A comparison of forearm and thumb muscle electromyographic responses to the use of laparoscopic instruments with either a finger grasp or a palm grasp

Laparoscopic techniques allow for less-invasive treatment of common surgica l problems. Laparoscopic instruments are different from standard surgical i nstruments and generally incorporate a pistol-grip handle configuration wit h rings for the fingers. This handle configuration has been reported as bei ng uncomfortable, leading to anger compression neuropathies in some cases. As an alternative, the surgeon can choose to grasp laparoscopic instruments using a mon powerful palm grip during grasping motions. This study evaluat es the hypothesis that the use of the palm grip requires less muscle tensio n than the finger-grip when grasping with laparoscopic instruments. Nine ge neral surgeons used an Autosuture(R) laparoscopic grasper with a ringed pis tol-grip handle held in both a finger-in-ring (F) or palm (P) hand grip pos ition to grasp and close two spring-loaded metal plates. The same task was performed with a surgical haemostat clamp (H) for comparison, Each subject performed the grasping task in a random sequence for the three instrument c onfigurations at two grasping forces levels (0.7 and 4.2 N), and with the i nstrument at three angles to the subjects' sagittal plane (0 degrees, 45 de grees and 90 degrees). Surface electromyographic (EMG) signals were acquire d from the flexor carpi ulnaris (FCU), flexor digitorum profundus (FDP), fl exor digitorum superficialis (FDS), extensor carpi ulnaris (ECU). extensor digitorum comunis (EDC) and the thenar compartment (TH). The peak root mean squared (RMS) ER IG voltage was averaged for five repetitions at each inst rument, force and angle condition. Statistical analysis was carried out by repeated measures ANOVA. The muscle EMC RMS amplitude while using the palm grip was decreased in the FDS, TH and EDC, was unchanged in the ECU and FCU ? and was slightly higher in the FDP when compared with the finger grip. Th ese differences were most prominent at 90 degrees to the sagittal plane whe re the subjects' wrists neared maximal flexion. It is concluded that the pa lm grip is more powerful than the finger grip when grasping with laparoscop ic instruments, particularly at angles perpendicular to the surgeon's sagit tal plane.