Trapeziometacarpal joint loading during key pinch grip: A cadaver study.

To our knowledge, no study has directly measured the loads in the trapeziometacarpal joint during an isometric key pinch. The aim of this study was to measure the load acting on the trapeziometacarpal joint for increasingly greater key pinch forces (0.5 kg-1.5 kg). We performed a cadaver study using 10 fresh-frozen, unembalmed adult forearms and hands (5 right and 5 left). Thumb pinch was simulated by loading the main actuator tendons involved in the key pinch grip (i.e., adductor pollicis, flexor pollicis longus, extensor pollicis longus, extensor pollicis brevis and abductor pollicis longus tendons). Measurements were made inside the joint using a force-sensing resistor sensor (Tekscan® FlexiForce™ force sensor). All specimens were tested twice in a row in the same condition. The median load values recorded in the trapeziometacarpal joint were 1.9 kg (IQR 2.2-1.5), 3 kg (IQR 3.4-2.7) and 4.1 kg (IQR 4.4-3.9) during 0.5 kg, 1 kg, and 1.5 kg key pinch, respectively. For each specimen, similar load values were observed during both loading trials. Our findings indicate that the loads measured directly in the trapeziometacarpal joint during a simple key pinch are materially lower than those estimated in biomechanical models of the thumb (generally greater than 10 kg for 1 kg of applied force) probably due to intersubject variability. This pilot study will serve as a basis for further studies, for example, comparing biomechanical thumb models and experimental measurements under the same set-up conditions.

Assessment of trapezial prosthetic cup migration: A biomechanical study.

We performed a biomechanical study using 60 Sawbones® rigid foam blocks of two simulated densities (osteoporotic, n = 30 and non-osteoporotic, n = 30) and 10 cadaveric trapezium bones from fresh-frozen, unembalmed adult cadaver hands to assess the trapezial prosthetic cup migration with progressively greater compression loads (10-40 kg). Two cups from the Touch® prosthesis were compared: 9-mm conical cup and 9-mm spherical cup. Uniaxial compression tests were carried out using an MTS Criterion® Series 40 Electromechanical Testing System. Cup migration was measured in millimeters (mm) at 10, 20, and 40 kg of compression load. Median cup migration values were similar in the cadaveric trapezium bones and Sawbones® non-osteoporotic blocks, and higher in the Sawbones® osteoporotic blocks. In the cadaveric trapezium bones and the Sawbones® non-osteoporotic blocks, migration values were less than or equal to 0.1 mm for 10 and 20 kg loads; it was 0.2 mm for 40 kg load. In the Sawbones® osteoporotic blocks, migration values were less than or equal to 0.3 mm for 10 and 20 kg loads; it was 0.4-0.5 mm for 40 kg load. There was no significant difference between the two cup shapes in both cadaveric trapezium bones and Sawbones® non-osteoporotic blocks. In Sawbones® osteoporotic blocks, the largest difference between the two cup shapes was 0.1 mm for loads up to 40 kg, which corresponded to our measurement accuracy. Our findings indicate that the trapezial component of total trapeziometacarpal joint arthroplasty undergoes very weak migration for axial compression loads up to 40 kg, presumably below the threshold of clinical relevance. The cup shape did not have an obvious influence; however, low bone mineral density may result in greater cup migration.

Comparison of two radiographic landmarks for centering the trapezial component in total trapeziometacarpal arthroplasty.

We performed a retrospective review of standard anteroposterior and lateral radiographs of the thumb in 80 patients, to compare two radiographic landmarks, in terms of mediolateral bone support, for centering the trapezial component in total joint arthroplasty. On anteroposterior view, we identified the distal articular surface of the trapezium and trapezium width, and defined the two midpoints as radiographic landmarks for positioning a 9-mm trapezial cup. Mean trapezium width was significantly greater than the distal articular surface of the trapezium, and the midpoints did not match. Thus, after positioning simulated 9-mm prosthetic cups centered on each landmark, the residual radial bone distance was significantly greater using the landmark based on trapezium width. The mean value was 33% greater with this landmark, and the minimum value was 2.1 mm, compared to 0.2 mm using the landmark based on the distal articular surface. Our study thus suggested that the midpoint of the trapezium width is the more relevant radiographic landmark for centering the trapezial prosthetic cup in total joint arthroplasty, by preserving better bone stock on the radial side without depleting the ulnar side. On an intraoperative anteroposterior fluoroscopic view, this landmark could be used to check cup positioning.

Alterations of musculoskeletal models for a more accurate estimation of lower limb joint contact forces during normal gait: A systematic review.

Musculoskeletal modelling is a methodology used to investigate joint contact forces during a movement. High accuracy in the estimation of the hip or knee joint contact forces can be obtained with subject-specific models. However, construction of subject-specific models remains time consuming and expensive. The purpose of this systematic review of the literature was to identify what alterations can be made on generic (i.e. literature-based, without any subject-specific measurement other than body size and weight) musculoskeletal models to obtain a better estimation of the joint contact forces. The impact of these alterations on the accuracy of the estimated joint contact forces were appraised. The systematic search yielded to 141 articles and 24 papers were included in the review. Different strategies of alterations were found: skeletal and joint model (e.g. number of degrees of freedom, knee alignment), muscle model (e.g. Hill-type muscle parameters, level of muscular redundancy), and optimisation problem (e.g. objective function, design variables, constraints). All these alterations had an impact on joint contact force accuracy, so demonstrating the potential for improving the model predictions without necessarily involving costly and time consuming medical images. However, due to discrepancies in the reported evidence about this impact and despite a high quality of the reviewed studies, it was not possible to highlight any trend defining which alteration had the largest impact.

[Barriers related to the use of self-catheterization : preliminary survey of perception and implications]. / Freins à l'auto-sondage intermittent en 2016 : enquête préliminaire de perception et implications.

INTRODUCTION: the use of clean intermittent catheterization (CIC) has been widely advocated after spinal cord injury. Nevertheless, implementing this technique remains problematic in practice; reasons for this reluctance range from lack of experience to availability of material. MATERIAL AND METHODS: 1. To identify a list of barriers related to the use of intermittent catheterization ; 2. To identify specific assessment tools in relation with these barriers ; 3. To conduct a survey on four groups of people: patients - nurses in neurology, neurosurgery and intensive care - nurses in rehabilitation, - nurses in home-care. Each group has to select from this list and rank the ten most important barriers ; 4. To compare the barriers those that have been highlighted by each of these groups. RESULTS: overall, the main preoccupation of the patient is mostly related to the material, while a large proportion of care-givers consider that the most prevalent barrier for the implementation of the CIC lies in the patient himself. An analysis was also carried out to highlight trends within groups (i)-(iv) of care-givers. CONCLUSION: the perception of burden is different for patients and care-givers, depending on the service within which they operate. A careful analysis will enable us to adapt the therapeutic education of the patients and to tailor the information transmitted to care-givers. Such continuous process of care will emphasise the concept of 'pelvic perineal health- care pathway'.

INTRODUCTION: la littérature recommande l'utilisation du sondage urinaire intermittent comme mode mictionnel optimal chez les patients blessés médullaires. Néanmoins, l'implémentation de cette technique doit encore faire face à de nombreux freins liés tantôt aux patients, tantôt aux acteurs de soins de santé, tantôt au matériel. MATERIEL ET METHODES: 1. Identifier les barrières pouvant empêcher l'auto-sondage intermittent ; 2. Rechercher des tests d'évaluation spécifique en relation avec ces freins ; 3. Interroger 4 groupes identifiés : patients ­ infirmières de neurologie, neurochirurgie et soins intensifs ­ infirmières de rééducation ­ infirmières à domicile. Chaque participant retient et classe par ordre d'importance les 10 items leur semblant les plus significatifs ; 4. Comparer chaque groupe et envisager les conséquences pratiques au niveau de l'éducation thérapeutique et des programmes de formation. RESULTATS: de manière globale, le patient place les limites principalement au niveau du matériel, alors que les facteurs liés au patient lui-même sont le plus souvent rapportés par les professionnels de santé. Des différences significatives sont également observées entre les groupes de professionnels, selon leur domaine d'activité. CONCLUSION: cette enquête sur les freins principaux à l'implémentation de l'auto-sondage intermittent a permis de mettre en évidence des perceptions différentes entre patients et professionnels. La prise en compte de spécificités de service dans le contenu de la formation à apporter est retenue. Cette adaptation de la formation professionnelle et de l'éducation thérapeutique devra contribuer à la concrétisation d'un parcours de soins pelvi-périnéaux.