Ergonomic analysis of microlaryngoscopy

To apply ergonomic principles in analysis of three different operative positions used in laryngeal microsurgery.

Prospective case-control study.

Laryngologists were studied in three different microlaryngeal operative positions: a supported position in a chair with articulated arm supports, a supported position with arms resting on a Mayo stand, and a position with arms unsupported. Operative positions were uniformly photographed in three dimensions. Full body postural data was collected and analyzed using the validated Rapid Upper Limb Assessment (RULA) tool to calculate a risk score indicative of potential musculoskeletal misuse in each position. Joint forces were calculated for the neck and shoulder, and compression forces were calculated for the L5/S1 disc space.

Higher-risk postures were obtained with unfavorably adjusted eyepieces and lack of any arm support during microlaryngeal surgery. Support with a Mayo stand led to more neck flexion and strain. Using a chair with articulated arm supports leads to decreased neck strain, less shoulder torque, and decreased compressive forces on the L5/S1 disc space. Ideal postures during microlaryngoscopy place the surgeon with arms and feet supported, with shoulders in an unraised, neutral anatomic position, upper arms neutrally positioned 20 degrees to 45 degrees from torso, lower arms neutrally positioned 60 degrees to 100 degrees from torso, and wrists extended or flexed <15 degrees.

RULA and biomechanical analyses have identified lower-risk surgeon positioning to be utilized during microlaryngeal surgery. Avoiding the identified high-risk operative postures and repetitive stress injury may lead to reduced occupationally related musculoskeletal pain and may improve microsurgical motor control.