Prevalence and Factors Associated with Callus Formation on the Ulnar Aspect of the Dominant Thumb in Surgeons: A Cross-Sectional Survey in India

Background: A callus is a localized thickening of the stratum corneum that develops due to repeated pressure or friction. Surgical practice involves sustained pinch grip, thumb pressure, and instrument stabilization, which may predispose surgeons to localized hyperkeratosis. While musculoskeletal disorders among surgeons are well documented, cutaneous consequences of repetitive instrument pressure remain poorly studied. Callus formation over the ulnar aspect of the dominant thumb is frequently observed in clinical settings, but prevalence data and occupational determinants are limited. Aim: To determine the prevalence of callus formation on the ulnar aspect of the dominant thumb among surgeons and to assess its association with surgeon characteristics and occupational exposures. Methods: A cross-sectional questionnaire-based survey was conducted among surgeons across multiple specialties in India. Demographic variables, surgical workload, instrument handling habits, magnification use, and callus characteristics were recorded. The primary outcome was self-reported presence of callus on the ulnar aspect of the dominant thumb. Categorical variables were expressed as n (%). Associations were tested using chi square test, with p < 0.05 considered statistically significant. Results: A total of 110 consenting surgeons were included in the analysis. Mean age was 35.31 ± 7.23 years. Callus prevalence was 38.18% (42 of 110; 95% CI 29.65% to 47.51%). Callus presence showed significant association with years of surgical practice (p = 0.0046), frequency of resting instruments against the ulnar thumb (p = 0.0010), specialty grouping with higher prevalence in plastic surgery (p = 0.00027), and magnification use (p = 0.0048). Most calluses were confined to the dominant thumb (95.24%), were less than 5 mm in size (57.14%), and were asymptomatic (71.43%). Interference with surgical performance was minimal, and 88.18% of respondents supported ergonomic redesign of instruments. Conclusion: Callus formation on the ulnar aspect of the dominant thumb is common among surgeons and is significantly associated with cumulative surgical exposure and specific instrument handling habits. It may represent an occupational marker of repetitive mechanical stress. Ergonomic modifications and instrument redesign may help reduce focal thumb pressure and associated skin changes