Browsing by Author "Sivarasu, Sudesh"

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    Open Access
    A structured light solution for detecting scapular dyskinesis
    (2018) Verster, Jaco; Gray, Janine; Sivarasu, Sudesh; Mutsvangwa, Tinashe
    Scapular dyskinesis is a common occurrence in overhead athletes, i.e. athletes who participate in any sport where the upper arm and shoulder is used above the athlete’s head. However, no consensus has been reached on how to evaluate scapular dyskinesis quantitatively. In this thesis, we developed a measuring tool that can be used to evaluate certain key clinical parameters specific to scapular dyskinesis. The tool employs a 3D structured light computer vision approach to create a surface map of the soft-tissue across the scapula. This surface map is then analysed using surface curvature analysis techniques to identify the key clinical parameters associated with scapular dyskinesis. The main advantage of this method is that it provides a measurement tool that may facilitate future quantitative analysis of these key parameters. This may aid with diagnosis and monitoring of the condition by allowing measurement data to be collected both before and after treatment and rehabilitation. We expect that this tool will make the monitoring of treatment effectiveness easier while contributing to diagnostic computer vision.
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    An Attempt to Improve Stance Mechanics of Trans-Tibial Amputee Gait by the Design of a Modular Ankle Joint Prosthetic
    (2018) During, Alastair B; Vicatos, George; Sivarasu, Sudesh
    Background: A-priori research shows that trans-tibial (TT) amputees display poor gait parameters when walking with low-cost ankle-foot prosthetics (here referred to as baseline AFP’s). This has drastic implications for the amputee populations in the developing world specifically, as they have limited access to advanced prosthetic technologies. Low-cost AFP’s are unable to adequately replicate natural stance mechanics, and reliance on these devices results in increased energy expenditure, osteoarthritis and lower-limb joint deterioration. Methodology: This project details the design of a novel ankle joint prosthetic (AJP) that serves as an attachment to baseline AFP’s, with the aim of facilitating better stance mechanics via the restoration of ankle joint mechanisms. The work is presented in three core sections: Part 1 explains the rationale as to why adequately replicating natural stance mechanics is an appropriate need; Part 2 presents the design of the modular low-cost AJP that utilises only simple mechanical elements; and Part 3 presents the experimental quantification of the impact the AJP has on stance mechanics of a baseline AFP (Otto Bock 1D10) in a simulation of the TT amputee walking gait cycle, via the use of three able-bodied participants and a pseudo-prosthesis. Results: The results indicate that the AJP significantly improves the stance mechanics of the baseline AFP. During forefoot rollover a stable joint moment and an increase in joint range of motion (RoM) was observed, yielding a decrease in ankle stiffness. During initial weight acceptance of early stance, an increase in joint RoM displays the restoration of controlled plantarflexion, which indicates an improved transition from heelstrike to footflat. This is a critical mechanism that facilitates stability control during weight acceptance, and the results suggest that the designed AJP is performing better in this regard than its closest functional competitor. However, equipment errors limited the ability to accurately report on ankle stiffness of this phase. Conclusions: Overall the final conclusions are that the designed AJP improves rollover shapes of the baseline AFP, eases phase transitions, and facilitates stability control and forward tibial progression. In combination with the low cost price (±50 USD), its ease of assembly and modular design, the AJP is thus a preferable option for low-income amputees in developing countries. Finally, there is significant evidence of functional and mechanical reliability, and therefore testing of the device can progress to a clinical study involving amputee participants.
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    Biomechanical assessment of RTSA functional outcomes towards optimising the prosthesis configuration
    (2018) Glenday, Jonathan Daniel; Sivarasu, Sudesh; Roche, Stephen
    Reverse total shoulder arthroplasty (RTSA) alleviates pain and restores function to patients with cuff tear arthropathies or massive rotator cuff tears. The procedure uses a semi-constrained prosthesis to reverse the orientation of the glenohumeral joint, thereby altering the biomechanics of the deltoid and allowing it to restore shoulder function in the presence of an irreparably damaged rotator cuff. However, there are complications that can impact long-term success of RTSA. Adaptations to the design and placement of the prosthesis have been investigated to address these complications and this has led medical device manufacturers to develop divergent implants. This divergence, as well as previous literature regarding RTSA biomechanics, suggest that a configuration that optimises reverse shoulder functional outcomes has yet to be determined and that it can be obtained by combining multiple modifications. A biomechanical assessment framework was established to characterise reverse shoulder function and the effect of modifying prosthesis configuration. It utilised the Newcastle Shoulder Model (NSM) and a custom-made impingement detection algorithm to simulate seven standardised motions that either elevated or rotated the humerus. Four outcome measures (deltoid elongation, deltoid moment arm, joint stability and impingement-free range of motion) were evaluated for each motion. The framework took anatomical variability into consideration by performing the simulations using a subject-specific reverse shoulder cohort. Further, 36 modified configurations of the prosthesis (based on offsets to the placement of glenosphere, humeral tray and greater tuberosity) were evaluated. The effect of each of these modifiable parameters on the outcome measures was characterised as beneficial, detrimental, or negligible, in comparison to a default prosthesis configuration. Seven of the most beneficial parameters were then selected for combination and evaluated using the assessment framework. Due to an antagonistic relationship between the outcome measures, and differing functional requirements of the motions, none of the configurations were able to simultaneously maximise all outcome measures. Rather, the optimised configuration (which inferiorly translated the glenosphere and posteromedially translated the humeral tray) provided balanced, moderate improvements to majority of the outcome measures. Overall, the deltoid did not excessively elongate, and deltoid moment arms, joint stability, and impingement-free range of motion improved by 17.9%, 57.1%, and 32.1%, respectively compared to the default configuration. Subsequently, comparisons between the effect of the default and optimised configurations on muscle fatigue and micromotion at the bone-implant interface were made. Muscle fatigue was assessed by adapting the NSM, and micromotion was assessed through a finite element analysis of a subset of the reverse shoulder cohort. The optimised configuration had a beneficial impact on the time to initiate muscle fatigue by decreasing the force required by the middle deltoid to initially elevate the humerus, and it had no appreciable effect on micromotion. In summary, an optimised RTSA configuration has been presented in this thesis. For a rotator cuff deficient reverse shoulder, the proposed configuration provided balanced, moderate improvements to majority of the functional outcomes. Additionally, the configuration was able to mitigate the effect of muscle fatigue and did not affect micromotion. Future studies should look to experimentally validate these findings, determine their clinical significance, and enhance both the assessment techniques and framework.
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    Design and Development of a Lower Limb Rehabilitation Device for Spinal Cord Injury Patients
    (2021) Trusler, Matthew; Sivarasu, Sudesh; Stander, Juliette
    Introduction: Spinal cord injuries (SCI) are seen commonly in Southern Africa and can completely change the course of the affected's life. Lower limb disability is a common complication from this injury, but a patient can be rehabilitated in some cases. Research and clinical observations suggest that early mobilisation and rehabilitation leads to shorter hospital stays and better clinical outcomes. Relieving the time dedication placed onto the rehabilitation team could mean that patients receive a higher standard of care. Methods: A cyclic movement device has been designed to mimic the gait cycle that a patient is attempting to recover. The device was intended towards providing a ground reaction force simulation at the correct points of the gait cycle. The device was tested in-silico with validated skeletal models to determine joint torques and angles. In-silico testing was also utilised to determine the loads placed onto the patient by the device through its use. The force data could then be used to predict possible ground reaction forces. Results: The device allows for a gait similar trace path of the ankle, comparable to that found in the literature. The ankle has a range of motion of 3 1° as the device completes a full cycle in which the crank rotates 360 °. The hip has a range of motion of 28° and the knee 35° in this same movement. The shape of the displacements of the joints of the lower limb is comparable to that seen in researched gait patterns. However, the timing of the knee and hip joints' movements are not synchronous with that of the gait patterns. The device is validated to be sufficiently stable to use, and the motor and power components can provide the 7259N.mm of torque needed to move the model. Conclusion: The results suggest that the device has potentia l as an adjunct to rehabilitation schemes. In-silico testing showed that the device is able to simulate some of the kinetic and kinematic parameters seen in normal gait. Further work is needed to prototype the device to physically and clinically validate the device.
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    Design and development of a sensory feedback system for transradial amputees using body powered prostheses
    (2021) Gordon-Grant, Catherine; Sivarasu, Sudesh
    Introduction Although significant advancements have been made in the realm of prosthesis design over the last two decades, amputees still reject their prostheses largely owing to the lack of sensory feedback received. The aim of this study was to develop a non-invasive sensory feedback system, including proprioceptive feedback, to work in conjunction with an existing body powered prosthesis that provides the user with increased tactile and proprioceptive awareness demonstrated in the form of improved results in an object identification and size discrimination (OISD) test, improved percieved confidence and improved response time. Materials & Methods A sensory feedback system was developed using principles of rapid prototyping and testing. The system utilises capacitive sensors to mediate detection of proximity and touch, and makes use of a flex sensor to represent the position and motion of the finger digits of the prosthesis. A vibrotactile armband on the upper arm is used to feedback the sensed information to the user. Four able-bodied, adult volunteers participated in a preliminary study to test the efficacy of the capacitive sensor-vibrating motor disc combination. Five able-bodied, adult volunteers participated in a study conducted at the Medical Devices Lab at the University of Cape Town. The study investigated whether using the designed sensory feedback system in conjunction with a body powered prosthesis improves the participant's ability to locate and discriminate the size of spheres whilst visually and aurally restricted. Results & Observations The results from the preliminary study show that all participants were able to distinguish between 3 levels of touch (proximity, light and hard touch) intensity and locate the position of the stimulation for good electrical conductors such as metal, human skin, wood and sometimes ceramic and glass materials depending on the coating. Results from the object identification test indicate that participants performed worse when no sensory feedback was provided (at an average accuracy of 0%). All participants were able to identify the objects accurately and efficiently when sensory feedback was provided at an average accuracy of 100%. Similarly, average accuracy for object discrimination improved from 58.33% with no sensory feedback to 85% with sensory feedback. Response times for both object identification tasks and size discrimination tasks also improved illustrated by a significantly negative relationship (negative gradient) in all trend lines over the period of testing. This suggests a learnability with the device: as the user becomes more cognisant of the device, the better their performance is in accuracy and response time. Confidence levels for size discrimination were highest with sensory feedback active. There was a significantly positive correlation (positive gradient) between accuracy and confidence. With no sensory feedback, confidence was on average 70% which increased to 84% with sensory feedback. Conclusions The non-invasive sensory feedback system met all design requirements successfully. Future recommendations include minor adjustments to the design to optimise its capabilities after which, the design can be revalidated and tested on transradial amputees. Future work includes performing usability studies with amputee subjects, revalidation of the design through bench testing and with amputee subjects, and evaluating the scalability and manufacturability of the design with a variety of commercially available body powered prostheses.
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    Design and Development of a Traction Device for Semi-Automated Closed Cervical Spine Reduction Procedures
    (2021) De Villiers, Tertius; Sivarasu, Sudesh; Kruger, Nicholas
    Cervical facet dislocations are traumatic injuries which can cause severe compression to the spinal cord. This can lead to extreme adverse outcomes such as full body paralysis or loss of life. Treatment involves a closed reduction (CR) of the dislocated cervical facet joints and alignment of the spinal canal as the first step. This is the most rapid mechanism of decompressing the spinal cord and improving the neurological outcomes. This kind of injury is infrequent, with many clinicians seldom becoming well practiced in CRs, but when they do occur, these injuries require immediate urgent treatment. In addition to this, the existing equipment can be awkward to use and lacks an intuitive framework for operation. This led to the development of the collaTract, a device taking the form of a single item of equipment, able to guide a user through the performance of a CR procedure while avoiding cumbersome and heavy equipment. It is wedge shaped, with an articulating arm, connecting to a patient's skull via commonly used traction callipers. It was designed to apply force to, and alter the angle of the patient's neck allowing it to perform all operations required for a CR. The device was tested for functionality on a single cadaver, after which, a usability study was performed with ten clinicians of varying skill and experience comparing the traditional equipment of weights and a pulley to the collaTract. The device was able to perform all operations involved in a CR including, at any point, returning the neck to a neutral angle and removing the applied tension as would be the case when aborting a procedure. After the usability test, the participants rated the device excellent from a usability standpoint. Of the returned feedback all participants rated the collaTract easier to use than the current equipment and they viewed the collaTract as an improvement over the current equipment. It is important to state that the cadavers in this study had intact cervical spines with no dislocation; therefore, future studies must look into validating the collaTract device with real world spine dislocation models. In conclusion, the collaTract device can perform the functions necessary for a closed cervical reduction procedure. The device was rated by ten different clinicians of varying skill levels as excellent in terms of its usability and can be seen as a new state of the art device in treatment of cervical spine dislocations.
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    Design and development of an adaptive external bone fracture fixation system
    (2019) Herbert, Christopher; Sivarasu, Sudesh
    External fixation is a surgical treatment primarily utilised for long bone fracture stabilisation. External fixation, through either pin or wire insertion, is done by constraining bone fragments and providing support to the injury via external scaffolding built across the fracture., but it can also be used to solve both traumatic and congenital bony deformities. Certain devices, particularly the Ilizarov Ring Fixator, can employ external bone fixation to create a biomechanical environment to gradually correct deformities (comprised of: translation, rotation and angulation). A typical application for deformity correction is the fixation of lower leg fractures, particularly tibial fractures, which have been recognised as the most common incident in long bone fractures. External ring fixators have become more developed; manufactured from sophisticated materials; or designed to incorporate computational support, to achieve accurate correction, however these factors have created limitations regarding their accessibility, complexity and ease in application. In addition, standard systems are not as versatile or correctively exact as required to prove their cost of use, creating reluctance as well as added bias towards the more developed devices. Threedimensional and multi-planar deformity correction has become major factors for current devices, yet the feasibility to use such expensive and complex devices may not be beneficial for all parties. External Fixation Systems are considered operationally expensive. Standard systems still utilise expensive and cumbersome setups, while developed devices require computational consultation and extensive training. With such complex procedural actions required to facilitate multi-planar correction, most devices utilise computational support, which in turn minimizes the clinician’s control. The current study aims to design a light-weight Adaptive External Bone Fracture Fixation System that can offer definite treatment and full clinical control over the injury. The system is to be able to stabilise and offer correction of planar bony deformities via controlled shape change. The functional verification of the device was limited to (according to the scope) stress testing. The proposed device consists of hinge systems capable of allowing for full assembly expansion to permit quick installation for various injury structures or states. In addition, the design possesses longitudinal elements that can offer both rapid and finite lengthening (with lock-and-switch) to offer both rapid and gradual system shape change, improving the control over the injury fixation. The device stress testing had revealed limited capabilities in providing enough scaffolding stability for a certain directional stress condition. To determine the quality of its structural integrity, the device was loaded under direct compressive and tensile load. The strain generated was measured and analysed using a Load-Deformation Curve. The device could support tension close to [3.5 kN], equivalent to standard models, whilst unable to support compression for loads close to [1.2 kN]. The conclusive points that were made had detailed that it was limited by its structural integrity, however the design was evaluated as functionally versatile as and should be further developed. Future recommendations proposed include the addition of constrained joints; improved locking capabilities; implementation of failure modes for hinges and lastly improved structural integrity by using sophisticated materials to further validate the skeletal structure of the fixation system.
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    Design and Development of an Open-Source ADL-Compliant Prosthetic Arm for Transradial Amputees
    (2021) Timm, Lara; Sivarasu, Sudesh
    Transradial amputation is traumatic – leading to the amputee having a limited ability to perform activities of daily living (ADLs). Below-elbow prostheses are prescribed. The high cost associated with prostheses results in many amputees in low-to-middleincome countries relying on government subsidised devices, which are cosmetic rather than functional, or none at all. Open-source prostheses have the potential to increase the accessibility of functional prosthetic arms, but at present are not optimised to assist the dominant hand in performing bimanual ADLs. The aim of this study is thus to design and experimentally validate an open-source prosthetic arm that is functionally optimised for the performance of ADLs in the unilateral transradial amputee population. The ADL arm is functional open-source below-elbow prosthesis. This device is bodypowered; featuring a hand terminal device with thumb abduction and adduction, and wrist pronation and supination functionality. Elbow flexion of the residual limb is used to actuate the terminal device. The prosthesis requires no existing prosthetic hardware; and the majority of parts can be 3D printed. The ADL arm is designed to reliably perform the grasps required by the non-dominant hand in two-handed ADL activities. Device validation includes functional and simulated-use components. The functional assessment uses the Anthropomorphic Hand Assessment Protocol (AHAP); while the simulated-use assessment involves a practical ADL verification, and a usability assessment using healthy volunteer participants. The AHAP gives as result a grasping ability score (GAS) and partial GAS for ten grasp types associated with ADLs. The GAS represents the percentage of healthy limb function achievable by the prosthesis. The overall GAS of the ADL arm is found to be 68 %. The ADL arm achieved a partial GAS of greater than 75 % for four of five bimanual ADL grasps. A major design flaw resulted in a partial GAS of 33.3 % for the lateral pinch grasp type. The performance in this grasp, as well as others, would be greatly improved by the inclusion of a mechanism to lock the distal joint of the digits in extension during grasp. In this way, the hand would be better able to apply force to an object with the pads of the digits. Simulated-use validation of the ADL arm is performed on healthy participants using the designed bypass socket. The ADL assessment involves the completion of 86 ADL and instrumental ADL tasks; scored using the designed self-report questionnaire. The participant could perform all but seven tasks independently, and the perceived difficulty for tasks requiring the prosthesis was low overall. Seven healthy volunteers are used to assess the system usability. Participants performed a number of tasks and then completed the system usability scale (SUS). The perceived usability of the device is found to increase with increased device familiarity, yielding an overall score of 84.29. This result indicates that participants found the experience with the device to be ‘good' overall. In conclusion, the ADL arm is functionally competent and has proven its ability to assist in the performance of ADLs in a simulated-use environment; using healthy participants. A number of design modifications are recommended to overcome the limitations of the current design, which should be tested in the transradial amputee population to corroborate the results obtained in this study.
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    Design and Development Towards a Novel Prosthesis for Total Shoulder Arthroplasty to Reduce Aseptic Glenoid Loosening
    (2018) Dey, Roopam; Sivarasu, Sudesh; Roche, Stephen
    Total shoulder arthroplasty (TSA) is the most common surgical solution, that helps in restoring the structural and functional integrity of a diseased glenohumeral (GH) joint with intact rotator-cuff. A 300% increase in the usage of TSA has been observed since 2007, along with 2.5% increase in revision rate. Aseptic glenoid loosening accounts for 37% of postsurgical failures in TSA. Eccentric loading of the prosthetic glenoid cup, leading to the “rocking horse” effect, is one of the prevalent causes of aseptic glenoid loosening. Current anatomical total shoulder prosthesis (ATSP) geometry does not consider all the GH morphometric features, for example the elliptical shape of the humeral head. Moreover, the morphometric studies leading to the initial ATSP design did not consider the GH morphology of any sub-Saharan population. Hence, there exists a gap in understanding of the implications of certain morphometric features on the functionality of a post-TSA GH joint. This thesis had two primary aims to address this gap in knowledge. Firstly, to study the GH morphometric variations between cohorts representing native European (Swiss) and native sub-Saharan (South African) populations. Secondly, to develop anatomically inspired ATSP design concepts and test them using biomechanical and finite element (FE) models, insilico, under standardised testing protocols. The morphometric analysis suggested that an average Swiss humeral head radius of curvature was larger (P<0.05) than the average South African humeral head. By comparing the biological head sizes, across both the populations, with the dimensions of the commercially available humeral heads, it can be inferred that suitable humeral prostheses are currently not available for individuals with head sizes >28mm or <19mm. Considering both the populations, the inherent shape of an average humeral head was found to be elliptical. The thickest region of the head was found to lie in the posterior region and not at the geometric center. Hertzian contact theory was applied to calculate the GH stresses produced by symmetric and asymmetric elliptical heads. Higher concentric stresses (P<0.001), within the acceptable limit for polyethylene, were observed to be imparted by the asymmetric heads. Population-specific musculoskeletal models were developed to study the post-TSA kinematic variation. When an identical range of motion (RoM) was performed by these models, population-specific variation in muscle moment arms was observed. The novel glenoid designs were not found to alter the post-surgical kinematics. FE models of the biradial, compartmental and pear-shaped glenoid implant designs were subjected to compressive and shear loading according to the American Society for Testing and Materials (ASTM). Using the bi-radial the glenoid cup, with thickened posterior-superior surface, anatomically relevant force distribution patterns could be replicated. Compartmentalising the glenoid prosthesis into concentric and eccentric regions with the gaps, proved to be highly beneficial. When compared to a commercially available glenoid prosthesis, the compartmental prosthesis was able to contain the GH forces to the concentric region for longer, delaying the eccentric loading and therefore potentially reducing the “rocking horse” effect. In the light of the above observations, two conclusions can be drawn from this thesis. Firstly, it would be beneficial if population-specific ATSP were made available for natives of certain geographic locations. Secondly, glenoid prosthesis designs could be compartmentalised to contain the GH joint forces within the concentric regions of the cup which might aid in the reduction of post-TSA complications.
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    Design and in vivo verification of a stress radiography device towards it's suitability for multi-ligament laxity measurements
    (2017) Beukes, Giancarlo; Sivarasu, Sudesh
    The human knee is a hinge joint, primarily facilitating locomotion. Knee joint instability, due to ligament injuries, is a result of direct or indirect trauma, non-anatomical stresses during pivoting movements about the knee, imbalanced landing during jumping and rapid deceleration during high intensity locomotion. Biomechanical indications of an unstable knee joint include decreased joint integrity, hyperlaxity, abrupt locking and catching combined with clicking noises during locomotion. Approximately, two hundred and fifty thousand ACL injuries occur in the United States of America annually. Current diagnostic procedures are subjective according to the clinician's experience. This potentially leads to misdiagnosis of the injury and improper treatment. Non-invasive diagnostic techniques make use of manual methods, MRI and laxity measurement devices (e.g. arthrometers and stress radiography devices). Laxity measurement devices (the focus of this study) determine ligament health by measuring their elasticity and stiffness. Directional tibial and fibular bone translation is induced by applying an external load to the joint. The bone translation is measured in relation to the load applied, which denotes ligament laxity. The Laxmeter is a novel, cost effective and radiolucent multi-ligament laxity measurement stress radiography device. This device facilitates the measurement of MCL and LCL laxity at multiple degrees of knee joint flexion, however, it lacks the essential means to perform the laxity measurement technique. The current study aims to redesign the Laxmeter to perform ACL, PCL, MCL and LCL laxity measurement procedures at multiple fixed degrees of knee joint flexion. The in vitro functional verification of the device was limited to (according to scope) a single cadaver trial; to validate functionality, structural integrity, usability as well as demonstrate the Laxmeter concept prior to a prospective full clinical trial. The redesigned Laxmeter Prototype consists of a load applicator capable of applying a 250N load to various aspects of the proximal lower leg, to induce bone translation for laxity measurements. The load applicator is designed to integrate with the ergonomic patient support structure, the later potentially improving reproducibility and accuracy of the laxity measurement results. The cadaver trial demonstrated the device's capability of measuring the laxity of the ACL, MCL and LCL at predetermined knee flexion angles. To measure the ligament laxity, equal loads were applied to both proximal lower limbs independently. The bilateral average displacement of the tibia with respect to the femur for each ligament was noted. In the case of the ACL, the Laxmeter measured an average laxity of 3.07mm at 30° knee flexion and a load of 150N. The average laxities for the MCL and LCL at 30° knee flexion and 150N were 1.11mm and 2.02mm. The trial yielded preclinical results that were comparable with existing clinical and healthy cadaver based studies (using similar techniques), and suggests that the Laxmeter is capable of measuring the laxity of the ACL, MCL and LCL at various degrees of knee flexion. PCL laxity measurements could not be performed due to compromised structural integrity, which was essential to make the Laxmeter portable and lightweight. Future recommendations for the device include rotational ankle fixation; improved overall limb fixation; improved structural integrity to allow for PCL laxity measurements as well as further preclinical (functional) verification procedures prior to a full clinical trial.
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    Design of a Novel Video-Assisted Tube Over Tube Rigid Bronchoscope for the Removal of Foreign Bodies from the Bronchi Following Aspiration
    (2022) McEwan, Sarah Ann; Sivarasu, Sudesh; Myburgh, Adriaan
    Foreign body aspiration (FBA) is a prevalent occurrence in the paediatric population. FBA is when a foreign body (FB) is inhaled accidentally into the airways. The location of the FB may differ according to each patient, but in most cases, the FB is found in the right bronchial tree. FBA symptoms are often misdiagnosed, resulting in late discovery of the obstruction. There is an increase in difficulty to remove a FB, dependent on how long it remains within the airway. This poses a greater risk to the patient, fatality or other serious long-term complications. Currently, FBs are removed using a bronchoscope in conjunction with a pair of forceps. The two types of bronchoscopes used currently are the flexible and rigid bronchoscopes. The rigid scope is preferred for FB removal due to better control and clear visuals of the air way and an array of forceps ends. The costly flexible scope is more difficult to use and is used in cases where radiological findings of a FB are inconclusive. During insertion of the scope, no ventilation is supplied to the patient, posing a high risk of hypoxia. Both instruments require considerable skill and extensive training, limiting the procedure applicability. The difficulty experienced when handling the current instruments and the high risk of hypoxia are motivations for a product redesign. Therefore, this study aims to design and develop a novel video-assisted tube-over-tube rigid bronchoscope to remove foreign bodies from the airways following aspiration, whilst providing constant ventilation and visualisation of the airway. The redesign compromises of several subsystems: the rigid bronchoscope (and attached camera), ventilation connector tube and an uncuffed endotracheal tube (ETT). These subsystems were designed to ensure constant ventilation throughout the insertion of the bronchoscope, whilst providing real-time imaging of the airways. The design incorporated a guiding mechanism to increase the usability further. A testing protocol was performed on a Laerdal airway management trainer using the designed device, named the ‘Re-Aspire' device and its competitor, the Karl Storz rigid bronchoscope. The testing participants were a group of anaesthesiologists who have had prior training in bronchoscopy, but do not practise the procedure. A common FB was placed inside the airway of the trainer, and both scopes were used to retrieve it. The facilitator timed the procedure and observed the participants. Post testing, each participant was interviewed about the functionality of each device and completed a system usability scale. A total of 34 attempts of FB removal was recorded for the rigid bronchoscope compared to 14 attempts for the Re-Aspire device. As hypothesised, the estimated average hypoxic time was more than double for the rigid bronchoscope compared to that of the Re-Aspire device. According to the system usability scale, the Re-Aspire device resulted in a higher average system usability score. These results demonstrated that the Re Aspire device has a higher perceived ease of use and system satisfaction according to the user's perspective. Therefore, achieving all the stated testing hypotheses. However, the design of the device can be improved to increase the usability and efficacy further.
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    Design of a wireless ureteropyeloscope
    (2015) Ncube, Mkhokheli; Sivarasu, Sudesh; Lazarus, John
    Ureteroscopy is a form of endoscopy that concerns itself with the urinary system. Flexible ureteropyeloscopes are instruments used to access the urinary system for diagnostic and therapeutic procedures. An average ureteropyeloscope requires a repair for every 3 to 13 hours of use, or alternatively 6 to 15 procedures. Therefore, there is a need to increase the durability of the ureteropyeloscope to lower the frequency of repairs required. In addition, the number of cables in the workspace needs to be reduced for improved handling by the clinician. The present study details the design of an ureteropyeloscope, which is modelled after currently existing instruments. Current endoscopes use fibre-optics for lighting area of interest as well as image acquisition. However, the ureteropyeloscope discussed was developed with a camera at the distal end of the insertion tube as its image acquisition system. The images captured were transmitted to a monitor for viewing via a wireless transmission module. The ureteropyeloscope discussed in the study was aimed at increasing the durability of the deflection unit of the ureteropyeloscope, with primary component made of nitinol, and reducing the number of cables around the workstation by using wireless means to transmit images from image acquisition system to monitor.
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    Design Optimization and in-vitro Verification of a Bone-Retentive Device to Repair Comminuted Radial Head Fractures
    (2019) Gasant, Muhammad Saadiq; Sivarasu, Sudesh; Roche, Stephen
    Introduction: Radial head fractures are common, accounting for approximately 30% of all elbow fractures. Mason type III fractures involve comminuted fractures of the radial head, with two or more articular fragments. There is conflict in the literature regarding optimal surgical treatment of these fractures. Current protocol indicates a preference towards bone retention, as this has a minimal impact on the elbow biomechanics. Thus, the preferred surgical open reduction and fixation (ORIF) methods which involve stabilizing the fracture using metal plates and screws. The main drawbacks of this method involve failure of fixation, particularly in more severely comminuted fractures. In these cases, revision surgery is needed. In addition, the metal ware interferes with surrounding tendons and ligaments, leading to discomfort. However, should the fracture be too severe for ORIF repair, the radial head is excised and replaced by a prosthesis. Unfortunately, this affects the biomechanics of the elbow and a loss of motion and strength is likely to result. Thus, there is need for a novel way of treating complex fractures of the radial head. The RadFix™ Fracture Fixation Solution was conceptualized to improve functional healing for these fractures. The concept involved three treatment options which focused on native bone retention and the preservation of radio-capitellar articulation and included a contingency plan in the event of failure of fixation. The main benefit of the device involved the concept of a central stem component and a partial prosthesis, which aimed to replace only the damaged portions of the radial head, whilst preserving the intact native bone. It is hypothesized that this will aid functional healing of the radial head. Aim The aim of the study is to optimize the existing design and experimentally verify the stability of a novel fixation device for comminuted radial head fractures to increase native bone retention. Methodology The existing anatomic prototypes were optimized to include different radial head sizes using Solidworks 3D-modelling software after which prototypes were manufactured from Nylon 12 at the Central University of Technology (CUT). A first pilot test was conducted to evaluate these prototypes - a stem and half-head prosthesis were implanted into a cadaver arm in a procedure which mimicked fracture to the lateral half of the radial head. Radiographic evaluation of the fixation showed stability of the prosthetic components. Recommendations for further development included remodelling the anatomic shape of the prosthetic heads to a generic shape (to allow repair to any quadrant of the radial head) and the development of a drill assist device to aid in the drilling process for stem implantation. The subsequent design modifications were made to the prosthetic head design and a drill assist guide was developed to aid in the relevant surgical processes. These new generic prostheses were 3D-printed from ABS plastic and were evaluated in a second pilot test. Once again, a stem and a half-head prosthetic head were implanted into a cadaver arm after a fracture to the radial head was imitated. Radiographic evaluation of the fixation showed that stability was achieved but that the drill assist device required modifications to its drill guide attachment and stabilizing mechanism. Once the modifications were completed, five more cadaver arms were used to conduct a wider scale study, in which one-third head, half head and full head prostheses were implanted. Each repair was radiographically evaluated before the subsequent repair was performed. Radiographic stabilization involved the evaluation of prosthesis reduction - a measurement of gaps between the prosthetic heads and the adjacent bone (gaps smaller than 2mm were acceptable, gaps bigger than 2mm were not) and an evaluation of screw fixation - optimal screw position involved penetration of cortical bone whilst any protrusion of a screw from the bone was not acceptable. Results Cadaver Arm 1 was used to conduct a half-head prosthetic repair followed by a full-head prosthetic repair. Radiographic analysis of the half-head repair showed that there was correct implant positioning, correct reduction of the prosthesis and correct screw placement. This meant that the repair was classified as successful. The full-head repair was classified as unsuccessful due to a large ulnar-sided overhang and a radial-sided recess, likely caused by movement of the stem during the transition between repairs. Cadaver Arm 2 was used to conduct a one-third head prosthetic repair. Radiographic analysis showed correct implant positioning and correct screw placement, however the repair was classified as unsuccessful due to a 2.04 mm gap between the prosthesis and the adjacent bone on the articular surface of the radial head. Cadaver Arm 3 was used to conduct a one-third head repair, followed by a half-head prosthetic repair and a full-head prosthetic repair. Radiographic analysis classified both the one-third and halfhead repairs as successful. Lastly, radiographic analysis of the full-head prosthetic repair showed that the distal (oblique) screw was too large and protruded from the radial head at both ends, leading to an unsuccessful repair. Cadaver Arm 4 was used to conduct a one-third head repair, followed by a half-head prosthetic repair and a full-head prosthetic repair. Radiographic analysis of the one-third repair saw it classified as successful. The half-head repair was classified as unsuccessful due to a 2.53 mm overhang on the distal-radial edge of the prosthesis. The full-head repair was classified as unsuccessful due to unsuccessful screw placement. Lastly, Cadaver Arm 5 was used to conduct a one-third head prosthetic repair followed by a full-head prosthetic repair. Radiographic analysis of the one-third head repair showed that there was a 2.97 mm gap between the prosthesis and the adjacent bone on the articular surface of the radial head, resulting in an incorrect reduction. This saw the repair classified as unsuccessful. Radiographic analysis of the full-head repair classified it as successful. Conclusion: The aims of the study were successfully completed.
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    Development of a Solution Method to Promote Proper Bandaging Techniques for Transfemoral Amputees
    (2021) Lalla, Bhaveen; Sivarasu, Sudesh; Dey, Roopam
    Post-operative care for lower limb amputees focuses on reducing swelling and promoting healing of the residual limb. Healing and desired residual limb maturation is necessary to achieve a conical shape suitable for prosthesis integration. Elastic bandaging is applied to the residual limb to achieve this conical shape. Bandaging requires skill and frequent reapplication. In many cases, the amputee is unable to bandage the residual limb effectively following surgery and professional assistance may not be readily available, increasing the risk of permanent damage due to improper bandaging. Transfemoral amputees are often confined to a wheelchair and spend the most time without a prosthesis fitted compared to any other lower limb amputee. An effective method in achieving the optimum residual limb shape, while promoting proper bandaging is therefore required. The aim of this study was to develop a solution method to assist transfemoral amputees with proper bandaging to achieve a shorter healing period and promote faster prosthesis integration through residual limb re-shaping. An overall solution method comprising of three sub-systems was designed to instruct bandaging. This included the development of a bandaging template, a mobile application and an elastic bandage dispenser. A printable bandaging template generated by a Python script based on the measurements of the patient's residual limb circumferences was developed to instruct bandaging. Development of a mobile application allowed for the design of an interface to control the dispensing device and instruct bandaging steps. The developed Bandage Utility Dispenser (BUD) transmits unrolled bandage length measurements to the mobile application using Bluetooth, to meet the target bandage lengths. Target bandage lengths are calculated by a second Python script to recommend sufficient bandage lengths. Target bandage lengths are expected to apply adequate pressure, while covering the exposed area of the residual limb for the current bandaging step. Testing occurred on an anatomically correct residual limb model (ACM) and five constructed models (CM) assembled by altering proximal and distal ACM circumferential measurements in increments of 5 cm. Measurement and pressure testing were performed after successfully validating the use of the CMs using a Bland-Altman analysis on the ACM and a CM of equal dimensions. Measurement testing utilised a chi-square goodness of fit test to compare observed and expected bandage length measurements for each model. Results for all models indicated that observed and expected measurements did not differ significantly. Pressure testing was performed by measuring the pressure application along the perimeter of the models with assembled pressure pads. Readings were analysed using a one sample t-test to compare differences between sample means and the recommended pressure application from literature. Testing results indicated that pressure application for five of the six models were in an acceptable range. Future recommendations have been established to potentially improve design, functionality and testing of the current iteration of the BUD solution method.
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    Eccentric cycling rehabilitation after anterior cruciate ligament reconstruction: a randomised controlled trial of strength and biomechanical outcomes
    (2017) Milandri, Giovanni; Sivarasu, Sudesh
    After anterior cruciate ligament reconstruction (ACL-R), persistent strength and biomechanical deviations remain. Reducing these by training may reduce risk of re-injury or osteoarthritis for these patients. A cross-sectional study investigated biomechanics of ACL-R male patients long-term (~5 years) post surgery. Fifteen ACL-R and fifteen healthy controls were tested in walking and running using motion capture. Devi- ations were found, primarily between-limbs, and also between groups. Largest deviations were lower knee angles and moments in the affected limb during running. However, these were not found during walking; thus, differences were highlighted by the higher-intensity task. During running, knee abduction moment was lower (more valgus) for the affected compared to unaffected and control limbs. The larger effects in moment show greater clinical potential than knee valgus angle. The ACL-R patients had lower impact foot strike during running than controls. The above results indicate chronic, clinical changes in joint loading. A randomised controlled intervention trial evaluated progressive eccentric cycling for ACL-R males, compared to concentric controls. This is one of the first trials of eccentric vs. concentric training for ACL-R, matched by rating of perceived exertion. Twenty-six adult males, 12 weeks post hamstring-graft ACL-R trained three times/week for 8 weeks under supervision. During training the eccentric group limb powers absorbed were higher than those produced by the concentric group, with a lower heart rate. For both groups, pain scores were low, and one of the patient-reported outcomes (IKDC) improved. Hamstring strength increased in the eccentric group by 15%, but this was not seen in the concentric group. For both groups, 60°/s quadriceps strength increased by a similar amount, approximately 28%. Biomechanically, eccentric training was more effective than matched concen- tric training at resolving knee (P=0.022, walk) and hip (P =0.010, run) flexion angle deviations in the affected limb. In both groups, knee extension moments increased, reducing asymmetries. Large knee abduction moment deviations at baseline were not reduced by either programme (P >0.05). At follow-up (~6 months), both groups showed similar return-to-sports progress; several patients passed using one criterion (IKDC), and none passed using a stricter four-criteria method (Univ. Delaware). Thus it can be concluded that for adult ACL-R males, eccentric cycle training is clinically acceptable, with similar or in some cases better outcomes than concentric cycle training. It improves patient-reported outcomes, strength recovery, biomechanical deviations, and return-to-sports measures.
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    A modular and adjustable ptosis crutch as a non-surgical solution to elevating the upper eyelid of myasthenia gravis patients
    (2017) Findlay, Megan; Sivarasu, Sudesh; Heckmann, Jeannine M
    Myasthenia Gravis (MG) is a treatable autoimmune disorder that affects the neuromuscular junction. MG is characterised by fatigable muscle weakness of voluntary skeletal muscles with the most commonly affected muscles being the eye and facial muscles. Patients of African genetic ancestry, particularly juveniles, are more likely to develop ocular muscle complications of MG compared to their European counterparts. MG ophthalmoplegic complications include persistent difficulty with moving the eyes and blepharoptosis, despite treatment. Blepharoptosis, or ptosis, describes the condition of a lowered upper eyelid(s), beyond its normal anatomic position. Surgical correction of ptosis is often contraindicated in MG patients with severe weakness of the muscles involved in eye closure and in patients with active disease. In these cases, a non-surgical solution to elevating the ptotic eyelid above the visual axis is required. Objective: To design a patient specific, modular and low cost ptosis crutch to elevate the eyelid(s) of myasthenia gravis patients. The ptosis crutch should be low cost, modular and adjustable in nature. Method: 16 MG patients (42 ± 23 years) volunteered to participate in the pre-design phase of the project. Initial eye measurements of each participant were taken using photographic measurement. A bottomup approach was followed for the design of the ptosis crutch. 3D CAD models of the modular ptosis crutch were created in SolidWorks, according to the measured dimensions and the predefined design parameters. The ptosis crutch was prototyped using 3D printing. Eightyseven design failures were observed before the final design was realised. A design feedback loop lead to the discovery of a device that satisfied the specified requirements. The final ptosis crutch was tested, in the clinical setting, on 12 MG patients (43 ± 24 years). Results: The ptosis crutch was designed to fit onto the superior border of the spectacle frame. The ptosis crutch is adjustable along the x- axis to cater for the inter-individual variability of globe protrusion. The crutch bar is adjusted along the z-axis and elevated the ptotic eyelid by 1.96mm (±1.11mm). All of the participants indicated that they would be interested in using the ptosis crutch on a long-term basis. Conclusion: The immediate feedback on the ptosis crutch from the MG patients has shown a positive outcome for the device. Future work will include obtaining long term feedback on the ptosis crutch from all of the users as well as investigating manufacturing methods using materials with increased durability.
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    Optimisation of insertion point during latissimus dorsi tendon transfer
    (2018) Thompson, Seth Mkhanyisi; Sivarasu, Sudesh; Roche, Stephen
    Problem and Motivation: Posterior rotator cuff injuries are common (Yamaguchi et al., 2006), (Neri et al., 2009) and often debilitating and irreparable (Sim et al., 2001). Latissimus dorsi (LD) tendon transfers have been shown to be an effective treatment for these massive or irreparable tears (Habermeyer, 2006), (De Casas et al., 2014). This procedure can have unpredictable outcomes (Ling et al., 2009). This is partially caused by discrepancies in the suggested insertion site for the LD tendon during transfers. The current literature is composed of in-silico studies which ignore the practicalities of the human body (Magermans et al., 2004), in-vivo studies which use subjective pain scores, and small scale cadaver trials. For these reasons, a study is needed that uses the power of in-silico modeling in a way that is verified using in-vitro testing on cadavers. Aims and Objectives: The aim of this study is to determine the effects of varying the insertion point of the LD tendon on the humeral head to treat posterior rotator cuff tears in terms of the effects on strength, primarily in rotation and in flexion over a range of motion. The objectives are to use an in-silico model to define the effects of various insertion points and validate this model using a cadaver trial before presenting the final findings. Methods: In-silico Model The Upper Extremity Model (Holzbaur et al., 2005) was used to simulate tendon transfers. The moment arms in flexion and rotation were measured and recorded at angles of 0° and 90° of forward ix elevation. The moment arms at each point were then projected onto humeral maps to display the results. Cadaver Trial Four fresh frozen cadaver torsos (eight shoulders) were mounted into a specifically designed rig. The LD was transferred to 7 points illustrative of the humeral head. The strain generated by the humerus in rotation on the clamps was measured at 0° and 90° of forward flexion for each point. These were then compared. Results In-silico Model The in-silico moment arm maps were generated and analysed. The optimal point for external rotation at 0° of flexion was the lesser tuberosity. Moment arms to produce external rotation were found over the entire greater tuberosity. Flexion was only generated on the posterior edge of the greater tuberosity. At 90° of flexion, little to no rotation generating moment arms were found in the lesser tuberosity and the anterior ridge of the greater tuberosity. Rotation generating moment arms were not significantly different between the posterior edge and the face of the greater tuberosity. No areas generated flexion moment arms. Cadaver Trial At 0° of flexion, the lesser tuberosity (point 1) generated the most flexion, with the greater tuberosity (points 2-7) also generating external rotation, but at reduced levels. At 90° of flexion, the lesser tuberosity and the anterior ridges of the greater tuberosty (points 1-3) generated no significant rotation. The posterior ridge and face of the greater tuberosity generated similar amounts of flexion, greater than points 1-3 Conclusions: The in-silico model was validated in rotation by the cadaver trials and this validation was extended to flexion. For maximum rotation strength at 0° of flexion and no flexion strength, the x lesser tuberosity is the optimal point. For maximum rotation strength and no flexion throughout the motion of flexion, the middle of the face of the greater tuberosity is the optimal area. For maximum rotation throughout the motion of flexion, points 4 and 5 (the posterior edge of the greater tuberosity) represent the optimal area for insertion. This area represents the optimal compromise in terms of range of motion and strength.
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    A portable robotic rehabilitation system towards improving impaired function of the hand due to stroke
    (2017) Opiyo, Albert; Sivarasu, Sudesh
    Background: Stroke is the leading cause of adult disability with 70 to 85% of initial strokes resulting in hemiparesis. Physical imparity as a result of stroke tends to be severe and majority of impairments are upper limb-related. Impairment is usually accompanied by long term functional loss which requires dedicated post-stroke rehabilitation to regain motor function. The incidence of stroke is increasing rapidly while there remains a shortage of therapists to provide sufficient rehabilitation. There is therefore a high demand for therapists to attend to the rising number of stroke survivors. Robot-aided therapy has emerged as a beneficial tool for providing continuous rehabilitation of the upper limb and is widely being implemented. With this technology, there is great potential to reduce the ill-effects brought about by the low therapist-patient ratio which has hindered sufficient rehabilitation and consequently the effective recovery of motor function among stroke survivors. Hypothesis: The use of a portable robotic rehabilitation system, as a complementary tool, in hand therapy, would promote continuous rehabilitation by encouraging repetition of task oriented exercises which would enhance motor function of an impaired hand. Task-oriented writing practice would potentially improve hand coordination and result in better accuracy while repetitive training would potentially increase hand motor strength. Objectives: 1.To design and manufacture a portable robotic rehabilitation system. 2. To test the performance and usability of the system. Methods: The system was manufactured and its performance tested in a pilot pre-clinical trial involving three participants. The system's ease of use was assessed using a standardised usability scale. Writing accuracy and hand motor strength were also assessed and the results analysed at the end of the study. Results: The average overall score of usability for the rehabilitation system was a few points higher than the average score. The users of the system also experienced increased motivation whilst performing the repetitive and task oriented exercises. There was an improvement in the completion time of the writing accuracy test and the tasks of the trace sample test. The variation in grip strength of the non-dominant hand during the rehabilitation period was small for each of the participants. Conclusion: The rehabilitation system motivated its users to repetitively perform rehabilitative training which may have improved writing accuracy.
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    Simplified finite model based evaluation of tissue stress distribution on anesthetic feet of Leprosy patients for 3 dimensional orthosis fabrication
    (BioMed Central Ltd, 2014) Paul, Sathish; Sivarasu, Sudesh
    The Subtalar joint position during static stance is a crucial determinant of the peak plantar pressures and forms a base for any intervention in foot related problems for leprosy affected patients[1]. Studies have stated that the subtalar joint when in neutral position is more ideal for orthotic fabrication. In this study a hypothesis was formulated and pursued [2,3]. Central to the hypothesis is that the stress will be minimal in the distal joints of the foot when the subtalar joint is neutral at static stance position.
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    South African medical device regulatory pathways: A case study of the effect of the emergency authorization protocols during the Covid-19 pandemic
    (2023) Etuket, Maureen; Sivarasu, Sudesh; Salie Faatiema
    Local medical device translation in Low-and Middle-Income countries (LMICs) is unpredictable and accompanied by demanding, complex, and time-consuming regulatory processes. This complicates local innovation and manufacturing and further restricts access to safe, dependable, and appropriate medical devices (World Health Organisation, 2012). The Covid-19 pandemic accelerated medical technology advancement through the use of Emergency Use Authorisation (EUA) protocols. One such case, which used EUA protocols, is South Africa's National Ventilator Project (NVP). In this study, the NVP is presented as a case study to explore medical device regulations during the Covid-19 outbreak. Semi-structured interviews were held with eight significant NVP participants and this was the primary source of data for the case study. These participants were identified through documents and snowball sampling. The participant's employment history, NVP role and experience, and regulatory recommendations were discussed in the interviews. Interviews were transcribed and iteratively coded with NVivo software (QSR International Pty Ltd., 2020), resulting in three major themes: People, processes, and products in EUAs; the medical device regulatory space; and sustainability of the local medical device industry. Most participants credited the success of the NVP to the interdisciplinary project team. Some participants, from highly-regulated, but non- medical device industries, found the medical regulatory environment frustrating. All participants agreed that systems engineering (SE) methodologies must be implemented in the regulatory space. During the NVP, adapting SE enabled the coordination and facilitated the integration of multiple stakeholder's needs from ideation, through translation to commercialisation and end-use of the device. Additionally, ensuring the sustainability of local innovation through preferential procurement was emphasised. In the contexts of South Africa and Africa, the case study's findings can be utilized to guide policy and provide long-term regulatory paths for medical devices.