Sound-producing voice prostheses: 150 years of research.

Advanced laryngeal cancer sometimes necessitates the removal of the complete larynx. This procedure involves suturing the trachea to an opening in the neck, the most disturbing consequence of which is the loss of voice. Since 1859, several devices have been developed for voice restoration, based mainly on a vibrating reed element. However, the resulting sound is very monotonous and thus unpleasant. Presently the most successful way of voice restoration is the placement of a one-way shunt valve in the tracheo-esophageal wall, thus preventing aspiration and allowing air to flow from the lungs to the esophagus, where soft tissues start to vibrate for substitute voicing. However, the quality of this voice is often poor. New artificial vocal folds to be placed within the shunt valve have been developed, and a membrane-principle concept appears very promising, owing to the self-cleaning construction and the high voice quality. Future developments will include electronic voice sources. Hopefully these developments will result in a high-quality voice, after 150 years of research.

Effects of individually optimized rocker midsoles and self-adjusting insoles on dynamic stability in persons with diabetes mellitus and neuropathy.

BACKGROUND: Persons with diabetic peripheral neuropathy (DPN) may face challenges such as balance issues due to reduced somatosensory feedback and an increased risk of developing diabetic foot ulcers (DFUs) due to increased plantar pressure. Pressure reducing footwear is thought to further impair balance. We introduced 3D-printed rocker midsoles and self-adjusting insoles that are able to reduce elevated plantar pressure values and aimed to prevent balance deterioration. However, their effect on the balance during walking (dynamic stability) is not analyzed yet. RESEARCH QUESTION: Is dynamic stability of persons with DPN impaired compared to healthy individuals and what is the effect of the 3D-printed rocker midsoles and self-adjusting insoles on the dynamic stability in this population? METHODS: Dynamic stability, specifically the margins of stability (MOS) in the anterior-posterior (AP) and medio-lateral (ML) direction, was measured in ten healthy and nineteen persons with DPN. Independent-samples t-test was applied to analyze the difference in the MOS between groups. One-way repeated measures analyses of variance (ANOVA) was conducted to test the difference between the therapeutic footwear combinations within the DPN group. RESULTS: There is no significant difference between the healthy and DPN group in MOS-AP. MOS-ML is significantly larger in DPN compared to the healthy participants. Using the self-adjusting insole shows a significantly lower (negative) MOS-AP compared to when using a rocker shoe within the DPN group. SIGNIFICANCE: This study provides valuable information on whether DPN and our therapeutic footwear have a negative effect on the dynamic stability. DPN does not have a negative effect on dynamic stability in the AP direction. For the ML direction, DPN seems to cause larger MOS-ML by likely using a compensation strategy (e.g., wider steps) while our experimental footwear does not further impair the MOS-ML.

New concept of orthosis treatment for knee osteoarthritis: Clinical and radiological outcomes.

BACKGROUND: Given the increasing numbers of young patients with knee osteoarthritis there is a need for treatments that can postpone a joint prosthesis (total knee replacement). OBJECTIVE: As an alternative to the effective yet invasive knee joint distraction procedure, a knee orthosis was developed aiming to unload the affected knee and improving synovial fluid flow. The aim of this study was to examine the effectiveness of using a load-reducing orthosis for two months on functioning, pain, and disease progression (e.g. amount of damaged cartilage) in patients with symptomatic osteoarthritis of the knee for at least one year. METHODS: This is an interventional single-center pilot study. Ten patients with symptomatic osteoarthritis of one knee (5 males/5 females; median age 57; age range 42-59) used a custom-made orthosis for 60 days during daily life activities that involved knee loading (e.g. standing, walking, but not during stair climbing). Cycling was not allowed. Clinical outcomes were assessed up to 24 months after intervention at 6 timepoints using patient reported-outcome measures Western Ontario and McMaster Universities Osteoarthritis (WOMAC) range 0-100; Visual Analogue Scale (VAS), range 0-100 for pain. Minimum joint space width (mJSW) was assessed using knee images digital analysis (KIDA) and articular cartilage volume with magnetic resonance imaging (MRI) using custom software at baseline and at 12 and 24 months follow-up. RESULTS: Clinically beneficial effects were found for functioning (WOMAC improvement compared to baseline ranged between 18 points at 3 months follow-up and 31 points at 12 months follow-up, with only the 24-months follow-up (improvement of 27 points) not reaching statistical significance (p< 0.05)) and for pain (VAS improvement compared to baseline at follow-up time points ranged between 41-56 points; all p< 0.05). No improvements in mJSW- or MRI-derived parameters were found. CONCLUSION: This study demonstrates that use of a custom-made knee-unloading orthosis for 60 days can result in improved functional ability and decrease in pain in relatively young patients with knee osteoarthritis. No effect on disease progression could be evidenced.

Effects of individually optimized rocker midsoles and self-adjusting insoles on plantar pressure in persons with diabetes mellitus and loss of protective sensation.

INTRODUCTION: Rocker shoes and insoles reduce peak pressure (PP) in persons with diabetes (DM) and loss of protective sensation (LOPS). However, they are handmade, leading to inconsistent effectiveness. If foot structure changes over time, high PP-locations also change. To address this, individualized algorithm based 3D-printed rockers and self-adjusting pressure-reducing insoles are applied. METHODS: PP across seven foot regions was analyzed in 21 persons with DM and LOPS. Regions with PP < 200 kPa were considered not at risk (RnoR); regions with PP ≥ 200 kPa at risk (RaR). The aim was to offload RaR, while remaining PP < 200 kPa in RnoR. RESULTS: Individualized rockers and self-adjusting insoles combined successfully reduce PP < 200 kPa (on average 24 % - 48 %) in all feet with toes, central and lateral forefoot identified as RaR. Same intervention reduces PP in 68 % of the feet with medial forefoot identified as RaR. With the heel as RaR, no intervention reduces PP successfully in all feet. CONCLUSIONS: Individualized 3D-printed rockers combined with self-adjusting insoles reduce PP (< 200 kPa) in toes, central and lateral forefoot, but not in heels. Alternative insoles with medial arch support, heel cup and compliant midsole materials might enhance success rate across entire foot.

Bone fixation techniques for managing joint disorders and injuries: A review study.

The majority of surgical procedures treating joint disorders require a technique to realize a firm implant-to-tissue and/or a tissue-to-tissue fixation. Fixation methods have direct effects on survival, performance and integration of orthopedic implants This review paper gives an overview of novel fixation techniques that have been evaluated and optimized for orthopaedic joint implants and could be alternatives for traditional implant fixation techniques or inspirations for future design of joint implantation procedures. METHOD: The articles were selected using the Scopus search engine. Key words referring to traditional fixation methods have been excluded to find potential innovative fixation techniques. In order to review the recent anchorage systems, only articles that been published during the period of 2010-2020 have been included. RESULTS: A total of 57 studies were analyzed. The result revealed that three main fixation principles are being employed: using mechanical interlockings, employing adhesives, and performing tissue-bonding strategies. CONCLUSION: The development of fixation techniques demonstrates a transformation from the general anchoring tools like K-wires toward application-specific designs. Several new methods have been designed and evaluated, which highlight encouraging results as described in this review. It seems that mechanical fixations provide the strongest anchorage. Employing (bio)-adhesives as fixation tool could revolutionize the field of orthopedic surgery. However, the adhesives must be improved and optimized to meet the requirements of an anchorage system. Long-term fixation might be formed by tissue ingrowth approaches which showed promising results. In most cases further clinical studies are required to explore their outputs in clinical applications.

Does the patch fit the stoma? A study on peristoma geometry and patch use in laryngectomized patients.

OBJECTIVE: To determine the geometry of (peri)stomas of laryngectomized patients in relation to patch use. This data will enable improvement of tracheostoma interfaces, specifically addressing patients currently unable to use stoma patches. The low use of Heat-and-Moisture-Exchange (HME) filters and (hands-free) speech valves, although very important to the quality of life of laryngectomized patients, is mainly attributed to poor fit of the adhesive patches to the stoma site. Current patch shapes are not based upon an objective (peri)stoma geometry because this geometry is unknown. DESIGN: Observational anthropometric study of the (peri)stoma of laryngectomized patients. SETTING: Ten hospitals or institutes in eight countries. PARTICIPANTS: About 191 laryngectomized patients, at least 1 year post operative. MAIN OUTCOME MEASURES: (Peri)stomas were photographed and measured. Patients completed a questionnaire on patch-use. Concavity of commercially available patches was measured. RESULTS: In countries with a financial reimbursement system 58% of the patients use patches, compares to only 9% in other countries. Patches stay in situ for an average of 33.3 h. Patch and non-patch users differ on five out of ten measured geometrical parameters. Most striking differences are that patch users have much shallower peristomas (13 versus 18 mm), and stomas far more parallel to the anterior neck plane. The deepest commercially available patch is only 7 mm deep. CONCLUSIONS: This study provides detailed (peri)stoma geometry data of a divers population, and for the first time in relation to patch-use. It reveals a serious mismatch between patients and patches. With these data new patches can be developed that could dramatically improve rehabilitation after laryngectomy.

Effects of Longitudinal Bending Stiffness of forefoot rocker profile shoes on ankle kinematics and kinetics.

INTRODUCTION: Rocker profile shoes with a proximally placed apex are currently one of the most prescribed shoe modifications for treatment and prevention of lower leg deficits. Three geometrical rocker design parameters apex position (AP), apex angle (AA) and rocker radius (RR) influence both plantar pressure redistribution and kinetic and kinematic alterations of the lower leg. In addition, longitudinal bending stiffness (LBS) of the outsole influences these parameters as well. This study aims to investigate the effects of the LBS in combination with different forefoot radii of rocker shoes on kinematics and kinetics of the lower limb. METHODS: 10 participants walked in standard shoes and six experimental shoe conditions with high and low LBS and three different forefoot rocker radii with the same (proximal) AP and AA. Lower extremity kinematics and kinetics were collected while walking on an instrumented treadmill at preferred walking speed and analysed with a repeated measures ANOVA and Statistical Parametric Mapping (SPM) (α = .05; post hoc α = .05/6). RESULTS: SPM analyses revealed no significant differences for LBS and interaction LBS*RR for most research variables in terminal stance (ankle angle, ankle moment, ankle power, foot-to-horizontal angle, shank-to-vertical angle, external ankle moment, ground reaction force angle). A significant LBS effect was found for anterior-posterior position of the centre of pressure during pre-swing and peak ankle dorsiflexion angle. No relevant significant differences were found in spatio-temporal parameters and total work at the ankle between low and high LBS. CONCLUSION: This study showed that longitudinal bending stiffness does not affect the biomechanical working mechanism of rocker profile shoes as long as toe plantarflexion is restricted. Providing that the forefoot rocker radius supports at least a normal foot-to-horizontal angle at toe-off, there is no reason to increase sole stiffness to change ankle kinematics and kinetics.

Effect of different forefoot rocker radii on lower-limb joint biomechanics in healthy individuals.

INTRODUCTION: Previous studies showed that rocker shoes with a stiff forefoot rocker profile significantly reduce peak plantar flexion moment at the ankle (PFM) and peak ankle dorsiflexion (DF). Both parameters are related to Achilles tendon and Plantar Fascia unloading. The shape of an outsole with a forefoot rocker is described with multiple rocker design parameters. The aim of this research is, to determine the relation between different forefoot rocker radii on peak DF and peak PFM at a self-selected walking speed. METHODS: 10 participants walked in standard shoes and three experimental pairs of shoes with different forefoot rocker radii. Lower extremity kinematics and kinetics were collected while walking on an instrumented treadmill at preferred walking speed and analysed with Statistical Parametric Mapping (SPM) (α = .05; post-hoc α = .05/6). RESULTS: Peak value analyses showed significant decreases in peak DF, peak PFM, and peak ankle power generation for the rocker conditions. No relevant significant differences were found in spatio-temporal parameters and total work at the ankle joint. SPM showed a significant decrease (% gait cycle) in DF (40-69 %), PFM (7-15 %; 41-68 %; 69-81 %), ankle power (10-15 %; 32-51 %; 55-64 %; 64-67 %; 72-80 %) and foot-to-horizontal angle (FHA) (0-4 %; 40-62 %; 92-100 %) and an increased shank-to-vertical angle (SVA) (44-84 %) for the rocker conditions. CONCLUSION: The results of this study suggest that rocker shoes with a proximally placed apex significantly reduce DF and PFM during the third rocker compared with control shoes. This effect is mainly explained by a change in the FHA. Smaller radii cause the largest reductions in DF and PFM, so therefore, a uniform standardisation of the forefoot rocker radius is essential.

Can breathing gases be analyzed without a mouth mask? Proof-of-concept and concurrent validity of a newly developed design with a mask-less headset.

A portable headset has been developed to analyze breathing gases and establish the energetic workload of physically active workers. This proof-of-concept study aimed to investigate the following: (1) the validity of the headset compared to indirect calorimetry using a mouth mask; (2) the validity of the headset compared to the validity of oxygen consumption (V̇O2) estimated on the basis of heart rate; (3) the influence of wind on validity; and (4) user experiences of the headset. Fifteen subjects performed a submaximal cycling test twice, once with the headset, and once with a mouth mask and heartrate monitor. Concurrent validity of the headset was analyzed using an intraclass correlation coefficient (ICC). Across all phases, a good correlation between the headset and mouth mask was observed for V̇O2, carbon dioxide production (V̇CO2) and exhaled volume (V̇E) (ICC≥0.72). The headset tended to underestimate V̇O2, V̇CO2 and V̇E at low intensities and to overestimate it at higher intensities. The headset was more valid for estimating V̇O2 (ICC = 0.39) than estimates based on heart rate (ICC = 0.11) (n = 7). Wind flow caused an overestimation (md ≥ 18.4 ± 16.9%) and lowered the correlation of V̇O2 between the headset and the mouth mask to a moderate level (ICC = 0.48). The subjects preferred the headset over the mouth mask because it was more comfortable, did not hinder communication and had lower breathing resistance. The headset appears to be useable for monitoring development of the energetic workloads of physically active workers, being more valid than heart rate monitoring and more practical than indirect calorimetry with a mouth mask. Proof-of-concept was confirmed. Another design step and further validation studies are needed before implementation in the workplace.

Monitoring core temperature of firefighters to validate a wearable non-invasive core thermometer in different types of protective clothing: Concurrent in-vivo validation.

This study aims (1) to test the validity of a new non-invasive core thermometer, Cosinuss°, in rest and (2) during firefighting simulation tasks, against invasive temperature pill and inner-ear temperature and (3) to compare the change in core temperature of firefighters when working in two types of protective clothing (traditional turnout gear versus new concept). 11 active firefighters performed twice a selection of tasks during their periodic preventive medical examination and a fire-extinguishing task. Without correction no correlation between the Cosinuss° and thermometer pill (ICC≤0.09, p ≥ 0.154, LoA≥1.37) and a moderate correlation between Cosinuss° and inner-ear infrared (ICC = 0.40, p = 0.044, LoA±1.20) was observed. With individual correction both correlations were excellent (ICC≥0.84, p = 0.000, LoA≤0.30). However, during and after working all correlations were poor and non-significant (ICC≤0.38, p ≥ 0.091, LoA≥1.71). During firefighting tasks, the Cosinuss° is invalid for measuring the core temperature. No differences in heat development in the two types of protective clothing was proven.

Surface properties of Indonesian-made narrow dynamic compression plates.

The enormous need of orthopaedic (surgical) implants such as osteosynthesis plates is difficult to be fulfilled in developing countries commonly rely on imported ones. One of the alternatives is utilization of local resources, but only after they have been proven safe to use, to overcome this problem. Surface properties are some of the determining factors of safety for those implants. We have succeeded in developing prototype of osteosynthesis plate and the results indicate that Indonesian-made plates need improvement with regards to the surface quality of physical characterization.

Rapid decrease of cast-induced forces during the treatment of clubfoot using the Ponseti method.

AIMS: The Ponseti method is an effective evidence-based treatment for clubfoot. It uses gentle manipulation to adjust the position of the foot in serial treatments towards a more physiological position. Casting is used to hold the newly achieved position. At first, the foot resists the new position imposed by the plaster cast, pressing against the cast, but over time the tissues are expected to adapt to the new position and the force decreases. The aim of this study was to test this hypothesis by measuring the forces between a clubfoot and the cast during treatment with the Ponseti method. PATIENTS AND METHODS: Force measurements were made during the treatment of ten idiopathic clubfeet. The mean age of the patients was seven days (2 to 30); there were nine boys and one girl. Force data were collected for several weeks at the location of the first metatarsal and the talar neck to determine the adaptation rate of the clubfoot. RESULTS: In all measurements, the force decreased over time. The median (interquartile range) half-life time was determined to be at 26 minutes (20 to 53) for the first metatarsal and 22 minutes (9 to 56) for the talar neck, suggesting that the tissues of the clubfoot adapt to the new position within several hours. CONCLUSION: This is the first study to provide objective force data that support the hypothesis of adaptation of the idiopathic clubfoot to the new position imposed by the cast. We showed that the expected decrease in corrective force over time does indeed exist and adaptation occurs after a relatively short period of time. The rapid reduction in the forces acting on the foot during treatment with the Ponseti method may allow significant reductions in the interval between treatments compared with the generally accepted period of one week.

Influence of cast change interval in the Ponseti method: A systematic review.

BACKGROUND: Clubfeet are commonly treated using the Ponseti method. This method involves weekly manipulation and casting which gradually corrects the position of the foot. However, the reasons for following a weekly interval are not clear. QUESTION / PURPOSE: The aim is to investigate the influence of the cast change interval on treatment outcomes in the Ponseti method. METHODS: We performed a systematic review of comparative studies in which the cast change interval was varied. Scientific databases were searched for relevant publications, screened for eligibility and assessed for a risk of bias. A 'best evidence' synthesis tool was used to synthesize the results of the included studies and draw conclusions from relevant clinical outcomes. RESULTS: Nine papers matched the inclusion criteria, which provided data of 587 subjects who had a total of 870 clubfeet. There is strong evidence for a positive relation between cast change interval and treatment duration. However, there is no evidence for any relation between the cast change interval and the required number of casts, tenotomy rate, required surgery or failure rate. CONCLUSIONS: Accelerated versions are as effective and safe as the traditional Ponseti method. However, more research is needed to assess the long-term results and to identify an optimal cast change interval.

A numerical study of the flow-induced vibration characteristics of a voice-producing element for laryngectomized patients.

A computational model for exploring the design of a voice-producing voice prosthesis, or voice-producing element (VPE), is presented. The VPE is intended for use by laryngectomized patients who cannot benefit from current speech rehabilitation techniques. Previous experiments have focused on the design of a double-membrane voice generator as a VPE. For optimization studies, a numerical model has been developed. The numerical model introduced incorporates the finite element (FE) method to solve for the flow-induced vibrations of the VPE system, including airflow coupled with a mass-loaded membrane. The FE model includes distinct but coupled fluid and solid domains. The flow solver is governed by the incompressible, laminar, unsteady Navier-Stokes equations. The solid solver allows for large deformation, large strain, and collision. It is first shown that the model satisfactorily represents previously published experimental results in terms of frequency and flow rate, enabling the model for use as a design tool. The model is then used to study the influence of geometric scaling, membrane thickness, membrane stiffness, and slightly convergent or divergent channel geometry on the model response. It is shown that physiological allowable changes in the latter three device parameters alone will not be sufficient to generate the desired reduction in fundamental frequency. However, their effects are quantified and it is shown that membrane stiffness and included angle should be considered in future designs.

Quantifying the Ponseti method.

The Ponseti method is the accepted treatment of idiopathic clubfoot. Although the method of manipulating the baby feet is described in great detail, current study aimed to investigate the magnitude and course of the applied forces in order to optimise the treatment of clubfoot. An instrumented clubfoot model was constructed with force sensors on the location of the first metatarsal (FM) and the talar neck (TN) and treated with the Ponseti method by 17 practitioners. Applied forces on FM and TN were measured during manipulation (4.2N; 12N), during casting (3.2N; 3.5N) and after casting (2.9N; 2.2N). The forces during manipulation were significantly higher than during casting on TN (p<0.001) but not on FM (p=0.129). No 'correct' amount of force could be determined and inter-practitioner variability was measured to be 70%. The resulting pressure of the cast on the clubfoot model as measured directly after casting was significantly higher than local tissue perfusion. The results of this study suggest potential for the optimisation of the application of the Ponseti method.

Can a smart chair improve the sitting behavior of office workers?

Prolonged sitting can cause health problems and musculoskeletal discomfort. There is a need for objective and non-obstructive means of measuring sitting behavior. A 'smart' office chair can monitor sitting behavior and provide tactile feedback, aiming to improve sitting behavior. This study aimed to investigate the effect of the feedback signal on sitting behavior and musculoskeletal discomfort. In a 12-week prospective cohort study (ABCB design) among office workers (n = 45) was measured sitting duration and posture, feedback signals and musculoskeletal discomfort. Between the study phases, small changes were observed in mean sitting duration, posture and discomfort. After turning off the feedback signal, a slight increase in sitting duration was observed (10 min, p = 0.04), a slight decrease in optimally supported posture (2.8%, p < 0.01), and musculoskeletal discomfort (0.8, p < 0.01) was observed. We conclude that the 'smart' chair is able to monitor the sitting behavior, the feedback signal, however, led to small or insignificant changes.

Influence of a downstream narrowing on the flow profile in a tube.

The distance over which the upstream flow conditions in a tube are disturbed by a stenosis downstream, i.e. the outlet length, was investigated for Reynolds numbers in the range 210-2900. Two methods were used, the Navier-Stokes equations were solved with a computer and a physical model was constructed and maximal velocities were measured with an ultrasound Doppler system. The computer model showed that Re number does not influence the outlet length, varying the stenosis area from 25% to 90% has an effect. However, the outlet length remained small, below 70% of the diameter of the tube. The physical model confirmed for a 75% stenosis that the outlet length is small, this method set the limit at not more than 1.2 times the tube diameter.

Development of the isolated dual perfused rat liver model as an improved reperfusion model for transplantation research.

The Isolated Perfused Liver (IPL) model is a widely used and appreciated in vitro method to demonstrate liver viability and metabolism. Reperfusion is performed in a controlled setting, however, via the portal vein only. To study transplant related questions concerning bile and transport of bile, the in vitro Isolated dual Perfused Liver model is revisited. The IdPL is an in vitro reperfusion model, using both portal vein and hepatic artery. Livers from 12 Wistar rats were flushed with University of Wisconsin-organ preservation solution, procured and reperfused in either the conventional IPL-model (n = 6) or the new IdPL-model (n = 6). Liver injury, assessed by the release of aspartate amino transferase and lactate dehydrogenase, showed similar levels during both IPL and I dPL reperfusion, only alanine amino transferase showed an improvement. Cumulative bile production showed an improvement: 176.3 +/- 8.4 in the IdPL compared to 126.1 +/- 12.2 microg/g-liver in the IPL (p < 0.05). Clearance of phenol red (PR) and taurocholic acid (TC) remained similar. At 90 minutes reperfusion the PR clearance showed 0.11 +/- 0.01 and 0.11 +/- 0.02 mg/30min/g-liver and the TC clearance 1.01 +/- 0.10 and 1.01 +/- 0.07 micromol/ml/30min/g-liver in the IPL and IdPL, respectively. Increasing the reperfusion time beyond the normally used 90 minutes resulted in a significant increase in transaminases and LDH and a decrease in bile production, liver morphology remained intact and glycogen content was appropriate. In conclusion, the IdPL-model showed similar or better results than the IPL-model, but the liver could not endure an extended reperfusion time using the IdPL.