Often called movie-goers knee, pain behind your patella (kneecap) is one of a few tell-tale signs you might be suffering from this common knee issue. Patellofemoral Pain Syndrome (PFPS) is characterised by pain felt behind your kneecap, in the joint that articulates your patella and your femur (thigh bone). It is just as commonly found in the young, active population as it is in the more sedentary, older age groups.
What causes the pain?
As your knee bends and straightens, your kneecap normally glides up and down the femoral (also known as trochlear) groove, which is located at the end of your thigh bone. As your knee bends, the kneecap pulls tightly into the groove increasing the pressure between your kneecap and the groove. If your kneecap repeatedly does not glide normally through the groove, but rather maltracks (i.e. it travels or rubs more to one side), gradual irritation to the joint surfaces occur and pain behind the kneecap starts to be felt.
Image credit: Ortho Info
What are the symptoms?
- Gradual onset of pain felt behind or around the kneecap
- Pain felt with weight bearing activities that involve bending of the knee like squatting, lunging, kneeling, and walking up and down stairs
- Pain with sitting, especially worse with low chairs (hence the term movie goers knee)
What factors lead to developing PFPS?
As mentioned above, generally the onset of pain is gradual. The condition develops slowly, often as a result of other issues in your lower limb, or sudden changes in activities requiring more bending in your knee.
On examination of your knee, it is common to see a muscle imbalance between your quadriceps muscles.
Image credit: Get Back To Sport
If there is a muscle imbalance between the quadriceps muscles – vastus lateralis (VL), which pulls your patella up and outwards, and the vastus medialis oblique (VMO), which is the only quadriceps muscle that pulls your kneecap up and slightly in – then your patella will track laterally in the groove, causing maltracking.
The two main ways the imbalance will occur is with VMO weakness and or tight lateral structures. VMO weakness can be caused by trauma or from post-surgery knee pain. Tight lateral structures can occur from training errors and poor biomechanics.
Research also shows your hip muscles are very important in the control of your thigh. Reduced glute muscle control allows your knee to roll in and cause an outwards pull on the patella. Similarly, poor foot posture (e.g. flat feet) can also allow the knee to excessively roll inwards and create an outwards pull on the patella. When poor biomechanics are repeated with each step of your walking and running, maltracking will slowly cause pain to develop. Factors outside of your control that can also lead to developing PFPS are usually shaped patellae, femoral grooves and hip angles.
What can be done?
As mentioned above, VMO is a muscle on the inside of your knee that forms the large muscle group quadriceps quads. The action of the VMO is very important in walking, running and any activity that involves bending your knee.
Researchers have confirmed that physiotherapy intervention is a very effective short and long-term solution for PFPS. VMO activation is crucial to this and your physio will be able to commence you on appropriate VMO exercises for your level. These exercises can take some time to notice results, so patience is key. Doing too much and causing more pain will stall your progress. Other exercises prescribed may focus on other weaknesses found – for example glute and calf muscles.
Other treatments may involve:
- soft tissue release to tight lateral structures
- McConnell taping of the patella to ensure your patella tracks more normally
- advising on orthotics or shoes to help correct your biomechanics
If you think you may be suffering from PFPS, book and appointment or call Revive Physiotherapy and Pilates today for a full biomechanical assessment and treatment plan for this very treatable condition.