Purpose:The aim of the study was to investigate the feasibility of developing a standardized brim set with a scalable design to streamline transfemoral prosthetic socket production.Design:A two-phase mixed-methods study comprising: (1) a design based on quantitative analysis and (2) an observational, cross-sectional approach.Methods:In phase 1, existing brims were analyzed to develop a standardized brim set. Participants using hybrid transfemoral prosthetic sockets were selected, and the dimensions of the 3D-scanned brims were measured, including circumference, ischial-trochanteric distance, ischial support area, and trimline heights. Statistical analyses were performed to explore potential correlations to inform the scalable brim design. In phase 2, appropriate brims were fitted to participants with transfemoral residual limbs, and each brim section was evaluated using a custom-designed questionnaire.Results:Phase 1 resulted in a standardized brim set based on 13 brims, revealing a statistically significant exploratory correlation between brim circumference and ischial-trochanteric distance. In phase 2, involving eight participants, most brim sections achieved satisfactory fitting scores. However, some participants reported discomfort in the groin area and issues with ischial support placement.Conclusions:While limited by a small sample size, this study demonstrates the feasibility of developing a scalable brim design for transfemoral sockets. The exploratory findings suggest potential for broader applicability, but further validation with a larger dataset and additional fittings is needed. This approach may improve the consistency, efficiency, and quality of transfemoral prosthetic socket fittings.Clinical Relevance:This study contributes to more consistent and anatomically accurate transfemoral prosthetic socket design by introducing a standardized, data-driven hybrid brim set, with the potential to improve clinical efficiency and user outcomes.

Objective A medial open-wedge high tibial osteotomy (MOWHTO) may increase the posterior tibial slope (PTS). The purpose of this study was to determine the effect of the osteotomy inclination angle (in the sagittal plane) in combination with different hinge positions (in the transverse plane) on the change in PTS due to a MOWHTO. Methods We developed a mathematical approach to determine the effect of the osteotomy inclination angle combined with different hinge positions. The change in PTS was determined for different osteotomy inclination angles, hinge positions, and intended wedge angles. Anterior-inclined, parallel, and posterior-inclined osteotomy inclination angles were simulated. Hinge positions varied between 5° anterolateral and −45° posterolateral. The wedge angles were 5°, 10°, and 15°. Moreover, 2 in silico osteotomies were performed to verify the results of the mathematical model. Results The PTS was maintained when the osteotomy cut was performed parallel to the tibial plateau with a lateral hinge position. The PTS changed when the osteotomy was not aligned in the sagittal plane, ranging between 0.0° and 0.6°. Different hinge positions, however, had a large effect on postoperative PTS change, ranging between 0.1° and 10.7°. Conclusions Our mathematical approach showed that the hinge position has a strong effect on the PTS. The sagittal osteotomy inclination angle had little effect on the PTS. An inclination angle parallel to the medial tibial plateau combined with a lateral hinge position does not change the PTS.

Micro-controlled lower limb prosthetic devices typically employ onboard sensors on the amputated side of the user's body to generate control patterns. However, balanced ambulation in a healthy subject requires synchronized neural control to facilitate appropriate positioning and orientation of both limbs. Building upon this idea, this study introduces a control architecture that utilizes information acquired from both limbs using only two inertial measurement units (one placed on the left shank, and one placed on the right thigh) to generate the control commands for a transtibial prosthesis prototype clamped to a table-top. Multiple trials were performed with a healthy subject walking on level ground at different speeds and undertaking an obstacle avoidance task. The results of the experiments suggest that incorporating data from each side provides comprehensive information about the limb's positions and orientations, thereby enabling a controller that can handle actuation timing and assist in precise prosthesis control through an understanding of the user's gait states.

In this study, a combined subject-specific numerical and experimental investigation was conducted to explore the plantar pressure of an individual. The research utilized finite element (FE) and musculoskeletal modelling based on computed tomography (CT) images of an ankle-foot complex and three-dimensional gait measurements. Muscle forces were estimated using an individualized multi-body musculoskeletal model in five gait phases. The results of the FE model and gait measurements for the same subject revealed the highest stress concentration of 0.48 MPa in the forefoot, which aligns with previously-reported clinical observations. Additionally, the study found that the encapsulated soft tissue FE model with hyper-elastic properties exhibited higher stresses compared to the model with linear-elastic properties, with maximum ratios of 1.16 and 1.88 MPa in the contact pressure and von-Mises stress, respectively. Furthermore, the numerical simulation demonstrated that the use of an individualized insole caused a reduction of 8.3% in the maximum contact plantar pressure and 14.7% in the maximum von-Mises stress in the encapsulated soft tissue. Overall, the developed model in this investigation holds potential for facilitating further studies on foot pathologies and the improvement of rehabilitation techniques in clinical settings.

Control strategies for lower limb prostheses have made multiple significant advancements over the years. In this work, we investigate the scope and capabilities of a controller for ankle-foot prostheses that relies only on a one-degree-of-freedom inertial sensor, supplemented with a control algorithm that can perform a real time update of actuation parameters using gait information available from past gait cycles. The updated actuation parameters are applied to the subsequent gait cycle and the cycle repeats itself. The idea behind this controller is to allow a user to have infinite possible variations in gait speeds (within the allowable limits of actuation) while keeping the required sensory inputs to a minimum. As a consequence of this controller design, the user is not forced to choose discrete speeds of walking (slow, medium, fast) and is capable of freely varying his gait speeds on each step, while utilizing only a single-degree-of-freedom sensor. We implement the controller on an actuated transtibial prosthesis prototype based on a series-elastic spring configuration, and conduct tests for level ground walking at a self-selected walking speed, to explore the achievable range of response pertaining to daily living tasks. The pilot tests on a healthy participant, conducting level ground walking with turns and remotely controlling the prosthesis, suggest that it is possible to control a transtibial prosthesis using a simple uni-sensor framework, with a maximum angular deviation of 5°, and maximum deviation in angular velocity of $20^{\circ} /s$ compared to that of healthy humans.

BACKGROUND:Shoulder orthoses reduce the gravitational pull on the shoulder by providing an upward force to the arm, which can decrease shoulder pain caused by stress on the glenohumeral structures. OBJECTIVE:In this interventional study, the clinical effects of a recently developed dynamic shoulder orthosis were assessed in 10 patients with chronic shoulder pain. The shoulder orthosis provides an upward force to the arm with 2 elastic bands. These bands are arranged to statically balance the arm, such that the supportive force is always directed toward the glenohumeral joint and shoulder movements are not impeded. STUDY DESIGN:Clinical effect study. METHODS:The study population was provided with a dynamic shoulder orthosis for 2 weeks. In the week before the orthosis fitting, the participants had no intervention. The primary outcome measures were the mean shoulder pain scores before and during the intervention, and the distance between the humeral head and the acromion without and with orthosis. RESULTS:Ultrasound evaluation showed that the shoulder orthosis resulted in a reduction of the distance between the acromion and humeral head at different levels of arm support. In addition, it was demonstrated that the mean shoulder pain scores (range 0-10) decreased from 3.6 to 3 (in rest) and from 5.3 to 4.2 (during activities) after 2 weeks of orthosis use. In general, patients were satisfied with the weight, safety, ease in adjusting, and effectiveness of the orthosis. CONCLUSIONS:The results of this study show that the orthosis has the potential to reduce shoulder complaints in patients with chronic shoulder pain.

Introduction: Sacroiliac joint fusion (SIJF) is a minimally invasive treatment for sacroiliac (SI) dysfunction. It involves placing implants through the SI joint under fluoroscopic guidance, requiring precise implant positioning to avoid nerve injury. Preoperative virtual surgical planning (VSP) aids in optimal positioning, but replicating it accurately in the operating room is challenging. Research question: This study aims to assess the feasibility of superimposing VSP onto intraoperative fluoroscopic images to aid in optimal implant placement. Material and methods: A method for intraoperative guidance using 3D/2D registration was developed and tested during SIJF as an available and potentially efficient alternative for costly and more invasive navigation systems. Preoperatively, a VSP is performed and simulated fluoroscopic images are generated from a preoperative CT scan. During surgery, the simulated image that visually best matches the intraoperative fluoroscopic image is selected. Subsequently, the VSP is superimposed onto the intraoperative fluoroscopic image using a developed script-based workflow. The surgeon then places the implants accordingly. Postoperative implant placement accuracy was evaluated. Results: Five interventions were performed on five patients, resulting in a total of 15 placed implants. Minor complications without clinical consequences occurred in one case, primarily attributable to the patient's anatomy and pathological manifestations. Mean deviations at implant apex and 3D angle were 4.7 +/- 1.6 mm and 3.5 +/- 1.3 degrees, respectively. Discussion and conclusions: The developed intraoperative workflow was feasible and resulted in implants placed with low deviations from the VSP. Further research is needed to automate and validate this method in a larger cohort.

Introduction Fracture reduction, implant selection and tuberosity reattachment propose significant challenges in reverse shoulder arthroplasty (RSA) for proximal humerus fractures (PHFs). It is hypothesised that preoperative virtual surgical planning (VSP) can improve implant positioning and tuberosity reattachment, resulting in better functional outcomes, reduced surgery time, and decreased complication risk. Therefore, this study aims to develop, implement, and evaluate a VSP protocol for RSA in complex PHFs. Methods The VSP protocol is developed using 3D medical image processing software based on CT scans from four previously treated patients with RSA for complex PHF. Next, the VSP was applied prospectively in a patient with a PHF planned for RSA. Evaluation was done using an expert opinion questionnaire evaluating surgical confidence, a comparison between implant positioning on postoperative radiographs and the VSP, functional outcomes and the Oxford Shoulder Score (OSS). Results The study showed that VSP is a useful preoperative tool to optimize clinical outcome by digital fracture reduction, determination of surgical cuts, calculating implant size and height, and optimising tuberosity shape and reattachment. After two and six months, the patient showed good functional outcomes (OSS: 48/48 points), healing of tuberosities, and had minimal pain complaints. Conclusion VSP for RSA in PHF might create a more thorough preoperative understanding of the fracture pattern and implant and fracture fragment placement. Further investigative study would be required to demonstrate this.

There is a growing number of personal healthcare devices that are in prolonged contact with the skin. The functionality of these products is linked to the interface formed by the contact between the medical apparatus and the skin. The interface can be characterised by its topology, compliance, and moisture and thermal regulating capabilities. Many devices are, however, described to have suboptimal and occlusive contacts, resulting in physiological unfavourable microclimates at the interface. The resulting poor management of moisture and temperature can impact the functionality and utility of the device and, in severe cases, lead to physical harm to the user. Being able to control the microclimate is therefore expected to limit medical-device related injuries and prevent associated skin complications. Surface engineering can modify and potentially enhance the regulation of the microclimate factors surrounding the interface between a product's surface and the skin. This review provides an overview of potential engineering solutions considering the needs for, and influences on, regulation of temperature and moisture by considering the skin-medical device interface as a system. These findings serve as a platform for the anticipated progress in the role of surface engineering for skin-device microclimate regulation.

Objective: Hypertrophic obstructive cardiomyopathy (HOCM) develops in at least 1 out of 715 young adults. Patients who are refractory to medical therapy qualify for septal myectomy. Due to anatomy, serious complications such as ventricular septal defect and heart block may occur. Establishing cardiovascular magnetic resonance (CMR)–based 3-dimensional (3D) models as part of preoperative planning and training has the potential to decrease procedure-related complications and improve results. Methods: CMR images were used to segment cardiac structures. Left ventricular wall thickness was calculated and projected on top of the in silico model. A 3D model was printed with a red layer indicating a wall thickness exceeding 15 mm and used for preoperative resection planning and patient counseling. To provide preoperative patient-specific in situ simulation, the planned resection volume was replaced with silicone in a second model. For perioperative quality control, resected silicone was compared with resected myocardial tissue. The impact of the models was evaluated descriptively through consultation of both the cardiothoracic surgeon and patients and through patient outcomes. Results: Three-dimensional in silico and 3D-printed heart models of 5 patients were established preoperatively. Since the introduction of the models in October 2020, the surgeon feels better prepared, more confident, and less difficulty with making decisions. In addition, patients feel better informed preoperatively. Conclusions: Using 3D heart models optimized preoperative planning and training, intraoperative quality control, and patient consultation. Reduction of procedure-related complications and clinical outcome should be studied in larger cohorts.

In this paper we presented the mechanical design and evaluation of a low-profile and lightweight exoskeleton that supports the finger extension of stroke patients during daily activities without applying axial forces to the finger. The exoskeleton consists of a flexible structure that is secured to the index finger of the user while the thumb is fixed in an opposed position. Pulling on a cable will extend the flexed index finger joint such that objects can be grasped. The device can achieve a grasp size of at least 7 cm. Technical tests confirmed that the exoskeleton was able to counteract the passive flexion moments corresponding to the index finger of a severely affected stroke patient (with an MCP joint stiffness of k = 0.63Nm/rad), requiring a maximum cable activation force of 58.8N. A feasibility study with stroke patients (n=4) revealed that the body-powered operation of the exoskeleton with the contralateral hand caused a mean increase of 46° in the range of motion of the index finger MCP joint. The patients (n=2) who performed the Box & Block Test were able to grasp and transfer maximally 6 blocks in 60 sec. with exoskeleton, compared to 0 blocks without exoskeleton. Our results showed that the developed exoskeleton has the potential to partially restore hand function of stroke patients with impaired finger extension capabilities. An actuation strategy that does not involve the contralateral hand should be implemented during further development to make the exoskeleton suitable for bimanual daily activities.

BACKGROUND CONTEXT: Adolescent idiopathic scoliosis (AIS) is a major skeletal deformity that is characterized by a combination of apical rotation, lateral bending and apical lordosis. To provide full 3D correction, all these deformations should be addressed. We developed the Double Spring Reduction (DSR) system, a (growth-friendly) concept that continuously corrects the deformity through two different elements: A posterior convex Torsional Spring Implant (TSI) that provides a derotational torque at the apex, and a concave Spring Distraction System (SDS), which provides posterior, concave distraction to restore thoracic kyphosis.PURPOSE: To determine whether the DSR components are able to correct an induced idiopathic -like scoliosis and to compare correction realized by the TSI alone to correction enforced by the complete DSR implant.STUDY DESIGN/SETTING: Preclinical randomized animal cohort study.PATIENT SAMPLE: Twelve growing Goeurottingen minipigs.OUTCOME MEASURES: Coronal Cobb angle, T10-L3 lordosis/kyphosis, apical axial rotation, relative anterior lengthening.METHODS: All mini-pigs received the TSI with a contralateral tether to induce an idiopathic-like scoliosis with apical rotation (mean Cobb: 20.4 degrees; mean axial apical rotation: 13.1 degrees, mean lordosis: 4.9 degrees). After induction, the animals were divided into two groups: One group (N=6) was corrected by TSI only (TSI only-group), another group (N=6) was corrected by a combination of TSI and SDS (DSR-group). 3D spinal morphology on CT was compared between groups over time. After 2 months of correction, animals were euthanized.RESULTS: Both intervention groups showed excellent apical derotation (TSI only-group: 15.0 degrees to 5.4 degrees; DSR-group: 11.2 degrees to 3.5 degrees). The TSI only-group showed coronal Cobb improvement from 22.5 degrees to 6.0 degrees, while the DSR-group overcorrected the 18.3 degrees Cobb to-9.2 degrees. Lordosis was converted to kyphosis in both groups (TSI only-group:-4.6 degrees to 4.3 degrees; DSR-group:-5.2 degrees to 25.0 degrees) which was significantly larger in the DSR-group (p<.001).CONCLUSIONS: The TSI alone realized strong apical derotation and moderate correction in the coronal and sagittal plane. The addition of distraction on the posterior concavity resulted in more coronal correction and reversal of induced lordosis into physiological kyphosis.CLINICAL SIGNIFICANCE: This study shows that dynamic spring forces could be a viable method to guide the spine towards healthy alignment, without fusing it or inhibiting its growth.(c) 2022 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Long-term fixation of orthopaedic implants can be enhanced by tissue ingrowth techniques. As such, the deposition of a bioactive bone-like coating could be considered a promising method to facilitate the integration of implants onto bone tissue. In this study, we identified the optimized osteo-conductive Calcium Phosphate (CaP) coating parameters for deposition on PolyCarbonate-Urethane (PCU) foils. The oxygen plasma surfaceactivated PCU specimens were suspended in simulated body fluid (SBF) and supersaturated SBFs for 4 h, 8 h, 24 h, or 6 days at a temperature of 20 degrees C, 37 degrees C, or 50 degrees C. This resulted in semi-crystalline CaP coatings on a thin flexible foil via a one-step low-temperature aqueous technique. The deposited CaP coatings demonstrated high stability and remained intact upon bending deformation. According to the in vitro cell assessments, the conducted CaP coatings did not influence cell viability nor cell proliferation compared to the bare PCU substrate. In addition, the deposited CaP coatings enhanced the cell-mediated calcium deposition. All in all, this paper demonstrates a promising method to apply stable bioactive coatings to flexible PCU foils, which can be a promising strategy for the enhanced integration of PCU implants onto bone.

BACKGROUND:An accurate estimation of the glenohumeral joint center of rotation (CoR) is important during alignment of braces and exoskeletons, as a misalignment will introduce undesired forces on the human body. The aim of this research was to develop a new method to estimate the glenohumeral CoR and register the location to the body using a single camera and two printed markers.METHODS:During shoulder anteflexion, the arm roughly describes an arc in the sagittal plane, with the glenohumeral joint in the center. Two binary square-fiducial ArUco markers were secured to the upper arm and the scapula, their position and orientation were obtained, and a sphere was fitted to the coordinates of the arm marker. The sphere center position was then registered on the skin. The accuracy was assessed with a test bench with a known rotational center. The repeatability was assessed in vivo with five healthy participants.RESULTS:The mean absolute offset between the true CoR of the test bench and the fitted sphere centers across multiple trials was 2.7 mm at a velocity of 30 degrees/s, and 2.5 mm at 60 degrees/s. The root mean squared distance from the estimated sphere centers after each trial to the mean sphere center across all trials per participant was 5.1 mm on average for the novice examiner and 5.2 mm for the expert examiner.CONCLUSIONS:The proposed method is able to accurately and precisely estimate the glenohumeral CoR.

Abstract There is no specific distraction device available for the metacarpophalangeal joint (MCPJ) of the thumb. Joint distraction is required to facilitate the implantation of MCPJ spacers. In addition, expanding the joint space is essential for MCPJ arthroscopy. For these reasons, a novel device has been designed to create some space in the MCPJ. This articulating joint distractor uses a finger trap to apply the distraction force to the thumb and a strap to fixate the hand. There is the possibility to flex the thumb while maintaining the distraction force. In a first cadaveric experiment, we have determined that the force required to create 2 mm of distraction is approximately 30N. A prototype of the articulating joint distractor has been built and was tested during a second cadaveric study. As a result of the second cadaveric experiment, the desired functions of the prototype have been validated. By adjusting and optimizing the design to minimize the risks found partly during the experiment, the final design of the non-invasive MCPJ distractor has been realized.

Dear Editor, We read with interest the article entitled “Biomechanical Stability of the Sacroiliac Joint With Differing Implant Configurations in a Synthetic Model” by Andrew L. Freeman, Joan E. Bechtold, and David W. Polly, published in the International Journal of Spine Surgery in October

Sacroiliac (SI) joint dysfunction can lead to debilitating pain but can be treated with minimally invasive sacroiliac joint fusion (SIJF). This treatment is commonly performed using 2D fluoroscopic guidance. This makes placing the implants without damaging surrounding neural structures challenging. Virtual surgical planning (VSP) using simulated fluoroscopic images may improve intraoperative guidance. This article describes a workflow with VSP in SIJF using simulated fluoroscopic images and evaluates achieved implant placement accuracy. Ten interventions were performed on 10 patients by the same surgeon, resulting in a total of 30 implants; the median age was 39 years, and all patients were female. The overall mean implant placement accuracy was 4.9 ± 1.26 mm and 4.0 ± 1.44°. There were no malpositioning complications. VSP helped the surgeon understand the anatomy and determine the optimal position and length of the implants. The planned positions of the implants could be reproduced in surgery with what appears to be a clinically acceptable level of accuracy.

Objective To propose and validate a new method for estimating upper limb orthosis wear time using miniature temperature loggers attached to locations on the upper body. Design Observational study. Subjects Fifteen healthy participants. Methods Four temperature loggers were attached to the arm and chest with straps. Participants were asked to remove and re-attach the straps at specified time-points. The labelled temperature data obtained were used to train a decision tree classification algorithm to estimate wear time. The final performance (mean error and 95% confidence interval) of the trained classifier and the wear time estimation were assessed with a hold-out data-set. Results The trained algorithm can correctly classify unseen temperature data with a mean classification error between 1.1% and 3.1% for the arm, and between 1.8% and 4.0% for the chest, depending on the sampling time of the temperature logger. This resulted in mean wear time errors between 0.5% and 8.3% for the arm, and 0.13% and 13.0% for the chest. Conclusion The proposed method based on a classifier can accurately estimate upper limb orthosis wear time. This method could enable healthcare professionals to gain insight into the wear time of any upper limb orthosis. LAY ABSTRACT Upper limb orthoses are wearable devices that support the impaired shoulder, arm or hand. As orthoses can be effective only if they are worn, information about wear time will help physicians and therapists to evaluate the effectiveness of their prescribed treatment. Currently, physicians and therapists rely mainly on subjective data from patients, such as diaries or questionnaires, which may be biased and inaccurate. This study developed a new, objective method to estimate wear time, based on temperature readings from miniature sensors that can be attached easily to any upper limb orthosis. The results show that the wear time of upper limb orthoses can be assessed accurately using this method.