The Effects of Interferential Stimulation on Pain and Motion after Shoulder Surgery: A Prospective Randomized Study

Vishal Mehta

Fox Valley Orthopaedic Institute, USA.

DOI: 10.4236/ss.2015.610067                

Abstract

Purpose: The purpose of this study is to determine the effects of interferential stimulation on pain and motion after shoulder surgery. Study Design: Randomized Controlled Trial. Methods: 102 patients undergoing arthroscopic rotator cuff repair or labral repair were prospectively randomized to receive either an interferential stimulation unit immediately after surgery (STIM) or not to receive the unit (NO-STIM). Each patient was measured for the range of motion (ROM) in forward flexion (FF), abduction (ABD), internal rotation (IR) and external rotation (ER). These measurements were taken prior to surgery and at the 6 weeks post-operative time point. Visual Analogue Scale (VAS) scores (0 - 10) and the amount of narcotic taken (standardized to 10 mg equivalents of hydrocodone) were measured and compared between the two groups at 2 days and 4 weeks post-operatively. 51 patients were excluded due to failure to document VAS scores and medication usage, lack of follow-up at the 6 weeks post-operative time point or hospitalization after surgery. This left 27 patients in the STIM group and 24 patients in the NO-STIM group. Results: No difference was found in the amount of narcotic taken after 2 days (STIM 14.37 ± 1.02, NO-STIM 15.88 ± 1.22, p = 0.34) or after 4 weeks (STIM 45.32 ± 4.36, NO-STIM 48.96 ± 5.50, p = 0.60). No difference in mean VAS scores were found at 2 days (STIM 5.56 ± 0.53, NO-STIM 4.63 ± 0.57, p = 0.24) or 4 weeks (STIM 1.68 ± 0.39, NO-STIM 1.38 ± 0.34, p = 0.57). At 6 weeks post-operatively, a difference was found in ER (STIM 62.5 ± 4.09, NO-STIM 50.4 ± 4.09, p = 0.04), and no differences found in FF (STIM 134.2 ± 5.29, NO-STIM 133.3 ± 4.85, p = 0.60), ABD (STIM 124.8 ± 6.22, NO-STIM 119.6 ± 5.42, p = 0.53) or IR (STIM 60.0 ± 3.69, NO-STIM 55.9 ± 3.03, p = 0.39). A post-hoc power analysis performed using an á = 0.05 revealed the study to be 90% powered to identify a difference of one narcotic equivalent between groups and 90% powered to identify a 0.3 difference in VAS scores. Conclusions: The use of an interferential stimulator in the immediate post-operative period had no effect on pain or narcotic usage following arthroscopic rotator cuff repair or labral repair. External rotation was significantly greater in the interferential stimulator group while no differences were found in other motion parameters.

Keywords

Shoulder, Arthroscopy, Pain, Interferential Stimulation, Motion

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Ward, A.R. (2009) Electrical Stimulation Using Kilohertz-Frequency Alternating Current. Physical Therapy, 89, 181-190. http://dx.doi.org/10.2522/ptj.20080060
[2]	Robinson, A.J. and Snyder-Mackler, L. (2008) Clinical Electrophysiology: Electrotherapy and Electrophysiologic Testing. 3rd Edition, Lippincott Williams & Wilkins, Philadelphia.
[3]	Walker, U.A., et al. (2006) Analgesic and Disease Modifying Effects of Interferential Current in Psoriatic Arthritis. Rheumatology International, 26, 904-907. http://dx.doi.org/10.1007/s00296-006-0102-y
[4]	Zambito, A., et al. (2006) Interferential and Horizontal Therapies in Chronic Low Back Pain: A Randomized, Double Blind, Clinical Study. Clinical and Experimental Rheumatology, 24, 534-539.
[5]	Minder, P.M., et al. (2002) Interferential Therapy: Lack of Effect upon Experimentally Induced Delayed Onset Muscle Soreness. Clinical Physiology and Functional Imaging, 22, 339-347. http://dx.doi.org/10.1046/j.1475-097X.2002.00441.x
[6]	Johnson, M.I. and Tabasam, G. (2002) A Single-Blind Placebo-Controlled Investigation into the Analgesic Effects of Interferential Currents on Experimentally Induced Ischaemic Pain in Healthy Subjects. Clinical Physiology and Functional Imaging, 22, 187-196. http://dx.doi.org/10.1046/j.1475-097X.2002.00416.x
[7]	Cheing, G.L. and Hui-Chan, C.W. (2003) Analgesic Effects of Transcutaneous Electrical Nerve Stimulation and Interferential Currents on Heat Pain in Healthy Subjects. Journal of Rehabilitation Medicine, 35, 15-19. http://dx.doi.org/10.1080/16501970306101
[8]	Cramp, F.L., et al. (2000) A Controlled Study on the Effects of Transcutaneous Electrical Nerve Stimulation and Interferential Therapy upon the RIII Nociceptive and H-Reflexes in Humans. Archives of Physical Medicine and Rehabilitation, 81, 324-333. http://dx.doi.org/10.1016/S0003-9993(00)90079-0
[9]	Johnson, M.I. and Tabasam, G. (2003) An Investigation into the Analgesic Effects of Interferential Currents and Transcutaneous Electrical Nerve Stimulation on Experimentally Induced Ischemic Pain in Otherwise Pain-Free Volunteers. Physical Therapy, 83, 208-223.
[10]	Noble, J.G., et al. (2000) The Effect of Interferential Therapy upon Cutaneous Blood Flow in Humans. Clinical Physiology, 20, 2-7. http://dx.doi.org/10.1046/j.1365-2281.2000.00207.x
[11]	Hurley, D.A., et al. (2001) Interferential Therapy Electrode Placement Technique in Acute Low Back Pain: A Preliminary Investigation. Archives of Physical Medicine and Rehabilitation, 82, 485-493. http://dx.doi.org/10.1053/apmr.2001.21934
[12]	Almeida, T.F., et al. (2003) The Effect of Combined Therapy (Ultrasound and Interferential Current) on Pain and Sleep in Fibromyalgia. Pain, 104, 665-672. http://dx.doi.org/10.1016/S0304-3959(03)00139-8
[13]	Johnson, M.I. and Tabasam, G. (2003) An Investigation into the Analgesic Effects of Different Frequencies of the Amplitude-Modulated Wave of Interferential Current Therapy on Cold-Induced Pain in Normal Subjects. Archives of Physical Medicine and Rehabilitation, 84, 1387-1394. http://dx.doi.org/10.1016/S0003-9993(03)00151-5
[14]	Johnson, M.I. and Tabasam, G. (2003) A Single-Blind Investigation into the Hypoalgesic Effects of Different Swing Patterns of Interferential Currents on Cold-Induced Pain in Healthy Volunteers. Archives of Physical Medicine and Rehabilitation, 84, 350-357. http://dx.doi.org/10.1053/apmr.2003.50005
[15]	Taylor, K., et al. (1987) Effects of Interferential Current Stimulation for Treatment of Subjects with Recurrent Jaw Pain. Physical Therapy, 67, 346-350.
[16]	Van Der Heijden, G.J., et al. (1999) No Effect of Bipolar Interferential Electrotherapy and Pulsed Ultrasound for Soft Tissue Shoulder Disorders: A Randomised Controlled Trial. Annals of the Rheumatic Diseases, 58, 530-540. http://dx.doi.org/10.1136/ard.58.9.530
[17]	Jarit, G.J., et al. (2003) The Effects of Home Interferential Therapy on Post-Operative Pain, Edema, and Range of Motion of the Knee. Clinical Journal of Sport Medicine, 13, 16-20. http://dx.doi.org/10.1097/00042752-200301000-00004