The EndoHand: comparison with standard laparoscopic instrumentation

A remote palpation instrument for laparoscopic surgery: design and performance

This paper describes the design and performance of a prototype remote palpation instrument with tactile feedback for laparoscopic surgery. Psychophysical experiments aiming at comparing palpation with and without tactile feedback are also described. The remote palpation instrument is designed to provide the surgeon with information about size and contact force distribution. The instrument consists of a tactile sensor and a tactile display, both of which are small enough to fit onto a conventional laparoscopic grasper. Static tests showed that hardness, size and shape were successfully rendered by the tactile display. Dynamic testing showed that the bandwidth is suboptimal, but at low frequencies the output from the remote palpation instrument is useful. For the psychophysical testing, nine subjects were asked to discriminate hardness and size of objects with and without tactile feedback. The results indicated that the instrument with tactile feedback can be helpful for hardness discrimination, although the difference between the two instruments was not statistically significant for neither hardness nor size. Comparisons with earlier, similar experiments showed that the quality of the grasper and size of the forceps affected the results, indicating that there is a great potential for improving laparoscopic graspers in general.

Principles of ergonomic instrument handles

Minimally invasive surgery (MIS) has become firmly established during the last decade. The advantages for patients are well recognised. Surgeons, however, must cope with disadvantages caused by an unergonomic working place. This includes architecture, operating room (OR) design, team interaction, equipment and, finally, posture and instrument handles. To prevent pressure areas, persisting nerve lesions, muscle cramps and fatigue caused by unergonomic tools it is necessary for the surgeon, both as a purchaser and user of laparoscopic instruments, to know the principles of ergonomically designed handles for MIS instruments. Anatomical, physiological and ergonomic facts are presented. An ideal ergonomic working posture for the laparoscopic surgeon and an optimal grasp for manipulating the instrument's functional elements are recommended. Criteria for genuine 'ergonomic handles' are established. These criteria enable the surgeon to evaluate ergonomic handles for MIS instruments according to his/her particular needs.

Haptics in minimally invasive surgery--a review

This article gives an overview of research performed in the field of haptic information feedback during minimally invasive surgery (MIS). Literature has been consulted from 1985 to present. The studies show that currently, haptic information feedback is rare, but promising, in MIS. Surgeons benefit from additional feedback about force information. When it comes to grasping forces and perceiving slip, little is known about the advantages additional haptic information can give to prevent tissue trauma during manipulation. Improvement of haptic perception through augmented haptic information feedback in MIS might be promising.

The Role of Tactile Feedback in Laparoscopic Surgery

Two experiments aiming at comparing palpation with gloved fingers, conventional laparoscopic instruments, and a laparoscopic instrument with a sensor array attached to its end effector are described. The sensor array provides the surgeon with visually presented tactile information. Fifteen subjects were asked to discriminate hardness and size of objects (rubber balls hidden in pig's intestine) with the 3 palpation methods. The experiments showed that the gloved fingers are better at differentiating hardness and size compared with conventional laparoscopic instruments and the instrument with sensor. There was no significant difference between conventional instruments and the instrument with sensor, although the results showed a higher average score with the instrument with sensor. This indicates that visual presentation may not be an ideal way of presenting tactile information. It also indicates that the presence of the array does not make the task more difficult.

Objective assessment comparing hand-assisted and conventional laparoscopic surgery

BACKGROUND

Although several reports have subjectively highlighted the benefits of hand-assisted as compared with conventional laparoscopic surgery, there has been little objective analysis comparing these two techniques.

METHODS

For this study, 12 trained laparoscopic surgeons completed standardized knot-tying and dissection tasks in a laparoscopic trainer using both hand-assisted (HandPort) and traditional laparoscopic techniques. Motion analysis with the Imperial College Surgical Assessment Device was used to assess performance, measuring the number of movements made, the path length of hand travel, and the time taken. Mann-Whitney U tests were used to compare hand-assisted (HA) and conventional laparoscopic (L) performance. A p value less than 0.05 was deemed significant. Means and standard deviations are shown in the results.

RESULTS

In knot tying, for both the dominant and nondominant hands, hand-assisted rather than conventional laparoscopic techniques resulted in reduced movements (dominant: HA [114 +/- 50] vs L [321 +/- 118, p < 0.001], nondominant: HA [89 +/- 36] vs L [296 +/- 96, p < 0.001]); path length (dominant: HA [1,083 +/- 680 mm] vs L [3,637 +/- 1,852 mm, p < 0.001], nondominant: HA [549 +/- 339 mm] vs L [2,556 +/- 1,042 mm, p < 0.001]); and time taken (HA [162 +/- 50 s] vs L [460 +/- 179 s, p < 0.001]). However, there was no statistical difference for any measured variable with respect to the dissection task.

CONCLUSION

Hand-assisted surgery significantly improves the knot-tying ability among trained laparoscopic surgeons. However, there appears to be no improvement in performance for this specific dissection task.