AN ERGONOMIC COMPARISON OF IN-LINE VS PISTOL-GRIP HANDLE CONFIGURATION IN A LAPAROSCOPIC GRASPER

Background: Laparoscopic instruments incorporate both inline and pisto l-grip handle configurations, yet it is unclear which design is most a dvantageous for surgeons, particularly when operating at angles perpen dicular to the surgeon's position. We present a detailed electromyogra phic (EMG) comparison of these handle configurations under different f orce and angle conditions. Methods: Nine general surgeons used a Micro surge grasper with the handle in an in-line (MS-IL) and pistol (MS-PS) configuration, as well as a standard hemostat (HE), to grasp and clos e two spring-loaded metal plates. The task was performed randomly by e ach subject with the three instrument configurations at two forces lev els (0.7 N, 4.2 N) and at three angles to the surgeons' body (0, 45, a nd 90 degrees). Surface EMG was measured from the flexor carpi ulnaris (FCU), flexor digitorum profundus (FDP), flexor digitorum superficial is (FDS), extensor carpi ulnaris (ECU), extensor digitorum comunis (ED C), and thenar compartment (TH). The peak root mean squared (RMS) EMG voltage was calculated for each instrument, force, and angle condition . Statistical comparison was carried out by ANOVA. Results: Both lapar oscopic handle configurations required significantly higher contractio ns of all muscle groups compared to the hemostat at the high force lev el. TH was not affected by laparoscopic handle configuration. MS-IL re quired higher FCU, ECU, and EDC contractions at 45 degrees compared to MS-PS, However, MS-IL decreased the flexor compartment muscle contrac tions (FDP, FDS, FCU) at 90 degrees compared to MS-PS. Conclusions: La paroscopic grasping requires higher forearm and thumb muscle contracti ons compared to the use of a hemostat. The in-line handle configuratio n is no better than the pistol configuration except when grasping at 9 0 degrees to the surgeon, where rotation of the handle and wrist back toward the surgeon significantly decreases forearm flexor compartment muscle contractions.