1 Introduction

Total hip arthroplasties (THA) are considered to be successful surgical procedures in modern-day orthopaedics, with its improvements on patient outcomes well documented.¹ Accordingly, the volume of THAs are expected to dramatically increase in coming years, with current US projections anticipating a 71 % rise in THAs by 2030, 176 % by 2040, and 469 % by 2060.^2–4 A significant proportion of THA literature over the last 20 years has focused on implant survivorship and patient outcomes. However, the effects of THA on the health and longevity of surgeons must also be considered, particularly with the expected rise in patient demand.

Conventional THAs are physically and mentally demanding surgical procedures.^5–7 Surgeons performing conventional THAs operate at 40 % of their maximum cardiovascular capacity, and during each procedure surgeons expend comparable energy to that of an average weight individual performing moderate exercise for 1-h.^5,6 They also incur significantly greater intraoperative mental stress and physiological strain than when performing conventional THA.⁷ Current caseloads see orthopaedic surgeons typically perform 5–6 surgeries a day, leading to long operative days and significant fatigue which has been linked to reduced mental alertness and impaired surgical performance.^8,9

Studies suggest that conventional hip and knee arthroplasties may be a high-risk profession for work-related injuries and mental well-being, with 96 % of surgeons reporting chronic work-related musculoskeletal pain, leading to high levels of burnout, irritability, poor sleep patterns, and low happiness.¹⁰ Annual caseloads of more than 100 conventional THAs also significantly increases the risk of surgeons needing to take time off work due to work-related injuries, with 31 % requiring surgery for treatment.¹¹

The direct-anterior (DA) approach for THA has become increasingly popular among hip surgeons, particularly due to its tissue sparing and minimally invasive technique.¹² Conventional use of the DA approach for THA requires the use of intraoperative C-arm fluoroscopy to evaluate the position of the acetabular component and allow for intraoperative adjustments. However, the requirement to wear lead vest protection leads to significant physician fatigue and long-term musculoskeletal injuries commonly localized to the spine.^13–15

Computed tomographic (CT) based robotic-assisted THA is also observing a notable increase in patient interest and adoption amongst surgeons, with its significant improvements on patient-reported outcomes and superior accuracy in preparation and position of acetabular components, even when surgeons perform THA with the DA approach.^16–18 Additionally, CT-based robotic THA relies on a preoperative CT-scan to develop a 3D anatomic model of the patient's anatomy for preoperative and intraoperative case planning. Therefore, robotic-assisted THA allows surgeons to incorporate the DA approach without the use of intraoperative fluoroscopy to visualize component placement during the procedure.

Across several surgical disciplines, the increased utilization of robotic-assisted technologies have been shown to alleviate the intraoperative psychological stress and physical effort that surgeons experience, however, publications investigating these effects on joint arthroplasty surgeons are scarce.^19–22 Therefore, the aim of this study is to compare the physical and mental demand of surgeons when performing conventional DA THA with fluoroscopy and robotic-assisted DA THA without fluoroscopy.

2 Methods

Two orthopaedic surgeons with previous experience in THA were included in this study. Both surgeons were proficient with the DA approach, with both surgeons holding 11–20 years of experience performing conventional DA THA cases with fluoroscopy, and both surgeons had over 5 years of experience performing robotic-assisted DA THA cases without fluoroscopy.

Six fresh-frozen pelvis-to-toe cadaver specimen (12 hips, 6 matched pairs) were used for this study. For each specimen, one hip underwent a conventional DA THA with fluoroscopy and the contralateral hip underwent robotic-assisted DA THA without fluoroscopy.

Each surgeon performed three conventional DA and three robotic-assisted DA THAs procedures. The surgeons used their standard DA workflow for all cases and alternated the use of conventional and robotic-assisted THA surgery between right and left hips, so not all robotic-assisted cases were performed on one side. During conventional DA THA cases, surgeons wore lead vests under their surgical gowns to protect them from the radiation emitted during the use of intraoperative fluoroscopy. The Mako Total Hip Application (Mako Surgical Corp. (Stryker), Weston, FL, USA) was utilized for the robotic-assisted THA cases.

Biometric data was recorded for both surgeons throughout each procedure using GARMIN Venu® SQ (Garmin Ltd, Kansas, USA) smart watches, using software version 4.70. By using this technology biometric parameters were recorded for each case, including mean and maximum heart rate (HR), respiration, HR variability (stress), calories burned, and volume of sweat loss. HR and stress were both recorded at a sampling frequency of 0.3 Hz, while respiration was recorded at 0.17 Hz. The percentage change in biometric parameters were calculated relative to the measurements recorded at the beginning of each procedure.

Following each surgery, the surgeons were asked to complete a modified Surgery Task Load Index (SURG-TLX)²³ questionnaire to evaluate the physical and mental demand the overall procedure and for individual surgical steps.²³ The individual surgical steps which the questionnaire focused on included acetabular preparation, reaming, femoral preparation, and femoral broaching. Each response was ranked from 1 (lowest demand) to 10 (highest demand).

A normality test was performed on all biometric parameters including their percentage change values, and non-parametric statistics were adopted. A Mann-Whitney test was performed to assess statistical significance of physical and mental demand values for robotic-assisted vs conventional THA with the DA approach for both the biometric and questionnaire data. A p value of 0.05 was set for statistical significance.

3 Results

3.2

3.2 Questionnaire data

Questionnaire data collected from both surgeons were pooled together bases on surgical procedure. With regards to physical demand (Fig. 1), surgeons reported that robotic-assisted DA THA without fluoroscopy was significantly less physically demanding during acetabular reaming (1.8 ± 0.4 vs 4.2 ± 0.8, p = 0.005) and with regards to the overall procedure (2.5 ± 0.5 vs 5.0 ± 1.1, p = 0.005) when compared to conventional DA THA with fluoroscopy, respectively. Robotic-assisted THA was also less physically demanding during femoral broaching (2.8 ± 1.0 vs 4.0 ± 0.6, p = 0.078) and femoral preparation (2.5 ± 0.5 vs 2.67 ± 1.2, p = 0.873), though not statistically significant.

Close

Fig. 1 Surgeon's reported physical demand for the overall procedure and individual surgical steps.

Export to PPT

With regards to mental demand (Fig. 2), surgeons reported that robotic-assisted DA THA without fluoroscopy was significantly less mentally demanding during acetabular reaming (1.5 ± 0.5 vs 4.2 ± 1.0, p = 0.005), femoral broaching (2.5 ± 0.5 vs 3.6 ± 0.8, p = 0.037), and with regards to the overall procedure (1.6 ± 0.5 vs 4.7 ± 1.2, p = 0.005). Mental demand during femoral preparation was the same for robotic-assisted THA and conventional THA (p = 1.000).

Close

Fig. 2 Surgeons reported mental demand for the overall procedure and individual surgical steps.

Export to PPT

Surgeons also reported on the physical and mental demand of the use of intraoperative fluoroscopy for conventional DA THA. The average physical demand was 4 ± 0.6 and the average mental demand was 4.6 ± 1.3, similar values to the overall procedure for conventional DA THA.

4 Discussion

As robotic-assisted technology becomes more prevalent in orthopaedic operating rooms, it is important to understand how a surgeon's health is impacted by the technology. This study concluded that robotic-assisted DA THA without fluoroscopy resulted in less physical and mental demand for orthopaedic surgeons for the overall procedure and individual surgical steps. Interestingly, for several biometric parameters we found a reduction in their values relative to the beginning of the procedure for robotic-assisted THA. As surgeons interchanged between conventional and robotic-assisted DA THA, this further indicates that the surgeons found robotic-assisted less physically and mentally demanding than the prior conventional DA THA procedures.

Specifically, during acetabular reaming, robotic-assisted THA demonstrated a significant reduction in physical demand (maximum heart rate) and during acetabular prep there was a significant reduction in mental demand (stress). Additionally, this study demonstrated a correlation in results from biometric and questionnaire data. Surgeons reported via the questionnaire that robotic-assisted THA was significantly less physically and mentally demanding during acetabular reaming.

The DA approach for conventional THA relies on intraoperative fluoroscopy for accurate positioning and implantation of components. Our results indicate that this conventional DA THA with fluoroscopy resulted in increased physical and mental demand for orthopaedic surgeons. The increase in physical demand might be attributed to the use of lead vest worn by the surgeons throughout the procedure to protect them from radiation exposure. The benefit of robotic-assisted THA for DA approached is the use of the preoperative CT scan to allow for 3D visualization of the joint without the need for intraoperative fluoroscopy. Therefore, surgeons may omit the use of protective lead vest during the procedure and reduce their biometric energy output.

The increased mental demand observed in this study for conventional DA THA was demonstrated through the high percentage change in stress and via surgeon's questionnaire responses. The increase in mental demand could be attributed to the multiple fluoroscopic images that are taken during acetabular reaming to adjust acetabular component positioning.

Another cadaver-based study compared the physical and mental demand of robotic-assisted versus manual THA using the posterior approach.²⁴ Similar to our findings, this study also found that robotic-assisted THA demonstrated reduced energy expenditure (physical demand) and reduced mental demand during acetabular reaming compared to manual THA.²⁴

One potential reason for these results is that during CT-based robotic-assisted THA, surgeons use reamers that are held with haptic boundaries and allows the surgeon to ream directly up to final acetabular cup size and perform single-staged reaming.²⁴ This feature of robotic-assisted THA may enable surgeons to reduce their mental demand during reaming and performing other tasks.

The design of this cadaver lab study is subject to limitations. Given the sample size of six cadavers (12 hips), this study may be underpowered to reject the null hypothesis. Though our analysis demonstrated lower values in the biometric data for robotic-assisted DA THA without fluoroscopy, these values did not reach statistical significance. Further, the sampling frequency of the smart watches was low and made it difficult to accurately isolate the biometric readings at each stage of the procedures. Additionally, the data collected for this study had the potential to be impacted by a number of external factors. While cadaver-based studies are a great alternative, the environment of a cadaver lab does not accurately reflect the conditions in an operating room. Also, the surgeons selected for this study were highly experienced in both procedures, therefore these results may not be transferable to surgeons earlier in their learning curve. Additionally, the biometric data recorded in this study is dependent upon the accuracy of the Garmin smart watches. The authors also did not include baseline biometric parameters which may provide more comprehensive data on the change in biometric parameters through each THA. Finally, the sampling frequency of the smartwatch may have impacted the breakdown of the biometric data into individual surgical steps, as some steps may have been completed in a shorter period of time.

5 Conclusion

The robotic-assisted DA THA without fluoroscopy resulted in lower physical and mental demand compared to conventional DA THA with fluoroscopy with regards to biometric parameters, including maximum heart rate, caloric expenditure, and sweat loss, and through questionnaire results. This study has important implications for the health and longevity of orthopaedic surgeons as the demand for THA continues to increase.

Consent

Patient consent was not necessary for this investigation.

Funding

No funding was obtained for this investigation.

CRediT authorship contribution statement

Melanie Caba: Conceptualization, Methodology. Connor Gains: Conceptualization, Methodology. Joseph Nessler: Writing – review & editing, Software, Validation. Benjamin Frye: Writing – review & editing, Software, Validation. Laura Scholl: Writing – review & editing, Software, Validation. Sean B. Sequeira: Writing – original draft, Writing – review & editing. Michael Mont: Conceptualization, Methodology, Software, Validation, Writing – review & editing.