Electrostimulation has a positive effect on the knee function after knee arthroscopic surgery: A randomized trial

1. Introduction

Knee arthroscopy is one of the most common surgical interventions and is characterized by a low risk of complications [1]. Accompanying partial meniscectomy is most frequently performed in middle-aged individuals suffering from persistent knee pain [2]. On the other hand, arthroscopic reconstruction of the anterior cruciate ligament concerns athletes who do contact sports, where knee injuries with the ACL tearing occur most frequently [3, 4]. Problems impacting subjects after knee arthroscopy primarily include pain and related deterioration of everyday functioning and mental state [5, 6]. Other ailments include swelling, limited range of the knee motion and muscle atrophy affecting particularly quadriceps femoris [7, 8]. Rehabilitation, especially after the anterior cruciate ligament reconstruction is of critical importance [9, 10]. There is a wide range of postoperative protocols but they are all based on specialist exercises, comprise of specific stages and include key moments but should always be individualized and adjusted to the subject’s needs [11].

Postoperative rehabilitation procedure that primarily includes kinesiotherapy oftentimes involves physical therapy, especially electrotherapy [12, 13, 14, 15]. One of the treatments supplementing rehabilitation after knee arthroscopy is BodyFlow. The first treatise described the impact of Bodyflow application on the blood flow, fibrinolysis, and activation of anticoagulant factors [16] and the second one focused on its impact on healthy subjects after physical effort [17]. Henceforth, two other scientific works including findings on the BodyFlow application were published: One was published in 2010 and focused on its impact on lymphedema [18], while the other one was published in 2014 and discussed the impact of mild electrostimulation on the healing of wounds caused by the lower leg ulceration [19]. Given the short period of time and the fact that this is an innovative treatment, the number of studies published in peer-reviewed journals is small. The manufacturer recommends its application after knee arthroscopy, but, unfortunately, no studies on the efficacy of mild electrostimulation using BodyFlow after such interventions are available in the literature.

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The research question in our study was thus as follows: Does mild electrostimulation using the Body Flow device have an impact on the knee functioning and convalescence of subjects after arthroscopy?

All subjects were randomly assigned to the study or control group prior to the study. Study group subjects were treated according to a generally adopted scheme of rehabilitation procedure after knee arthroscopy and received devices for mild electrostimulation (BodyFlow Portable P2CH) to use independently for 3 weeks. The control group subjects were treated according to the generally adopted standards applied after knee arthroscopy. Randomization was performed by deployment of all subjects from one orthopedic center to the study group, while the subjects from another center were assigned to the control group. The measurements were taken 3 and 6 weeks after arthroscopy (study group subjects returned devices) and 9 weeks after arthroscopy, by a person who knew how the subjects were deployed (Fig. 1).

All consecutive patients who were operated at two orthopedics centers with knee arthroscopy (meniscectomy or reconstruction of the anterior cruciate ligament) were qualified for the study. Patients with implanted cardiological devices, history of systemic disorders, deep vein thrombosis, fractures of the involved limbs, neoplastic disease, and suspected pregnancy were excluded.

Study group subjects were given the BodyFlow Portable P2CH device for mild electrostimulation so that they were able to perform treatments on their own for 21 days (from day 21 to 42). The treatments were performed five times a day, every three hours. A local (sectional) 4-electrode stimulation was applied using flat, adhesive, rubber, 5 cm × 9 cm electrodes (placed 10 cm from the knee slit proximally and distally) where two circuits covered the knee after arthroscopy (Fig. 2). The standard program was applied: it was 20-minute long and amperage ranged between 1 and 40 mA depending on the patient’s feelings. The pulses generated during treatments were monophasic, triangular, 6 ms long, 500 ms – long break, frequency 1.5 Hz and cyclically repeated variable polarization of stimulating pulses occurred. Both groups were instructed about the future procedure according to the generally adopted schemes, including unweighting and weighting of the operated limb.

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The preliminary assessment was conducted to confirm or exclude the possibility of participating in the study. After a preliminary assessment had been made, symmetrical measurements of both lower limbs, knee motion range and knee extensor and flexor strength according to Lovett were taken. Moreover, subjects responded to the KOOS and SF-36 surveys. All measurements were collected at the time of surgery 3.6 and 9 weeks postoperatively.

Size measurements were taken by means of the tape, in the supine position, symmetrically, beginning from a healthy lower limb. Four measurements were taken on each limb, according to the methodology of measurements of the lower limb size – the first thigh measurement (taken around the largest part of upper leg), the second thigh measurement (6 cm from the upper pole of the knee cap), the knee measurement (through the knee joint cleft) and the first shank measurement (around the largest part of calf).

Measurements of the range of motion – knee flexion and extensions – were taken by means of the goniometer, symmetrically, beginning from a healthy limb, in the prone position, with feet placed beyond the couch and stabilized pelvis. The goniometer axis (corresponding to the crosswise axis of the knee) was located in the vicinity of the fibular head, a fixed arm was directed at greater trochanter (corresponding to a long axis of the thigh), while a movable arm at lateral ankle (along shanks).

Measurements of the muscle strength (according to the Lovett scale) were taken symmetrically, firstly on a healthy limb in the position depending on the group of muscles involved in the study. Testing of flexors was performed in the standing position, with the anterior body surface adhering to the wall and stabilized pelvis, with a non-tested limb placed on a rather low platform and a tested limb hanging freely. The assessed movement was tested in the following way: 3 according to the Lovett scale – free knee flexing, 4 according to the Lovett scale – flexing with submaximal resistance applied above tuber calcanei, 5 according to the Lovett scale – flexing the maximal resistance applied as in test 4. Testing of extensors was performed in the sitting position with lower legs hanging freely, with no support for the feet. The untested limb was placed in the position of abduction in the hip joint to the angle of 30 ∘ . Patients were asked to auto-stabilize themselves by gripping the edge of the couch and the anterior aspect of the thigh of the tested limb was stabilized. The assessed movement was tested in the following manner: 3 according to the Lovett scale – knee extension perpendicularly to the floor, 4 according to the Lovett scale – knee extension with submaximal resistance applied above ankles on the anterior aspect of a lower leg, 5 according to the Lovett scale – knee extension with maximal resistance applied as in test 4.

KOOS (Knee Injury and Osteoarthritis Outcome Score) and SF-36 (The Short Form (36) Health Survey) were used in the study.

The study group subjects were free to express their subjective, short, written opinion about the therapy using the BodyFlow device for mild electrostimulation.

A difference in specific measures of the knee after arthroscopy was used to analyze size, range of motion, and muscle strength. To analyze the KOOS and SF-36 survey scores, the differences in percentage results for specific elements assessing physical and mental functioning were considered. A mean and standard deviation were calculated for each group of assessed parameters. The t-student test was performed for independent groups, calculating statistical significance between the study and control group. A significance ratio p ⩽ 0.05 was applied in each test.

Out of 93 subjects included in the study, 6 could not be assessed on day 21 after intervention. Three study group patients did not perform mild electrostimulation, while 3 control group patients refused to participate in the study. Moreover, 10 patients, including 3 from the study group and 6 from the control group, were unavailable after 9 weeks (Fig. 1).

The characteristics of the participants from each group are shown in Table 1 and in the two first columns in Tables 2–4.