Potential Benets of a Selective Region High-frequency Diathermy with Therapeutic Exercises on Older Persons with Degenerative Knee Osteoarthritis

Background: Musculoskeletal degenerative diseases, such as osteoporosis, knee osteoarthritis and spondylolysis often occur in the elderly. The purpose of this case study was to investigate selective region high-frequency diathermy at trigger points with therapeutic exercises on pain, dysfunction, balance and gait in older patients with degenerative knee osteoarthritis. Methods. The patient who participated in this study was a 71-year-old woman, who had been diagnosed with moderate osteoarthritis with a Kellgren & Lawrence grading scale grade II. The treatment consisted of selective region high-frequency diathermy at trigger points, with hip and knee strengthening and stretching therapeutic exercises. Both treatments were applied simultaneously. The participant was given assessments before and after every training session using the Visual Analogue Scale (VAS), Western Ontario and McMaster Universities Arthritis Index (WOMAC), the Timed Up and Go test (TUG) and the 10 Meter Walk Test (10MWT). The participant was assessed a total of 19 times and treatment was performed 18 times for a total of 30 minutes each. Results. the Ontario and McMaster Universities Walk Conclusion. The results of this study suggest that selective region high-frequency diathermy at trigger points with therapeutic exercises may be an effective treatment to decrease pain, improve functional status, balance and gait in patients with degenerative knee osteoarthritis. The selective region high-frequency diathermy with therapeutic exercises may be feasible and provide potential benets for

points with therapeutic exercises may be an effective treatment to decrease pain, improve functional status, balance and gait in patients with degenerative knee osteoarthritis. The selective region highfrequency diathermy with therapeutic exercises may be feasible and provide potential bene ts for rehabilitation of degenerative knee osteoarthritis.

Background
Musculoskeletal degenerative diseases, such as osteoporosis, knee osteoarthritis and spondylolysis often occur in the elderly [1]. Among them, osteoarthritis occurs the most often. In fact, the prevalence of degenerative diseases occurring in the knees of people over 40 years old is as high as 15-45% [2,3].
Degenerative osteoarthritis causes joint deformity with irregular articular surfaces, and therefore, pain and joint stiffness occurs [4]. Both the quadriceps and hamstring muscles are shortened due to the thickening of the knee articular capsule, which results in the reduction in the range of motion and an increase in viscoelasticity and contractibility of the soft tissues [5][6][7][8]. In addition, joint function is undermined as activities are reduced due to joint deformity caused by continuous impact. Following this, lower extremity performing motions including gait are limited [9], hence physical activities are decreased, causing an inconvenience on a daily basis [4].
The treatment for degenerative knee osteoarthritis includes surgical options such as joint replacement, and non-surgical options such as medicinal and physical therapy, which alleviate in ammation using injections or medications. These methods are applied by considering the patient's condition and any risk [9]. Physical therapy methods include manual therapy, therapeutic exercise, taping, electrotherapy, and light therapy, among others [10].
High-frequency diathermy has been used as a physical therapy method. It generates a safe range of frictional heat deep inside the body without any burn risks, and does not stimulate sensory and motor nerves due to its very short pulse duration. The short pulse duration also does not induce muscle contraction during the diathermic process while increasing the temperature of local tissues, and thereby, reducing pain [11]. In particular, the simultaneous application of both high-frequency diathermy and therapeutic exercise further alleviates the pain of patients with degenerative knee osteoarthritis and is effective in improving the function levels [12], joint stiffness, balance [13] and gait [14].
There is, however, a study [15] demonstrating that the treatment using both high-frequency diathermy and therapeutic exercise cannot result in better improvement of degenerative knee osteoarthritis, than treatment with only therapeutic exercise. There is also a systematic review which cannot show that the treatment using both high-frequency diathermy and therapeutic exercise is more effective for functional performance, than using therapeutic exercise alone [16].
Trigger points, irregular and sensitive tubercles discovered in strained muscles, induce paresthesia, referred pain and impaired motor function [17], often occurring in tendons of muscles and can be caused by muscle tension, myositis, arthritis, motor abnormality and direct trauma [18]. The trigger points of quadriceps muscles result in pain at the front of the knees and around the kneecaps [19] and can involve pain and dysfunction experienced by patients with knee osteoarthritis [20]. The treatment applied to such trigger points is effective in recovering the function of quadriceps muscles [19]. Pain and sensitivity of trigger points can also be reduced by applying high-frequency diathermy to these points [21].
The electrodes of short-wave diathermy which are often used, are usually applied to relatively wide body parts due to their size, so selective diathermy for trigger points on muscles may be impossible. If electrodes with which high-frequency diathermy can be selectively applied to trigger points with the application of therapeutic exercise at the same time, better results may be expected. Although trigger points are involved with the pain and dysfunction of patients with degenerative knee osteoarthritis and can also reduce pain by increasing the pain threshold, there have been no studies on the simultaneous application of high-frequency diathermy and therapeutic exercise to these trigger points of patients and the effects thereof.
This study, therefore, attempted to investigate the feasibility and potential bene ts of selective region high-frequency diathermy at trigger points with therapeutic exercises on the pain, dysfunction, balance, and gait of a patient with degenerative knee osteoarthritis.

Patient history and systems review
The patient who participated in this study was a 71-year-old female with a height of 157.32 cm and a weight of 68.15 kg, which had been consistently maintained for 10 years. Her left upper and lower limbs were dominant.
She visited a local hospital eight years back because she started experiencing pain in her knees and was subsequently diagnosed with knee osteoarthritis; since then, she has received physical therapy intermittently. For the last three years, her knee pain has worsened, especially in her left knee, wherein it has signi cantly increased. The participant visited the C hospital outpatient clinic and her she was diagnosed with moderate osteoarthritis of the left knee (Kellgren & Lawrence grading scale grade II), and she was referred to physical therapy for pain alleviation.
The participant had no musculoskeletal, nervous and mental diseases, except for degenerative knee osteoarthritis and had not undergone any surgical or medicinal treatment for this condition. Her rehabilitative goal was to reduce pain, walk comfortably up the stairs and do housework easily.

Tests & Measures
This study evaluated the pain, functional status, balance, and gait of the subject a total of 19 times, once before and after each treatment session for 6 weeks. Each time evaluation completed was using the Visual Analogue Scale (VAS), Korean version of Western Ontario and McMaster Universities Arthritis Index (K-WOMAC), Timed Up and Go test (TUG) and 10 Meter Walk Test (10MWT), respectively. This study evaluated the subject's subjective pain by using VAS, recorded the pain in her left knee and asked her to check the pain by answering a questionnaire. With VAS, a 10-cm line was drawn and points were marked at the interval of 1-cm, with the far left = 0 (no pain) and the far right = 10 (severe pain). Then, the patient was asked to check the pain of her resting right knee. VAS is considered a reliable (ICC = 0.99) and valid pain scale [22].
K-WOMAC was used to evaluate the functional status through another questionnaire. K-WOMAC is a questionnaire for evaluating the pain, stiffness and functional status of patients with arthritis, and consists of a total of 24 questions including 5 items for pain; 2 items for joint stiffness; and 17 items for di culty of daily life performance. K-WOMAC is based on a 5-points scale (0-4 points) with a total score of 96: none = 0; a little = 1; average = 2; serious = 3; and very serious = 4. Higher total scores are associated with the worsening of symptoms and more limited activities. This scale's reliability and validity were a rmed [23].
TUG was used to evaluate balance and the subject was asked to start sitting down in a chair with armrests, get up at the sound of a starting signal, walk towards a point 3 m away, then return and again sit down in the chair. We then measured the duration of the process three times and averaged the results.
TUG has an advantage in that it can rapidly measure mobility and dynamic balance, with a retest reliability of ICC = 0.96 [24].
Lastly, we used the 10MWT to evaluate her gait and asked her to walk along a line with the length of 10 m, which was marked on the oor, at a convenient speed. We repeatedly measured her walking time for the distance of 6 m three times, excluding the rst 2 m for acceleration and the last 2 m for deceleration and averaged the measures. This test has a retest reliability of ICC = 0.93 [25].

Clinical impression
The patient was diagnosed with moderate degenerative knee osteoarthritis of the left knee (Kellgren & Lawrence grading scale grade II), and reported pain in the left knee. Although the subject did not use an assistive tool for gait, she reported serious di culty in walking up stairs and her performance was limited due to pain in one leg when standing. Her pre-assessment scores were as follows: VAS = 5 (indicating serious pain), K-WOMAC = 66 (indicating the patient's functional status had seriously deteriorated due to the degenerative knee osteoarthritis), TUG = 12.38 seconds (indicating the moderate reduction of balance), and 10MWT = 6.29 seconds (indicating pain in her left knee during walking).

Intervention
This study applied the selective region control high-frequency diathermy treatment and therapeutic exercise to the subject.
Winback 3SE, a high-frequency diathermy developed by WINBACK was used for the selective region control high-frequency diathermy treatment (Fig. 1). Winback 3SE can adjust the depth of in ltration, as it is able to select a variety of frequencies such as 300 KHz, 500 KHz, 1 MHz, etc. With it, the precise diathermy of injured regions is possible, since physical therapists can directly handle regions to which heat is transferred with their hands. This is an advantage as both high-frequency diathermy and therapeutic exercise can be applied to patients simultaneously. This study utilized the frequency of 500 KHz during every treatment session and used resistive electric transfer (RET) to facilitate the diathermy of muscles. The strength was gradually increased from 10% to the heat level that the patient could endure (0%-100%), with an average of 50%. The regions to which the treatment was applied included the quadriceps and hamstring muscles. For applying quadriceps muscles, the diathermy was conducted by attaching xed electrodes to and applying trigger points to regions below the waist, while for hamstring muscles, it was implemented by attaching xed electrodes to and applying trigger points to those below the abdomen. The selective region control high-frequency diathermy treatment was also applied to these muscles during the therapeutic exercise (Fig. 2).
According to the study by Kuru et al., 2005 [26], they examined the effects of therapeutic exercise applied to patients with knee osteoarthritis, including bridge exercise and squat, which strengthen the knee muscles and enhance their exibility. We gradually increased the exercise strength by changing the number of the exercises as well as the number of repetitions, and the manual resistance, depending on the subject's condition and performance (Table 1).  The selective region control high-frequency diathermy treatment was applied along with the therapeutic exercise, and the subject received a total of 18 sessions of the treatment: one 30 minute session, three sessions a week, for 6 weeks.

Data Analysis
This study used SPSS 18.0 for statistical analyses and analyzed the subject's general and medical characteristics, pain (VAS), functional status (K-WOMAC Index), balance (TUG) and gait (10MWT) by calculating their averages, standard deviations or frequencies.

Results
The results of pain, functional status, balance, and gait are shown in Table 2. The scores on VAS were 5 in the pre-evaluation before the treatment. After 9 sessions of the treatment the score remained 5; and only dropped to 2 after the last treatment. This indicates that there was no difference in the score between the pre-evaluation and the evaluation after 9 sessions, and the score was decreased by 3(60%) only in the evaluation after the last session (Table 2). The scores on K-WOMAC Index were 66 in the pre-evaluation; 41 after 9 sessions; and 13 after the last treatment session, indicating that the score decreased by 25 (37.88%) after 9 sessions, and by 53 (80.3%) after the last session ( Table 2).
The duration for the TUG test was 12.38 seconds in the pre-evaluation; 10.84 seconds after 9 sessions; and 9.13 seconds after the last treatment session, indicating that it decreased by 1.54 seconds (12.44%) after 9 sessions, and by 3.25 seconds (26.25%) after the last session ( Table 2).
The duration for the 10MWT test was 6.29 seconds in the pre-evaluation; 5.79 seconds after 9 sessions; and 5.15 seconds after the last session, indicating that it decreased by 0.5 seconds (7.95%) after 9 sessions and by 1.14 seconds (18.12%) after the last session (Table 2).

Discussion
This study examined the effect of selective region control high-frequency diathermy at trigger points with therapeutic exercise on the pain, functional status, balance, and gait of patients with degenerative knee osteoarthritis through a case report. The ndings showed that a total of 18 sessions of the treatment resulted in the reduction of pain and the enhancement of functional status, balance and gait, compared to before the treatment sessions. Cetin et al. (2008) applied both high-frequency diathermy and therapeutic exercise to patients with degenerative knee osteoarthritis at three sessions a week, for 8 weeks, and the ndings showed that the pain of one group of participants to which both of therapies were applied was more reduced than that of the other group to which only the therapeutic exercise was applied [12]. This study also demonstrated that the scores on VAS were reduced by 60% after the last treatment session, compared to before the rst.
The result of this case study is consistent with that of Cetin et al. (2008) showing that the application of both high-frequency diathermy and therapeutic exercise resulted in better improvement of the pain of patients with degenerative knee osteoarthritis, than the application of only the therapeutic exercise. Heat increases the blood ow [27], and therefore, alleviates the pain in patients with osteoarthritis [28] by dilating blood vessels and increasing the permeability of capillaries, cell metabolic rates and the expansibility of collagen, reduces muscle shrinkage and boosts nerve conduction. It might reduce the pain, since exercises for strengthening the muscles around knees has been known to decrease pain [29].
In addition, although the trigger points of quadriceps muscles worsen the pain of patients with degenerative knee osteoarthritis and result in dysfunction [20], the application of high-frequency diathermy reduced the pain [21]. From this we have seen the pain seemed to have greater reductions by selectively applying the high-frequency diathermy to only the trigger points.
In this study, the scores on the K-WOMAC index was reduced by 80.3% after the last treatment session, compared to before the rst, indicating the improvement of functional status. The result is likely to be similar to Rabini et al. (2012) demonstrating that the high-frequency diathermy decreases the scores of patients with degenerative knee osteoarthritis [30]. The joint pain results in hypoesthesia and reduces various muscles' functional motion [31]; knee pain, for example, weakens the strength of quadriceps muscles [32]. Patients with degenerative knee osteoarthritis can alleviate pain, enhance the bene ts of weight training and improve their functional status, through the combination of high-frequency diathermy and therapeutic exercises. These bene ts are derived through the therapeutic exercise improving the joint symptoms and enhance their motion [33], while the heat increases their knees' range of motion [34] and enhances the bene ts of weight training [35]. Moreover, the pain caused by trigger points result in the dysfunction of lower limbs of these patients [36], thus the function of lower limbs would to be improved by treating trigger points, and thereby resolving referred pain.
Giombini etal. (2011) divided 60 patients with degenerative knee osteoarthritis into experiment and control groups, and then applied the high-frequency diathermy to the former and attempted to verify the placebo effect from the latter. The ndings showed that the duration derived from TUG was signi cantly improved in the experimental group [13]. In this study, the duration was also decreased by 26.25% overall, corresponding to Giombini et al. (2011), demonstrating that the balance of patients with degenerative knee osteoarthritis is improved by high-frequency diathermy. There is usually a prominent reduction of the dynamic balance of patients who suffer from this condition [37], this reduction of balance is closely related with pain felt in the knees [38]. This effect is especially more prominently reduced, as pain of the quadriceps muscle increases [39], hence, the improvement of this pain is important for enhancing balance. In addition, the increase of both quadriceps and hamstring muscle strength signi cantly enhances the dynamic balance and decreases the risk of falling [40], while the decrease of the hamstring muscle's exibility induces the imbalance of main muscles [41]. Physical balance can be, therefore, maintained only after the exibility of the hamstring muscles is enhanced. This study thus suggests that balance might be enhanced, as knee pain is reduced by applying the high-frequency diathermy to trigger points, and increasing both the muscle strength and exibility through therapeutic exercise.
According to Ozen et al. (2019), the high-frequency diathermy decreases pain, improving the functional status and gait [14]. In the present study, the duration from 10MWT was decreased by 18.12% overall which corresponds to Ozen et al. (2019), demonstrating that the high-frequency diathermy enhances gait. The pain results in the disruption of normal gait patterns [42], function is especially limited with the pain occurring in one leg when standing [43]. Reduction of gait speed is a compensatory strategy for decreasing the load on the knee joints [44], which is imposed on knees [45] and muscle activities through the normal motion of the knees [46]. Patients with degenerative knee osteoarthritis, therefore, try to limit or even avoid walking altogether, as a strategy for managing their symptoms [47]. Hence, the reduction of pain may play an important role in enhancing the walking ability of patients this would also be improved by enhancing standing which otherwise may be limited due to the pain in one or both legs.
In addition, the weakening of the quadriceps muscles is one of the symptoms that prominently appears in patients with degenerative knee osteoarthritis [48]. The strength of the quadriceps muscles is associated with pain and gait [49], so the strengthening of quadriceps muscles is important for maintaining gait. This study reduced the pain by applying the high-frequency diathermy to the trigger points of patients with degenerative knee osteoarthritis, this results in the enhancement of weight bearing, while the increase of muscle activities enhances the gait. Moreover, gait is also thought to be enhanced, through the strengthening of quadriceps muscles with the help of the therapeutic exercise which facilitates weight bearing during walking.
The ndings showed that the selective region control high-frequency diathermy at trigger point with therapeutic exercise treatment may have a positive effect on the improvement in the pain, functional status, balance and gait of patients with degenerative knee osteoarthritis. This is a case study on only one patient with degenerative knee osteoarthritis; therefore, the ndings cannot be generalized because the sample size is very small. Further studies should thus continue to verify the effects of this treatment combination with the help of high quality research with larger sample sizes.
The ndings of this case study showed the reduction of pain and the enhancement of functional status, balance and gait. The selective region high-frequency diathermy at trigger point with therapeutic exercise would be an effective treatment for patients with degenerative knee osteoarthritis, who have pain in their knees or whose functional status, balance, and gait have deteriorated.

Conclusion
The ndings of this case study showed the reduction of pain and the enhancement of functional status, balance and gait after applying the selective region high-frequency diathermy at trigger point with therapeutic exercise. Thus, the intervention would be an effective treatment for patients with degenerative knee osteoarthritis. The selective region high-frequency diathermy with therapeutic exercises may be feasible and provide potential bene ts for rehabilitation of degenerative knee osteoarthritis. After the study received approval from the institutional review board of Kyungnam University, all subjects and their legal representatives listened to an explanation of the study purpose and procedures before voluntarily signing a children's agreement and a legal representative's agreement.

Availability of data and materials
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.