# Ergonomic Evaluation of Different Surgeon Positions for Total Knee Arthroplasty Surgery
## 4 Discussion  
Our study aims to make the first approach to the problem of surgeon ergonomics during knee arthroplasty. To the best of our knowledge, our research is the first study to define and evaluate the different positions adopted by orthopaedic surgeons when performing TKA from an ergonomic perspective. Therefore, we cannot compare our results to other studies. As the main result of our study, the position with the least ergonomic risk for the surgeon is option D, where the surgeon faces the operated knee. The lowest postural risk would be D \(<\) C \(<\) B \(<\) A. From the point of view of preventing these musculoskeletal disorders, we did not find any specific measures to reduce the risk for surgeons. However, some studies aim to study and extrapolate the ergonomic recommendations made in other work areas [6; 18]. According to the Occupational Safety and Health Administration (OSHA), workers should be in a workspace that allows them to work at 15% or less of their maximum capacity. In the case of surgeons, achieving these goals requires them to maintain a neutral posture of their axis and limbs for most of the procedure. To achieve this, the surgeon must have an upright neck and trunk posture, avoiding flexion-extension and torsion; shoulders at 0\({}^{\circ}\) with no flexion-extension, abduction, or rotation; elbows as close to 90\({}^{\circ}\) as possible; and wrists avoiding flexion-extension and lateral deviation (radial or ulnar) [6]. In our study, the postures with the highest REBA scores did not meet the above requirements, resulting in a higher postural strain and ergonomic risk for the surgeons. This could explain why position A, where the surgeon is furthest from the work area, has the highest score after applying the REBA method. In a study in which electromyographic measurements of specific muscle groups were taken for two surgeons to compare the differences in the effectiveness of operations performed on different sides, [PERSON] et al. [12] concluded that right-handed surgeons exert more effort when performing left-sided TKA and that left-sided knee operations cause more occupational injuries to surgeons. One element we did not include in our study, but which plays a fundamental role in achieving these positions, is the height of the worktable or desk. The relationship between working height and ergonomic risk has been extensively studied in other occupations [19; 20; 21] and the surgical field [22; 23], particularly in laparoscopic surgery [24; 25]. [PERSON] et al. suggest different working heights depending on the type of activity the surgeon is performing [6]. A table height of approximately 5 cm below the elbow is recommended for tissue dissection. For more straightforward tasks, such as suturing and screw threading, the table should be approximately 5 to 10 cm below the elbow. However, for heavy tasks that require force on the floor (drilling, sawing, or hammering), it is recommended to work at a height of between 20 cm and 40 cm below the elbow. In our study, the surgeon set the table height to his comfort level (73 cm) at the start of the simulation, and no changes were made to the table height, as is customary during knee arthroplasty surgery, even though the working plane changed when the knee position was changed. Usually, with this table height, the surgeon mainly controls the knee in 90\({}^{\circ}\) flexion and in maximum flexion for tibial and femoral cuts (TCG, FCG, DFC, AFC) and component implantation (DFI, DTI), and it is usually less comfortable for steps with the knee in extension (I, PE, C), which tend to be the least performed. However, the steps with the highest ergonomic risk according to the average REBA were precisely those of cutting and implant placement. This implies that orthopaedic surgeons do not know and, therefore, do not consider the recommendations described by [PERSON] et al. regarding the height of the work surface in relation to the activity to be carried out.