Snap-fits and upper limb functional limitations in German automotive workers

The use of snap-fit fasteners in automotive assembly has increased in the last 10 years. Their impact on musculoskeletal function of the upper limbs in assembly workers is not well described.

To investigate the association between snap-fit assembly and upper limb functional limitations (ULFLs) in workers after a large-scale expansion of snap-fit assembly by a German automotive company.

Cross-sectional data on blue-collar production workers' exposure to snap-fit assembly and ULFLs were collected from medical check-ups and company registers. The association between duration of snap-fit assembly and ULFLs, and the dose-response relationship between the two were analysed using logistic regression, adjusted for body mass index, gender and employment duration before snap-fit exposure.

The study group included 10722 workers. Within the company, 8.4, 6.9 and 10.3% were exposed to snap-fit 1-12, 13-24 and ≥25 months, respectively. After adjusting for confounders, snap-fit exposure for 1-12 months [odds ratio (OR) = 1.59, 95% confidence interval (CI) 0.88-2.88] and 13-24 months (OR = 1.48, 95% CI 0.76-2.88) was not statistically significantly associated with ULFLs compared with an unexposed group. However, exposure to ≥25 months of snap-fit assembly was statistically significant associated with ULFLs showing >2-fold risk (OR = 2.44, 95% CI 1.52-3.92). No clear dose-response relationship was found.

Our study suggests a negative long-term impact from snap-fit assembly on workers' upper limb function. Company physicians should be vigilant for signs of upper limb musculoskeletal disorders among workers exposed to snap-fit assembly.