Assessment of biomedical engineering knowledge using true-false questions.

The COVID-19 pandemic has caused a shift from on-campus to remote online examinations, which are usually difficult to invigilate. Meanwhile, closed-ended question formats, such as true-false (TF), are particularly suited to these examination conditions, as they allow automatic marking by computer software. While previous studies have reported the score characteristics in TF questions in conventional supervised examinations, this study investigates the efficacy of using TF questions in online, unsupervised examinations at the undergraduate level of Biomedical Engineering. We examine the TF and other question-type scores of 57 students across three examinations held in 2020 under online, unsupervised conditions. Our analysis shows significantly larger coefficient of variance (CV) in scores in TF questions (42.7%) than other question types (22.3%). The high CV in TF questions may be explained by different answering strategies among students, with 13.3 ± 17.2% of TF questions left unanswered (zero marks) and 16.4 ± 11.5% of TF questions guessed incorrectly (negative marks awarded). In unsupervised, open-book examination where sharing of answers among students is a potential risk; questions that induce a larger variation in responses may be desirable to differentiate among students. We also observed a significant relationship (r = 0.64, p < 0.05) between TF scores and the overall subject scores, indicating that TF questions are an effective predictor of overall student performance. Our results from this initial analysis suggests that TF questions are useful for assessing biomedical-theme content in online, unsupervised examinations, and are encouraging for their ongoing use in future assessments.

Comprehensive Gait Analysis of Healthy Older Adults Who Have Undergone Long-Distance Walking.

Many older adults do not adhere to the recommended physical activity levels. This study examines the gait changes upon long-distance walking among healthy older adults. Gait tests of 24 adults aged 65 or more were conducted at baseline and at the end of 30 and 60 min of treadmill walking. Spatial temporal, kinematic, and kinetic gait data were computed. Perceived level of exertion was evaluated for each subject. Ten subjects (group B) perceived higher exertion levels than the remaining 14 subjects (group A). After walking, group B had significant reductions in dominant-side ankle joint range of motion and power, suggesting lower-leg muscle fatigue, which appeared to be compensated by significantly increased nondominant-side knee and hip motions. These changes were not observed in group A. Differences in gait parameters between groups A and B implied that some biomechanical factors might contribute to the lack of walking of some older adults.

Does long-distance walking improve or deteriorate walking stability of transtibial amputees?

BACKGROUND: Falls are common in transtibial amputees which are linked to their poor stability. While amputees are encouraged to walk more, they are more vulnerable to fatigue which leads to even poorer walking stability. The objective of this study was to evaluate the dynamic stability of amputees after long-distance walking. METHODS: Six male unilateral transtibial amputees (age: 53 (SD: 8.8); height: 170cm (SD: 3.4); weight: 75kg (SD: 4.7)) performed two sessions (30minutes each) of treadmill walking, separated by a short period of gait tests. Gait tests were performed before the walking (baseline) and after each session of treadmill walking. Gait parameters and their variability across repeated steps at each of the three conditions were computed. FINDINGS: There were no significant differences in walking speed, step length, stance time, time of occurrence, and magnitude of peak angular velocities of the knee and hip joint (P>0.05). However, variability of knee and hip angular velocity after 30-minute walking was significantly higher than the baseline (P<0.05) and after a total of 60-minute walking (P<0.05). The variability of lateral sway velocity after 30-minute walking was significantly higher than the baseline (P<0.05). INTERPRETATION: The significant increase in variability after 30-minute walking could indicate poorer walking stability when fatigue was developed, while the significant reduction after 60-minute walking might indicate the ability of amputees to restore their walking stability after further continuous walking.

High-intensity stepwise conditioning programme for improved exercise responses and agility performance of a badminton player with knee pain.

OBJECTIVE: To examine the effect of a high-intensity stepwise conditioning programme combined with multiple recovery measures on physical fitness, agility, and knee pain symptoms of an injured player. DESIGN: A single case study. SETTING: University-based conditioning training laboratory. PARTICIPANTS: One 26-year-old male world-class badminton player (height, 190.0 cm; weight, 79.3 kg; left dominant hand; playing experience, 16 years; former world champion) with patellar tendinosis and calcification of his left knee. HIGH-CONDITIONING STEPWISE CONDITIONING PROGRAMME: The player received seven conditioning sessions over three weeks. During the programme, there was a gradual increase in training duration and load across sessions while cold therapy, manual stretches and massage were administered after each session to minimise inflammation. MAIN OUTCOME MEASURES: The training outcome was evaluated with three different testing methods: standard step test, badminton-specific agility test, and tension-pain rating. RESULTS: The conditioning programme reduced knee pain symptoms and improved actual performance and cardiopulmonary fitness during the agility task. The player was able to return to sport and compete within a month. CONCLUSIONS: A high-intensity stepwise conditioning programme improved the physical fitness while sufficient recovery measures minimised any possible undesirable effects and promoted faster return to elite level competition.

Evaluation of the Microsoft Kinect as a clinical assessment tool of body sway.

Total body center of mass (TBCM) is a useful kinematic measurement of body sway. However, expensive equipment and high technical requirement limit the use of motion capture systems in large-scale clinical settings. Center of pressure (CP) measurement obtained from force plates cannot accurately represent TBCM during large body sway movement. Microsoft Kinect is a rapidly developing, inexpensive, and portable posturographic device, which provides objective and quantitative measurement of TBCM sway. The purpose of this study was to evaluate Kinect as a clinical assessment tool for TBCM sway measurement. The performance of the Kinect system was compared with a Vicon motion capture system and a force plate. Ten healthy male subjects performed four upright quiet standing tasks: (1) eyes open (EOn), (2) eyes closed (ECn), (3) eyes open standing on foam (EOf), and (4) eyes closed standing on foam (ECf). Our results revealed that the Kinect system produced highly correlated measurement of TBCM sway (mean RMSE=4.38 mm; mean CORR=0.94 in Kinect-Vicon comparison), as well as comparable intra-session reliability to Vicon. However, the Kinect device consistently overestimated the 95% CL of sway by about 3mm. This offset could be due to the limited accuracy, resolution, and sensitivity of the Kinect sensors. The Kinect device was more accurate in the medial-lateral than in the anterior-posterior direction, and performed better than the force plate in more challenging balance tasks, such as (ECf) with larger TBCM sway. Overall, Kinect is a cost-effective alternative to a motion capture and force plate system for clinical assessment of TBCM sway.

Effects of heel lifting on transtibial amputee gait before and after treadmill walking: a case study.

BACKGROUND: Prosthetic alignment is usually unchanged once optimized. However, a previous study indicated that long-distance walking significantly altered gait patterns, suggesting some alignment adjustments after walking are required. This study investigated the effects of alignment changes (by inserting a heel lift) on gait of a transtibial amputee before and after treadmill walking. CASE DESCRIPTION AND METHODS: The subject walked, without heel lifts, on a treadmill until perception of fatigue. Gait changes upon heel lifting at the prosthetic side were studied before and after the treadmill walking FINDINGS AND OUTCOMES: For this subject before the treadmill walking, heel lifting induced drop-off with increased prosthetic-side knee flexion at mid-stance and pre-swing. The sound limb outreached to stabilize the gait. After the treadmill walking, the same heel lift did not induce drop-off. It reduced the plantar flexor power generation, potentially delaying its fatigue. CONCLUSION: After walking prosthetic-side heel lifting could be beneficial. CLINICAL RELEVANCE: Many lower-limb amputees have difficulties in long-distance walking due to muscle fatigue. This case study proposes that appropriate alignment changes after some walking potentially relieve fatigue and encourage them to walk longer distances.

Effects of long-distance walking on socket-limb interface pressure, tactile sensitivity and subjective perceptions of trans-tibial amputees.

PURPOSE: Many trans-tibial amputees could not tolerate long-distance walking. Lack of walking could explain for the increased cardiovascular diseases mortality rate. This study investigated the effects of long-distance walking (LDW) on socket-limb interface pressure, tactile sensitivity of the residual limb, and subjective feedbacks, which potentially identified the difficulties in LDW. METHOD: Five male unilateral trans-tibial amputees walked on a level treadmill for a total of one hour at comfortable speed. Tactile sensitivity of the residual limb and socket-limb interface pressure during over-ground walking were measured before and after the treadmill walking. Modified Prosthesis Evaluation Questionnaires were also administered. RESULTS: After the treadmill walking, the socket-limb interface pressure and the tactile sensitivity at the popliteal depression area were significantly reduced. This corresponds well with the questionnaire results showing that the level of discomfort and pain of the residual limb did not increase. The questionnaire revealed that there were significant increases in fatigue level at the sound-side plantar flexors, which could lead to impaired dynamic stability. CONCLUSIONS: Fatigue of sound-side plantar-flexor was the main difficulty faced by the five subjects when walking long-distances. This finding might imply the importance of refining prosthetic components and rehabilitation protocols in reducing the muscle fatigue. IMPLICATIONS FOR REHABILITATION: • After long-distance walking (LDW) of the trans-tibal amputee subjects, there were significant increases in fatigue level at the plantar flexors. These might explain the reduced walking stability as perceived by the subjects. • LDW did not produce any problems in residual-limb comfort and pain feeling. These were in line with the significant reductions of socket-limb interface pressure and the tactile sensitivity at the popliteal depression after LDW. • Refinements of prosthetic components and rehabilitation protocols should be attempted to reduce the fatigue of the plantar flexors and facilitate LDW.

Is it important to position foot in subtalar joint neutral position during non-weight-bearing molding for foot orthoses?

When taking molds for foot orthoses, it is accepted practice to position the subtalar joint in its neutral position. However, foot orthoses have no contact with the talus, and this leads to a hypothesis that as long as there is correction available to appropriately align the forefoot relative to the hindfoot when taking a mold, changes in subtalar joint angles do not lead to significant alterations in the plantar surface shapes of the molds taken. This study tested this presumption with 20 subjects between 22 and 46 years old. During non-weight-bearing casting, the subtalar joints were aligned at positions of 4° of eversion, 2° of eversion, 2° of inversion, and in neutral. At each orientation, forces were applied over the forefoot such that the metatarsal heads were aligned with the rearfoot. Digital scanning was used to analyze the shape of each negative mold. There were significant changes in projection volume in different subtalar joint orientations. However, the changes in arch heights, navicular height, and protrusion were insignificant and very small. It is therefore suggested that as long as the forefoot and hindfoot are appropriately aligned, variations in the orientation of the subtalar joint would be acceptable.

Comparison of custom-moulded ankle orthosis with hinged joints and off-the-shelf ankle braces in preventing ankle sprain in lateral cutting movements.

BACKGROUND: A custom moulded ankle orthosis with hinged joints potentially offers a better control over the subtalar joint and the ankle joint during lateral cutting movements, due to total contact design and increase in material strength. OBJECTIVES: To test the above hypothesis by comparing it to three other available orthoses. STUDY DESIGN: Repeated measures. METHODS: Eight subjects with a history of ankle sprains (Grade 2), and 11 subjects without such history performed lateral cutting movements in four test conditions: 1) non-orthotic, 2) custom-moulded ankle orthosis with hinges, 3) Sport-Stirrup, and 4) elastic ankle sleeve with plastic support. A VICON motion analysis system was used to study the motions at the ankle and subtalar joints. RESULTS: The custom-moulded ankle orthosis significantly lowered the inversion angle at initial contact (p = 0.006) and the peak inversion angle (p = 0.000) during lateral cutting movements in comparison to non-orthotic condition, while the other two orthoses did not. The three orthoses did not affect the plantarflexion motions, which had been suggested by previous studies to be important in shock wave attenuation. CONCLUSIONS: The custom-moulded ankle orthosis with hinges could better control inversion and thus expected to better prevent ankle sprain in lateral cutting movements. CLINICAL RELEVANCE: Custom-moulded ankle orthoses are not commonly used in preventing ankle sprains. This study raises the awareness of the use of custom-moulded ankle orthoses which are expected to better prevent ankle sprains.

Effectiveness of adjustable dorsiflexion night splint in combination with accommodative foot orthosis on plantar fasciitis.

Foot orthoses and night splints have been used separately to treat patients with plantar fasciitis, but were not always successful. Combined use of both orthoses might give better outcomes. This study evaluated the effectiveness of a soft and self-adjustable dorsiflexion night splint in combination with an accommodative foot orthosis for patients with plantar fasciitis. Twenty-eight patients were assigned to group A (foot orthosis only) and group B (combination of foot orthosis and dorsiflexion night splints). A foot function index (FFI) questionnaire was used to evaluate the pain and functions of feet just before, 2 weeks after, and 8 weeks after the treatments. Results showed that subjects in group B had significantly reduced pain scores at week 2 (p < 0.001) and week 8 (p < 0.001). In group A, no statistical differences were noted in the pain (p = 0.15), disability (p = 0.56), activity limitation (p = 0.75), and total FFI (p = 0.35) scores for the three time periods. The application of foot orthoses with adjustable dorsiflexion night splints was found to be more effective than the application of foot orthoses alone in relieving foot pain in patients with plantar fasciitis.

Dynamic impression insole in rheumatoid foot with metatarsal pain.

BACKGROUND: Custom molded insoles with metatarsal supports are used to redistribute excessive loading under the metatarsal heads in patients with metatarsalgia. However, these pressure reductions are usually insufficient for the rheumatoid foot with painful deformed metatarsal heads. We developed an effective insole made by sequential foam padding under successive walking impression. METHODS: Seventeen consecutive rheumatoid arthritic outpatients with metatarsal pain participated in this repeated measures study of 7-mm flat Ethylene Vinyl Acetate, custom molded and dynamic impression insoles. Peak plantar pressure, pressure-time integral, contact area and mean force were measured by a Pedar-X mobile system. Pain levels were assessed using a Visual Analog Scale (0-10). FINDINGS: Compared to the Ethylene Vinyl Acetate control, the metatarsal head peak pressure and pressure-time integral were significantly reduced in dynamic impression insoles by 46.3% (P<0.001) and 48.9% (P<0.001), respectively. Compared to the custom molded insole, the dynamic impression insole significantly reduced 18.3% of peak pressure (P<0.001) and 20.1% of pressure-time integral (P<0.001) by increasing 8.1% of contact area (P=0.005) at the metatarsal heads, but there were no significant differences in all variables at the heel. After using the dynamic impression insole, the mean pain score was significantly reduced from 7.6 to 1.1 (P<0.001), and six participants experienced total pain-relief in walking. INTERPRETATION: Dynamic impression insoles effectively relieve metatarsal pain because of a larger weight-bearing area. Forefoot shape during walking should be taken into consideration in orthotic designs for maximum pressure reduction. Consequently, we recommend using materials with memory properties to dynamically accommodate painful metatarsal heads.

Long-distance walking effects on trans-tibial amputees compensatory gait patterns and implications on prosthetic designs and training.

Trans-tibial amputees are advised to walk as much as able people to achieve healthy and independent life. However, they usually have difficulties in doing so. Previous researches only included data from a few steps when studying the gait of amputees. Walking over a long distance was rarely examined. The objective of this study was to investigate the changes in spatial-temporal, kinetic and kinematic gait parameters of trans-tibial amputees after long-distance walking. Six male unilateral trans-tibial amputees performed two sessions of 30-min walking on a level treadmill at their self-selected comfortable speed. Gait analysis was undertaken over-ground: (1) before walking, (2) after the 1st walking session and (3) after the 2nd walking session. After the long-distance walking, changes in spatial-temporal gait parameters were small and insignificant. However, the sound side ankle rocker progression and push-off were significantly reduced. This was due to the fatigue of the sound side plantar flexors and was compensated by the greater effort in the prosthetic side. The prosthetic side knee joint showed significantly increased flexion and moment during loading response to facilitate the anterior rotation of the prosthetic shank. The prosthetic side hip extensors also provided more power at terminal stance to facilitate propulsion. Endurance training of the sound side plantar flexors, and improvements in the prosthetic design to assist anterior rotation of the prosthetic shank should improve long-distance walking in trans-tibial amputees.

FE stress analysis of the interface between the bone and an osseointegrated implant for amputees--implications to refine the rehabilitation program.

BACKGROUND: The direct anchorage of lower-limb prosthesis to the bone has been shown to be an excellent alternative for amputees experiencing complications in using a conventional prosthetic socket. During rehabilitation phase, amputees are asked to apply static loading on the abutment perpendicular to a weigh scale to prepare the bone to tolerate the forces likely to be developed during walking. The weigh scale measures only the vertical force. A different loading protocol can affect the bone-implant interface stresses and the outcome of the rehabilitation. METHODS: This study developed a Finite Element model to study the stresses in the bone adjacent to the implant. Three loading conditions were applied based on the experimentally measured load: (1) vertical force applied along the long axis of the limb, corresponding to the load clinically prescribed in the weight bearing exercise; (2) loads applied on the three axes, corresponding to the "true" load measured simultaneously by a tri-axial load transducer during the same exercise; and (3) loads experienced during independent walking. FINDINGS: The model revealed that the weigh scale might in fact be applying much higher and less uniform stresses on the bone than expected. During walking, high stress occurred at various locations of the implanted region, which was different from the patterns of stress distribution during weight bearing exercises. INTERPRETATIONS: The difference in stress among three loading conditions implies that tri-axial load should be monitored during the weight bearing exercises and carefully prescribed.

Magnitude and variability of loading on the osseointegrated implant of transfemoral amputees during walking.

This study directly measured the load acting on the abutment of the osseointegrated implant system of transfemoral amputees during level walking, and studied the variability of the load within and among amputees. Twelve active transfemoral amputees (age: 54 +/- 12 years, mass: 84.3 +/- 16.3 kg, height: 17.8 +/- 0.10 m) fitted with an osseointegrated implant for over 1 year participated in the study. The load applied on the abutment was measured during unimpeded, level walking in a straight line using a commercial six-channel transducer mounted between the abutment and the prosthetic knee. The pattern and the magnitude of the three-dimensional forces and moments were revealed. Results showed a low step-to-step variability of each subject, but a high subject-to-subject variability in local extrema of body-weight normalized forces and moments and impulse data. The high subject-to-subject variability suggests that the mechanical design of the implant system should be customized for each individual, or that a fit-all design should take into consideration the highest values of load within a broad range of amputees. It also suggests specific loading regime in rehabilitation training are necessary for a given subject. Thus the loading magnitude and variability demonstrated should be useful in designing an osseointegrated implant system better able to resist mechanical failure and in refining the rehabilitation protocol.

Regulation of HAS expression in human synovial lining cells of TMJ by IL-1beta.

Hyaluronan (HA), a major glycosaminoglycan of synovial fluid, is synthesised by a class of membrane-bound HA synthase (HAS) proteins. In the present study, we investigated the regulatory roles of IL-1beta on HAS gene expression and HA production by the fibroblastic synovial lining cells. The synovial lining cells from synovial membrane in human temporomandibular joint (TMJ) were cultured and characterised using immunocytochemistry with CD14, CD44, and vimentin monoclonal antibodies. With or without treatment with IL-1beta, the production of HA was detected with radiometric assay and the expression of HAS mRNAs were analysed with a semi-quantitative reverse transcribed polymerase chain reaction (RT-PCR). HA synthesis was significantly augmented with 1ng/ml of IL-1beta for both 24 and 48h stimulation, however the production of HA declined if stimulated with 10ng/ml of IL-1beta. The expression of HAS2 and 3 mRNA were enhanced about 4.2- and 7.2-fold after 4h stimulation with 1ng/ml of IL-1beta, respectively. From these results, it is concluded that IL-1beta functions on regulating HAS expression and consequently promoting the secretion of HA in synovial lining cells from TMJ.

Kinetics of transfemoral amputees with osseointegrated fixation performing common activities of daily living.

BACKGROUND: Direct anchorage of a lower-limb prosthesis to the bone through an implanted fixation (osseointegration) has been suggested as an excellent alternative for amputees experiencing complications from use of a conventional socket-type prosthesis. However, an attempt needs to be made to optimize the mechanical design of the fixation and refine the rehabilitation program. Understanding the load applied on the fixation is a crucial step towards this goal. METHODS: The load applied on the osseointegrated fixation of nine transfemoral amputees was measured using a load transducer, when the amputees performed activities which included straight-line level walking, ascending and descending stairs and a ramp as well as walking around a circle. Force and moment patterns along each gait cycle, magnitudes and time of occurrence of the local extrema of the load, as well as impulses were analysed. FINDINGS: Managing a ramp and stairs, and walking around a circle did not produce a significant increase (P>0.05) in load compared to straight-line level walking. The patterns of the moment about the medio-lateral axis were different among the six activities which may reflect the different strategies used in controlling the prosthetic knee joint. INTERPRETATIONS: This study increases the understanding of biomechanics of bone-anchored osseointegrated prostheses. The loading data provided will be useful in designing the osseointegrated fixation to increase the fatigue life and to refine the rehabilitation protocol.

Using computational simulation to aid in the prediction of socket fit: a preliminary study.

This study illustrates the use of computational analysis to predict prosthetic socket fit. A simple indentation test is performed by applying force to the residual limb of a trans-tibial amputee through an indenter until the subject perceives the onset of pain. Computational finite element (FE) analysis is then applied to evaluate the magnitude of pressure underlying the indenter that initiates pain (pain threshold pressure), and the pressure at the prosthetic socket-residual limb interface. The assessment of socket fit is examined by studying whether or not the socket-limb interface pressure exceeds the pain threshold pressure of the limb. Based on the computer-aided assessment, a new prosthetic socket is then fabricated and fitted to the amputee subject. Successful socket fit is achieved at the end of this process. The approach of using computational analysis to aid in assessing socket fit allows a more efficient evaluation and re-design of the socket even before the actual fabrication and fitting of the prosthetic socket. However, more thorough investigations are required before this approach can be widely used. A subsequent part of this paper discusses the limitations and suggests future research directions in this area.

Fatigue test of low-cost flexible-shank monolimb trans-tibial prosthesis.

Monolimb refers to a kind of trans-tibial prostheses with the socket and shank moulded into one piece of thermoplastic material. If properly designed, the shank of a monolimb can deflect which may compensate for the lost ankle plantarflexion and dorsiflexion to some extent. However, provision of shank flexibility is usually accompanied by reduced structural strength of the entire prosthesis. In the recent work using finite element analysis and the Taguchi method, the dimensions of the shank for the monolimb were derived which aimed at giving high shank flexibility and reasonable strength to resist static load. Yet, fatigue testing has not been performed. Fatigue failure may happen when a relatively low level of load is applied repeatedly. This study aimed to document the fatigue life of two flexible-shank monolimbs, by applying cyclic force of 800 N at the forefoot region for 500,000 cycles. Results showed that the design of the foot bolt adaptor played an important role in the structural integrity of the monolimb. One monolimb completed the fatigue test of 500,000 cycles without visual material yield, but with 3.8 degrees change in dorsiflexion angle when the load was removed.

A robust design procedure for improvement of quality of lower-limb prosthesis.

Lower-limb prostheses are used to restore amputee's walking. Monolimb is one of the designs referring to socket and the shank being molded into one piece of thermoplastic material. Appropriate shank flexibility of a monolimb can improve gait of an amputee. However, during the fabrication, the variations of design variables are inevitably produced which may lead the unexpected shank deflection and directly influence on gait efficiency of an amputee. This paper presents a robust design procedure for improvement of quality of the monolimb by simultaneously minimizing performance variations caused by variations in design variables and bringing the mean value of performance on target. The robust design procedure embodies the integration of response surface methodology with genetic algorithms. Response surface models are developed for the responses of monolimb as functions of design variables over the region of interest and genetic algorithms are employed to find the robust solution. A robust design of monolimb is performed for an amputee subject and the results show that the robust design can design a "robust" monolimb which provides specified performance targets that are minimally sensitive to the variations of design variables. This indicates that robust design may have the potential application in improving the quality of the prescribed prosthesis.

Gait analysis of low-cost flexible-shank transtibial prostheses.

The latest lower-limb prosthetic designs have been incorporated with dynamic elastic response (DER) components to enhance prosthesis flexibility, which are suggested to be beneficial to gait. Although DER prosthetic. feet are preferred by most transtibial amputees and their benefits to gait are supported by some biomechanical studies, many are still utilizing the simple conventional solid ankle cushioned heel (SACH) designs because of the lower cost. The monolimb, a transtibial prosthesis with the socket and the shank molded from a single piece of thermoplastic material, perhaps is an alternative to DER feet for providing flexibility at the shank. In addition to shank flexibility, low cost and light weight are other characteristics of monolimbs. In spite of the potential benefits, little analysis has been done to examine the simple-structured monolimb prosthesis. The main aim of this study is to evaluate the gait and perception of unilateral transtibial amputees using a flexible elliptical-shank monolimb as compared to a thicker circular-shank monolimb and a conventional rigid-shank prosthesis. Results suggested that a properly designed monolimb may potentially offer similar functional advantages to the relatively expensive DER feet.