Application of General Anesthesia Combined with Saphenous Nerve-Tibial Nerve Block in Total Knee Arthroplasty.

Background: The study aimed to evaluate the safety and efficiency of the saphenous nerve plus selective tibial nerve block combined with general anesthesia in total knee replacement surgery (TKRS).
Methods: Sixty-four patients who underwent unilateral TKRS between October 2019 and June 2020 were selected as study subjects. All patients were divided into the control and observation groups using the random number table method, with 32 patients in each group. Conventional general anesthesia was performed preoperatively in both groups. The control group was given an ultrasound-guided saphenous nerve block before anesthesia induction, and the observation group was given a selective tibial nerve block on the basis of the control group. The dosage of general anesthetic drugs, recovery time from general anesthesia, hemodynamic index, inflammatory response, postoperative analgesic effect, and adverse reaction rate were compared between the two groups.
Results: Compared with the control group, the total amount of propofol and remifentanil used in the observation group was significantly less (P < 0.05). Compared with the control group, patients in the observation group experienced remarkably shorter time to recovery from respiration, time to extubation, and time in the PACU (P < 0.05). Compared with the control group, the observation group showed a significantly reduced SBP and MAP at T2, T3, and T4, respectively, and also showed a prominently lower HR at T3 and T4 (P < 0.05). Markedly lower CRP and IL-6 levels at 6 h and 24 h after surgery were found in the observation group compared to the control group (P < 0.05). Compared with the control group, patients receiving nerve block intervention got significantly lower VAS scores at 6 h, 24 h, and 48 h postoperatively (P < 0.05). However, there was no statistically significant difference in the incidence of adverse reactions between the two groups of patients (P > 0.05).
Conclusion: The application of the saphenous nerve plus selective tibial nerve block combined with general anesthesia in TKRS yields a promising analgesic effect, stable hemodynamics, low levels of postoperative inflammatory responses, and high safety.

1. Background

Total knee replacement surgery (TKRS) is the mainstay for severe knee disease and is performed under general anesthesia in most cases. Although most patients experience significant relief after treatment, nearly 20% are dissatisfied with the outcome, with major complaints including persistent residual pain, stiffness, and limited body functions in daily activities [1]. Moreover, the overall intraoperative hemodynamic stability, postoperative analgesia, and recovery of patients given TKRS are consequently less impressive, as most of them are the elderly usually complicated with hypertension, hyperlipidaemia, and diabetes [2, 3]. Therefore, screening out a safer and more effective anesthesia method has been a research hotspot in recent years. The nerve block is one of the commonly used anesthetic methods, with the advantages of the simplicity of operation, excellent analgesic effects, and fewer adverse reactions [4], and tibial nerve saphenous nerve block anesthesia was reportedly expected to be a suitable anesthetic technique [5]. In addition, the selective tibial nerve block combined with a continuous adductor canal saphenous nerve block yields a favorable outcome in the analgesic effect after TKRS [6]. However, there is a paucity of reports on the effect of general anesthesia combined with the tibial nerve plus selective saphenous nerve block on TKRS. Therefore, this study was conducted to analyse the effects of general anesthesia combined with the saphenous nerve plus selective tibial nerve block in 64 patients undergoing unilateral TKRS in our hospital.

2. Object and Methods

2.1. Research Object

Sixty-four patients who underwent unilateral TKRS between October 2019 and June 2020 were selected for the study, and the study was conducted after approval by our ethics committee. The included patients consisted of 29 males and 35 females, with the body mass index (BMI) from 19 to 23 kg/m2. All patients were assigned into the control and observation groups using the random number table method, with 32 patients in each group. All patients signed a consent form after being fully informed of the study.

2.1.1. Inclusion Criteria

The following patients were included in the study: (1) patients aged 58–76 years; (2) patients with primary osteoarthritis of the knee confirmed by computed tomography (CT) and other tests; (3) patients to have unilateral total knee arthroplasty; (4) patients with preoperative American Society of Anesthesiologists (ASA) classification [7] of grade I to III.

2.1.2. Exclusion Criteria

The following patients were excluded from the study: (1) patients with severe hepatic or renal insufficiency or cardiovascular disease; (2) patients with neurological and other diseases that prevent normal communication; (3) patients with infections or tumors at the proposed puncture site; (4) patients with coagulation disorders; (5) patients with a history of previous neuromuscular lesions of the lower extremities; (6) patients with allergies to the use of drugs; (7) patients with a history of analgesic drug abuse; (8) patients with a double knee replacement or renovated joint replacement.

2.2. Methods

Conventional general anesthesia was performed preoperatively in both groups [8]. The control group was given an ultrasound-guided saphenous nerve block before anesthesia induction, and the observation group was given a selective tibial nerve block on the basis of the control group. (1) Saphenous nerve block: the high-frequency probe (4–12 MHz), placed in the middle and lower 1/3 of the line between the anterior superior iliac spine and the patella, perpendicular to the femur, was used to clearly display the adductor canal, where in-plane puncture was performed. Ten mL of a mixture of 0.5% ropivacaine hydrochloride and lidocaine hydrochloride (Shandong Hualu Pharmaceutical Co., Ltd., State Drug Administration H37022147) was administered, and ultrasound showed uniform dispersion of the drug along the periarterial area. Subsequently, a continuous analgesia catheter was placed into the interstitial space of the adductor canal, connected to an electronic self-controlled analgesia pump, and 0.5% ropivacaine hydrochloride was continuously pumped postoperatively (background dose 5 mL/h, additional volume 5 mL/time, and lockout time 20 min). (2) Selective tibial nerve block: the probe was placed above the popliteal fossa, a cross-sectional sweep of the sciatic nerve was performed, and the sciatic nerve was traced beneath the bifurcation point, followed by an in-plane puncture at the tibial nerve below the bifurcation point. 15 mL of 0.5% ropivacaine hydrochloride was injected, and ultrasound observation showed dispersion of the drug along the tibial nerve. A continuous analgesia catheter was then placed into the interstitial space of the adductor canal, which was connected to an electronically controlled analgesia pump, and 0.5% ropivacaine hydrochloride was pumped continuously postoperatively (background dose 5 mL/h, additional volume 5 mL/time, and lockout time 20 min). General anesthesia and nerve block were performed by the same experienced anesthesiologist, and neither the patient nor his postoperative physician in charge of the evaluation was blinded to the grouping.

2.3. Outcome Measures

(1) The operating time and the dosage of remifentanil and propofol per unit time were recorded in the two groups. (2) The systolic blood pressure (SBP), mean arterial pressure (MAP), and heart rate (HR) levels were recorded before the anesthesia (T0), after induction of anesthesia (T1), at skin incision (T2), at 30 min of surgery (T3), end of surgery (T4), and 1 h after surgery (T5). (3) Venous blood (5 mL) was collected from the two groups of patients before surgery, 6 h after surgery and 24 h after surgery, and centrifugated at 2000 r/min for 15 min to obtain the serum; then, the levels of interleukin-6 (IL-6) and C-reactive protein (CRP) in the serum were determined by the enzyme-linked immunosorbent assay (ELISA). (4) The Visual Analogue Scale (VAS) was used to score the patients' postoperative pain level at 6 h, 24 h, and 48 h postoperatively. (5) Adverse reactions such as nausea, vomiting, drowsiness, and hypoglycaemia were recorded in the two groups. The formula is as follows: the number of those with adverse reactions divided by the total number of cases.

2.4. Statistical Analysis

SPSS 19.0 software was used for statistical analysis. Quantitative data such as the amount of used general anesthetic dosage, recovery time from general anesthesia, VAS score, hemodynamic indexes, inflammatory indexes, and analgesic effect that conformed to normal distribution were expressed as (), and the independent sample t-test was used for comparison between the two groups. Count data such as adverse reactions were analysed by the (x2) test. P < 0.05 indicated that the difference was statistically significant.

3. Results

3.1. Comparison of General Information of Patients between the Two Groups

There were no statistically significant differences between the two groups in terms of the age, gender, body mass index (BMI), ASA classification, and operation time (all P > 0.05) (see Table 1).

Table 1

Comparison of preoperative general information between patients of the two groups.

Group	Age	Gender		ASA classification		BMI (kg/m2)	Operating (time/min)
Group	—	Male	Female	I	II	(Level)	—
Control group	55.65 ± 6.28	14	18	20	12	22.36 ± 2.02	121.55 ± 8.02
Observation group	57.02 ± 5.15	12	20	19	13	23.45 ± 2.31	120.38 ± 7.43
t/χ2	0.95	0.26		0.07		1.97	0.61
P	0.34	0.61		0.80		0.05	0.55

3.2. General Anesthetic Drugs in the Two Groups of Patients

The total amount of general anesthetic drugs, propofol, and remifentanil, used in the observation group was (408.13 ± 51.23) mg and (0.15 ± 0.02) mg, respectively, while that in the control group was (520.42 ± 48.55) mg and (0.42 ± 0.03) mg, respectively. Therefore, compared with the control group, the total amount of propofol and remifentanil used in the observation group was significantly less (t = 9.46, 42.36, both P < 0.05) (see Figure 1).

Figure 1

Comparison of the amount of general anesthetic drugs used in patients of the two groups.

3.3. Recovery from General Anesthesia in the Two Groups

The time to recovery from respiration, time to extubation, and time in the PACU were (9.56 ± 2.02) min, (21.25 ± 3.15) min, and (43.55 ± 11.28) min in the observation group, compared with (12.32 ± 2.41) min, (32.36 ± 3.48) min, and (58.72 ± 13.65) min in the control group. Clearly, compared with the control group, patients in the observation group experienced a remarkably shorter time to recovery from respiration, time to extubation, and time in the PACU (t = 4.97, 13.45, 4.85, all P < 0.05 (see Figure 2).

Figure 2

Comparison of the recovery time from general anesthesia in patients of the two groups.

3.4. Comparison of Hemodynamic Indices between the Two Groups

Compared with the control group, the observation group showed a significantly reduced SBP (t = 7.69, 7.03, 9.40, P < 0.05) and MAP (t = 6.28, 8.20, 5.65, all P < 0.05) at T2, T3, and T4 and also showed a prominently lower HR at T3 and T4 (t = 4.64, 5.74, both P < 0.05) (see Table 2 and Figure 3).

Table 2

Comparison of hemodynamic indices between the two groups.

Group	Time	SBP (mm·Hg)	MAP (mm·Hg)	HR (次/分)
Control group	T0	126.97 ± 9.16	84.85 ± 6.06	81.21 ± 6.33
	T1	114.85 ± 8.47	73.23 ± 6.18	70.16 ± 5.72
	T2	98.32 ± 7.25	60.75 ± 4.74	63.89 ± 5.18
	T3	97.72 ± 7.64	58.75 ± 3.62	61.66 ± 4.93
	T4	95.56 ± 8.06	59.06 ± 4.54	60.15 ± 4.50
	T5	118.82 ± 7.93	76.02 ± 5.11	80.37 ± 5.85
Observation group	T0	128.58 ± 9.22	85.62 ± 5.21	80.35 ± 5.57
	T1	115.76 ± 8.50	71.55 ± 5.45	72.42 ± 6.11
	T2	113.15 ± 8.16	67.87 ± 4.32	65.26 ± 5.15
	T3	111.33 ± 7.85	66.19 ± 3.64	67.43 ± 5.02
	T4	114.46 ± 8.03	65.05 ± 3.92	66.80 ± 4.76
	T5	120.02 ± 8.26	74.48 ± 4.67	79.57 ± 6.20

Figure 3

Comparison of hemodynamic parameters between patients of the two groups.

3.5. Comparison of Inflammatory Responses between the Two Groups

Markedly lower CRP and IL-6 levels at 6 h and 24 h after surgery were found in the observation group compared to the control group (both P < 0.05) (see Table 3).

Table 3

Comparison of the inflammatory response between the two groups. ().

Group	CRP (mg/L)				IL-6 (pg/L)
	Before operation	Post-operative 6 h	Post-operative 24 h	Before operation	Post-operative 6 h	Post-operative 24 h
Control group	5.25 ± 1.31	58.36 ± 4.22	43.68 ± 3.15	37.45 ± 4.28	76.15 ± 6.39	58.36 ± 4.22
Observation group	5.57 ± 1.28	44.58 ± 2.31∗	30.42 ± 1.62∗	35.77 ± 3.36	70.52 ± 5.87∗	47.29 ± 4.58∗
t	0.99	16.20	21.18	1.75	3.67	10.06
P	0.33	<0.001	<0.001	0.09	<0.001	<0.001

PS: Comparison with control group, (P < 0.05).

3.6. Comparison of the Postoperative Analgesic Effect between the Two Groups

Compared with the control group, patients receiving nerve block intervention got significantly lower VAS scores at 6 h, 24 h, and 48 h postoperatively (P < 0.05) (see Table 4).

Table 4

Comparison of the postoperative VAS scores between patients of the two groups ().

Group	Postoperative 6 h	Postoperative 24 h	Postoperative 48 h
Control group	3.58 ± 1.21	2.75 ± 0.85	2.42 ± 0.66
Observation group	2.32 ± 1.18∗	1.66 ± 0.69∗	1.32 ± 0.42∗
t	4.22	5.63	7.95
P	<0.001	<0.001	<0.001

PS: Comparison with the control group, (P < 0.05).

3.7. Comparison of Adverse Reactions between the Two Groups

The two groups did not differ with regard to adverse reactions such as nausea, vomiting, drowsiness, and lower limb weakness (all P > 0.05), and there were no adverse phenomena such as respiratory depression and hypoglycemia that occurred in both groups (see Table 5).

Table 5

Comparison of adverse reactions between patients of the two groups (n, %).

Group	Nauseating	Vomiting	Drowsiness	Lower limb weakness	Adverse reaction rate (%)
Control group	1 (3.13)	1 (3.13)	2 (6.25)	2 (6.25)	6 (18.75)
Observation group	1 (3.13)	0 (0)	1 (3.13)	2 (6.25)	4 (12.50)
t					0.474
P					0.491

4. Discussion

Primary osteoarthritis is a common degenerative joint disease in the elderly [9], for which TKRS is one of the most important clinical treatments. Primary osteoarthritis results from a combination of risk factors, with increasing age and obesity being the most prominent ones. However, the low body immunity and comorbid chronic diseases in the elderly patients result in their less tolerance to anesthesia and surgery than young patients, with an adverse reaction of strong postoperative pain, which hinders the recovery of joint function [10, 11]. Currently, intravenous analgesia with intravenous opioid anesthetics is a mainstay to abate postoperative pain, but a regular dosage may induce discomfort such as nausea and vomiting among elderly patients [12]. With increasing aging worldwide, the number of patients given TKRS is growing dramatically each year [13]. Therefore, the selection of appropriate anesthetic methods to alleviate pain caused by TKRS in elderly patients exerts a tremendous fascination on scholars.

Laryngeal mask ventilation, one of the most important forms of general anesthesia, is widely used in clinical practice because of its simplicity and minimal irritation to the patient's airway [14, 15]. The ultrasound-guided nerve block is a flexible, visual, and radiation-free nerve block anesthetic technique that allows precise guide in the release of anesthetic drugs, block of the target nerve, and better maintenance of the hemodynamic stability, which contributes to a better anesthetic analgesic effect [16, 17]. The use of general anesthesia with a laryngeal mask alone does not allow transmission of surgically induced pain to the central nervous system by stimulated sensors, and its combination with nerve block anesthesia has gradually become a hot topic of research [18]. Jing et al. [19] found that in 60 patients undergoing TKRS, general anesthesia with the femoral nerve block and the laryngeal mask demonstrated a better analgesic effect than single general anesthesia because it reduced the total dosage of propofol and remifentanil and the incidence of adverse reactions. In addition, Gao et al. [7] reported that general anesthesia combined with the femoral nerve-sciatic nerve block was more effective in the analgesia for 60 patients undergoing TKRS compared with general anesthesia with the laryngeal mask alone. Kim et al. [5] also found that the tibial nerve-saphenous nerve block anesthesia showed great potential for an appropriate adjuvant anesthetic technique. Moreover, Zhang et al. [6] revealed that the selective tibial nerve block combined with the continuous retractor canal saphenous nerve block had good analgesia in 97 patients undergoing total knee arthroplasty. However, the effectiveness of general anesthesia combined with the selective tibial nerve plus saphenous nerve block in TKRS is still poorly understood. Of note, the patients with joint stiffness after TKA were treated with traditional Chinese massage manipulation. Previous studies showed that the knee joint range of motion (ROM) after TKA massage manipulation significantly benefits the knee joint range of motion (ROM).

The results of this study showed that the total amount of propofol and remifentanil and time to recovery from respiration, time to extubation, and time in the PACU were significantly lower in patients treated by general anesthesia combined with the selective tibial nerve plus saphenous nerve block than those treated by general anesthesia alone. The SBP and MAP levels at T2, T3, and T4 and the HR levels at T3 and T4 were also significantly lower in patients treated with the combined selective tibial nerve plus saphenous nerve block compared with the group given single general anesthesia. The VAS is an important index commonly used in clinical practice to assess the degree of pain, and the higher the score, the more severe the pain [20, 21]. Moreover, there was no significant difference in the incidence of adverse reactions between the two groups. These results suggest that general anesthesia combined with the saphenous nerve plus selective tibial nerve block has potential clinical application in TKRS, with contributions to a lower dosage of required general anesthetic drugs, more stable hemodynamic indexes, and better analgesic effects. In the course of operation, the long-term use of a tourniquet may cause local limb ischemia-reperfusion injury and inflammation. IL-6 is a proinflammatory factor secreted by lymphocytes and macrophages in response to stimulation, and CRP is a model-responsive protein secreted by stem cells early in the course of infection. They are associated with postoperative cognitive dysfunction and endothelial dysfunction [22, 23]. In the present study, the CRP and IL-6 levels at 6 h and 24 h postoperatively were significantly lower in patients treated with the combined nerve block methods than those in the general anesthesia group. The results suggest that the tibial nerve-saphenous nerve block anesthesia can inhibit the occurrence of postoperative inflammatory response in patients. The selective tibial nerve plus saphenous nerve block is an invasive operation with a propensity for infection and haematoma [24, 25].

It is worth noting that the nerve block may trigger following complications: (1) postinjection infection, due to the contamination of the needle; (2) needle fracture and other complications such as edema, haematoma, gingival lesions, soft tissue injury, and taste alteration; (3) motor dysfunction, such as unexpected falls.

There are several additional limitations in the current study that need to be addressed. First, the small sample size should be stated as a major limitation of this study. We planned to investigate our hypothesis in a minimum sample size. Second, the short duration of this study is yet one more issue, which should be considered in future studies. Third, the possible disadvantage of this option failed to be investigated. Forth, the dose-dependent toxicity is another issue since we did not perform the related trial to test the dosage efficacy. However, it is suggested that future trials should be planned with a larger sample size and longer period of intervention to make better judgment on the efficacy and safety of this strategy.

5. Conclusions

The application of the saphenous nerve plus selective tibial nerve block combined with general anesthesia in TKRS yields a promising analgesic effect, stable hemodynamics, low levels of postoperative inflammatory responses, and high safety.