The effect of surgeon hand anthropometry on surgical glove sizing and implications
Stellon, Michael Anthony
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Though now seen everywhere in the hospital and operating theater, there was a time when surgeons used no hand protection. In the late 19th century, however, as the science of bacteriology became more advanced, surgical glove usage spurred. Today, gloves serve an extremely important role, helping to maintain the sterile field and protect hospital staff from the transfer of bloodborne pathogens. Since they are so valuable, it is equally important that gloves fit properly as to not be detrimental to the surgeon. Gloves that are too tight increase fatigue rate and decrease fine finger dexterity. Gloves that are too loose can reduce tactile sensitivity caused by bunching of material at the fingers. Traditionally, the larger of measurement of hand circumference and hand length are used to determine glove size, but most select a size based on comfort of fit. To assist manufacturers with creating certain sizes, anthropometry is often used. Anthropometry is the study of the physical measures of the human body. Human-factors engineering is the science of applying anthropometric information to the design of devices intended for human use. In this study, two anthropometric databases, studies by Greiner and Pheasant, were utilized to obtain hand measurements representative of the general population, due to the population studied. For this study, 59 general surgeons (51 male, 8 female) were invited on separate dates to the Medtronic Minimally Invasive Therapies Group in North Haven, CT for Voice of Customer laboratories. While there, they completed surveys where they listed their preferred glove size, double gloving sizes, dominant hand, etc. In addition, the following six measurements were taken: hand circumference, maximum grip diameter, Digit 1 (D1) length, Digit 2 (D2) link length, Distance from D2 Metacarpo-phalangeal (MCP) to Distal Interphalangeal (DIP) joint, and D2 distal phalanx length (extrapolated). These measurements were averaged and compared to the numbers reported in the Greiner and Pheasant studies for analysis using a novel Microsoft Excel tool. Commonly used laparoscopic staplers were also measured to assess ergonomic usability amongst the surgeon population. Male surgeons had statistically significantly larger hands than female surgeons with respect to all measurements taken. Compared to men of the general population, male surgeons had significantly smaller grip diameter, D2 link length, yet a greater D1 Length. Compared to women of the general population, female surgeons had a greater hand circumference, yet smaller D2 link length. All other measurements recorded were statistically equivalent. In general, surgeons seem to select a preferred glove size based on their hand circumference (Pearson’s Correlation 0.799, R2 63.9%), followed by D2 Link Length (Pearson’s Correlation 0.631, R2 39.9%). The median glove size for male surgeons was 7.5 (0.50) and 6.0 (0.25) for female surgeons (p > 0.001). To evaluate the ergonomic usability of laparoscopic staplers, the measurement “Distance from D2 MCP to DIP joint” was developed internally to roughly assess effective trigger distance, where larger lengths would force the user to adjust their hand position. The handles of two commonly used laparoscopic staplers were measured to determine what proportion of the surgeon population could use them effectively. Based on these measurements, for the Medtronic Endo GIA™ Ultra Stapler, nearly all male surgeons and 99.8% of female surgeons could use it ergonomically. For the Ethicon ECHELON FLEX™ ENDOPATH® Stapler, only 78.2% of male surgeons and 30.9% of female surgeons could use it ergonomically. This study demonstrated that there exists a large amount of variability between each part of the hand based on the different measurements. Therefore, to best assure proper fitting gloves for the majority of users, a two metric system involving hand circumference and finger length would be useful to accommodate the inherent variability of the hand. With respect to laparoscopic stapling platforms, this study demonstrated that the instruments are simply too large to be used ergonomically by a large portion of the intended audience. Medical device manufacturers should look to create an adjustable handle such that the trigger distance can be manipulated to fit the needs of those surgeons with smaller hands.