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The prevalence of musculoskeletal symptoms (MSS) like neck and back pain is high among open-surgery surgeons. Prolonged working in the same posture and unfavourable postures are biomechanical risk factors for developing MSS. Ergonomic devices such as exoskeletons are possible solutions that can reduce muscle and joint load. To design effective exoskeletons for surgeons, one needs to quantify which neck and trunk postures are seen and how much support during actual surgery is required. Hence, this study aimed to establish the biomechanical profile of neck and trunk postures and neck and lumbar joint loads during open surgery (training). Eight surgical trainees volunteered to participate in this research. Neck and trunk segment orientations were recorded using an inertial measurement unit (IMU) system during open surgery (training). Neck and lumbar joint kinematics, joint moments and compression forces were computed using OpenSim modelling software and a musculoskeletal model. Histograms were used to illustrate the joint angle and load distribution of the neck and lumbar joints over time. During open surgery, the neck flexion angle was 71.6% of the total duration in the range of 10~40 degrees, and lumbar flexion was 68.9% of the duration in the range of 10~30 degrees. The normalized neck and lumbar flexion moments were 53.8% and 35.5% of the time in the range of 0.04~0.06 Nm/kg and 0.4~0.6 Nm/kg, respectively. Furthermore, the neck and lumbar compression forces were 32.9% and 38.2% of the time in the range of 2.0~2.5 N/kg and 15~20 N/kg, respectively. In contrast to exoskeletons used for heavy lifting tasks, exoskeletons designed for surgeons exhibit lower support torque requirements while additional degrees of freedom (DOF) are needed to accommodate combinations of neck and trunk postures.

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Surgeons are at high risk for developing musculoskeletal symptoms (MSS), like neck and back pain. Quantitative analysis of 3D neck and trunk movements during surgery can help to develop preventive devices such as exoskeletons. Inertial Measurement Units (IMU) and markerless motion capture methods are allowed in the operating room (OR) and are a good alternative for bulky optoelectronic systems. We aim to validate IMU and markerless methods against an optoelectronic system during a simulated surgery task. Intraclass correlation coefficient (ICC (2,1)), root mean square error (RMSE), range of motion (ROM) difference and Bland-Altman plots were used for evaluating both methods. The IMU-based motion analysis showed good-to-excellent (ICC 0.80-0.97) agreement with the gold standard within 2.3 to 3.9 degrees RMSE accuracy during simulated surgery tasks. The markerless method shows 5.5 to 8.7 degrees RMSE accuracy (ICC 0.31-0.70). Therefore, the IMU method is recommended over the markerless motion capture.

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Aimed at preventing heat strain, health problems, and absenteeism among workers with physically demanding occupations, a continuous, accurate, non-invasive measuring system may help such workers monitor their body (core) temperature. The aim of this study is to evaluate the accuracy and explore the usability of the wearable non-invasive Cosinuss° °Temp thermometer. Ear canal temperature was monitored in 49 workers in real-life working conditions. After individual correction, the results of the laboratory and field study revealed high correlations compared to ear canal infrared thermometry for hospital use. After performance of the real-life working tasks, this correlation was found to be moderate. It was also observed that the ambient environmental outdoor conditions and personal protective clothing influenced the accuracy and resulted in unrealistic ear canal temperature outliers. It was found that the Cosinuss° °Temp thermometer did not result in significant interference during work. Therefore, it was concluded that, without a correction factor, the Cosinuss° °Temp thermometer is inaccurate. Nevertheless, with a correction factor, the reliability of this wearable ear canal thermometer was confirmed at rest, but not in outdoor working conditions or while wearing a helmet or hearing protection equipment.

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A sensor-based system using inertial magnetic measurement units and surface electromyography is suitable for objectively and automatically monitoring the lumbar load during physically demanding work. The validity and usability of this system in the uncontrolled real-life working environment of physically active workers are still unknown. The objective of this study was to test the discriminant validity of an artificial neural network-based method for load assessment during actual work. Nine physically active workers performed work-related tasks while wearing the sensor system. The main measure representing lumbar load was the net moment around the L5/S1 intervertebral body, estimated using a method that was based on artificial neural network and perceived workload. The mean differences (MDs) were tested using a paired t-test. During heavy tasks, the net moment (MD = 64.3 ± 13.5%, p = 0.028) and the perceived workload (MD = 5.1 ± 2.1, p < 0.001) observed were significantly higher than during the light tasks. The lumbar load had significantly higher variances during the dynamic tasks (MD = 33.5 ± 36.8%, p = 0.026) and the perceived workload was significantly higher (MD = 2.2 ± 1.5, p = 0.002) than during static tasks. It was concluded that the validity of this sensor-based system was supported because the differences in the lumbar load were consistent with the perceived intensity levels and character of the work tasks.

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Femoral-tibial alignment is a prominent risk factor for Knee Osteoarthritis (KOA) incidence and progression. One way of assessing alignment is by determining the Femoral-Tibial Angle (FTA). Several studies have investigated FTA determination; however, methods of assessment of FTA still present challenges. This paper introduces a new method for semi-automatic measurement of FTA as part of KOA research. Our novel approach combines preprocessing of X-ray images and the use of Active Shape Model (ASM) as the femoral and tibial segmentation method, followed by a thinning process. The result of the thinning process is used to predict FTA automatically by measuring the angle between the intersection of the two vectors of branching points on the femoral and tibial areas. The proposed method is trained on 10 x-ray images and tested on 50 different x-ray images of the Osteoarthritis Initiative (OAI) dataset. The outcomes of this approach were compared with manually obtained FTA measurements from the OAI dataset as the ground truth. Based on experiments, the difference in measurement results between the FTA of the OAI and the FTA obtained using our method is quite small, i.e., below 0.81° for the right FTA and below 0.77° for the left FTA with minimal average errors. This result indicates that this method is clinically suitable for semi-automatic measurement of the FTA.

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STUDY DESIGN: Basic research (cross-sectional). INTRODUCTION: Dupuytren disease can cause disabling contractures of the finger joints. After partial fasciectomy, postoperative hand splinting helps to maintain extension range of motion. PURPOSE OF THE STUDY: To measure how the contraction forces of the finger on the splint change over time. METHODS: Subjects who were treated for Dupuytren contracture with partial fasciectomy were invited to participate in this study. Force sensors were placed in their dorsal extension splint, and the applied force was measured continually for several weeks. RESULTS: Eleven subjects (aged 59-75 years) with the metacarpophalangeal (8) or proximal interphalangeal (3) as their most severely affected finger joint participated. Each night, the measured force consistently decreased to reach a plateau after about 3 hour (adaptation time, 2.55; 95% confidence interval, 0.2-31.8 hours). The time to reach this plateau decreased with time after surgery (≈5%/day, P = .0005, R2 = 0.08). DISCUSSION AND CONCLUSIONS: The observed rate of decrease in the measured force indicates a tissue adaptation time of approximately 3 hours.

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The currently accepted interval of weekly cast changes in the treatment of clubfeet seems unsubstantiated. A force sensor is needed to determine the adaptation rate of a clubfoot to establish what cast change interval would be most effective and efficient. We developed a force sensor based on the principle that the resonance frequency of an LC-tank changes when a metal target is brought in close proximity. A thin rubber ring between the LC-tank and the metal target transformed this proximity sensor into a force sensor. With a static load test and an incremental load test, the performance of the constructed force sensors was characterized. The custom-made sensor showed excellent sensitivity ((1.7±0.8×105) counts/N), resolution ((0.15±0.06) mN), and accuracy ((3.5±3.0) %) for the application. The observed drift was (2.1±0.7) %/log10(h), which is lower than other thin force sensors. Preliminary results of measurements in the treatment of Dupuytren fingers and clubfeet show good functioning for long-term force measurements.

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ADJUST, a novel ankle-foot orthosis (AFO) that we have developed, allows the ankle a normal range of motion (ROM) while providing support for flaccid ankle-muscle paresis. It consists of two leaf-spring hinges that independently control plantarflexion and dorsiflexion stiffness. To evaluate whether ADJUST meets the minimum mechanical requirements, we quantified its ankle ROM and stiffness. To evaluate whether it meets the minimum ankle kinematic and kinetic goals for normal gait, a patient with both plantarflexor and dorsiflexor paralysis used it, and his own AFO, to walk. When fitted with stiff springs, ADJUST met all requirements and goals. During the stance and the swing phases, ankle ROM was within the normal range when ADJUST was fitted with stiff springs. Ankle ROM during stance was outside the normal range both with the patient's own AFO and with ADJUST when it was fitted with flexible springs. Power at the ankle met the minimum goal but was lower with ADJUST than with the patient's own AFO. The optimal stiffness configuration that would result in a higher power at the ankle with a normal ankle ROM was not reached for this patient. Walking with ADJUST seems feasible and could be profitable in patients with flaccid ankle muscle paresis.

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BACKGROUND: Improving ankle-foot orthosis design can best be done by implementing a user-centered approach. OBJECTIVE: To provide insight into the ideas of ankle-foot orthosis users with flaccid ankle muscle paresis on the importance of activities and suggestions for an improved ankle-foot orthosis design. STUDY DESIGN: A focus-group discussion with eight ankle-foot orthosis users (57 ± 5 years, 50% female). METHODS: Main inclusion criteria were as follows: ⩾18 years, unable to stand on tip-toe and unable to lift toes. Main exclusion criterion was spasticity of lower extremity muscles. Transcribed data were coded according to the International Classification of Functioning, Disability and Health. Thematic analysis with inductive approach was chosen to order and interpret codes. RESULTS: Ankle-foot orthosis users ranked walking the most important activity followed by sitting down/standing up from a chair. Their opinion was that ankle-foot orthoses facilitate walking and standing. Ankle-foot orthosis users suggested that an improved ankle-foot orthosis design should balance between stability and flexibility. CONCLUSION: Current ankle-foot orthoses facilitate walking which was the most important activity according to ankle-foot orthosis users. An improved ankle-foot orthosis design should enable walking and should optimize between stability and flexibility dependent on the activity and the paresis severity. Clinical relevance Experienced users of ankle-foot orthosis agreed that matching ankle-foot orthosis functions to daily-life activities is a trade-off between stability and flexibility. An improved ankle-foot orthosis design should at least enable level walking.

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BACKGROUND: People with floppy ankle muscles paresis use ankle foot orthoses to improve their walking ability. Ankle foot orthoses also limit ankle range of motion thereby introducing additional problems. Insight in effects of ankle foot orthoses on body functions and activities in people with floppy paretic ankle muscles aids in clinical decision making and may improve adherence. METHODS: Studies published before October 27th, 2014, were searched in Pubmed, Embase, Cinahl, and Cochrane Library. Studies evaluating effects of ankle foot orthoses on body functions and/or activities in people with floppy paretic ankle muscles were included. Studies solely focusing on people with spastic paretic ankle muscles were excluded. Study quality was assessed using a custom-made scale. Body functions and activities were defined according to the International Classification of Functioning, Disability and Health. FINDINGS: Twenty-four studies were included, evaluating 394 participants. Participants were grouped according to paresis type (i) dorsiflexor paresis, (ii) plantar flexor paresis, (iii) both dorsiflexor and plantar flexor paresis. Dorsal, circular, and elastic ankle foot orthoses increased dorsiflexion during swing (by 4-6°, group i). Physical comfort with dorsal ankle foot orthoses was lower than that with circular ankle foot orthoses (groups i and iii). Dorsal ankle foot orthoses increased push-off moment (by 0.2-0.5 Nm/kg), increased walking efficiency, and decreased ankle range of motion (by 12-30°, groups ii and iii). INTERPRETATION: People with dorsiflexor paresis benefit more from circular and elastic ankle foot orthoses while people with plantar flexor paresis (and dorsiflexor paresis) benefit more from dorsal ankle foot orthoses.

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Total hip replacement is an often-performed orthopedic surgical procedure; the amount of procedures undertaken will increase since our life expectancy is growing. In order to optimize function, hip biomechanics should be restored to as near normal as possible. The goal of this pilot study was to determine whether or not it is feasible to compute the vectorial hip reaction force pathways on the head of the prosthesis and the force angles relative to the cup of the prosthesis that occur during gait in total hip replacement patients, serving as an objective measurement of the functional outcome following hip replacement. A three-dimensional gait analysis, measuring ground reaction forces and kinematics, was performed. The data retrieved from the gait analysis was used as the input for the musculoskeletal model to compute vectorial joint reaction forces for data processing. To evaluate the position and orientation of the joint reaction forces, the force path, as well as the force angles for the operated and non-operated joint, has been calculated during the stance phase of the specific leg. The force path for subject 2 on the non-operated side is only located in the posterior-lateral quarter, as is the force path for subject 1. In contrast to this subject, the force path for subject 2 at the operated hip joint can be found only within the anterior quarter of the head of the implant, where it is nearly equally distributed in the medio-lateral half of the prosthesis head. The force-inclination angles on the cup of subject 1, with respect to the plane of the socket face, indicates that the force vector is mainly positioned in the same quadrant when compared with subject 2 (in a cup-fixed coordinate system). The force-anteversion angle behaves similarly to the force-inclination angle, even when the effects are not as pronounced. The proposed methods in this article are aiming to define two functional outcomes of total hip replacement that are related to wear and rim loading. It is accepted that wear is not only a function of time, but a function of use. Owing to the methods listed in this article, we are able to determine a) the applied force and b) the sliding distance (force pathway) in a subject-specific manner. The computed hip-reaction force angles and the distance to the rim cup are a measurement for cup or rim loading, and occurs in the so-called safe-zones. This method may well give us insight into the biomechanical situation during gait, after receiving total hip replacement, that we need to fully understand the mechanisms acting on a hip joint and to prove a possible increase of functional outcome after receiving total hip replacement.

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Unreliable spinal X-ray radiography measurement due to standing postural variability can be minimized by using positional supports. In this study, we introduce a balancing device, named BalancAid, to position the patients in a reproducible position during spinal X-ray radiography. This study aimed to investigate the performance of healthy young subjects' standing posture on the BalancAid compared to standing on the ground mimicking the standard X-rays posture in producing a reproducible posture for the spinal X-ray radiography. A study on the posture reproducibility measurement was performed by taking photographs of 20 healthy young subjects with good balance control standing on the BalancAid and the ground repeatedly within two consecutive days. We analyzed nine posterior-anterior (PA) and three lateral (LA) angles between lines through body marks placed in the positions of T3, T7, T12, L4 of the spine to confirm any translocations and movements between the first and second day measurements. No body marks repositioning was performed to avoid any error. Lin's CCC test on all angles comparing both standing postures demonstrated that seven out of nine angles in PA view, and two out of three angles in LA view gave better reproducibility for standing on the BalancAid compared to standing on the ground. The PA angles concordance is on average better than that of the LA angles.

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Rehabilitation of laryngectomees has been furthered by the introduction of heat and moisture exchange (HME) filters, placed over a tracheostoma or on a tracheostoma valve (TSV). The airflow resistance of HME filters is an important factor with regard to the comfort of the patient. The goal of this study was to determine the airflow resistance (defined as the pressure drop over the device divided by the squared airflow through the device) of 4 commercially available HME filters with and without a TSV. The pressure drop over and the airflow through the devices were measured in vitro. Distinct differences among the devices were found. The mean airflow resistance of the HME filters ranged from 135 to 346 Pa x s2/L2, that of TSVs was between 66 and 297 Pa x s2/L2, and that of the combination was between 263 and 454 Pa x s2/L2. The Stom-Vent 2 HME filter and the Adeva Window TSV with an Adeva filter had the lowest airflow resistance of the devices measured in this study.

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