Effectiveness of Two Electrotherapy Techniques to Treat Subacromial Impingement Syndrome
Condition: Subacromial Impingement Syndrome
MeSH terms: Shoulder Impingement Syndrome; Syndrome; Rotator Cuff Injuries
Study type: Interventional

Summary: 
      Objective: The investigators aimed to compare the effectiveness of transcutaneous electrical
      nerve stimulation (TENS) and interferential currents (IC) to improve shoulder functionality
      and to reduce perceived pain in patients with subacromial impingement syndrome (SIS). Design:
      Thirty-six patients with unilateral shoulder pain and diagnosed as having SIS were randomly
      assigned into two groups: TENS (n=18; 51±7 years) and IC (n=18; 47±6 years). Patients in both
      groups received fifteen 30-min sessions of the assigned treatment for a period of 3 weeks.
      Before and after the treatment, shoulder pain was measured using a 100-mm visual analog scale
      and shoulder functionality was measured using the Constant-Murley scale.
    

Detailed description: 
      Subjects

      The subjects for this study were recruited from a waiting list from patients with acute
      shoulder pain at the Almendrales Medicine and Physiotherapy Center (Madrid, Spain). To be
      included in the list they had to be older than 18 years and have had unilateral shoulder pain
      for more than 1 month. Potential participants were then examined by an independent specialist
      and the diagnosis of SIS was made according to the Hawkins and Jobe tests. The use of X-ray,
      ultrasonography and magnetic resonance imaging permitted objective diagnoses of SIS and the
      exclusion of patients with other shoulder pathologies. With these inclusion criteria, a total
      of 63 patients were recruited for the experiment. The following participants were excluded
      from the investigation: individuals with rotator cuff tears or calcification; individuals
      with the presence of acute trauma; patients who were receiving treatment for their SIS with
      another method; patients with previous surgery or intra-articular injections; individuals
      with contraindications against electrotherapy. Ethical approval for this experiment was
      previously obtained by the local Institutional Review and all participants signed an informed
      consent prior to enrolling in the investigation.

      Treatment groups

      The experimental design was a randomized and double-blind clinical trial. After preliminary
      examination, the patients were randomly assigned into two groups: transcutaneous electrical
      nerve stimulation (TENS) and interferential currents (IC). A set of sealed and sequentially
      numbered opaque envelopes was used for group assignment. The study was double-blind because
      the examiner had no contact with the patient during the duration of the treatment and
      patients were not informed about the electrotherapy technique they received during the
      investigation.

      Intervention

      For both experimental groups, the treatments were applied over a period of 3 weeks, including
      a total of 15 sessions (approximately 5 sessions per week). In each session, the electrical
      stimulation technique was administered for 30 minutes while the subjects were comfortable
      seated in an adjustable chair. The group with TENS received electrical stimulation (Endomed
      182, Enraf-nonius, Germany) at a frequency of 80 Hz and with a pulse width of 150 ns. The
      TENS was applied by using 4 surface electrodes (5x5 cm Prim-Trode, Spain) into two channels:
      supraspinatus fossa and the insertion of the rotator cuff (channel 1) and "V" deltoid "
      (channel 2). The current intensity was set 3 times during each session according to each
      patient's sensitivity. Current was strong but it did not exceed the threshold of pain. The
      group with IC received a base frequency of 4000 Hz (Endomed 182, Enraf-nonius, Germany) with
      an amplitude-modulated frequency (AMF) and slope of 1/1 in tetrapolar mode, as previously
      indicated. For IC, the same number and type of surface electrodes (5x5 cm Prim-Trode, Spain)
      were placed onto the anterior and posterior deltoid, supraspinatus fossa and "V" deltoid.
      Similarly, the intensity of the current was set 3 times per session and the stimulation was
      strong but comfortable (without exceeding the threshold of pain). The treatments were
      administered by an experienced physiotherapist blinded to the aim of this investigation.

      Outcome measurements

      Shoulder pain was evaluated before and the day after the end of treatments by using a 100 mm
      visual analog pain scale. Functional status in the shoulder joint was evaluated two days
      before, after 8 sessions of treatment and the day after the end of the treatment by using the
      Constant-Murley scale. This scale is valid to assess the overall functionality of a normal, a
      diseased or a treated shoulder. In this scale, 35% of the total value was allocated from
      subjective assessments of pain (20%) and self-evaluation of activities of daily living (15%;
      including shoulder pain during sleeping, dysfunction during free time or sports and
      dysfunction during working activities). The remaining 65% of the total value came from
      objective measures of range of movement and shoulder strength. Within the objective
      evaluation, the range of motion during internal and external rotation, arm flexion and
      lateral elevation (all measured by using an inclinometer) amounted to 10% each of the total
      score. Strength was measured using the muscular balance system by Daniels30 and counted for
      25% of the total score. Thus, a young and healthy patient can have a maximal punctuation of
      100 points. The pre-to-post treatment shoulder evaluation was performed by the same
      independent experimenter using the same instruments. This experimenter was blinded to the
      treatment assigned to each participant.

      Statistical analysis

      All the data were analyzed using SPSS v.20 statistical package. Descriptive statistics were
      calculated for each group (mean and standard deviation). Normality was tested with the
      Shapiro-Wilk test. All the variables presented a normal distribution in this test (P > 0.05).
      Baseline characteristics were compared using the analysis of variance (ANOVA) for measuring
      independent data. Pre-to-post treatment data and the comparison between groups were performed
      by using two-way ANOVA (group x time). After a significant F test, differences between means
      were identified using Tukey's HSD post hoc procedure. The level of significance was
      established at P < 0.05.
    

Intervention name(s): Transcutaneous nerve stimulation; Interferential Currents
Intervention type(s): Device; Device
Intervention description(s): The group with TENS received electrical stimulation (Endomed 182, Enraf-nonius, Germany) at a frequency of 80 Hz and with a pulse width of 150 ns. The TENS was applied by using 4 surface electrodes (5x5 cm Prim-Trode, Spain) into two channels: supraspinatus fossa and the insertion of the rotator cuff (channel 1) and "V" deltoid " (channel 2). The current intensity was set 3 times during each session according to each patient's sensitivity. Current was strong but it did not exceed the threshold of pain.; The group with IC received a base frequency of 4000 Hz (Endomed 182, Enraf-nonius, Germany) with an amplitude-modulated frequency (AMF) and slope of 1/1 in tetrapolar mode, as previously indicated. For IC, the same number and type of surface electrodes (5x5 cm Prim-Trode, Spain) were placed onto the anterior and posterior deltoid, supraspinatus fossa and "V" deltoid. Similarly, the intensity of the current was set 3 times per session and the stimulation was strong but comfortable (without exceeding the threshold of pain).
Other intervention name(s): TENS; IC
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Transcutaneous electrical nerve stimulation (TENS); Ultrasound; Interferential current therapy; Rehabilitation; Shoulder pain