Patello-Femoral knee (PFP) pain? It could be your foot!
The Foot’s contribution to Patello-Femoral Knee Pain (PFP) and the role running shoes and orthotics play
Knee pain is the most common lower limb overuse injuries of the lower limb (Hutchison et al, 2015). In particular patello-femoral knee pain (PFP) is a very common knee overuse injury which affects up to 25% of active individuals (Molgaard et al., 2017). PFP can be described as pain around the patella (knee cap) during activities that load the knee such as running.
Causes of PFP
Two common causes of PFP are muscle imbalances and poor biomechanical control.
Focusing specifically on the feet for this blog, poor foot biomechanics or excessive pronation of the feet is often flagged as a major contributing factor to PFP.
How the feet contribute to PFP
How the feet are thought to contribute to PFP is that when the foot excessively pronates (excessive rolls in) it creates an increase in internal rotation or twisting forces through the knee. This contributes to an imbalance in the muscles in the thigh that are trying to correct or control the knee position. A mal-alignment of the patella is the consequence and the “rubbing” on the articulation edges or groove underneath it during loading activities is what causes the pain.
Foot related treatment for PFP
One of the treatments for PFP therefore is trying to reduce the amount of pronation of the foot to reduce the aforementioned forces. Two ways of doing this include the use of a stability shoe (a running shoe that has firmer/denser foam on the medial part of the mid-sole) and/or orthotics either off the shelf or customised.
In a recent study by Molgaard et al. (2017) they concluded that the addition of foot targeted exercises and foot orthoses for 12 weeks was more effective than knee targeted exercises alone in individuals with patella-femoral knee pain. The exact reason why foot targeted exercises and foot orthoses reduced pain among individuals is currently unknown but it is postulated that foot orthoses may work by changing the biomechanics of the foot and therefore altering the kinematics of the entire lower limb (Molgaard et al., 2017).
In another study by Hutchison et al. (2015) they showed a stability shoe reduced the peak knee internal rotation throughout stance phase of jogging more than any other condition. Although they did not compare the use of a stability shoe and an orthotic (only a neutral shoe and an orthotic) the correct type of running shoe alone could help in improving lower limb biomechanics and therefore help reduce the load on the knees.
In summary, your foot biomechanics and your running shoes need to be a major consideration when you are being assessed by your practitioner to ascertain whether or not improvement to these will form part of your overall treatment plan. This will ensure best outcomes, a quicker return to running load and a decreased chance of a re-occurring knee or lower limb running injury.
To read more about causes of knee pain from our Physio Director Brad Beer click here>>
BSc (Biomed), BHlthSc (Pod)
Featured in the Top 50 Physical Therapy Blog
Hutchison, L., Scharfbillig, R., Uden, H., & Bishop, C. (2015). The effect of footwear and foot orthoses on transverse plane knee motion during running – A pilot study. Journal of Science and Medicine in Sport, 18(6), 748-752. doi:10.1016/j.jsams.2014.11.007
Mølgaard, C. M., Rathleff, M. S., Andreasen, J., Christensen, M., Lundbye-Christensen, S., Simonsen, O., & Kaalund, S. (2017). Foot exercises and foot orthoses are more effective than knee focused exercises in individuals with patellofemoral pain. Journal of Science and Medicine in Sport. doi:10.1016/j.jsams.2017.05.019