Compared with Electric Cautery, Better Clinical Outcomes can be Obtained by using the Scalpel in Primary Total Knee Arthroplasty


 Background: Whether using the scalpel can provide better and faster recovery during the primary total knee arthroplasty (TKA) is still controversial. The aim of this research was to compare the clinical outcomes of using the scalpel and the electric cautery in primary TKA.Methods: From January 2016 to December 2017, a retrospective cohort study was conducted in 313 patients who underwent unilateral primary TKA by using scalpel (group S). Duringthis period, we selected 313 patients who underwent unilateral primary TKA by using electric cautery (group E) for comparison. The tourniquet time, operative time, blood loss, wound complications, visual analog score for pain, range of motion, Knee Society Scorewere assessed between the two groups. The Forgotten Joint Scorewas used to analyze the ability to forget the joint.Results: There were no significant differences intourniquet time, operative time, blood loss between the two groups (p> 0.05). In the group S, the visual analog score for pain, range of motion, Knee Society Score were found better results at 1 month, 3 months, 6 months, 12 months and 24 months after surgery (p< 0.05). In addition, during the follow-up period, the Forgotten Joint Scorewas significantly higher compared with group E (p< 0.05).Conclusion: In this research, the patients who underwent TKA by using the scalpel could achieved better clinical outcomes. In addition, if forgotten artificial joint after TKA was the final goal, the patients who underwent TKA by using the scalpel would acquired better quality of life.


Background
More than 100 million people around the world are affected by osteoarthritis (OA) [1]. It is a chronic disease, the knee joint is the most affected joint, and there is no doubt that total knee arthroplasty (TKA) is a beneficial surgical method for the treatment of end-stage knee OA [2].
The main advantages of TKA are to relieve the pain of knee, improve the knee function, restore lower limb alignment, and improve the quality of life of patients [3]. In the process of TKA, some surgeons like to use scalpel and others like to use electric cautery to expose the articular cavity. However, which of these two methods is better is still controversial.
In the past ten years, many surgeons believe that using electric cautery can reduce blood loss during surgery, so there is a tendency to use electric cautery instead of scalpel [4,5]. But many experienced orthopaedic surgeons still prefer to use scalpels to cut skin and soft tissue quickly and efficiently to complete the TKA [6]. The electric cautery is one of the common instruments in surgery, it has the advantages of good hemostatic effect, convenient and simple operation, etc. The unipolar electric cautery is a traditional device that transfers current through a resistance wire electrode to generate heat. Heating electrode suitable for tissue coagulation [7]. Although using electric cautery in surgery is very effective, it has the potential to cause complications. At the end of the 20th century, the incidence of electrosurgical injuries remained at about 2 to 5 per 1,000 people [8,9]. One study discovered that using electric cautery during surgery resulted in poor wound healing and high wound infection rates [10]. Some studies have noted that using the electric cautery during surgery not only increases the cost of the operation, but also generates a lot of harmful smoke during the operation, which affects the health of the surgical staff [11,12]. Because the electric cautery generates a lot of heat, mistakes in operation may lead to more soft tissue damage [13,14].
We found few studies comparing the clinical outcomes in primary TKA by using the electric cautery or the scalpel. Consequently, we conducted a retrospective, case matched research to compare the clinical outcomes between the two methods, with a follow-up of at least 2 years. We assumed that using the scalpel may achieve better clinical outcomes and promoting faster recovery compared to the electric cautery in primary TKA.

Methods
With the approval of the Institutional Review Committee, we performed a retrospective case-matched study from January 2016 to December 2017. 313 patients who underwent unilateral primary TKA by using scalpel were included in group S. During this period, we selected 313 patients who underwent unilateral primary TKA by using electric cautery (group E) for comparison. To improve the reliability of this research, the two groups matched in a 1:1 ratio based on age, sex, body mass index (BMI), and follow-up time. Inclusion criteria were (1) unilateral primary knee osteoarthritis; (2) flexion-contracture deformity < 20°; (3) varus deformity < 20°. Patients who had valgus or stiff knee, neurological problems, anticoagulant therapy, revision TKA, or previous open knee surgery were excluded. All surgeries were performed in our center by the same senior orthopaedic surgeon.

Surgical technique
In the two groups, the skin was incised with a scalpel, and tranexamic acid (1000 mg) was administered intravenously to all patients before surgery. According to the patient's physical condition, using hypotensive anesthesia with low mean arterial pressures. All surgeries were accomplished through the medial parapatellar arthrotomy. Pneumatic tourniquets were used during surgery to help stop bleeding, and the tourniquet was released when the wound was closed. In the group S, we used scalpel number 22 (Jinhuan® surgical blade, Jinhuan medical supplies Co., Ltd., Shanghai Pudong, China) for the midline skin incision, and then scalpel number 10 (Jinhuan® surgical blade, Jinhuan medical supplies Co., Ltd., Shanghai Pudong, China) to dissect the sub-fascial layers and opened the joint cavity by incision of the medial retinacular tissue. Then release the medial deep collateral ligament. The synovium, meniscus and anterior cruciate ligament were removed. Some major small blood vessels around the knee joint did not coagulate. In group E, using the same number scalpel for the midline skin incision. Then, using electric cautery (Peng's Multifunctional Operational Dissectors(PMOD), Co., Ltd., Zhengjiang Shuyou, China), set at 65 W coagulation mode, to separate and cut the soft tissues in the knee joint cavity mentioned above. Bleeding points were coagulated by electric cautery during the surgery. All patients received the same type of knee prosthesis (CR, Mobile bearing, LINK, Germany, Gemini MK II) and postoperative treatment options, including rehabilitation programs and pain control.

Outcome evaluation
The assessments were conducted by a senior orthopaedic surgeon who did not participate in the treatment. Patients demographics in regard to age, sex, BMI, follow-up time, operative time, tourniquet time, blood loss, wound complications were examined. Routine blood tests were performed one day before and one day after surgery to avoid the effect of perioperative infusion on the test results.
The range of motion (ROM), visual analog score (VAS) for pain, Knee Society Score (KSS) [15] were assessed. For comparing the postoperative status of the patients who received TKA via the two different method, we used the Forgotten Joint Score (FJS; a 12-item questionnaire with a maximum of 100) to analyze the ability to forget the joint [16]. Higher scores represented better results. All data were assessed at 1 month, 3 months, 6 months, 12 months, and 24 months after surgery.

Statistical Analysis
All statistical data were used the Shapiro-Wilks test to check the normality of continuous variables. If the data were normally distributed, the two groups would be compared using t-test; if not, the non-parametric test would be performed. And the Fisher's exact test was performed for categorical variables. The correlation between the FJS score and surgery method (scalpel versus electric cautery), sex, gender and BMI were analyzed by multiple linear regression. The data were analyzed with the SPSS 19.0 (IBM, Chicago, Illinois, USA). A p < 0.05 was considered statistically significant.

Results
All patients in both groups were followed up at least 2 years. No significant differences were found between the two groups in regard to age, sex, BMI, ROM, VAS, KSS, operative time, blood loss, tourniquet time before surgery (p > 0.05) (Tables 1, 2). Wound complications accounted for 2 cases (0.6%) in group S; 9 cases (2.9%) in group E (p = 0.033). No revision surgery was performed in either group.  In the group S, the results of VAS, ROM, and KSS were better than those in the group E at 1 month, 3 months, 6 months, 12 months and 24 months after surgery (p < 0.05) ( Tables 3, 4). Furthermore, during follow-up, the FJS score in group S was significantly higher than that in group E (p < 0.05) ( Table 5). The multiple linear regression showed that higher FJS score was correlated with the scalpel method (p < 0.05) ( Table 6).

Discussion
The most significant finding in this research was that the patients who underwent TKA by using the scalpel could achieved better clinical outcomes. In addition, if forgotten artificial joint after TKA was the final goal, the patients who underwent TKA by using the scalpel would acquired better quality of life.
Most surgeons believed that, like abdominal surgery [17] and spinal surgery [18], electric cautery could reduce blood loss during TKA too. In present study, we did not calculate the estimated blood loss by weighing the gauze and calculating the amount of liquid in the suction bottle. Instead, we adopted a method mentioned in the previous article [19], the blood loss was compared between the two groups by comparing haemoglobin, hematocrit before and after surgery. It has known that one unit of blood loss has an effect of 3% on hematocrit levels and 1 g/dL on hemoglobin. In our research, we found that there was no significant difference in the hemoglobin levels and hematocrit whether using the electric cautery or the scalpel. Perhaps it was related to the tourniquet, tranexamic acid, and hypotensive anesthesia with low mean arterial pressures during surgery. Furthermore, Tammachote et al. [11] believed that the main cause of intraoperative blood loss may be due to osteotomy and femoral medullary hemorrhage during surgery.
Postoperative wound infection is one of the most serious complications after TKA. The causes of infections are diverse, for example, incision hematoma, contaminated incisions, and less stringent aseptic procedures. Although we used broad-spectrum antibiotics to prevent this problem, we had not got satisfactory results. Some studies have pointed out [20][21][22] that electric cautery causes delayed wound healing and histological reports indicate that tissue damage from electric cautery can increase, leading to increased infection rates at the incision site. In addition, previous researches have reported that the inflammatory response at the wound affects early functional exercise after joint replacement [23,24]. And, the damage caused by electric cautery to surrounding tissues may be the main factor leading to the inflammatory response [13,14]. These findings were consistent with our study, in present study, we found higher wound complications by using electric cautery after TKA.
The FJS is a newly developed scoring system in recent years, which is often used to measure patients' ability of forgotten joint replacement or joint awareness in daily life. Even if the patient's knee function is improved and no pain is felt, the FJS score will be lower if the patient is "aware of " the presence of artificial joints in daily life. As a result, minor complaints that are not identified by specific issues (such as "Can you do sports?") are called "aware" joints, which may reduce the ceiling effect and more sensitively reflect postoperative quality of life [16,25]. Ozaki et al. believed that FJS is a scoring system that can express "sense of stability" as "awareness" [26]. Morten et al. believed that FJS combines factors such as stiffness, pain, ability of daily activities, and patients' expectations to reflect patients' ability of forgetting artificial joints in activities, so this scoring system may be the best tool to evaluate the results of TKA [27]. Another study found that when using the FJS scoring system to evaluate the difference in knee awareness of patients who underwent patellofemoral arthroplasty, unicompartmental knee arthroplasty and TKA treatment, they found that patients who underwent different joint arthroplasties had very large differences in the FJS [28]. In our study, we found higher FJS score by using the scalpel after TKA, and this might mean that the patients had a higher quality of life.
Increased potential smoke plume risk is another risk factor for electric cautery [11,12]. Surgical smoke exposure may increase the risk of acute or chronic lung diseases such as pneumonia or asthma. One study noted that in Mexico, as a result of exposure to electric cautery smoke, many surgical surgeries developed lump (58%) and sore throat (22%) in the throat [29]. Some studies have also shown that perioperative nurses have twice as many respiratory diseases as asthma, bronchitis, allergies, and sinus infections in the general population [30,31]. Therefore, for the safety of patients and medical staff, we should pay more attention to the problem of smoke generated by electric cautery during surgery. However, a previous study pointed out that traditional surgeries with the scalpel were more cost-effective than the electric cautery [11]. Therefore, we recommended that using the ordinary scalpel as much as possible when performing primary TKA.
The limitation of this research was that it had a retrospective short-term follow-up design, which has its potential weaknesses. A prospective and long-term research should be performed to confirm these findings.

Conclusion
In this research, the patients who underwent TKA by using the scalpel could achieved better clinical outcomes. In addition, if forgotten artificial joint after TKA was the final goal, the patients who underwent TKA by using the scalpel would acquired better quality of life.

Declarations
Ethics approval