Evaluation of the Effect of Hand Size on Forearm Muscle Activity While Using Laparoscopic Instruments.

Surgical ergonomics focuses on optimizing the interface between clinicians and specialized tools to prevent musculoskeletal disorders. Prior research has shown that repetitive strain and high muscle exertion during minimally invasive procedures contribute significantly to surgeon fatigue. Standardized metrics like Percent Maximum Voluntary Contraction (Percent MVC) allow researchers to quantify these physical demands across diverse populations. While tool design often targets a median user profile, the physiological impact on individuals with smaller hand dimensions remains poorly characterized. Sustained exertion above specific thresholds is known to elevate the risk of chronic injury and decrease procedural precision. The physical environment of the operating room necessitates tools that accommodate various grip strengths and anatomical sizes. This absence of evidence motivated an investigation into how anatomical variations influence the neuromuscular load during laparoscopic tasks.

This investigation quantifies the Percent Maximum Voluntary Contraction (Percent MVC) of specific forearm muscles during the operation of four distinct laparoscopic energy devices. Researchers sought to determine if surgeons with smaller glove sizes experience disproportionate muscular strain compared to those with larger hands. The study evaluates the relationship between hand anthropometrics and the activation levels of the Flexor Digitorum Superficialis (FDS) and other key muscles. By comparing these physiological responses, the team aimed to identify potential ergonomic disparities inherent in current instrument designs. Establishing these correlations provides a basis for recommending design modifications that accommodate a broader range of surgeon demographics. The project also examines whether specific instrument/muscle combinations exceed safety thresholds for muscle fatigue. Understanding these dynamics is vital for improving the longevity of surgical professionals and reducing occupational health risks.

Investigators conducted a non-experimental correlational study within a simulation laboratory at the Mayo Clinic Arizona. The cohort consisted of twenty-four surgeons and trainees who regularly perform robotic or laparoscopic procedures. Surface Electromyography (sEMG) electrodes were positioned on the Flexor Digitorum Superficialis (FDS), Extensor Carpi Ulnaris (ECU), Extensor Carpi Radialis Longus (ECR), and Extensor Pollicis Longus (EPL). Participants performed isometric Maximum Voluntary Contraction (MVC) maneuvers to establish baseline values for normalization. Each subject completed standardized cycles of opening, closing, and activating four different advanced energy devices with their dominant hand. Data analysis involved filtering the raw EMG signals and categorizing participants into small (glove size ≤ 6.5) or large (> 6.5) groups. The researchers also collected demographic information, glove size, and grip strength to control for confounding variables during the statistical evaluation.

Surgeons in the small-handed group exhibited significantly higher activation in the Flexor Digitorum Superficialis (FDS) and Extensor Carpi Radialis Longus (ECR) muscles. Statistical analysis revealed p-values of 0.0012 for the FDS and 0.013 for the ECR when adjusting for training level and tool type. Ten out of sixteen muscle and instrument combinations exceeded the 15% Percent MVC threshold for participants with smaller hands. In contrast, only one combination resulted in a mean activation greater than 15% for the large-handed cohort. The data indicate that smaller hand size correlates with increased neuromuscular effort across multiple laparoscopic tasks. These findings highlight a substantial disparity in the physical workload required to operate standard surgical hardware. The 15% cutoff was specifically selected due to its association with increased risks of muscle fatigue and injury during sustained use.

The study demonstrates that current laparoscopic instrument designs impose a higher physical burden on surgeons with smaller hand dimensions. Increased forearm muscle activation suggests that these individuals face a greater risk of rapid fatigue and long-term musculoskeletal injury. Manufacturers should integrate hand size variations into the development process for future surgical energy devices. Addressing these ergonomic gaps is essential for ensuring equitable safety standards across the diverse surgical workforce. Future research might explore how specific handle geometries or trigger mechanisms could mitigate excessive muscle exertion. Implementing inclusive design principles will likely improve surgeon longevity and procedural outcomes in minimally invasive surgery. Industry partners must consider these variations to prevent disproportionate injury risks among surgeons with smaller hands.