Using a finite element model of the thumb to study Trapeziometacarpal joint contact during lateral pinch

BACKGROUND

Finite element (FE) analysis is widely used in different fields of orthopaedic surgery, however, its application to the trapeziometacarpal joint has been limited due to the small size, complex biconcave-convex joint geometry, and complex musculature. The goal of this study was to improve upon existing models by creating a muscle-driven FE thumb model and use the model to simulate the biomechanical effect of hand therapy exercises and ligament reconstructive surgeries.

METHODS

Bone and cartilage geometry were based on a CT dataset of a subject performing a static lateral pinch task. A previously validated musculoskeletal model was utilized to extract electromyography (EMG)-driven muscle forces. Five ligaments with biomechanical significance were modeled as springs using literature values and attached according to their anatomical landmarks.

FINDINGS

The biomechanical consequence of various interventions was proxied as a change in the maximum cartilage stress. The result shows tightening the dorsal ligament complex (dorsal radial ligament, dorsal central ligament, posterior oblique ligament) is the most effective, achieving a stress reduction of 4.8%. Five exercises used in hand therapies were modeled, among which thenar eminence strengthening showed the most prominent stress reduction of 4.0%. Four ligament reconstructive surgeries were modeled, with Eaton-Littler reconstruction showed the most significant stress reduction of 25.0%.

INTERPRETATION

Among the routinely utilized treatment options for early thumb osteoarthritis, we found that three methods: dorsal ligament imbrication, thenar eminence exercise, and the Eaton-Littler method may confer biomechanical advantages cartilage loading. These advantages align with the clinically observed favorable outcomes.

[Retrospective study of restraining measures in a population of patients admitted under a regimen of involuntary commitment]

The application of the 06-26-1990 law for the protection of mentally ill persons has confronted the psychiatrists working in general psychiatry wards with the problem of keeping up patients hospitalized against their own will and following a judiciary authority decision. Having to deal with this problem, the authors first reviewed the literature about the use of restraint techniques in psychiatry. They observed that these universally used techniques were strikingly denied in the psychiatric literature so that their accurate application was made difficult because of the lack of information about their indications, contra-indications and application modalities. Afterwards, the authors have compared the different restraint techniques in a retrospective study over a one year period among voluntarily hospitalized patients and patients admitted against their wil in application of the 06-26-1990 law. They reported that the application of the law undoubtedly increased the number of restraint but did not modify either the population characteristics of the treatment modalities. These results have to be further confirmed in a prospective study.

A double-blind comparative study of remoxipride and haloperidol in schizophrenic and schizophreniform disorders

The antipsychotic effect of remoxipride was compared to that of haloperidol in a randomized double-blind study with parallel group design comprising 98 patients with schizophrenia or schizophreniform disorder according to DSM-III. After a 3-7 day placebo washout period, patients received either 150-600 mg of remoxipride or 5-20 mg of haloperidol daily for 6 weeks. No significant differences in efficacy were found between the two treatments. Treatment-emergent checklist symptoms such as hypokinesia, rigidity, and tremor occurred more frequently and were more severe during haloperidol than during remoxipride treatment despite a significantly higher concurrent use of anticholinergic drugs in the haloperidol group. Haloperidol-treated patients reported greater increases in sleep and salivation than remoxipride-treated patients. Shoulder shaking and tremor were reported as occurring more frequently in the haloperidol group according to the Simpson and Angus rating scale for extrapyramidal symptoms. In summary, the two drugs seemed to be equally efficacious, though the tolerability profile favoured remoxipride.