Effect of excessive Arm Swing on Speed and Cadence of walking

Introduction: One of the changes in the movement patterns that can be seen in upper limb swing is the excessive increase in upper limb movement and swing during walking. As temporal parameters such as cadence and speed in stationary and mobile environments can be equally used to determine early fall potentials, Therefore, this study aims to investigate the effect of excessive arm swing on speed and cadence of walking. Material and Methods: 30 healthy subjects were exposed to Vicon 10 motion capture system analysis and were asked to first walk normally at normal speeds and then move their hands excessively while walking at the same speed. The temporal data were extracted and analyzed by Matlab software. Descriptive (mean, SD) and Shapiro-Wilk test for normality of data distribution, and paired sample t-test were used to compare the patterns. Results: there was a significant difference in cadence and speed variables, between the means of natural arm swing and excessive arm swing modes (p ≤ 0.05). Conclusion: Given these results, it should be considered that the effects of upper limb pattern changes on the lower limbs and gait can compensate for the lack of attention to movement and pattern of upper extremity positioning during walking

Bone density may affect primary stability of anterior cruciate ligament reconstruction when organic core bone plug fixation technique used

© The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Purpose: Core Bone Plug Fixation (CBPF) technique is an implant-less methodology for ACL reconstruction. This study investigates the effect of bone density on CBPF stability to identify the bone quality that is likely to benefit from this technique. Methods: Artificial blocks with 160 (Group 1), 240 (Group 2), and 320 (Group 3) kg/m3 densities were used to simulate human bone with diverse qualities. These groups are representative of the elderly, middle age and young people, respectively. A tunnel was made in each test sample using a cannulated drill bit which enabled harvesting the core bone plug intact. Fresh animal tendon grafts were prepared and passed through the tunnel, so the core bone was pushed in to secure the tendon. The fixation stability was tested by applying a cyclic load following by a pullout load until the failure occurred. The selected group was compared with interference screw fixation technique as a gold standard method in ACL reconstruction. Results: The Group 2 stiffness and yield strength were significantly larger than Group 1. The graft slippage of Group 1 was significantly less than Group 3. The ultimate strengths were 310 N and 363 N, in Groups 2 and 3, significantly larger than that of Group 1. The ultimate strength in fixation by interference screw was 693.18 N, significantly larger than the bone plug method. Conclusions: The stability of CBPF was greatly affected by bone density. This technique is more suitable for young and middle-aged people. With further improvements, the CBPF might be an alternative ACL reconstruction technique for patients with good bone quality. Clinical relevance: The CBPF technique offers an implant-less organic ACL reconstruction technique with numerous advantages and likely would speed up the healing process by using the patient’s own bones and tissues rather than any non-biologic fixations.Peer reviewe

Aseptic loosening of femoral components - materials engineering and design considerations

Aseptic loosening is one of the main reasons for the revision of a total knee replacement (TKR). The design of the key component of a TKR, the femoral component, is particularly problematic because its failure can be the result of different causes. This makes the development of new biomaterials for use in the femoral component a challenging task. This paper focuses on the engineering design aspects in order to understand the limitations of current materials and design deficiencies. The paper describes the introduction of a new biomaterial for a femoral component and justifies the recommendation to use multi-functional materials as a possible solution to aseptic loosening. The potential advantages of applying functionally graded biomaterials (FGBMs) in prosthetic femur are explained by reducing the leading causes of failure including wear, micro-motion and stress-shielding effect. The ideas presented in this paper can be used as the basis for further research on the feasibility and advantages of applying FGBM in other superior implant designs

PATIENT-SPECIFIC SPINAL BONE SCREW FIXATION: HOMOGENIZED VERSUS VOXEL-BASED FINITE ELEMENT ANALYSIS

Bone screws are vital for orthopedic procedures but often lead to issues like dislocation and bone problems. Current testing with cadaver bones is slow and lacks consistency [1,2]. Computer simulations provide a faster, cost-effective way to assess screw designs and reduce the need for human samples. Numerical models consider factors like geometry and materials but struggle with bone variability [3]. Micro finite element analysis shows promise but needs to accurately represent non-linear effects and the bone-screw interface. Few studies have compared numerical models to mechanical tests, especially concerning stiffness and strength [4]. This study aims to quantify pull-out characteristics of bone screw in both homogenized and non-homogenized material

An Improved Approach for Output Feedback Model Predictive Control of Hybrid Systems

In this paper, a modified robust model predictive control scheme is proposed for linear parametric variable (LPV) and hybrid systems based on a quasi-min-max algorithm. Using a new cost function resulted in reduced unwanted disturbances during switching. In addition, the effects of uncertainties are reduced in the prediction dynamics, and robust stability of piecewise switching LPV systems subjected to linear matrix inequality (LMI) input constraints are guaranteed. Simulation results demonstrate the performance of the proposed controller compared to prior research

Design, Implementation and Testing of a Novel Prototype Orthotic Knee Joint with Two Degrees of Freedom in a Patient with Medial Knee Osteoarthritis

Knee braces are a conservative treatment option for patients with knee osteoarthritis (KOA). However, no commercially available orthotic knee joint currently reflects natural knee movements. A prototype orthotic knee joint with two degrees of freedom (DOF) in the sagittal and transverse planes was developed to more closely simulate the natural motion of the knee joint. The prototype was tested on a male subject with medial KOA during a sit-to-stand task. The efficacy of the transverse plane DOF was assessed by comparing the limb-orthosis interaction force when the transverse plane was locked to mimic a one-DOF setting versus when it was unlocked. Unlocking the transverse plane eliminated the 45-Newton shearing force produced with the one-DOF setting at wide angles of flexion. The two-DOF orthotic knee joint prototype demonstrated greater conformity to natural knee movements, allowing the wearer to better tolerate bracing-related difficulties.  Keywords: Knee Joint; Knee Osteoarthritis; Orthotic Devices; Braces; Rotation; Movement; Materials Testing

The Effects of Knee Orthosis with Two Degrees of Freedom Joint Design on Gait and Sit-to-Stand Task in Patients with Medial Knee Osteoarthritis

Objectives: Knee bracing as a conservative treatment option for patients with medial knee osteoarthritis (KOA) is of great interest to health practitioners and patients alike. Optimal orthotic knee joint structure is essential to achieve biomechanical and clinical effectiveness. Therefore, this study aimed to identify the effects of a knee orthosis with a new two-degrees-of-freedom (DOF) joint design on selected gait parameters and in a sit-to-stand task in patients with mild-to-moderate medial KOA. Methods: This study was conducted both at the Physical Medicine and Rehabilitation Clinic in Shahid Modarres Academic Hospital and the Biomechanical Laboratory of Rehabilitation Faculty of Iran University of medical Sciences in Tehran, Iran from September 2015 to October 2017. The gait performance of 16 patients was assessed without an orthosis, using a common one-DOF (DOF) knee orthosis and using the same knee orthosis with a two-DOF orthotic joint design. The interactive shearing force between limb and brace in the shell area during a sit-to-stand test was also identified. Repeated measures analysis of variance was used to analyse the data. Results: Compared with walking with no orthosis, both orthosis conditions reduced the external knee adduction moment significantly (P ≤0.05). A significant increase between the one-DOF and two-DOF conditions in terms of walking speed (P = 0.041 and P = 0.009, respectively) and stride length (P = 0.028 and P = 0.038, respectively) was observed. In a sit-to-stand test, wearing the orthosis significantly decreased knee transverse plane range of motion (P ≤0.05). There was a 41.31 ± 8.34 Newtons reduction in knee flexion constraint force. Conclusion: The two-DOF knee orthosis was more comfortable compared to the one-DOF knee orthosis during deep knee flexion. Otherwise, the one- DOF- and two-DOF-braces performed similarly. Keywords: Knee Osteoarthritis; Orthosis; Braces; Gait Analysis; Rotations; Kinematics; Kinetics; Patient Comfort

Synthesis And Characterization Of 3D-Printed Functionally Graded Porous Titanium Alloy

This study aims to 3D print titanium alloy constructs incorporating gradient of porosities, from the fully dense core to the porous outer surface. Gradient porous specimens were prepared using selective laser melting (SLM). Fully dense specimens fabricated by SLM were used as the control group. Characterization of samples was done using X-ray tomography, uniaxial compression testing, and optical and scanning electron microscopes. The biocompatibility of fabricated samples was investigated using human periodontal ligament stem cells via assessment of cell attachment, viability, and proliferation by direct and indirect assays. The data were analyzed using ANOVA and Tukey’s post hoc test. Characterization of constructs reveals interconnected gradient porosities and higher contact angle in porous samples. The introduction of porosity leads to a significant decrease in compression strength. However, Young’s modulus of the samples with gradient porosity was more similar to the natural bone modulus. The surface microstructure consists of loosely bonded spherical particles. Biocompatibility of the dense and porous samples is appropriate. Although the porosity size led to a reduced cell proliferation rate in the gradient sample, the extract of the gradient sample results in more cell proliferation than the dense sample’s extract. The study demonstrates that a biocompatible functionally graded porous titanium structure can be well fabricated by SLM, and this structure leads to a good match of Young’s modulus to that of the bone

Clinical Study Rehabilitation after ACL Injury: A Fluoroscopic Study on the Effects of Type of Exercise on the Knee Sagittal Plane Arthrokinematics

A safe rehabilitation exercise for anterior cruciate ligament (ACL) injuries needs to be compatible with the normal knee arthrokinematics to avoid abnormal loading on the joint structures. The objective of this study was to measure the amount of the anterior tibial translation (ATT) of the ACL-deficient knees during selective open and closed kinetic chain exercises. The intact and injured knees of fourteen male subjects with unilateral ACL injury were imaged using uniplanar fluoroscopy, while the subjects performed forward lunge and unloaded/loaded open kinetic knee extension exercises. The ATTs were measured from fluoroscopic images, as the distance between the tibial and femoral reference points, at seven knee flexion angles, from 0 ∘ to 90 ∘ . No significant differences were found between the ATTs of the ACL-deficient and intact knees at all flexion angles during forward lunge and unloaded open kinetic knee extension ( < 0.05). During loaded open kinetic knee extension, however, the ATTs of the ACL deficient knees were significantly larger than those of the intact knees at 0 ∘ ( = 0.002) and 15 ∘ ( = 0.012). It was suggested that the forward lunge, as a weight-bearing closed kinetic chain exercise, provides a safer approach for developing muscle strength and functional stability in rehabilitation program of ACL-deficient knees, in comparison with open kinetic knee extension exercise