Ergonomic Benefits From a Laparoscopic Instrument With Rotatable Handle Piece Depend on the Area of the Operating Field and Working Height.

Objective To evaluate the effect of a laparoscopic instrument with a 360° rotatable handle piece (rot-HP) on biomechanical stress and precision in different areas of a simulated operating field at two working heights. Background Surgeons performing laparoscopic procedures are exposed to biomechanical stress and have an increased risk of musculoskeletal complaints. Method Fifty-seven healthy subjects (27 men, median age 26) without experience in laparoscopy performed a precision task in four quadrants (A-D) of the operating field using the rot-HP or a common fixed handle piece (fixed-HP) at an individually adjusted lower or higher working height. Biomechanical stress was assessed by surface EMG, wrist joint angles, and arm postures and precision by the number of mistakes. Results Using the rot-HP reduced muscle activity of the biceps brachii and flexor carpi radialis muscle. An interaction of flexor activity and area of the operating field occurred with the lowest activity in Quadrant C. Wrist joint angles were more neutral using the rot-HP, especially when the lower working height was applied and in Quadrants B and C. However, increased wrist dorsal flexion occurred in Quadrant A while using the rot-HP. Arm postures and precision were less affected. Conclusion The rot-HP allows some reductions of stresses in the arm and hand region, whereas the stress in the shoulder neck region is not modified. Application The instrument's position and the working height may have to be considered as mediatory factors when describing the effectiveness of an ergonomic handle design for laparoscopic instruments.

Effect of a laparoscopic instrument with rotatable handle piece on biomechanical stress during laparoscopic procedures.

OBJECTIVE: To investigate the effect of a pistol grip laparoscopic instrument with a rotatable handle piece (rot-HP) on biomechanical stress and precision as well as a possible interaction between the instrument and working height (WH). BACKGROUND: Biomechanical stress induced by laparoscopic surgery (LS) is associated with work-related upper limb musculoskeletal disorders in surgeons. Ergonomic handle designs of laparoscopic instruments may reduce the risk of musculoskeletal disorders. METHODS: Without LS experience, 57 healthy subjects (30 women; 27 men, median age: 26) were observed while performing a laparoscopic exercise. Subjects had to pick up coloured pins and place them into a colour-coded wooden set-up inside a pelvitrainer. The exercise was performed at two WHs using the rot-HP and a standard laparoscopic (fixed) handle piece in randomized sequence. Biomechanical stress was monitored via surface electromyography (sEMG) on fife muscles from the upper limb and shoulder region. Further, the wrist angle (palmar and dorsi flexion) and posture of the dominant upper arm were recorded. Precision was assessed using the number of validly placed pins and process time. RESULTS: sEMG parameters and upper arm postures indicated no differences in biomechanical stress related to either laparoscopic handle piece. The higher WH was associated with higher trapezius and deltoid activity and elevated arm postures (p < 0.05). Neutral wrist positions were more frequent using the rot-HP, and the lower WH resulted in slightly more neutral wrist positions. Precision was similar during all experimental conditions. CONCLUSIONS: The rot-HP did not decrease biomechanical stress in the shoulder or lower arm muscles. However, wrist angle position may be optimized without affecting precision. Long-term effects of the rot-HP on preventing complaints of the upper extremity should be evaluated. Low WH is recommended to reduce biomechanical stress in the shoulder during laparoscopic surgery.

Influence of clinical expertise and practical experience on transfer accuracy in guided dental implant placement - an in vitro study.

PURPOSE: To investigate whether inexperienced users applying a static navigation system can perform in-vitro a fully guided implant placement protocol and achieve similar results in terms of accuracy compared to experienced clinicians. METHODS: Based on 36 identical resin models, a computer-assisted implant planning was performed and a surgical guide was produced accordingly. Three study groups were composed with 12 operators, each: control group with experienced surgeons (DOC), test group 1 with dental technicians (TEC) and test group 2 with non-specialists (OFC). Using a fully guided drilling protocol, two implants were placed into each of the 36 models. Subsequently, the differences between the virtually planned and final implant positions were determined and the transfer accuracy was evaluated. RESULTS: For the control group DOC, the mean value of axial deviation was 1.90 ± 1.15 degrees, for 3-dimensional deviation at the implant base 0.52 ± 0.33 mm, for 3-dimensional deviation at the implant tip 0.76 ± 0.39 mm and for vertical deviation at the implant tip - 0.11 ± 0.51 mm. For corresponding parameters, the mean values of test group TEC were 1.99 ± 0.87 degrees, 0.42 ± 0.21 mm, 0.68 ± 0.30 mm and - 0.03 ± 0.33 mm and for test group OFC 2.29 ± 1.17 degrees, 0.63 ± 0.35 mm, 0.89 ± 0.43 mm and - 0.24 ± 0.57 mm, respectively. The results did not reveal any statistically significant differences between the control and the 2 test groups (p˃0.05). CONCLUSION: The results of the present in-vitro study demonstrated that inexperienced users applying a static navigation system can perform a fully guided implant placement protocol and achieve similar results in terms of accuracy compared to experienced clinicians in this specific in vitro setup.