A comparison between low & medium frequencies of electrotherapy and ultrasound combined as a single modality in the management of trapezius upper fibers active trigger points

Combination Therapy is the simultaneous application of electrotherapy and ultrasound at the same time, used as a single modality. Electrotherapy used can be low frequency as transcutaneous electrical nerve stimulation (TENS) or medium frequency as amplitude modulated frequency (AMF; the bipolar technique of interferential therapy). This study will be conducted at a private clinic located at Heliopolis, Egypt; to compare between the effect of medium (interferential current) and low frequency (TENS) combination therapy on the cervical range of motion (ROM) and pressure pain threshold (PPT) on upper fibers of trapezius trigger points. To ensure fidelity we explained the entire procedure to the patient; with its aims, and potential unpleasant sensation experience from TENS application and informed him that he has the right to withdraw at anytime during the study duration. 6 free sessions after the completion of the study will be offered to all participants to improve fidelity. Randomized controlled pre-post experimental design will be used. Sixty patients from both gender will participate in the study after signing institutionally approved consent form prior to data collection. Subjects will be randomly assigned into three groups; Group A: 20 subjects will receive medium frequency (AMF) combination therapy, progressive pressure release and passive stretch to the upper trapezius; 3 times per week for 4 weeks. Session duration will be approximately 30 minutes. Group B: 20 subjects will receive low frequency (TENS) combination therapy, progressive pressure release and passive stretch to the upper trapezius; 3 times per week for 4 weeks. Session duration will be approximately 30 minutes. Group C: control group; 20 subjects will receive sham combination therapy, progressive pressure release and passive stretch to the upper trapezius; 3 times per week for 4 weeks. Session duration will be approximately 30 minutes. A blinded physical therapist with more than 7 years experience will locate, identify and assess tenderness of myofascial trigger points (MTrPs) and range of motion for all subjects prior to the procedure, Outcome measure will include pressure pain threshold obtained via a digital electronic algometer, as well as active flexion/extension and side bending using a smart phone mobile application (Audette et al., 2010 and Tousignant et al., 2006) Data will be collected prior to the first treatment session as baseline measure and at the end of the last treatment session (after 4 weeks) as a post-treatment measure. MTrP1: this central MTrP is found in the mid portion of the anterior border of the upper trapezius and involves the most vertical fibers that attach anteriorly to the clavicle. MTrP2: lies caudal and slightly lateral to MTrP1 which is located in the middle of the more nearly-horizontal fibers of the upper trapezius A second physical therapist with more than 5 years experience will carry out the treatment procedure and register attendance at sessions. a) Combination therapy device Features of the device: Intelect Neo therapy system will be used in this study; with model number 6001 (Chattanooga DJO industries; made in USA) It has a Full-colour, 10.4” (26.4 cm) LCD touch screen that displays in sharp, vivid detail Its Main Power output is 100-240 VAC, 50-60 Hz Its assembled with more than 34 medium and low frequency electrical currents Ultrasound technical specification includes; a frequency of 1 MHz, +/- 5% and 3.3 Mhz, +/-5%; duty cycles of 10%, 20%, 50% and continuous; a pulse repetition rate of 16, 48 or 100 Hz; a pulse duration of 1 mSec, +/-20%; 2 mSec, +/-20%; 5 mSec, +/-20%. Its Output Power includes a medium crystal with 0-6W at 1 and 3.3 MHz, and an effective radiating area of 2.0 cm'^2' . Its output accuracy is set at +/- 20%, 10% of maximum. Parameters used; The ultrasound parameters will consist of 1 MHz pulsed US with 50% duty cycle and an intensity of 1.2 W/cm'^2' . The electrical current parameters will include; i) Amplitude modulated frequency (AMF); Interferential therapy at bipolar form; set at a carrier frequency of 4,000 Hz, continuous duty cycle; sweep beat frequency of 80-200 Hz. Intensity will be set at a bearable sensorial threshold for the patient. (Moretti et al., 2012 and Almeida et al., 2003). If adaptation occurs the intensity will be raised accordingly. ii) Acupuncture like Transcutaneous electrical nerve stimulation (TENS); will be set at an asymmetric biphasic waveform; with a phase duration 400 microseconds; cycle time continuous and frequency 2-10 Hz (Weng et al., 2005). Intensity will be increased until the patient feels a strong unpleasant and uncomfortable sensation, If adaptation occurs the intensity will be raised accordingly. Combination therapy application: The subject will be comfortably seated and the muscle will be placed in a slightly stretched position to take up the slack; making it easier to find MTrPs. The dispersive negative electrode of channel two will be placed distal to the active MTrPs; on the deltoid muscle (Loharjun, 2013), while the ultrasound head will act as the positive electrode. After adjusting both electrical current and ultrasound parameters, the intensity will be raised up until the sensory threshold for AMF current and a strong uncomfortable sensation for the TENS current. Then circular stroking of ultrasound head over active MTrP1 and 2 of upper fibers of trapezius muscle will be applied throughout the 10 minutes of treatment period. For the Control group that will receive sham combination therapy; the same therapeutic ultrasound machine and the electrode placement will be applied as experimental group but the electrical current during treatment period will be turned-off (Loharjun, 2013) b) Progressive pressure release technique; using the thumbs, knuckles or four fingers of one or both hands, steady pressure was applied over the MTrP, moving inward toward the center. Once tissue resistance is felt, we will stop and wait until resistance dissipates, and then when a slow release or a “melting away” sensation of the tissue under the treating fingers is felt, further steady pressure moving again inward toward the center will be applied. Once new tissue resistance appears, steady force will be maintained against the tissue, The muscle will placed in a position to maximize stretch, but in a relaxed one. Pressure application will vary in quantity and will start from a few ounces up to a couple of pounds and will be guided by the patient’s pain tolerance, where constant feedback will be provided by the patient. It will applied for at least 30 seconds and up to two (2) minutes at a time and repeated 3-5 times. The patient will breathe deeply and slowly while we progressively increase the pressure (Travell and Simons, 1992). c) Passive stretch: with the patient in a seated position; we will stabilize the patient's scapula with one hand pressing laterally and downward on the scapula, while the other hand placed on the side of the head applying the stretching force towards flexion, side bending to the opposite side and rotation to the same side. The stretched position will be sustained for 30 seconds, then a relaxation period of 30 seconds and repeated 3-5 times. Release is augmented by having the patient coordinate downward eye motion and slow exhalation with relaxation. (Simons et al., 1999)