Surgeon Upper Extremity Kinematics During Error and Error-Free Retropubic Trocar Passage

Objectives: Surgeon kinematics play a significant role in injury prevention. Our objective was to identify upper extremity surgeon kinematics associated with injury during a simulated midurethral sling (MUS) procedure.

Methods: We used an OptiTrack Flex13 motion capture system to measure 3D positions of reflective markers placed on surgeons’ (three experts and three novices: five right-handed, one left-handed) upper extremities, which were then used to calculate flexion/extension, abduction/adduction, and internal/external rotation angular time series for shoulder, elbow, and wrist joints. (Figure) Time series were truncated and divided into stages ending with contact with the following: (1) pubic bone; (2) most cephalad point of the pubic bone; (3) most ventral point of the pubic bone; and (4) rectus fascia. In each stage, we assessed passes towards and away from the bladder and extracted starting and ending angles, minimum and maximum angles, and angular range of motion (ROM). Location data was post-processed using Motive software and fed into an anatomical multibody model scaled to each participant and containing 3D geometries of the simulator and trocar. We applied linear mixed modeling to compare kinematics between trials with versus without bladder contact, anterior versus posterior trocar passage relative to pubic bone, and expert versus novice surgeons.

Results: Out of 85 passes, 62 were posterior to the bone and 23 anterior. 20 of the posterior passes made contact with the bladder and 42 did not. Trials with versus without bladder contact were associated with higher initial wrist dorsiflexion (30.07 vs 11.82 degrees, p=.01), less final elbow flexion (41.19 vs 61.72, p=.03), and greater ROM in both the wrist (28.16 vs 17.23, p=0.02), and elbow (20.96 vs 14.67, p=0.04) during Stage 3 for passes towards the bladder. (Table) These differences were not present in the passes away from the bladder or in other stages. Wrist deviation, arm pronation, and shoulder adduction were not associated with bladder contact. Passage of the trocar anterior versus posterior to the bone was significantly associated with less initial shoulder flexion (14.16 vs 31.63 degrees, p< .01), less final shoulder flexion (14.65 vs 30.59, p=.04), and less elbow flexion (91.67 vs 95.07, p< .01). Wrist flexion/extension was not associated with anterior passage. Compared to experts, novices had more ROM in elbow flexion (12.32 degrees vs 6.90, p< 0.01). Experts had more ROM in wrist flexion (25.09 vs 16.29, p=0.02) and arm supination (50.61 vs 4.89, p< 0.01).

Conclusions: Bladder contact during MUS is associated with wrist dorsiflexion and elbow flexion, but not by internal wrist deviation or arm supination. Anterior passage is associated with more shoulder extension and less elbow flexion. Expert surgeons exerted control with the wrist and forearm, novices at the elbow. Teaching surgeons should pause the MUS surgery and check for posterior passage.