Objective assessment of the impact of patient Body Mass Index on the postural kinematics of surgeons in training

Laparoscopic Surgery (LS) has become an integral part of modern clinical care, due to the vast benefits the surgical technique offers for the patient, healthcare system and surgeons compared to open surgery. In many clinical specialities the gold standard interventional procedure has shifted from open to laparoscopic due these benefits. The major beneficiary of the transition in surgical technique is the patient, as LS generally facilitates shorter hospital stays, a quicker return to work and reduced trauma and scarring. However, an ever-increasing volume of literature reports a plethora of musculoskeletal disorders (MSDs) or musculoskeletal-related complaints amongst surgeons performing LS. Musculoskeletal disorders have a multifactorial aetiology, especially amongst laparoscopists, with many studies reporting the inherent postural and kinematic requirements of performing LS as major contributors of MSDs. In addition, further investigations suggest that external factors to the surgeon, such as ergonomic design, patient pathology, and high BMI patients are negative impactors on surgeon physical wellbeing. Anecdotally, high BMI patients are reported to have a substantial degrading impact on the ability of a surgeon to perform optimally, however few objective analyses had investigated this issue.

To conduct objective analyses involving surgeons, an optimised simulated/dry laboratory setup was assembled in order to induce a genuine performance response from surgeons during laparoscopic procedures. Obese (30 kg/m²) and severely obese (40 kg/m² and 50 kg/m²) patient models were developed from pre-operative patient waist circumference data and a normal BMI model (20 kg/m²) was also created to represent the baseline physical performance of surgeons. Further, a method capable of the objective quantification of human posture and kinematics was identified and validated for use during simulated laparoscopy. Novice, intermediate and expert surgeon posture and kinematics were measured and assessed during simulated laparoscopic training tasks. Surgeon posture was assessed using the postural loading on the upper body assessment (LUBA) which found significant increases in total LUBA score at BMI 50 kg/m² as compared to the baseline 20 kg/m² model. Surgeon kinematics were firstly assessed to identify the translational and rotational derivatives of position that exhibited the most frequent and significant differences between BMI levels. The parameters with the most frequent and significant differences were found at BMI levels of BMI 40 kg/m² and 50 kg/m² as compared to the baseline. Both assessments indicated patients with high BMIs significantly degrade the physical performance of surgeons, which may increase the risk of MSDs. While the use of the ergonomic framework proved to appropriately assess surgeon posture, it was noted that the framework overlooked several key aspects of laparoscopic physical performance, which if considered, could provide a more holistic assessment of surgeons. Some key aspects of physical performance that are overlooked by existing ergonomic frameworks include: the consideration and measurement of the length of time spent in non-neutral posture and objective quantitative definitions for what motion or lack of it constitutes static, repetitive, or uncontrolled anatomical motion.

A novel assessment model was developed specifically for the performance of surgeons conducting LS, predicated on key ergonomic principles to consider aspects of physical performance that previous ergonomic frameworks overlooked. These included prolonged non-neutral posture, uncontrolled motion, and objectively implementable quantitative definitions for static and repetitive motion. The model was applied to the acquired LS dataset and found a significant change in the magnitudes in the intermediate sub-group. This result would have otherwise been overlooked by the previous ergonomic analysis. This outcome showed that the inclusion of the additional parameters and the method utilised to combine postural and kinematic variables identified limitations of physical performance that may contribute to MSDs. Finally, a number of areas of this research were identified for future development with discussion on the possible directions for the continuation of this work.