Skin effects of occupational kneeling.

To evaluate chronic knee trauma associated with kneeling, we conducted a cross-sectional questionnaire survey among floorlayers and tilelayers, two trades that require kneeling. Bricklayers and millwrights were studied for comparison. Approximately 28% of the 432 questionnaire respondents volunteered for a subsequent medical examination. Ultimately, data were analyzed for 112 floorlayers, 50 tilesetters, and 235 "comparison" workers. We found that the history of past skin infection in the knee area was about four times more prevalent among floorlayers (7.1%) than among workers in the other two categories combined (1.8%). Unilateral or bilateral patellar skin thickening and erythema were found to be more prevalent among those who kneel: 79% of floorlayers and 98% of tilelayers vs 35% of the control group were found to have skin thickening; 52% of floorlayers and 49% of tilelayers vs 24% of the control group were found to have erythema on the frontal aspect of the knee.