Talar Cartilage Deformation and Spatiotemporal Gait Patterns in Individuals with and without Chronic Ankle Instability.

ABSTRACT Context: Research has demonstrated individuals with chronic ankle instability (CAI) present with alterations in the compositional structure of the talar articular cartilage. These alterations likely influence how the talar cartilage responds to loading associated with activities of daily living, such as walking. Ultrasonography has emerged as an alternative imaging modality to assess the amount of cartilage deformation in response to loading because it can be clinically accessible and cost-effective for routine measurements. Objective: To compare talar cartilage deformation in response to a standardized exercise protocol between those with and without chronic ankle instability. Secondly, to examine the association between spatiotemporal walking gait parameters and cartilage deformation. Design: Case-control. Setting: Research Laboratory. Patients or Other Participants: A volunteer sample of 24 participants with self-reported CAI (age = 23.2 ± 3.9 years; BMI = 25.1 ± 3.7 kg/m2) and 24 un-injured controls (age = 24.3 ± 2.9 years; BMI = 22.9 ± 2.8 kg/m2). Main Outcome Measure(s): Spatiotemporal walking gait was first assessed from five self-selected trials using an electronic walkway with data sampled at 120Hz. An 8-to-13MHz linear-array ultrasound transducer placed transversely in line with the medial and lateral malleoli captured three images before and after a standardized loading protocol consisting of 30 single and double-limb squats, 2-minute single-limb balance and 10 single-leg drops from a 40cm height box. Results: After controlling for body mass index, participants with chronic ankle instability had greater deformation compared to the un-injured controls (p=0.034). No other significant between group differences were observed (p>0.05). No significant partial correlations were observed between talar cartilage deformation and spatiotemporal gait parameters when controlling for body mass index (p>0.05). Conclusions: Individuals with CAI had greater talar cartilage deformation in response to a standardized exercise protocol than controls. The amount of talar cartilage deformation was not associated with spatiotemporal walking gait.

Use of the Human Walking Gait Cycle for Assistive Torque Generation for the Hip Joint Exoskeleton

The development of an assistive robot to assist human beings in walking normally is a difficult task. One of the main challenges lies in understanding the intention to walk, as an initial phase before walking commences. In this work, we classify the human gait cycle based on data from an inertial moment unit sensor and information on the angle of the hip joint and use the results as initial signals to produce a suitable assistive torque for a lower limb exoskeleton. A neural network module is used as a prediction module to identify the intention to walk based on the gait cycle. A decision tree method is implemented in our system to generate the assistive torque, and a prediction of the human gait cycle is used as a reference signal. Real-time experiments are carried out to verify the performance of the proposed method, which can differentiate between various types of walking. The results show that the proposed method is able to predict the intention to walk as an initial phase and is also able to provide an assistive torque based on the information predicted for this phase.

Analysis of a Cam-Follower Mechanism for a Passive Parallel Lower Limb Exoskeleton

This project focused on the implementation of a novel cam-follower mechanism that was deemed to have good potential for practical application into a passive lower limb exoskeleton to determine its effectiveness in reducing the energy requirement of the user and its ability to match the walking gait of the user. The design of this novel-cam follower mechanism is inspired by the retractable mechanism of a ballpen. The cam follower mechanism was incorporated into a passive lower limb exoskeleton that was available prior to the study. Passive exoskeletons are intended to augment the load carrying capacity of the user through mechanical means instead of relying on external power. The walking gait study was conducted using physical testing. The mechanism was found to cause the user to bend below his natural centre of gravity a couple of times throughout the walking cycle. The user also had to stabilize himself from being rocked from side to side. Energy calculations were likewise conducted to investigate the energy consumption for a full cycle. The interchange among gravitational potential energy, spring potential energy and kinetic energy of the mechanism for a full walking cycle did not indicate possible advantage for the user.

Multiview Running and Walking Gait Analysis using the First and Third Person Data

Gait recognition, which allows to recognise someone from a distance, has a lot of applications. The gait of a person is commonly used as a biometric approach to identify or categorise them by gender and age. Biometric systems are a fast-growing subject that necessitates the development of creative solutions to problems that have plagued previous attempts. By initially looking at the design of a gait detection system, two different types of gait datasets have been reported and presented in this paper. While running at the same time, the first person (FP) data containing the camera motion gathered from the movement of the volunteer’s body and the third person (TP) data captured from a distant view were recorded. The dataset contains a total of 23 participants (14 males and 9 females). The discussion is expanded to include a comparison of the results obtained using TP and FP data, as well as an examination of the physiological motions recorded while running and walking.

The in vivo location of edge-wear in hip arthroplasties

Aims Acetabular edge-loading was a cause of increased wear rates in metal-on-metal hip arthroplasties, ultimately contributing to their failure. Although such wear patterns have been regularly reported in retrieval analyses, this study aimed to determine their in vivo location and investigate their relationship with acetabular component positioning. Methods 3D CT imaging was combined with a recently validated method of mapping bearing surface wear in retrieved hip implants. The asymmetrical stabilizing fins of Birmingham hip replacements (BHRs) allowed the co-registration of their acetabular wear maps and their computational models, segmented from CT scans. The in vivo location of edge-wear was measured within a standardized coordinate system, defined using the anterior pelvic plane. Results Edge-wear was found predominantly along the superior acetabular edge in all cases, while its median location was 8° (interquartile range (IQR) -59° to 25°) within the anterosuperior quadrant. The deepest point of these scars had a median location of 16° (IQR -58° to 26°), which was statistically comparable to their centres (p = 0.496). Edge-wear was in closer proximity to the superior apex of the cups with greater angles of acetabular inclination, while a greater degree of anteversion influenced a more anteriorly centred scar. Conclusion The anterosuperior location of edge-wear was comparable to the degradation patterns observed in acetabular cartilage, supporting previous findings that hip joint forces are directed anteriorly during a greater portion of walking gait. The further application of this novel method could improve the current definition of optimal and safe acetabular component positioning. Cite this article: Bone Joint Res 2021;10(10):639–649.

An Atypical Case of Catatonia, Abnormal Gait and Psychosis in an Adolescent with Chronic Cannabis Use

An association between cannabis and psychosis is well established. Cannabis use is known to precipitate schizophrenia in vulnerable individuals and it can exacerbate existing psychosis. However, there is a paucity of knowledge about the emergence of catatonia and abnormal gait associated with cannabis use. History of cannabis use is associated with long-lasting changes in open-chain elements of walking gait. Cannabinoid receptors are located in movement-related brain regions and cannabis use is suggested to affect gait. This report is a unique case of a 16-year-old male with no known past medical history, no past psychiatric history, with family history significant for psychosis who presented to the hospital for bizarre, disorganized behavior, and decreased oral intake following heavy cannabis use over the past three months in the context of a break-up. Upon arrival, he was found to be in a catatonic state with an impaired gait. As catatonia resolved with treatment, he was able to speak and the psychosis surfaced which was addressed with antipsychotics. This case report highlights an atypical but serious clinical picture observed to be precipitated by chronic, heavy cannabis use.

Biomechanical Analysis of an Improvement of Prosthetic Liner using Polyurethane Focusing at the Anterior-Distal Part of Residual Limb: A Case Study

Most transtibial prosthesis users always experience pain sensation at the distal of the residual limb due to bony prominences and nerve endings. Many initiatives have been taken to resolve this problem, including using softer materials such as silicone or gel liner and designing a distal off load prosthetic socket. Another promising approach is to incorporate polyurethane foam in the manufacturing of prosthetic liner. This study aimed to design a new prosthetic liner using polyurethane at the anterior-distal part of the residual limb as a Pelite replacement and to compare the biomechanical gait analysis between the new modified polyurethane liner and the common Pelite liner. A unilateral transtibial amputee was recruited as the subject. Two Patellar Tendon Bearing transtibial prostheses with different liners were fabricated for the subject, which were Pelite liner and a modified polyurethane foam liner. The modified liner using polyurethane foam consisted of Ethylene vinyl-acetate – Polyurethane – Ethylene vinyl-acetate sandwich placed at the anterior-distal part of the residual limb. The Ethylene vinyl-acetate – Polyurethane – Ethylene vinyl-acetate sandwich function was to improve the walking gait and compensate for the pain sensation experienced by the subject when wearing the Pelite liner. Biomechanical analysis was done using the Vicon Motion Analysis System on the subject when using the two newly fabricated transtibial prostheses and the subject’s original prosthesis with Pelite liner. During the loading response phase, the original liner exerted a slightly higher force than the Pelite and the modified liner. At 30% and 50% of the gait cycle, the original liner exerted low force than the Pelite liner and the modified liner for Ground Reaction Force at the amputated side. However, no significant difference (p>0.05) was found between all prosthetic liners for Ground Reaction Force (Non-Amputated). The biomechanical analysis showed that the modified liner using polyurethane foam improved the prosthesis user gait cycle and the walking gait of the prosthesis user.