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.

[Barriers related to the use of self-catheterization : preliminary survey of perception and 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'.