Taping the patella medially: a new treatment for osteoarthritis of the knee joint?

Introduction

Osteoarthritis of the knee is a major cause of pain and disability in older people.^1,2 There is no specific treatment to modify the disease; current treatment is aimed at reducing symptoms and improving function.3 Analgesic and anti-inflammatory drugs are used widely, in spite of potential side effects and doubts about their efficacy.*RF 3- 5* Some forms of physical therapy, such as quadriceps exercises, are known to be of benefit,6 and walking aids can improve function. Surgical procedures, particularly knee joint prostheses, are increasingly being used. However, most current treatments are both expensive and potentially dangerous.

Simple, inexpensive treatment is needed for common disorders such as knee osteoarthritis, which is not life threatening but can cause years of painand handicap for a large number of people in the community. Inexpensive interventions that give patients some control over their symptoms are particularly attractive. If effective, they could reduce the financial burden of these patients as well as improving their quality of life.

Recent reports have emphasised the importance of the patellofemoral compartment in knee osteoarthritis.^7,8 Disease of this part of the joint can cause severe pain, particularly when the patient is using stairs, squatting, or kneeling.9 Malalignmentof the patella, with consequential abnormal force distribution on the lateral facet, is thought to be the cause of these symptoms. Taping of the patella to pull it medially, followed by quadriceps exercises, has recently been recommended for the treatment of young people with anterior knee pain arising from the patellofemoral joint (chondromalacia patellae).^10,11 However, data from controlled clinical trials to support such recommendations have not been published. The aims of this study were, firstly, to evaluate the symptomatic benefit of knee taping designed to realign the patella in older subjects with knee osteoarthritis and, secondly, to apply rigorous clinical trial methodology to a physical form of treatment.

Fig 1

Tape being applied with force to pull patella into medial position

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Patients and methods

The study protocol was approved by the local ethics committee. Fourteen consecutive patients attending a hospital based rheumatology clinic who fulfilled entry criteria and were willing to take part were recruited to the study. Entry criteria included the American College of Rheumatology criteriafor knee osteoarthritis,12 anterior knee pain, and difficulty walking and with steps and stairs. The mean age of the patients was 70.4 years (range 55-84) and the mean duration of knee symptoms was 8.3 years (range 1-20); 10 patients were women.

Current radiographs of both knees were obtained to establish disease severity and compartmental involvement. Standing anteroposterior views for thetibiofemoral joint and skyline views in 45° flexion (which visualise the two facets of the patellofemoral joint and its alignment) were reviewed by a single observer and graded according to a recently described system.13 All patients had radiographic evidence of osteoarthritis (defined as definite joint space narrowing with osteophytosis) in the patellofemoral compartment, predominating in the lateral facet in 12 cases. Evidence of osteoarthritis in the tibiofemoral joint was also present in all cases, although in eight of the 14 patients the disease was more severe in the patellofemoral than in the tibiofemoral compartment.

The study design was a single blind, blind observer, crossover trial of three different forms of taping of the knee joint. In each patient only the most troublesome knee at entry, nominated by the patient, was treated. The order of the three treatments was randomised (but not balanced) by random number allocation before the entry of the first patient; of six possible orders, four were used three times and one twice. The three types of taping were: neutral, in which the tape was applied directly over the front of the patella, without any pressure; medial, in which the tape pulled the patella to the medial side of the knee joint; and lateral, in which the tape was used to pull the patella to the lateral side. The taping consisted of a strip of Leukotape P (Beiersdorf, UK) applied by the same person in each case (figure). This same therapist, who remained blind to all pain scores and other outcome data throughout the study, applied all tapes. The single observer was blinded to the tape application and order of taping. Patients were not told which type of application was thought likely to be effective.

Knee pain was recorded with 10 cm visual analogue scales before and 1 hour after each tape application. Each tape was kept on for four days and overall pain on each of the four days was recorded in a diary, again with 10 cm visual analogue scale. After four days patients removed the tape and were asked to score change in symptoms in the treated knee joint (better, the same, or worse) compared with those present before the tape treatment. Aftera three day interval the procedure was repeated for the second tape position and after a further four days' tape application and three day interval, they entered the third and final arm of the study. At the end of the study period the assessor recorded which week of treatment each patient had preferred.

The crossover analysis was carried out using the outcome measures as the dependent variables, with analysis by patient, week of trial, treatment, and carryover effect (previous treatment), using recommended procedures.14 Data were also submitted to one way analysis of variance. Patient preferences were examined by an exact test, carried out under the null hypothesis.

Results

All patients tolerated the procedures well, keeping all tapes on for thefull four days. No adverse reactions were encountered. No significant period effect was detected, neither was there any carryover effect, precluding the need for further complex crossover analyses. The severity of pain did not differ one hour after each tape application. Comparisons of the daily visual analogue pain scales for each of the three types of treatment showed a significant reduction in pain for the medial tape compared with the lateral and neutral tapes (fig 2) (P<0.05, Student's t test; visual analogue scores were checked for normality with a Shapiro-Wilk test).

Fig 2

Diary pain scores by direction of tape. Bars indicate 95% confidence intervals; p=0.025

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The hypotheses that neutral tape was significantly different from either lateral or medial taping were further investigated for pain recorded on each day of treatment. As shown in table I, medial but not lateral taping produced a significant reduction in pain from day two onwards. The patients' change scores also favoured the medial tape (table II), significantly more “better” scores being recorded for the medial tape than for taping in the neutral or lateral positions (P<0.05, Kruskal- Wallis test). Eight patients preferred the week the medial tape had been applied, compared with one preferring the lateral and three the neutral tape position (two were unable to express a preference). Analysis of these data under the assumption that subjects who did not express a preference were split equally resulted in a significant difference between medial and neutral preferences (9 v 4; P<0.05) but no difference between lateral and neutral positions.

Discussion

The data indicate that tape applied with a force pulling the patella medially reduced knee pain and was preferred to taping in the lateral or neutral positions. The differences for all observations except pain at one hour or one day were statistically significant, and all favoured the medial taping. The degree of pain relief was clinically as well as statistically significant, many patients spontaneously reporting great relief as well as improved function.

The trial was carefully designed to preserve blinding to tape positions and likely benefits for both the patients and the observer. The use of three similar physical procedures by the same therapist in randomised order provides a relatively powerful test of medial taping and illustrates that rigorous trial technology can be applied to physical as well as drug treatments. The use of the same therapist and same observer for the whole study, neither of whom had expectations that were likely to influence the study, strengthens the design. The randomisation led to all but one of six possible orders being used, and the data had sufficient rank to be analysed. The absence of any period or carryover effect, and the confidence intervals for the pain recordings, suggest that the data are valid.

Patellofemoral joint osteoarthritis is common, two recent studies indicating that this compartment of the knee joint is the one most commonly affected.^7,8 The disease causes considerable pain and disability.15 All of the 14 patients treated had radiographic evidence of patellofemoral osteoarthritis, as well as symptoms (anterior knee pain) that are likely to arise from this site. The mechanism of pain relief by taping may be by relieving pressure on the damaged lateral facet of the patellofemoral joint and improving tracking of the patella and function of the quadriceps mechanism.^10,11,16 Both the mechanism of action and the value of this treatment in relation to other interventions require further investigation. The reasons for the delay in achieving significant relief of pain are unclear.

Knee osteoarthritis presents a serious health care problem: the combination of its effect on patients and the therapeutic procedures used produce a huge burden on society.^1,2,17 Simple, safe, physical treatment procedures such as taping could be of great value and might be combined with other simple, non-invasive interventions such as improved patient contact.18 In our experience, patients are able to learn to apply their own patella tape after minimal instruction. This provides them with a low cost, easy means of treatment that is under their own control. Relief of symptoms might be maintained by concurrent exercises to strengthen the medial part of the quadriceps muscle to permanently realign the patella.^6,10,11,16

This study was performed over a relatively short period and does not prove that taping is either safe or effective in the long term. Further trials to investigate taping in other patient groups, with longer periods of taping, and to test the relative costs and benefits of this and other interventions in knee osteoarthritis should be undertaken.

We thank Dr Philip Young for statistical advice and the Arthritis and Rheumatism Council for financial support.