Effectiveness of Electrotherapy Techniques to Treat Low Back Pain
Condition: Chronic Low Back Pain
MeSH terms: Back Pain; Low Back Pain
Study type: Interventional

Summary: 
      Objective: The aim of this investigation was compare the effectiveness of transcutaneous
      electrical nerve stimulation (TENS) and interferential currents (IC) on chronic low back
      pain. Forty-eight patients diagnosed as having chronic low back pain were randomly assigned
      to three groups: control (sham electrotherapy; age 47 ± 8 years), interferential currents
      (IC; age 48 ± 8 years) and transcutaneous electrical nerve stimulation (TENS; age 48 ± 8
      years). Patients in all groups received 12 × 30-min sessions of the assigned treatment for a
      period of 4 weeks plus therapeutic exercises. Before and after the treatment, low back pain
      was measured using a 100-mm visual analogue scale and functional disability level was
      measured using the Rolland Morris Disability Questionnaire. Participants status was followed
      up 3 months after the end of the treatment.
    

Detailed description: 
      Subjects

      The subjects for this study were recruited from a waiting list at the Almendrales
      Physiotherapy Center (Madrid, Spain). Potential participants had to be older than 18 years
      and present continuous low back pain for more than 12 weeks. Potential participants were then
      examined by an independent specialist and the diagnosis of LBP was made according the medical
      diagnosis, the Roland Morris Disability Questionnaire (RMQD)24 and an X-ray. With these
      inclusion criteria, a total of 96 patients were contacted to participate in the experiment.
      Twenty-one participants were excluded because they fulfilled one or several of the following
      exclusion criteria: individuals presenting trauma, disc disease or lumbosciaticas;
      individuals who were receiving pain-relieving treatments with another physiotherapy method at
      the same time; patients with previous surgery or intra-articular injections; individuals with
      contraindications against electrotherapy; and declined to participate.

      Treatment groups

      The experimental design was a randomized, double-blind sham-controlled clinical trial. After
      the preliminary examination, 48 patients were randomly assigned to three groups: control
      (sham electrotherapy), 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

      Each treatment was applied 3 times per week on alternate days (excluding weekends) over a
      period of 4 weeks, including a total of 12 sessions. All the treatments were administered by
      an experienced physiotherapist. Four surface electrodes (5×5 cm Prim-Trode®, Spain) were
      symmetrically placed over the L1 and L5 transverse processes with respect to the spine; the
      current intensity was set 3 times during each session according to each patient's
      sensitivity. The patients were informed that they may or may not feel any sensation at the
      application site of the electrodes. The group with IC received a base frequency of 4000 Hz
      with AMF = 65 Hz, sweep = 95 Hz and slope of 1/1 in tetrapolar mode (Endomed 492
      Enraf-nonius, Netherlands). The group with TENS received current at a frequency of 80 Hz and
      with a pulse width of 150 μs with two channels (P-82 TENS med Enraf-nonius, Netherlands).
      Participants in the control group received the same procedures (e.g., electrode placement)
      but the current was always equal to 0. In each session, the electrical stimulation technique
      was administered for 30 minutes while the subjects were comfortable seated in an adjustable
      chair. After the electrostimulation procedures, all participants performed a 30-min session
      of therapeutic exercises. The session included lumbar stabilization (5 different exercises)
      and conventional stretching (5 different exercises). Each exercise was performed for 10
      repetitions and with 60 s of rest between exercises. These exercise routines were added to
      the all the electrotherapy techniques investigated at the request of the Ethics Committee in
      order to provide treatment to all participants.

      Outcome measurements

      The day before the onset of the treatment (pre-treatment) and the day after the end of the
      treatment (post-treatment), the intensity of low back pain was evaluated by using a 100-mm
      visual analogue pain scale (VAS). The functional status of each individual was measured using
      the Rolland Morris Disability Questionnaire(RMDQ) at these same time-points. The RMDQ is a
      simple, fast and valid questionnaire to assess the LBP disability. It consists of 24 items
      that reflect limitation in different activities of daily living attributed by the patient to
      low back pain. Each item receives a score of 1 point, so the RMDQ score ranges between 0 (no
      disability) and 24 points (the maximum possible disability). The use of disability scales,
      such as RMDQ, has been shown to correlate with physical incapacity better than the scales
      that measure the intensity of pain, X Rays, magnetic resonance imaging scans (MRIs), and
      computerized tomography scans.

      The straight leg raise (SLR) in both legs was also used to measure the range of motion of the
      leg. For this measurement, an inclinometer (Baseline, Enterprises Inc., USA) was applied to
      the anterior tibial tuberosity with the patient lying on a treatment stretcher. To prevent
      the external rotation of the hip, the contralateral leg was fixed with a strap to the
      stretcher. The examiner passively flexed the participant's hip with the knee fully extended
      until the subject felt tightness in the hamstring area or until the lower back was
      destabilized. The SLR (in degrees) was calculated separately for each leg by using one
      repetition.

      Pressure pain threshold (PPT) was measured at the lumbosacral joint and at the right and left
      sacroiliac joints with the application of a pressure algometer (FPK 20, Wagner Instruments,
      USA) with a rubber tip of 1 cm2. The PPT recorded the maximal pressure (kg/cm2) applied until
      the participant perceived it as painful. The PPT measured at each location was repeated three
      times with 1 min of rest between repetitions. The average value of these 3 measurements was
      used for further analysis.

      Three months after the end of the treatments, the RMDQ was applied to all participants to
      evaluate the LBP disability and the maintenance of the improvements obtained by the
      treatments. The follow-up was performed by the same independent experimenter and in the same
      experimental conditions.

      Statistical analysis

      All the data were analyzed using the 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 changes and the comparison between groups were
      performed by using a 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): Sham Transcutaneous nerve stimulation; Transcutaneous nerve stimulation; Interferential currents
Intervention type(s): Device; Device; Device
Intervention description(s): The group with sham transcutaneous nerve stimulation (TENS) did not receive any electrical treatment. We placed 4 surface electrodes (5x5 cm Prim-Trode, Spain) over the L1 and L5 transverse processes with respect to the spine but we did not delivery any current. The patients were informed that they may or may not feel any sensation at the application site of the electrodes.; The group with transcutaneous nerve stimulation (TENS) received electrical stimulation for 12 sessions at a frequency of 80 Hz and with a pulse width of 150 ns. The TENS was delivered by using 4 surface electrodes (5x5 cm Prim-Trode, Spain) placed over the L1 and L5 transverse processes with respect to the spine. The current intensity was set 3 times during each session according to each patient's sensitivity.; The group with IC received a base frequency of 4000 Hz with AMF = 65 Hz, sweep = 95 Hz and slope of 1/1 in tetrapolar mode (Endomed 492 Enraf-nonius, Netherlands). The current was applied by using 4 surface electrodes (5x5 cm Prim-Trode, Spain) into two channels: were symmetrically placed over the L1 and L5 transverse processes with respect to the spine; the current intensity was set 3 times during each session according to each patient's sensitivity.
Other intervention name(s): Sham TENS; TENS; IC
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Transcutaneous electrical nerve stimulation (TENS); Interferential currents therapy; Therapeutic exercises; Low back pain; Rehabilitation