Assessment of the scalpel blade as an objective tool for measuring dermatome cut thickness.

Dermatomes are widely used for split thickness skin graft harvest. The graft thickness depends in part on the cut thickness setting, adjusted by the surgeon using a lever on the dermatome. This study aimed to assess whether a #15 scalpel blade placed in the dermatome blade aperture may reliably confirm the cut thickness setting (the scalpel dermatome test). Discrepancies between the blade-measured aperture and the cut thickness setting and the intra- and interobserver reliability of the technique were evaluated. The thickness of ten #15 blades (n=10) was measured using a micrometer. Six dermatomes were each assessed by two surgeons in triplicate each for the narrowest cut thickness setting that would permit passage of an entire surgical blade through the dermatome blade aperture, starting at zero and increasing cut thickness intervals of 1/1000 in. The mean scalpel blade thickness was 0.391 mm (~15/1000 in). The mean cut thickness setting which would permit the blade was 6/1000 in (range 2-9), p<0.001. Intra-observer reliability was good (intra-class correlation coefficient 0.89). Inter-observer reliability was moderate (intra-class correlation coefficient 0.52) and a mean difference of 1.5/1000 in was observed (6.8 versus 5.2, t-test p<0.018). Individual dermatome apertures differed, with the mean of three measurements for each ranging from 5.0 to 7.8/1000 in, p<0.001. Differences exist between scalpel blades, dermatomes and surgeons, however intra-observer reliability is good. The test is a simple maneuver, which can objectively validate the dermatome blade aperture, thereby preventing harm and optimising graft thickness.