INTERFERENTIAL CURRENT, ULTRAHIGH-FREQUENCY CURRENT, AND EXERCISES FOR RECURRENT KNEE PAIN DUE TO OSTEOARTHRITIS
Authors:   Department of Physical Medicine and Rehabilitation, Medical University-Sofia, Bulgaria., Nikolova-Shopova S. , Aleksiev A. ,   Department of Physical Medicine and Rehabilitation, Medical University-Sofia, Bulgaria., Dimitrova V. ,   Department of Physical Medicine and Rehabilitation, Medical University-Sofia, Bulgaria.
Published: June 2021

Introduction:- There are no studies in the literature on the combined effect of interference current, ultrahigh-frequency current, and exercise in recurrent knee pain due to osteoarthritis. There is no consensus on the optimal frequency, duration, and intensity of exercise. Aim:- To study the effect of interferential current, ultrahigh-frequency current, and exercises in recurrent knee pain due to osteoarthritis and to discover the optimal frequency, intensity, and duration of exercises. Material and Methods:- Twelve outpatients (age 63.43Â±6.24 years) with recurrent knee pain due to osteoarthritis (average pain duration 6.71Â±5.21 years and last recurrence 3.92Â±1.56 before study enrolment) were followed-up for one month. They were treated for the first two weeks with interferential current, ultrahigh-frequency current, and exercises. All outpatients were instructed to perform the exercises as often as possible, as long as possible, and as intense as possible at home for one month. The pain was measured by a visual analogue scale daily for the two-week course and after one month. In the beginning, in the middle, and at the end of the month were recorded the mobility in the knee joints by goniometry, the strength of the periarticular muscles by manual muscle testing, WOMAC parameters, frequency, intensity, and duration of the exercises. Results:- During the two-week course, the pain was decreasing every following day (P>0.05). Over the weekend the pain increased (P<0.05). After two weeks and after one month the pain (P<0.05), mobility (P>0.05), muscle strength (P>0.05), and WOMAC parameters (P>0.05) significantly improved. There was a significant correlation and regression between pain and exercise frequency (P<0.05). With an exercise frequency greater than five times daily, the pain regressed to zero (P<0.05). There was no correlation between pain and exercise intensity (P>0.05) and between pain and exercise duration (P>0.05). Discussion:- The improvement of the pain during the week and its worsening during the weekend showed that interferential current and ultrahigh-frequency current had a short-term analgesic effect. The improvement of all parameters after one month showed that exercises had a long-term effect. The presence of a correlation and regression between pain and exercise frequency, combined with a lack of correlation between pain and exercise intensity or duration, indicated that frequent, short, and low-intensity exercises were optimal. Conclusion:- The combination between interferential current, ultrahigh-frequency current, and exercise is effective in recurrent knee pain due to osteoarthritis. Short and low-intensity exercises with a frequency of more than five times a day are optimal.