Many people experience anterior knee pain at some time in their life, and chances are that if you are one of those people, you will have had your knee taped by your health professional. Typically the explanation given is that the patella is not tracking correctly in the femoral groove and taping will assist this alignment, and therefore reduce pain. Whilst there is no doubt that taping around the knee can reduce pain in many people, this mechanical explanation has been debated for some time. A recent study from the University of Nevada has further questioned this notion.
The researchers in Nevada had 14 young female subjects with anterior knee pain and tested them in a crossover trial using an MRI to look at patella position with no tape, “McConnell tape” (the traditional method using rigid tape), and kinesiology tape (K-tape). They also had the subjects rate their pain during a step-down task with each condition (no tape, rigid tape and K-tape). This is a commonly used functional task used in knee pain studies. Each subject completed the MRI study and step-down task without tape, then were randomly allocated to rigid tape or K-tape next, then the remaining condition last. The MRI was set up to be done in 25% weight bearing as this has been shown in previous studies to be the upper threshold for patella engagement in the trochlear groove and further weight-bearing does not change alignment or contact area. MRI images were taken at extension (0? flexion), 20? flexion and 40? flexion. The parameters examined were lateral displacement of the patella, mediolateral tilt, patella height and contact area.
The study found that there was no significant effect on any parameter of patella position with either tape condition. Whilst we may observe a “medialisation” of the patella when applied to a patient in non-weight bearing in supine, this effect was not shown on MRI in weight bearing even at 0? flexion. However, despite the lack of changes to patella position on MRI, the self-rated pain score during the step-down task was significantly reduced with K-tape, and reduced, but not to statistical significance, in the rigid tape condition. So in this study, the K-tape had superior reduction of anterior knee pain compared with rigid tape.
This raises the question of by what mechanism does this occur- pain reduction but no change in patella position? This question is not answered in this study but one would assume that the answer then lies in the neural input that tape provides. Altered afferent and nociceptive input, perhaps leading to altered pain perception, and possibly an alteration in efferent output to the muscles/lower leg. However the mechanism, clinically pain reduction is a very important outcome that may then lead to being able to optimise biomechanics and exercise strategies.
Obviously this study takes a myopic view of knee pain and it is well understood that femoral motions/control and foot motions/control may have the largest impact on the successful treatment of anterior knee pain. The study also has its limitations, with a small sample size and only young females being included, affecting the ability to generalise the finding to other populations. However, the study does add the evidence that debunks a very common myth that we frequently tell our patients. It might be time to come up with a better explanation!
Ho, K., Epstein, R., Garcia, R., Riley, N., Lee, S., & Turner, C., (2017). Effects of patellofemoral taping on patellofemoral joint alignment and contact area during weight bearing. Journal of Orthopaedic and Sports Physical Therapy. 47 (2) 115-123.