Ergonomics of disposable handles for minimally invasive surgery.
BACKGROUND
The ergonomic deficiencies of currently available minimally invasive surgery (MIS) instrument handles have been addressed in many studies. In this study, a new ergonomic pistol handle concept, realized as a prototype, and two disposable ring handles were investigated according to ergonomic properties set by new European standards.


METHODS
In this study, 25 volunteers performed four practical tasks to evaluate the ergonomics of the handles used in standard operating procedures (e.g., measuring a suture and cutting to length, precise maneuvering and targeting, and dissection of a gallbladder). Moreover, 20 participants underwent electromyography (EMG) tests to measure the muscle strain they experienced while carrying out the basic functions (grasp, rotate, and maneuver) in the x, y, and z axes. The data measured included the number of errors, the time required for task completion, perception of pressure areas, and EMG data. The values for usability in the test were effectiveness, efficiency, and user satisfaction. Surveys relating to the subjective rating were completed after each task for each of the three handles tested.


RESULTS
Each handle except the new prototype caused pressure areas and pain. Extreme differences in muscle strain could not be observed for any of the three handles. Experienced surgeons worked more quickly with the prototype when measuring and cutting a suture (approximately 20%) and during precise maneuvering and targeting (approximately 20%). On the other hand, they completed the dissection task faster with the handle manufactured by Ethicon. Fewer errors were made with the prototype in dissection of the gallbladder. In contrast to the handles available on the market, the prototype was always rated as positive by the volunteers in the subjective surveys.


CONCLUSIONS
None of the handles could fulfil all of the requirements with top scores. Each handle had its advantages and disadvantages. In contrast to the ring handles, the volunteers could fulfil most of the tasks more efficiently using the prototype handle without any remarkable pressure areas, cramps, or pain.
Experimental OR and Ergonomics, University Hospital of Tübingen, Ernst-Simon-Strasse 16, 72072 Tübingen, Germany. dirk.buechel@experimental-op.de
D
D
Büchel
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R
Mårvik
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B
Hallabrin
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U
Matern
D004209:Disposable Equipment / Q000592:standards*; D004576:Electromyography; D004867:Equipment Design; D006804:Ergonomics / Q000592:standards*; D005260:Female; D006225:Hand / Q000033:anatomy & histology* / Q000502:physiology; D006801:Humans; D008297:Male; D019060:Minimally Invasive Surgical Procedures / Q000295:instrumentation*; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D012016:Reference Values; D013525:Surgical Instruments / Q000592:standards*; D013647:Task Performance and Analysis; D013997:Time Factors