In this study, we found that cases undergoing TKA operations later in the day were associated with increased risk of arthroplasty infection rates, decreased surgical time (before the fourth case), reduced blood loss, and longer hospital stays. With similar patient characteristics between groups, our results illustrate differences in infection rates based on surgery case order among operations performed on the same day.
Surgical time continually decreased among the first one-third of operations. Significantly increased operative time was noted for the fifth-round TKA with an approximately eight-minute increase compared with fourth-round cases and a thirteen-minute increase compared with third-round cases. This finding suggests that fatigue might play a role. These results indicate that the effects of practice before surgery and surgeon fatigue during in the day. Studies have shown that a good command of psychomotor skills and cognitive performance before a sport could improve surgical performance . It has been demonstrated that performing preoperative warm-up exercises for approximately 15 minutes with simple surgical tasks lead to a substantial increase in surgical skill proficiency . A few studies found that surgeon fatigue increased throughout the operative day, causing an increase in the time required to complete surgeries [9, 13–14]. A study by Willis-Owen et al. suggested that a longer duration of surgery for TKA led to an increased infection rate . The main reason for the increased infection rates may be more prolonged operative site exposure to the air. A total of 115 infections, a main adverse event, were found in our research . In our study, cases performed later during the day had a higher risk of infection (2.16% in the first round, 2.26% in second, 3.29% in third, 3.67% in fourth, 5.04% in fifth), demonstrating the effect of surgical case order on the risk of subsequent periprosthetic joint infection. However, a study conducted by Chen et al. suggested that TKA cases operated later in the day do not exhibit an increased risk of infection .
In the present study, our findings indicated that surgical cases performed later in the day were associated with increased complication rates, which is similar to the findings of some previous studies in other fields. A significant increase in arthroplasty-related complications was observed in patients when surgeons had performed three or more procedures during a day. The surgeon's accumulated fatigue was considered the primary reason for this adverse event and may cause worse operative outcomes. However, different results have been reported in other surgical fields regarding the effects of surgeon fatigue on clinical outcomes . Previous research indicated that surgery started later in the day may increase the risk of intraoperative complications for THA . Other studies reported that sleep deprivation in attending surgeons does not lead to higher mortality or complications [19–20]. Similarly, Govindarajan et al. found that the incidence of elective daytime procedure complications was similar regardless of whether the physician had provided medical services the previous night .
One shortcoming of our study is its retrospective nature. This is vitally important given that fatigue resistance varies among surgeons. For further analysis, it is necessary to assess each of the level of fatigue in each surgeon. Moreover, operating room staff were shift changes not analysed in our study because there were different levels of surgeons associated with these cases and itinerant and instrumental nurses, which undoubtedly affected the efficiency and surgical outcome. Importantly, two potential factors can also contribute to the infection rate, which was not analysed in the present study. One factor is bacterial transmission. A study found that contaminant build-up during the first case is carried over and amplified during subsequent cases .
Another element must be considered as a contributor to infectious risk, as it has two sides when practised correctly. Specifically, it is proper sterilization of medical instruments. However, if any sterilization process goes wrong, there is undoubtedly an effect on adequate sterilization of the medical equipment. Previous literature has shown that cases using flash sterilization have a higher rate of infection than those using standard sterilization methods .
Despite these limitations, the study has several significant advantages. Our study analysed data generated from a single medical centre over ten years based on five dedicated and high-volume surgeons (200–400 TKAs per year). Additionally, the cohort size and event statistics also provide this study with adequate power to demonstrate clinical significance. To our knowledge, this is a relatively comprehensive study to assess the impact of surgical case sequence on perioperative outcomes for TKA patients. Future studies may help to illuminate whether these effects translate to other noteworthy clinical consequences.