of 45 mins in an interval format.

The influence of continuous versus interval walking exercise on knee joint loading and pain in patients with knee osteoarthritis.

Objective: To evaluate whether knee contact force and knee pain are different between continuous and interval walking exercise in patients with knee osteoarthritis (OA).

Methods: Twenty seven patients with unilateral symptomatic knee OA completed two separate walking exercise sessions on a treadmill at 1.3m/s on two different days: 1) a continuous 45min walking exercise session, and 2) three 15min bouts of walking exercise separated by 1h rest periods for a total of 45min of exercise in an interval format.

Knee joint contact mechanics during downhill gait and its relationship with varus/valgus motion and muscle strength in patients with knee osteoarthritis.

Objective: The objective of this exploratory study was to evaluate tibiofemoral joint contact point excursions and velocities during downhill gait and assess the relationship between tibiofemoral joint contact mechanics with frontal-plane knee joint motion and lower extremity muscle weakness in patients with knee osteoarthritis (OA).

Methods: Dynamic stereo X-ray was used to quantify tibiofemoral joint contact mechanics and frontal-plane motion during the loading response phase of downhill gait in 11 patients with knee OA and 11 control volunteers. Quantitative testing of the quadriceps and the hip abductor muscles was also performed.

Alterations in walking knee joint stiffness in individuals with knee osteoarthritis and self-reported knee instability.

Increased walking knee joint stiffness has been reported in patients with knee osteoarthritis (OA) as a compensatory strategy to improve knee joint stability. However, presence of episodic self-reported knee instability in a large subgroup of patients with knee OA may be a sign of inadequate walking knee joint stiffness. The objective of this work was to evaluate the differences in walking knee joint stiffness in patients with knee OA with and without self-reported instability and examine the relationship between walking knee joint stiffness with quadriceps strength, knee joint laxity, and varus knee malalignment.

Altered frontal and transverse plane tibiofemoral kinematics and patellofemoral malalignments during downhill gait in patients with mixed knee osteoarthritis.

Patients with knee osteoarthritis often present with signs of mixed tibiofemoral and patellofemoral joint disease. It has been suggested that altered frontal and transverse plane knee joint mechanics play a key role in compartment-specific patterns of knee osteoarthritis, but in-vivo evidence in support of this premise remains limited. Using Dynamic Stereo X-ray techniques, the aim of this study was to compare the frontal and transverse plane tibiofemoral kinematics and patellofemoral malalignments during the loading response phase of downhill gait in three groups of older adults: patients with medial tibiofemoral compartment and coexisting patellofemoral osteoarthritis (n=11); patients with lateral tibiofemoral compartment and coexisting patellofemoral osteoarthritis (n=10); and an osteoarthritis-free control group (n=22).

Knee motion variability in patients with knee osteoarthritis: The effect of self-reported instability.

Background: Knee osteoarthritis has been previously associated with a stereotypical knee-stiffening gait pattern and reduced knee joint motion variability due to increased antagonist muscle co-contractions and smaller utilized arc of motion during gait. However, episodic self-reported instability may be a sign of excessive motion variability for a large subgroup of patients with knee osteoarthritis. The objective of this work was to evaluate the differences in knee joint motion variability during gait in patients with knee osteoarthritis with and without self-reported instability compared to a control group of older adults with asymptomatic knees.

Altered tibiofemoral joint contact mechanics and kinematics in patients with knee osteoarthritis and episodic complaints of joint instability.

Background: To evaluate knee joint contact mechanics and kinematics during the loading response phase of downhill gait in knee osteoarthritis patients with self-reported instability.

Methods: Forty-three subjects, 11 with medial compartment knee osteoarthritis and self-reported instability (unstable), 7 with medial compartment knee osteoarthritis but no reports of instability (stable), and 25 without knee osteoarthritis or instability (control) underwent Dynamic Stereo X-ray analysis during a downhill gait task on a treadmill.

Findings: The medial compartment contact point excursions were longer in the unstable group compared to the stable (P=0.