The effect of interferential current treatment duration on chronic low back pain

Abstract

Background to the study: Chronic low back pain (CLBP) is a common musculoskeletal complaint, which results in increased absenteeism from work and other disabilities. Interferential current (IFC) is one of the treatment modalities used by manual and physical therapists to alleviate CLBP. Interferential current involves electrical stimulation of medium frequency using two currents that cross over each other.

There have been numerous mechanisms proposed on how IFC works with regard to pain inhibition; however, these remain unconfirmed. Common theories include those based on the gate control theory of pain and integrated pain theories.

Although the placement of the electrodes used in the IFC application has been well defined, the optimum treatment time for CLBP has not been well researched. Therefore, this study aimed to determine what protocol regarding the duration of IFC is most appropriate in the treatment of CLBP.

Aim: The aim of this study was to investigate the effect of interferential current in the treatment of chronic low back pain using variable time intervals

Methodology: This study was a randomised single-blinded clinical trial which consisted of 45 participants residing in the eThekwini municipality, divided into three groups of 15 each. The participants were randomly assigned using concealed allocation to one of three treatment groups of 15 each viz. 15, 20 or 30 minutes of interferential current (IFC). Low back pain level was determined using a numerical pain rating scale (NRS-101). Pain pressure thresholds (PPT) were measured with a pain pressure algometer. The effect of low back pain on participants’ activities of daily living was assessed using the Oswestry low back questionnaire (OLBQ).The participants received three treatments over a two week period with the fourth consultation being used for the final subjective and objective measurements a week later.

Results: Repeated measures ANOVA testing was used to examine the intra-group effect of time and the inter-group effect of treatment on the outcomes of NRS-101 and algometer readings. Profile plots were used to assess the direction and trends of the effects. An intra-group analysis revealed that, objectively and subjectively, all groups responded positively to treatment over time, with no significant time-group interaction.

Conclusion: This study concluded that neither group is more effective than the other with respect to participants’ pain perception and the OLBQ. However, groups one and three showed the largest individual improvement between consultation one and three, compared to group two which showed consistent improvement throughout for the NRS-101 readings. Based on the results collected from this study, the shortest time frame of 15 minutes of IFC application can be used in the treatment of CLBP.