Centre for Sports Medicine Research and Education, School of Physiotherapy, The University of Melbourne, Parkville, Victoria, 3010, Australia
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Abstract |
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Methods. Using a within-subjects study design, 18 participants were tested under three conditions in random order: untaped, wearing therapeutic knee tape and wearing neutral knee tape. Outcome measures included assessment of pain during each of four activities (using a visual analogue scale) and assessment of observed disability (walking speed, timed up and go test, and the step test).
Results. Therapeutic tape significantly reduced pain on three of the four activities assessed, when compared with the neutral and untaped conditions (P<0.017). The only statistically significant change in observed disability was detected in the step test (P<0.001), in favour of the therapeutic tape.
Conclusions. Therapeutic knee tape is a simple, inexpensive strategy that increases the treatment options for therapists and patients in the conservative management of knee OA. Whilst effective in immediately reducing pain, it does not appear to have a significant immediate impact on observed disability associated with the disease. Therapeutic tape may be used as an adjunct to drug and exercise therapies, potentially augmenting the individual benefits of each.
KEY WORDS: Osteoarthritis, Taping, Pain, Disability, Physiotherapy, Intervention.
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Introduction |
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Knee tape is used by physiotherapists to manage knee pain. Initially developed to treat patellofemoral pain syndrome (PFPS) [6], evidence suggests taping may benefit individuals with knee OA. In 14 patients with patellofemoral joint (PFJ) OA, Cushnaghan et al. [7] found medial patellar taping significantly reduced pain compared with neutral and lateral taping. Although encouraging, further investigation must verify these findings before taping is accepted as a valid treatment for knee OA.
Much of the disability associated with knee OA is attributed to quadriceps weakness and pain, rather than radiographic change [3, 810]. Taping benefits not only pain but various physical impairments in PFPS patients. Improved quadriceps force, knee joint kinematics and onset timing of the vasti have been noted in this population [1115]. Despite lack of investigation to date, knee taping has the potential to improve disability in knee OA via beneficial effects on pain and physical impairments.
Our aim was to compare pain and observed disability in individuals with symptomatic, generalized knee OA under three conditions: untaped; a therapeutic taping protocol designed to alter patellar alignment and unload the infrapatellar fat pad; and a neutral taping protocol designed to provide sensory input only. It was hypothesized that therapeutic taping would result in greater improvements in pain and disability than neutral taping.
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Methods |
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Participants
Eighteen participants (12 female, six male) with knee OA were recruited by advertisements in local clubs and newspapers. Diagnosis was based on the American College of Rheumatology clinical and radiological criteria [17]. Inclusion criteria were knee pain on most days of the previous month (average pain >3 cm on a 10-cm visual analogue scale, VAS), osteophytes on radiography (any view), and pain on climbing stairs (average pain >3 cm on a VAS). All participants were independent in activities of daily living. Those taking non-steroidal anti-inflammatory drugs had been on a stable dose over the previous fortnight. Exclusion criteria included physiotherapy treatment or knee surgery (previous 12 months), lower limb joint replacement, Synvisc® or intra-articular steroid injection (previous 6 months), systemic arthritic condition, severe medical condition precluding safe testing or a past allergic tape reaction.
Mean (S.D.) age, height, weight and body mass index (BMI) of the participants was 66.9 (6.5) yr, 1.6 (0.1) m, 79.7 (10.9) kg and 29.4 (4.0) kg/m2, respectively. All but one reported bilateral knee symptoms. The most painful knee was tested (non-dominant leg in 72%). Mean (S.D.) duration of symptoms was reported as 9.8 (8.6) yr. The Western Ontario and MacMaster Universities Osteoarthritis Index (WOMAC) [18] evaluated mean (S.D.) knee pain (possible scores ranging from 0 to 20), stiffness (range 08) and function (range 068), and was found to be 7.9 (2.8), 4.0 (1.9) and 27.6 (11.6), respectively. Higher WOMAC scores indicate poorer outcome.
All participants had knee radiographs [skyline, weight-bearing anteroposterior (AP) and lateral views] within the previous 12 months and these were evaluated by a single radiologist. Forty-four per cent of participants were graded as mild (grade I/II) and 56% as severe (grade III/IV) [19]. The PFJ was evaluated with regard to the presence of osteophytes and/or joint space narrowing. Eleven per cent of participants had no PFJ involvement, 50% displayed osteophytes and 39% displayed both PFJ osteophytes and narrowing.
The study was approved by the University of Melbourne Human Research Ethics Committee. All participants provided written informed consent.
Taping procedure
Therapeutic tape was applied in a standardized manner by the same investigator, regardless of clinical presentation. Skin was shaved prior to tape application. Two pieces of rigid tape (Leuko Sportstape Premium Plus, Beiersdorf Australia Ltd) applied a medial patellar glide and corrected lateral and AP tilt. Two further pieces of tape applied distal to the patella unloaded the infrapatellar fat pad. Hypoallergenic undertape (Fixomull® stretch, Beiersdorf Australia Ltd) was applied beneath the rigid tape to prevent skin irritation. For the neutral taping condition, hypoallergenic undertape was applied over the same areas of skin as therapeutic tape, but with no force applied to realign the patella or unload soft tissues. Participants were not told which taping condition was considered therapeutic. Participants were asked to report any adverse symptoms whilst wearing tape and the investigator inspected the knee after tape removal.
Participants rested for 5 min between test conditions to minimize carry-over effects of tape on cutaneous sensation. Pilot investigations, utilizing pressure-sensitive monofilaments [20], showed that tape initially increases sensitivity to touch around the knee, but cutaneous sensibility returns to baseline within 5 min of tape removal.
Pain measurement
Pain experienced whilst ascending and descending six steps, and during each of the three disability tasks, was evaluated using a 10-cm horizontal VAS [21]. Results were scored from 010 cm in increments of 1 cm.
Observed disability measures
Walking speed
As reduced gait velocity is a common feature of locomotor disability in knee OA [22], walking speed was measured at a self-selected fast pace on a level surface. Participants walked in shoes along a 7.5 m walkway. Custom-made timing gates with infrared sensors attached to a stop watch were used to calculate walking speed (m/s) over the middle 2.5 m. Results were averaged over five trials.
Step test
The step test is a functional, dynamic test of standing balance with known reliability and validity [23]. Bare-footed in front of a 15 cm step, participants stood on the osteoarthritic limb, whilst stepping the opposite foot on and off the step as many times as possible over 15 s. The number of times the participant could place the foot on to the step and return it to the floor was recorded, with higher scores indicating better balance.
Timed up and go (TUG)
This is a validated and reliable test of function in older individuals [24]. Participants were instructed to rise from a standard arm chair, walk around a cone on the floor 3 m away, return to the chair and sit down again, whilst being timed by a stop watch. Participants performed the test barefoot, once only and at their own pace.
Data analysis
Data were analysed using SPSS (Norusis/SPSS Inc., Chicago, IL, USA) and were first examined for normality and homogeneity of variance. Pain outcomes across testing conditions were compared using the Friedman test, with values of P<0.05 regarded as significant. Wilcoxon signed ranks tests were used to locate significant differences using a Bonferroni adjusted of 0.017. Disability measures were compared using one-way repeated-measures analysis of variance (ANOVA) with paired t-tests used to locate differences.
Potential predictors of change in pain and disability with therapeutic tape were analysed. Predictors included age, gender, BMI, radiographic features, and baseline pain and physical function (WOMAC). The relationship between change in pain and change in disability whilst wearing therapeutic tape was also analysed. Change in pain was determined by subtracting the severity of pain experienced under the no tape condition from the severity of pain experienced whilst wearing therapeutic tape. Similar calculations were made to determine change in the disability variables. Associations were determined using the Spearman rho coefficient.
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Results |
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Effect of tape on disability
Tape did not significantly affect walking speed or TUG (Table 1). A significant difference in the step test was evident, with therapeutic tape enabling participants to take more steps (P<0.001), indicating improved balance.
Adverse reactions
No participant reported adverse symptoms whilst wearing either form of tape, nor did the investigator observe any adverse skin responses.
Predictors of outcome with therapeutic tape
A significant association between gender and change in pain on stairs was evident, with women demonstrating a greater pain reduction than men (r=-0.47, P<0.05). No other variable was associated with change in pain whilst wearing therapeutic tape. Individuals with less severe OA on radiographs displayed greater improvement in walking speed (r=-0.56, P<0.05), but less improvement on the TUG test (r=-0.47, P<0.05) with therapeutic tape. Participants with PFJ osteophytes and narrowing demonstrated less improvement in walking speed (r=0.55, P<0.05 and r=0.56, P<0.05, respectively). However, individuals with PFJ osteophytes displayed a greater improvement in the TUG test with therapeutic tape (r=0.55, P<0.05).
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Discussion |
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Several mechanisms may explain the pain-relieving effect of therapeutic tape. Tape can improve patellar alignment in healthy controls and those with PFPS [2628]. PFJ degeneration is present in most people with knee OA [29, 30], predominantly affecting the lateral compartment [31, 32]. Given that PFJ OA is correlated with patellar malalignment [33], and this in turn is associated with increased peak patellofemoral contact pressures and loading of the lateral facet [34], therapeutic tape may thus ease pain by improving patellar alignment. The infrapatellar fat pad is pain-sensitive, often inflamed secondarily to other knee joint pathology [35] and proposed as a source of pain in knee OA [3638]. Therapeutic tape, by shortening the soft tissue of the fat pad, may relieve pain based on the principle that inflamed soft tissue does not respond well to stretching [39]. Whilst a placebo effect of tape has been suggested [40], this is an unlikely mechanism given the superior effect of therapeutic tape over neutral tape.
Our findings support Cushnaghan et al. [7]. In their cohort of 14 patients with PFJ disease, the effect of tape was evaluated over 4 days. Although medial patellar taping reduced overall daily pain (VAS) by 25% compared with neutral and lateral taping, a significant difference was not observed until day 2, with pain unchanged 1 h following application. We demonstrated an immediate pain reduction of 3555% in our cohort, which may be a result of the different taping techniques utilized. Our selection criteria were non-specific with regard to compartmental involvement of the disease. Despite the range of disease severity and PFJ involvement in our cohort, we still demonstrated beneficial effects of tape on pain, suggesting that taping may be generalizable to the wider knee OA population, and not just those with PFJ OA. These results are further supported by the lack of association between radiographic features and change in pain with tape evident in our study.
Despite participants demonstrating disability on all measures (compared with healthy elderly subjects [23, 24, 41]), little effect of tape on these parameters was apparent, suggesting that a longer period of tape application may be required before an effect on disability is evident. Dynamic standing balance (step test) was improved with therapeutic tape, but was not attributable to concurrent pain reduction. As participants reported a sense of support when wearing therapeutic tape, improved confidence in the knee may have resulted in more steps with the contralateral limb whilst standing on the symptomatic limb.
Several limitations to this study exist. A small cohort was used, and although the within-subjects design ensured adequate power to detect changes in pain, larger subject numbers are required to confirm the present findings. Also, it was not possible to allow a prolonged rest time between test conditions, thus cumulative effects of multiple testing procedures possibly resulted in participant fatigue and symptom exacerbation. The randomized testing order ensured one test condition was not favoured over another, thus these effects should have been distributed equally over all test conditions. Given the key role that quadriceps strengthening plays in rehabilitating patients with knee OA [4, 5], knowledge of knee tape effects on muscle output is desirable and warrants investigation.
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Conflict of interest |
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Acknowledgments |
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Notes |
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References |
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