I have painful and noisy knee cap! Do I have arthritis?
Many people who suffer with knee pain, complain of a nagging pain that seems to arise from behind the knee cap . They don’t recall any precipitating injury, only that the knee has go sore and, now, affects daily activities such as climbing stairs crouching or sitting with the knees bent for long periods and sometimes it develops this grinding noise.
The knee is composed mainly of 2 joints: one between the shin bone and thigh bone (tibio-femoral joint) and another one between the knee cap and the thigh bone (patella-femoral joint).As the knee cap moves quite freely when the knee is straight, the patella-femoral joint relies on structures that stabilise the knee cap centred in
the femoral groove as it moves up and down when you bend and straighten the knee (i.e. going up the stairs, squatting).
Sometimes, due to imbalances on these structures, specific weakness and poor stability in the hip or ankle joints or even an imbalanced workout at the gym, this tracking of the kneecap on the thigh bone, just behind it, goes wrong and you can hear and feel the friction, which will sooner or later lead to discomfort in the front of the knee. As demonstrated, this tends to be purely dysfunctional, therefore an appropriate course of Physiotherapy will help you normalising the function and balance of the knee and other lower limb structures in order to improve your symptoms .
Now, answering the question, there may be some wear and tear (i.e. osteoarthritis) of these surfaces that slide on each other, but it doesn’t mean your pain arises from it, as even people with some level arthritis tend to respond well to Physiotherapy.
Image on the left - different components of muscles ac on the kneecap3
Image on the right - - Illustration and MRI image demonstrating outside maltracking of the kneecap and increased contact area (red arrows)4
1. Smith B, Selfe J, Thacker D, Hendrick P, Bateman M, Moffatt F, et al. Incidence and prevalence of
patellofemoral pain: a systematic review and meta-analysis. PLoS One. 2018; 13: e0190892.
https://doi.org/ 10.1371/journal.pone.0190892 PMID: 29324820
2. Petersen W, Ellermann A, Gösele-Koppenburg A, et al. Patellofemoral pain syndrome. Knee Surg
Sports Traumatol Arthrosc 2014; 22(10):2264–2274
3. Kapandji ,I.A., The Physiology of the Joints, Volume 2: Lower Limb, 5Ed, Churchill Livingstone -
4. Norris, R. & Massey, D. (2018), Patellar Dislocation, The Knee Resource [WWW document]
https://thekneeresource.com/conditions/patellar-dislocation/ [accessed 9 th November 2018]