Introduction Jewelry handcrafting activity is strongly associated with biomechanical constraints and high risk of upper limb musculoskeletal disorders (UL-MSDs).

Objective This study aims to assess biomechanical constraints and specific tasks and subtasks at risk of UL-MSDs among jewelry craftsmen.

Methods Open observations were conducted in several jewelry workshops during whole working days. These observations allowed us to identify representative work periods, tasks and subtasks and to set the number of recordings at fourteen according to ‘homogeneous exposure group’ (HEG) sampling recommendations. For each video recording (duration=30 to 40 minutes), 100 images were extracted through regular stops on fixed time intervals. In each image, postures were encoded and analyzed by ERGOROM software. Gestural Variability Score (GSV) was calculated based on variability of posture from one image to the next.

Results Six main tasks composed handcrafting jewelry activity (mold making; fusion and gluing metal; demoulding; sanding; crimping and polishing). These tasks were associated to eleven subtasks (the creation of impression in the mold, the heating of the metal, the welding during assembly of the piece.).Objective analysis revealed that jewelers spent 38%of their working time with the neck in flexion exceeding 40° or extension, and the shoulders in adduction, extension or visible rotation during 60.8% of the time. The elbow articulation was maintained in extreme pronation in 40.4% of the working time and flexion between 60° and 100° during 78.1% this time. The ulnar deviation of the wrist was observed during 40.9% of work time and the pinch grip for over 79.5% of it. In addition, the high variability score was noted especially for elbow joint and shoulder, reflecting a rapid postural change and high repetitiveness.

Conclusion Our results, suggest the necessity of preventive actions among jewelers craftsmen, with mainly the introduction of ergonomic design of hand tools .