Authors: Yosuke Kawaguchi, Atsushi Oda, Takaaki Ishikawa, Yoichi Omi, Hirotsugu Omi
Categories: Original Article, Kinesio tape, Knee osteoarthritis, Muscle weakness
Source: Journal of Physical Therapy Science
Doi: 10.1589/jpts.36.791
Authors: Yosuke Kawaguchi, Atsushi Oda, Takaaki Ishikawa, Yoichi Omi, Hirotsugu Omi
[Purpose] Symptoms of knee osteoarthritis include pain, limited range of motion, and muscle weakness. Conservative treatment for knee osteoarthritis includes exercise therapy, physical therapy, and taping therapy. Kinesiology taping has gained traction in clinical practice for knee osteoarthritis treatment owing to its therapeutic benefits. However, the effects of kinesiology taping on pain and muscle strength remain unclear, although these two factors are known to be related in patients with knee osteoarthritis. This study aimed to examine the effectiveness of physical therapy combined with kinesiology taping on pain and quadriceps muscle weakness in patients with knee osteoarthritis and compare it with that of placebo treatment. [Participants and Methods] The study included 31 patients diagnosed with knee osteoarthritis. We examined and compared the effects of taping between the kinesiology taping group and the placebo group with respect to knee extension muscle strength, pain, range of motion, walking speed, and quality of life after 4 weeks of physical therapy. [Results] Significant main effects of time were observed for all parameters, except the contralateral range of motion. However, significant main effects of group factors were not observed for any parameter. [Conclusion] The combination of physical therapy and kinesiology taping did not show significantly greater effectiveness than placebo treatment in alleviating pain and quadriceps weakness in patients with knee osteoarthritis.
Knee osteoarthritis (KOA) results from systemic, genetic, or intrinsic cartilage disorders, aging, and mechanical factors. It is categorized into primary KOA, attributed to increased articular cartilage stress linked with factors such as obesity and quadriceps muscle weakness, and secondary KOA, arising from post-trauma or meniscectomy, or due to inflammatory or metabolic conditions1^)^. Approximetry 80% of individuals aged ≥65 years worldwide develop KOA2^)^, with more than 25 million affected individuals in Japan, mainly according to radiographic evidence of primary KOA3^)^. Recently, KOA has been recognized to involve the entire joint complex, encompassing cartilage, meniscus, subchondral bone, synovium, ligaments, and muscles4, 5^)^. Symptoms include pain, restricted range of motion, lower limb muscle weakness, and hypertonia, which often leading to progressive symptoms and deformity. Conservative treatment is generally the initial approach, with surgical intervention considered when conservative measures is proven inadequate. Conservative treatments such as physical therapy focus on muscle strengthening, range of motion (ROM) exercises, walking regimens, with additional modalities such as taping and insole therapy. Kinesiology Tape (KT), originally used in sports settings, has gained traction in clinical practice for its therapeutic benefits.
KT possesses elasticity akin to skin and muscle, aiming to enhance subcutaneous circulation and facilitate natural healing by creating a slight separation between the skin and fascia6^)^. Studies have demonstrated that applying KT to the vastus medialis in healthy individuals increases muscle activity7^)^ and that a double-taped application to the quadriceps reduces subjective pain following a fatigue task8^)^. However, a meta-analysis indicated no significant impact on muscle strength in healthy participants9^)^. We previously reported that KT showed no effect on quadriceps peak torque in healthy individuals10^)^; thus, the direct influence of KT on muscle weakness remains uncertain. Based on these findings, the author’s preliminary study was able to clarify the immediate effects of KT on pain and knee extensor strength in KOA participants.
Recently, the impact of KT on pain has garnered considerable attention. Donec et al.11^)^ observed pain improvement in patients with KOA after applying KT to the quadriceps and around the knee for 4 weeks. Similarly, Kim et al.12^)^ found significant pain improvements in the Korean Western Ontario and McMaster Universities Questionnaire scores, staircase ascent test, and timed-up-and-go test scores after applying KT three times a week for 4 weeks. On the other hand, although pain and quadriceps strength are known to be related in patients with KOA13^)^, the effect of KT on muscle strength remains unclear.
We hypothesized that applying KT to the quadriceps muscles of patients with KOA together with exercise therapy would alleviate pain-associated muscle weakness. We also thought it would be possible to clarify the effectiveness of KT by comparing two the correct method of applying KT and the method of applying KT that is unlikely to be effective. The anticipated effects of KT include pain relief through skin stimulation14^)^ and improved circulation, such as increased blood flow15^)^. Since these effects are expected to persist as long as the patch is applied, KT could potentially enhance and sustain the benefits of physical therapy. Therefore, this study aimed to determine the effectiveness of physical therapy combined with KT in treating pain and quadriceps weakness in patients with KOA.
The participants included 31 patients diagnosed with KOA from Omi orthopedic clinic, all of whom were selected for conservative treatment. They were required to undergo outpatient physical therapy at least twice a week. This study adhered to the ethical principles of the Declaration of Helsinki and was approved by the ethics committee of the researchers’ institution (serial 2020-034). The participants of this study received study explanations, and provided consent. Exclusion criteria included patients diagnosed with hip or ankle OA; undergoing treatment for lumbar diseases; with a history of knee joint surgery on the measured limb; with neuromuscular diseases, hearing impairments, or parallel functional disorders; unable to walk independently; wearing knee braces, and those with reduced cognitive function or comprehension. The participants were randomly divided into two groups using block the KT group and the placebo group, differing in the KT application method. To exclude a placebo effect due to the presence or absence of KT application, KT was also applied to the placebo group. Before the intervention, background information such as age, height, body mass index (BMI), and Kellgren-Lawrence grade (K-L grade) was obtained from the hospital’s medical records.
A 75 mm kinesiology tape (Nittoms, Tokyo) was used for the KT therapy. Pain over the past week was assessed for both knees using a visual analog scale (VAS), and the side with the highest pain value was designated as the measurement limb. In the KT group, KT was applied along the muscle belly of the rectus femoris muscle on the measurement limb, with a split created just above the patella to surround the patella and converge on the tibial tuberosity. In the placebo group, KT was applied once around the short axis as a sham tape, 5 cm proximal to the upper edge of the patella and 5 cm distal to the lower edge. This method is not expected to be effective because it does not follow the course of the rectus femoris muscle and does not involve the knee joint. KT was applied twice a week, with participants instructed to keep it on for 5–6 hours. If any subjective symptoms, such as itching, occurred, it was to be removed immediately.
The measurement items included bilateral knee extension strength, the 10-m walking test (10MWT), knee extension and flexion range of motion, heel buttock distance (HBD) test, quality of life (QOL), and a subjective questionnaire. All items, except the subjective questionnaire, were measured at the initial stage, 2 weeks, and 4 weeks after the onset of treatment. The subjective questionnaire was administered 2 and 4 weeks after the onset of experiment. Knee extension strength was measured using a handheld dynamometer (Mobie; Sakai Medical, Tokyo). A pull sensor was used for the traction method. Measurements were obtained with the participant seated at the top of the bed, with the knee joint flexed at 70° and the pelvis tilted backward. The pelvis was manually stabilized to prevent movement, and a belt pad was adjusted to the end of the lower leg. After several practice sessions, three measurements were taken. During each measurement, the knee was extended isometrically for 5 s, with a 30-s rest between measurements. As the index of the knee extension strength, the average of the three measurements divided by body weight (kgf/kg) was used.
The 10MWT was performed three times at maximum effort, measuring maximum walking speed and number of steps. The walkway was 10 m long, with a 2-m runway at each end. The knee joint’s ROM was passively measured in 5° increments using a University of Tokyo goniometer. For the HBD test, with the pelvis stabilized in the prone position and the knee passively flexed,and the distance between the heel and buttocks was measured using a tape measure.
QOL was assessed using the Japan Knee Osteoarthritis Measure (JKOM) and the Knee injury and Osteoarthritis Outcome Score (KOOS). The JKOM is a patient-based self-administered questionnaire designed to evaluate QOL in patients with KOA, with confirmed reliability and validity through comparisons with the 36-item Short Form Health Survey and WOMAC16^)^. It includes a VAS assessment of pain and 25 questions across four “pain and stiffness”, “activities of daily living (ADL) status”, “usual activities”, and “health status”, with lower scores indicating higher QOL. The KOOS, another self-administered questionnaire, consists of 42 questions divided into five “Symptoms”, “Pain”, “ADL”, “Sports”, and “QOL”. Each subscale score is normalized by percentage, with higher scores indicating better QOL. Both JKOM and KOOS are recommended in Japan’s guidelines for knee osteoarthritis and are widely used in knee studies.
The subjective questionnaire, completed after 2 and 4 weeks from the beginning of the treatment, consisted of self-administered items to assess current pain using VAS scores and changes in pain and ease of movement due to KT application on a 5-point scale (much better, slightly better, unchanged, slightly worse, much worse). Additionally, itching caused by the KT application was evaluated on a 3-point scale (itching occurred but did not affect movement; itching occurred and affected movement; and no itching occurred), and participants were invited to provide other opinions and impressions through free responses.
Physical therapy was conducted twice a week for 4 weeks, totaling eight sessions. Before each intervention, heat therapy using a hot pack was applied for 15 min with the KT attached, followed by 20 min of the ROM exercises for the target limb. The exercise therapy included six types of patella setting, weight-loaded knee extension exercise, hip adduction isometric contraction exercise with a ball between both knees, hip abduction exercise in the lateral position, squats, and calf raises. The intensity of each exercise was varied from 11 to 13 (easy to somewhat difficult) on the Borg scale. Patients were also instructed to perform these exercises at home once a week for 4 weeks. Compliance with the home exercises was assessed through interviews during the physical therapy sessions and recorded in the hospital’s medical record. The same physical therapist conducted all measurements and physical therapy interventions.
Statistical analysis was conducted using R version 4.2. Participant background characteristics (age, height, weight, and K-L grade) were tested for normality using the Shapiro–Wilk test. The ordinal scale scores were compared between groups using a two-sample t-test, and nominal scales were tested for independence using a χ^2^ test. A mixed effect model for repeated measures (MMRM) was employed to analyze each evaluation item, with the attachment method (KT group, placebo group) as the between-participants factor, and time (0, 2, and 4 weeks) as the within-participant factor. The main effects and interactions of group and time were assessed, and comparisons were made using t-tests with the Bonferroni method for post-hoc tests. The significance level was set at 5% for all tests.
The participants of this study comprised 37 KOA patients who visited the orthopedic department of the author’s institution between April 2021 and August 2023, Among them, 31 patients were included in the final 16 in the KT group (1 man and 15 women) and 15 in the placebo group (all women). Reasons for dropout included the onset of unrelated illnesses during the study period and scheduling conflicts. Table 1Table 1. Baseline characteristics of the participants (N=31)VariablesKT (n=16)Placebo (n=15)Gender: Male/Female1/150/15Age (years)70.7 ± 8.966.9 ± 8.5Height (m)1.54 ± 0.071.56 ± 0.05Weight (kg)56.7 ± 10.959.6 ± 9.0BMI (kg/m^2^)24.0 ± 3.824.4 ± 2.9Target right/left7/98/7TargetOppositeTargetOppositeK-L Grade00404Ⅰ4472Ⅱ8467Ⅲ3312Ⅳ1110Mean ± SD, K-L Grade: Kellegren-Lawrence Grade; SD: standard deviation. displays the baseline characteristics of each group. The mean ages were 70.7 ± 8.9 years for the KT group and 66.9 ± 8.5 years for the placebo group, with the mean BMIs of 24.0 ± 3.8 kg/m^2^ and 24.4 ± 2.9 kg/m^2^, respectively, showing no statistically significant differences between the groups. The distribution of K-L grades showed χ^2^ values of 2.07 for the target limb and 2.66 for the contralateral limb, indicating no significant differences.
The MMRM analysis are shown in Tables 2,Table 2. Analysis of variance table using mixed effect model for repeated measures (MMRM) in physical function evaluationOutcomesUnitKT (n=16)Placebo (n=15)p-value0W2W4W0W2W4WTime-comparisonBetween-group-comparisonInteractionKnee extension muscle strengthTargetkgf/kg0.32 ± 0.100.36 ± 0.090.39 ± 0.110.32 ± 0.010.35 ± 0.120.38 ± 0.13Oppositekgf/kg0.41 ± 0.120.43 ± 0.100.46 ± 0.10.40 ± 0.130.43 ± 0.140.45 ± 0.1410MWTspeedsec7.4 ± 1.66.7 ± 1.66.5 ± 1.47.2 ± 1.86.8 ± 1.56.6 ± 1.3Stepsstep17.9 ± 2.317.8 ± 2.017.1 ± 2.218.1 ± 2.117.6 ± 2.017.3 ± 2.4Knee flexion ROMTarget°137.8 ± 7.1142.2 ± 5.5142.8 ± 8.0140.3 ± 6.4143.0 ± 6.5144.0 ± 5.7Opposite°145.0 ± 8.0145.9 ± 8.2147.5 ± 7.1148.0 ± 6.5148.0 ± 6.5147.7 ± 6.8****Knee extension ROMTarget°−6.3 ± 5.6−5.3 ± 5.3−4.1 ± 4.2−5.7 ± 6.5−5.7 ± 5.6−4.0 ± 5.1Opposite°−3.8 ± 4.7−3.1 ± 4.4−3.1 ± 3.6−3.3 ± 4.9−3.0 ± 4.9−2.7 ± 4.6HBDTargetcm13.1 ± 5.28.9 ± 5.87.5 ± 5.813.0 ± 7.59.7 ± 7.99.1 ± 6.9Oppositecm8.7 ± 7.07.4 ± 6.76.6 ± 6.07.1 ± 6.76.4 ± 6.14.9 ± 5.4Mean ± SD, p<0.01 10MWT: 10minute walk test; HBD: heel buttock distance; SD: standard deviation. 3Table 3. Analysis of variance table using mixed effect model for repeated measures (MMRM) in quality of life (QOL) evaluationOutcomesUnitKT (n=16)Placebo (n=15)p-value0W2W4W0W2W4WTime-comparisonBetween-group-comparisonInteractionJKOMScorePoints30.8 ± 17.020.6 ± 11.314.9 ± 10.524.3 ± 13.218.4 ± 10.816.5 ± 9.3VASmm49.5 ± 32.721.8 ± 25.116.6 ± 26.443.3 ± 23.421.0 ± 18.017.5 ± 15.6KOOSSymptomsPoints64.7 ± 18.375.0 ± 11.480.8 ± 11.069.3 ± 14.771.7 ± 12.274.5 ± 12.1PainPoints56.4 ± 21.071.5 ± 14.578.0 ± 15.163.0 ± 16.369.8 ± 10.573.3 ± 13.8ADLPoints72.2 ± 17.284.3 ± 11.486.7 ± 13.279.4 ± 12.084.7 ± 8.985.5 ± 10.6SportsPoints45.0 ± 22.658.1 ± 18.665.6 ± 20.052.7 ± 20.760.3 ± 16.563.0 ± 16.9QOLPoints46.9 ± 22.251.9 ± 20.860.2 ± 20.453.5 ± 14.850.8 ± 16.458.6 ± 12.5Mean ± SD, p<0.05, p<0.01 JKOM: Japan knee osteoarthritis measure; KOOS: knee injury and osteoarthritis outcome score; VAS: visual analog scale; SD: standard deviation., 4Table 4. Post-hoc test results for items where interaction was observedOutcomesUnit0W2W4Wp-value0W–2W0W–4W2W–4Wknee flexion ROMOppositeKT°145.0 ± 8.0145.9 ± 8.2147.5 ± 7.1placebo°148.0 ± 6.5148.0 ± 6.5147.7 ± 6.8KOOSSymptomsKTPoints64.7 ± 18.375.0 ± 11.480.8 ± 11.0***placeboPoints69.3 ± 14.771.7 ± 12.274.5 ± 12.1Mean ± SD, *p<0.05 **p<0.01. ROM: range of motion; KOOS; knee injury and osteoarthritis outcome score; SD: standard deviation.. The results revealed a significant main effect of time on all items except the contralateral ROM. However, no significant main effects of group factors were observed for all items. There was a significant interaction between time and group for the contralateral knee flexion ROM and KOOS symptoms subscale. Post-hoc analyses for knee flexion ROM indicated significant improvement at 4 weeks than at baseline (0 weeks) in the KT group, as well as at 4 weeks compared to 2 weeks. For the KOOS symptoms subscale, post-hoc tests showed significant improvement at both 2 weeks and 4 weeks than at baseline (0 weeks).
Surveys assessing subjective changes in pain and ease of movement due to KT application at 2 and 4 weeks indicated that a majority of participants in both the KT and placebo groups reported either “much improved” or “slightly improved”. By 4 weeks, two participants in the KT group noted “no change” in pain, and one reported “no change” in ease of movement. Similarly, in the placebo group, two participants reported “no change” in pain, and one reported “no change” in ease of movement. None of the participants in either group reported their condition as “much worse” throughout the study period. Regarding itching caused by KT application, no participants in either group reported that itching occurred and affected their movements over the 4-week duration.
This small-scale randomized trial investigated the impact of physical therapy combined with KT on pain and quadriceps muscle weakness in patients with KOA. The MMRM results demonstrated a significant main effect of time across all parameters, except for knee extension ROM in the contralateral limb, indicating the effectiveness of the physical therapy program to a certain extent. However, no significant main effect of the group comparison was observed in any parameter, suggesting that the KT application method did not produce discernible changes. There was no clinically significant difference in muscle strength between the KT and placebo groups, with both showing similar improvements. Notably, knee extension strength in the target limb reached a level equivalent to the baseline strength of the contralateral limb after 4 weeks, underscoring the efficacy of the muscle-strengthening exercises implemented in this protocol. In the placebo group, the compression effect of KT applied around the short axis may have facilitated muscle exertion, contributing to improved knee extension strength. In the placebo group, KT was applied so as not to cover the rectus femoris muscle and the knee joint, a method that is thought to be ineffective. However, it is possible that the application of KT itself had a beneficial effect on pain and subjective symptoms. Furthermore, both groups showed improvements in knee extension strength in the contralateral limb, likely influenced by bilateral exercises such as squats incorporated into the therapy. Additionally, enhancements in the ADL and KOOS sports subscales suggest improved activity levels in daily life among participants.
Furthermore, improvements in the pain subscale also significantly enhanced exercise therapy and daily life efficiency. KT application is believed to stimulate mechanoreceptors in the skin, tendons, and ligaments, thereby increasing afferent feedback to the central nervous system and reducing pain14^)^. Abolhasani et al.16^)^ found that applying KT to the rectus femoris muscle of patients with KOA significantly improved pain, knee joint ROM, and timed-up-and-go (TUG) test results. Their study contrasted with ours, where the placebo group showed no improvement, possibly due to different application methods. Additionally, our study applied KT for approximately 6 hours, whereas their study applied it for 72 hours. This difference may have resulted in different clinical outcomes. We chose a 6-hour application time to balance clinical effectiveness with potential skin adverse effects and tape management during daily activities like bathing. Subjective questionnaire responses indicated that neither group experienced itching affecting daily life, suggesting no adverse skin effects.
A significant interaction between group and time was observed in the contralateral knee flexion ROM and the KOOS symptoms subscale. Post-hoc tests revealed that the contralateral knee flexion ROM significantly improved at 4 weeks than at both 0 weeks and 2 weeks in the KT group. Similarly, the KOOS symptoms subscale scores showed significant improvement at 2 weeks and 4 weeks than at baseline (0 weeks) in the KT group. The lack of improvement in the contralateral knee flexion ROM in the placebo group may be attributed to the already high baseline flexion ROM of 148°. In contrast, the KT application likely contributed to pain and swelling reduction at the application site, enhancing the perceived ease of knee movement among patients. Kim et al.12^)^ reported significant improvements in the K-WOMAC, TUG, and stair climbing test results among participants undergoing exercise therapy with KT compared to those receiving standard exercise therapy. They stated that the reason for improved performance and quality of life was an increase in knee extensor strength, but they did not actually measure knee extensor strength. Therefore, while this research protocol supports the possibility that it contributes to pain reduction, good daily living activities, and increasing of range of motion, we could not clearly demonstrate the effectiveness of KT as there was no clear difference from the placebo group. The correct method of applying KT can be considered to affect not only muscle strength but also swelling and perceived ease of movement. Regarding swelling, it is thought that it can be confirmed using ultrasound imaging, and this will be a topic for future investigation.
One limitation of this study was the absence of a non-tape group where KT was not applied at all. A placebo group was set on the assumption that there would be no effect from KT, but KT was also applied in the placebo group, the effectiveness of KT could be better elucidated by including a control group without any tape application. Another limitation was the inability to blind both the participants and evaluators owing to the different application methods used in the two groups. While the participants were unaware of the hypothesis favoring the KT group and efforts were made to avoid administering interventions simultaneously to both groups in the same environment, complete elimination of the placebo effect influence was challenging. In future research, the clinical effectiveness of KT could be more rigorously evaluated by including three KT, placebo, and a non-tape group where no tape is applied, allowing for clearer comparisons of treatment effects.
The summary of this paper was presented at the 12th Japanese Society of Musculoskeletal Physical Therapy.
The authors of this paper have no conflicts of interest to declare.