This is a common condition that presents to the clinic. To best understand this painful condition, it is crucial to understand anatomy and biomechanics of the knee joint. The patellofemoral joint is quite unique in the fact it involves a sesamoid bone (patella). The patella (knee cap) articulates with the femur (thigh bone) on a bony structure known as the trochlear groove. The powerful quadriceps group and its tendon envelope the patella and suspend it like a pulley system to the tibia (shin) via the patella ligament. When the knee is straight the quadriceps are in their shortened position and this is when the kneecap rests more superiorly and patellofemoral joint forces are low. When the knee bends, large forces pull the patella down where it starts to occupy more surface area on the trochlear groove of the femur. Maximal joint contact results between 60-90 degrees of knee flexion.

The patellofemoral joint is exposed to large amounts of compressive forces. These forces are influenced by quadriceps muscle forces at different knee flexion joint angles. At 90 degrees of knee flexion (like a squat, where the quadriceps produce large amounts of force) the angle between the quadriceps tendon and patella ligament is quite low. This results in the high compressive forces being transmitted directly to the patellofemoral joint. So if the knee joint is not accustomed to absorb these compressive loads, then pain can possibly result. It is important to remember that biomechanics are only one part of the multifactorial pain experience.

What is patellofemoral pain?

Pain around or behind the patella that is aggravated by activities that load the patellofemoral joint during weightbearing tasks on a flexed knee. This can be caused via squatting, running, walking, rising from a seated position and stair climbing.

It colloquially is known as ‘runner’s knee’ and is one of the most common causes of anterior knee pain. In the active population it can account for 25-40% of all knee pain presentations according to some research. Women are more commonly affected at a ratio of 2:1, with biomechanics likely influencing this statistic. It is more prevalent in individuals in their 2nd and 3rd decade of life. The adolescent population have a prevalence over 20%, which is quite a significant number.

What about the overweight population?

With the knee joint very well known to be a large load bearing joint in the body, having a healthy weight does significantly reduce joint forces. Those with uncontrolled weight that is increasing, will significantly load the knee joint to increased stress. This is known to result in increased synovitis and cartilage defects.

Is the pain due to chondromalacia patellae?

This very controversial label has actually been refuted by arguably the world leading expert in patellofemoral pain. Chondromalacia is a term that describes the softening, tearing, fissuring and erosion of the hyaline cartilage that coats the articular surfaces of bones. This is found commonly on the back surface of the patella via imaging, however scans don’t show pain. Chondromalacia patellae is a normal finding for the general adult population. Furthermore, the cartilage is aneural (no nerve supply) and therefore cannot cause the pain. The pain as already discussed is due to the pressure in the knee joint.

How do we improve the way the knee absorbs this pressure? We need to restore confidence in the knee for starters, so reducing fear on activity is the first point of call. By guiding you through a structured exercise rehabilitation program that encompasses many physical aspects of strength, we improve the load capacity of the patellofemoral joint. At The Reform Lab Osteopathy, we are unique and fortunate to have a fully equipped gym in Project Reform. Patellofemoral pain certainly needs a holistic approach which osteopathy provides. If your knee pain is affecting the way you function and live, ensure you book in to take control back.

Ensure you read our informative blog with scientific research ‘Pain and Exercise – Is it safe and beneficial?’