Blood-saving dissection with monopolar tungsten needle electrodes and Teflon-coated spatula electrodes in tumor orthopedics

Reduction of blood loss

We observed a relevant reduction of intraoperative blood loss in the intervention group using monopolar tungsten needle electrodes and PTFE-coated spatula electrodes for tumor dissection. In the literature for orthopedic surgery, only two previous studies evaluated the effect of electrosurgical dissection as a blood-saving measure. Widman et al. in 1999 found no significant difference in total blood loss in 67 patients with primary hip arthroplasty [7]. In 33 patients the scalpel was used throughout the operation and diathermy only for coagulation of bleeding spots. In 34 patients a diathermy knife was used solely. No wound infections or relevant postoperative bleeding occurred in either group.

Byrne et al. in 2007 found a reduction of blood loss in relation to the wound size using electrosurgery in hemiarthroplasty in 100 patients with hip fractures operated on by one single surgeon [8]. Bleeding from bone marrow during reaming was considered a confounder, reducing the overall effect of electrosurgery on total blood loss in their study. In our study, the blood-saving effect was still very pronounced, although we did not differentiate between blood loss during soft tissue dissection and the following reconstruction phase.

Reduction of intraoperative transfusions of PRBCs

In total, fewer PRBCs were transfused and a lower number of patients received transfusions in the intervention group during surgery. To date, there are only a few reports of surgical liver resections in which the use of monopolar electrodes has resulted in a reduction of the number of required transfusions of PRBCs [9]. So far, no comparable results have been published in the current orthopedic literature.

Reduction of wound drainage

A significant reduction in postoperative wound drainage was observed in the intervention group. This drainage fluid consists of portions of blood and wound exudate released over the wound surfaces. Persistent wound secretion over several days may cause delayed wound healing or even promote development of infection, and may require surgical revision. The combination of cutting and simultaneous sealing of small blood and lymphatic vessels during dissection might have created a dry wound that resulted in reduced wound discharge. In this instance, our results contradict earlier studies that found larger formation of postoperative seroma when electrosurgery was used. A meta-analysis of Ismail et al., including eleven studies (1258 participants), reported higher rates of seroma formation in the diathermy group [10]. The authors suggested that heat damage to adjacent tissues resulted in inflammation, promoting excessive wound discharge and seroma formation. Higher cytokine levels in drainage fluids after mastectomy indicated that electrosurgery could in fact induce a stronger acute inflammatory response compared with scalpel dissection [11]. Whether the use of PTFE-coated electrodes and tungsten needle electrodes used in our study, powered by a modern oscillator unit that can deliver pure sinusoidal current, may cause less thermal damage than earlier diathermy electrodes reported in the literature cannot be conclusively determined here.

Wound healing disorders and postoperative hemorrhage

The overall rate of wound healing disorders and postoperative hemorrhage needing surgical revision in our study is in keeping with reports in the literature [12, 13]. These complications occurred with comparable frequency in the control and the intervention group. Ismail et al. also found no difference in wound healing and infections, length of hospital stay, and scar formation in their meta-analysis [10]. They included 41 studies with 6422 participants, but they were mainly abdominal surgeries, and there were only two studies in the orthopedic field [7, 8]. Early animal studies from 1980 raised concerns about potential increased wound healing disorders and infections when diathermy was used for skin incisions [6] and the National Institute for Health and Clinical Excellence (NICE) guidelines in 2008 objected to the use of diathermy for skin incisions [14]. This recommendation has not been revisited in the current 2019 edition [15]. Nevertheless, clinical trials, including our study, have not found an association between wound healing disorders and monopolar electrosurgery [16, 17].

Limitations

To our knowledge, this is the first study to evaluate the use of these novel electrodes regarding blood-saving potential in tumor orthopedics. However, several limitations need to be considered when interpreting these results. This is a retrospective analysis with a historical control group, which has an inherent risk of bias, as other conditions and parameters may have changed over time, affecting our parameters of interest. In order to achieve a high level of standardization between the groups we limited the inclusion criteria to patients that were operated on by one single surgeon who already had 20 years of experience in this field at the beginning of the observation period. So, the potential bias due to a learning curve or varying skills of different surgeons was eliminated. We assume that after 20 years of experience in tumour orthopedics, surgical skills have matured to a level where an additional 9 years might not significantly influence the outcomes of interest.

Furthermore, the intervention group was on average 9 years older. An explanation could be that older patients are increasingly considered fit for surgery. Chronological age is no longer regarded to be contraindication in attempting curative surgical procedures in oncological surgery [18]. Age-matched groups would be desirable to investigate our hypothesis in conditions that are as standardized as possible, but would further reduce the number of patients available for analysis. We proceeded from the assumption that higher chronological age in adults does not itself contribute to a reduction in blood loss and have therefore refrained from age adjustment.

The principles of patient blood management were already introduced in our hospital at the beginning of our observation period in 2012, but an influence on the reduction of intraoperative transfusions by more restrictive transfusion triggers, which were increasingly applied during our study, cannot be completely excluded [19]. However, blood loss during surgery is a parameter that is not affected by this. In addition, the postoperative transfusion rate after surgery and the hemoglobin levels after surgery were similar in both groups. This suggests that the criteria for administering transfusions did not change significantly during the observation period, otherwise lower hemoglobin levels should be observed in the intervention group. Due to the retrospective design, this is not a confirmatory, but an exploratory approach, and the observed results would need to be confirmed in prospective studies.

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