Papers by Keyword: Biomechanics

Abstract: Background: Knee joint replacement surgery is a widely used procedure for managing severe knee osteoarthritis, rheumatoid arthritis, and traumatic arthritis. The selection of implant materials plays a crucial role in the long-term success of the procedure, influencing biomechanical stability, biocompatibility, and wear resistance. Polyether ether ketone (PEEK), a high-performance thermoplastic polymer, has recently gained attention as a potential alternative to conventional metal and polymer implants due to its closer elastic modulus to human bone, excellent biocompatibility, and radiolucency. However, the intrinsic bio-inertness and wear resistance limitations of PEEK have raised concerns regarding its early osseointegration and long-term durability. Methods: To overcome these challenges, researchers have explored various modifications, including bioactive coatings, composite reinforcement, and porous structuring, to enhance it clinical performance. This review evaluates the current applications of PEEK in knee surgery, comparing its properties with commonly used materials such as ultra-high-molecular-weight polyethylene (UHMWPE), cobalt-chromium (CoCr), and titanium. Results: We analyze its role in procedures such as high tibial osteotomy (HTO) and anterior cruciate ligament reconstruction (ACLR). While PEEK demonstrates promising mechanical and biological advantages, further studies on long-term performance, wear behavior, and improved osseointegration techniques are essential to determine its suitability as a standard implant material in knee surgery. Conclusions: PEEK has the potential to serve as an alternative implant material for knee joint replacement due to its biomechanical compatibility and favorable biological properties. However, addressing its bio-inertness and wear resistance limitations through material modifications remains a key area for future research.

Abstract: This study presents the design and pilot evaluation of a computer vision–based system for monitoring exercise performance in older adults, aiming to reduce frailty-related risks without the need for wearable sensors. Using MediaPipe and OpenCV, the system tracks posture and movement in real time and provides feedback on exercise execution. A pilot test was conducted with 14 volunteers performing seven exercises from the Vivifrail Spanish program (Wheel A). Performance was evaluated using perfomance analysis, yielding recognition rates between 91.06\% and 100\% across exercises. While the system showed high accuracy in detecting posture and repetitions, challenges such as camera positioning, clothing variability, and the absence of validation in the target population remain. These findings demonstrate the feasibility of computer vision for exercise monitoring and support its potential as an accessible tool for fall prevention and functional assessment in older adults. Future work will focus on clinical validation and integration into mobile platforms for home based use. This approach will allow older population to adequately perform exercises from the Vivifrail program, while professionals, as physiotherapists and geriatricians, can monitor their progress remotely, adjusting the program when needed.

Abstract: The absence of customized prostheses for animals significantly limits the rehabilitation of amputated canines in Honduras. Due to the lack of local prosthetic solutions, full limb amputations are commonly performed, which eliminate the possibility of preserving functional joints. As a result, no clinical cases with partial limb preservation are available for study, this paper presents the design and validation of a modular canine exoprosthesis in a simulated transradial amputation scenario. Anatomical data were obtained through zoometry, plaster molding, and 3D scanning. The modular prosthesis was modeled in SolidWorks and Meshmixer, fabricated with FDM 3D printing. Materials used include carbon fiber-reinforced PETG for structural components and TPU with varying hardness for flexible sections. Structural validation was performed through finite element analysis (FEA), followed by experimental compression tests. Results show that the design and materials withstand peak gait forces within safe limits. The modular configuration proved effective for assembly and potential future adjustments. This study provides a technical foundation for the development of anatomically adapted canine prostheses in Honduras, offering an alternative that contributes to improving the quality of life of amputee dogs and supporting their rehabilitation within the local context.

Abstract: The in vivo measurement of the cartilage contact area (CCA) during shoulder rotation remains unexplored. This study, therefore, investigates changes in the CCA and cartilage contact pattern (CCP) between the humeral head and glenoid during static rotation with abduction using magnetic resonance imaging (MRI) in subjects with normal shoulders. The study subjects were 14 Japanese men without a previous history of shoulder injury or disorder. MRI data were obtained from the transverse sections of the shoulder using a 3T-MRI scanner in the following four postures: neutral posture, posture at neutral rotation with 120° of abduction (AB posture), posture at 100° of external rotation with 120° of abduction (ER posture), and posture at 30° of internal rotation with 120° of abduction (IR posture). The CCA and CCP (contact centroid) of the glenohumeral joint were determined from the MRI data. The CCA in the AB posture was significantly smaller than that in the neutral posture (p = 0.015). The CCAs in the ER and IR postures were approximately 23.1% and 35.2% larger, respectively, than that in the AB posture. The contact centroid at the AB posture was located significantly more superior to those at the neutral, ER, and IR postures (p < 0.001, p = 0.012, p < 0.001, respectively). Results offer new insights into the CCA and CCP of the glenohumeral joint during in vivo shoulder rotation. This study provides a useful reference dataset obtained from young participants with normal shoulders for understanding cartilage contact mechanics. Improved understanding of the contact pattern can help detect shoulder joint disorders and develop subsequent treatment and surgical strategies.

Abstract: Sports biomechanics is a specialized discipline that seeks to optimize sports performance through the analysis of biomechanical parameters. However, research conducted in the context of sports in low-resource countries is limited, as specialized systems for these analyzes can be expensive. This study presents a quantitative and descriptive research on the kinematics of the quality of the soccer-pass, by proposing a low-cost system solution using IMU sensors and Kinovea software for the evaluation of the quality of the pass. Inertial sensors were used to collect data on linear acceleration, angular velocity, and orientation of the athlete during the execution of the pass. These sensors were strategically placed on the players' bodies to detect movement during the technical gesture. The results obtained from the combination of Kinovea software and inertial sensors allowed precise kinematic measurements of angles and distances between key anatomical points, providing valuable information on the quality and effectiveness of the movements performed by athletes. Joint angles and distances were evaluated, revealing different approaches between subjects. Significant correlations were found between the speed, acceleration, and flexion of the performing knee. The analysis of anthropometric variables also showed correlations between Body Mass Index and knee flexion in both types of support. In the end, a significant relationship was revealed between speed and flexion of the supporting knee during the technical gesture. The proposed system has the potential to be used as a low-cost solution for the analysis of biomechanical parameters in athletes of soccer.

Abstract: The neurological rehabilitation focuses on enhancing functional recovery and improving the quality of life for people who have experienced injuries or diseases affecting the central or peripheral nervous system. This functional recovery includes a follow up of the kinematics of the patients limbs. The use of a open source software such as OpenSim, has been previously proposed as a tool for kinematic analysis, this software allows for highly specialized 3D musculoskeletal modeling, facilitates kinematic analysis and the assessment of force and angles in the lower and upper limbs of the human body. In this context, the propose of this research was to test the reliability of OpenSim for kinematic analysis during neurological rehabilitation. For this goal, the Motricity Index test was done by a group of three healthy participants, this values were used for comparison to the stroke patient who is currently undergoing neurological rehabilitation process. The results demonstrates all the limitations in the range of motion of the patient in comparison to the healthy group due his motor issues, such as muscle spasticity and weakness. This research shows the advantages and limitations of this software and its application in neurological rehabilitation. The goal is to contribute to the development of effective and personalized therapeutic strategies to improve the recovery process for these patients.

Abstract: Background: Patients with chronic ankle instability (CAI) demonstrated altered movement patterns during unanticipated landing compared to coper patients. Understanding the effects of kinematics, dynamics and energetics on individual movement patterns during landing could enhance motor control strategies for patients with ankle sprains while avoiding the transition of coper patients to CAI patients. Therefore, the purpose of this study was to investigate the differences in movement patterns of coper patients compared to CAI patients during the unanticipated landings; Methods: Fifteen individuals with CAI (age: 22.8±1.4 years; height: 180.1±4.2 cm; weight: 81.5±5.8 kg) and fifteen copers (age: 23.1±1.2 years; height: 179.8±4.4 cm, weight: 80.4±6.2 kg) participated in an unanticipated landing task, during which three-dimensional motion capture, ground reaction force (GRF), and muscle activation data were collected. A musculoskeletal model was used to estimate muscle force and joint power among these two groups. Joint power was calculated as the product of angular velocity in the sagittal plane and joint moment data, reflecting the energy transfer at the ankle, knee, and hip joints. Furthermore, energy dissipation and generation within these joints were determined by integrating specific regions of the joint power curve; Results: Individuals with CAI demonstrated a greater muscle force in the vastus lateralis compared copers during the unanticipated landing task, while copers exhibited higher peak muscle forces in the medial gastrocnemius (p=0.007), lateral gastrocnemius (p=0.002), soleus (p=0.004). The muscle activation patterns of CAI patients also differ from those of coper patients. Compared to copers, CAI patients exhibit earlier activation of the rectus femoris (p<0.001) and lateral gastrocnemius muscles (p=0.042). Conversely, copers demonstrate earlier activation of the soleus (p=0.004) and medial gastrocnemius (p=0.003) muscles. In addition, joint power in CAI individuals during unanticipated landing shifted from the ankle to the knee and hip (p<0.001); Conclusions: These findings suggest that individuals with CAI exhibit a change in motion control strategy during unanticipated landing tasks. The variations in peak forces and the ability of proximal muscles to generate force might enable them to offset the deficits noted in distal muscles. Energy redistribution issues observed in CAI patients may help to prevent the transition of coper patients towards developing CAI patients.

Abstract: In the context of this numerical study is particularly to analyze and observe the effect of mechanical properties and masticatory efforts on the intensity and distribution of biomechanical stresses induced in the mandibular bone (the cortical bone, the spongy bone) and in the elements which constitute the structure of the dental bridge (abutments, implants, bridge). The 3D model studied is subjected to loading in the three directions of space (corrono-apical, disto-medial, bucolingual). The numerical analysis allowed us to highlight the localization of the stress concentration zones, on the one hand, at the level of the regions of contact between the elements of the dental bridge structure and on the other hand, at the level of the mandibular bone. This parametric approach for the mechanical properties of bridges is used to better visualize and quantify the biomechanical behavior of dental bridges.

Abstract: Designers are still seeking novel, smart and advanced materials. Moreover, a designed geometry for special purposes is also required for structures. In this regard, metamaterials are artificial structures with optimized topology. Furthermore, the multi-material metamaterial (4M) structure could be a frontier technology in different industries, especially in biomechanics, which provides various functions. In this short perspective, 4M structures have been introduced by emphasizing the application of bones and implants. Under cyclic loading, such a smart material should be topology-optimized with the objective of fatigue properties, the fretting fatigue lifetime, reliability, and weight. In addition, the constraint in this finite element modeling-based multi-objective optimization is the strength or the deformation of the structure.

Abstract: The knowledge of the complex biomechanical behaviour of the injured knee joints is of paramount importance in various clinical situations. A review of the biomechanical effects of meniscal tears based on experimental and finite element analysis has not been reported in the literature. The objective of this study is to present a review of experimental and finite element investigations on the consequences of meniscal tears such as longitudinal, radial, horizontal cleavage and root tears in the medial and lateral menisci. It is found that larger longitudinal tear in the medial meniscus has a significant impact on the magnitude of strain in the meniscus associated with a dramatic increase in CP in the tibial cartilage. Also, the untreated fragment of the torn meniscus leads to a significant rise in contact pressure in the cartilage resulting in the progressive degeneration of the cartilage surface. The radial tears in the lateral meniscus of more than 66% width and those in the medial meniscus of more than 75% width result in a substantial increase in the contact pressure in the cartilage compared to that in the intact knee joint. The root tears in the menisci demonstrate a significant influence on the biomechanical response of the knee joint. The results of finite element analysis studies are compared with experimental findings. Finally, some recommendations for future work are proposed to predict the realistic biomechanical response of the knee joints with meniscal tears. The results of this study present a rationale that could help surgeons in making clinical decisions when managing patients with meniscal tears.