Anterior knee pain and running

AKP is generally concerned with problems related to the patellofemoral joint. The patellofemoral joint is found between the under-surface of the patella (knee cap) and the lower end of the femur (your thigh bone). For this reason, it is also termed ‘patellofemoral pain syndrome’.

There are some depressing findings, for runners, relating to AKP, such as: it is the most common symptom which runners present to specialists and it is the most common overuse injury in sports people generally.

So, what is AKP, how is it caused by running and can it be treated?
Some background information is needed first to allow understanding of this unfortunately common running condition.

The patella (knee cap), is a piece of free-floating bone situated within the body of the quadriceps tendon. It acts as a pulley to allow the quads tendon to run smoothly and efficiently over the front of the thigh, to move and control movement of your tibia (shin bone).

As the knee bends and straightens the patella tracks up and down the groove on the front of the lower end of the femur (thigh bone). It is guided and held in place by a number of structures including contractile (muscle) and non-contractile structures, such as the ligaments at the front of the knee (retinaculum) and the patella tendon. Other factors also figure in the equation such as the shape of the runner's patella itself.

Problems arise, when these structures fail in their function or alter how the patella moves. Contributory factors which affect the mechanics of the how the patella moves include alignment of the running leg and thus how forces, when you run, are transmitted from the foot.

So, the following all affect the mechanics of the joint and how the patella is loaded during running:

• Overpronation of the forefoot
• Stiff hip joints
• Tight hamstrings, calf and quads muscles
• Poor quads function and strength, particularly the portion of the quads known as VMO

You might equate this to having poor tracking on a front tyre of your car which leads to uneven wear of the tyre. When load is distributed inadequately across the patella under surface, the patella cartilage can get damaged. This may then lead to trauma and inflammation to the cartilage, which causes pain and possible degeneration of the runner's articular cartilage.

Pain may also arise from soft tissue structures around the knee, such as the fat pad which lies just under the patella (and gives rise to a ‘puffy’ knee) and irritation to the nerves supplying the knee joint.

Symptoms of AKP in runners
Pain is typically felt over the front of the knee without being able to pinpoint the source. Usually pain is felt during and after running - it may be acute enough to limit distance or not allow any running at all.

• Pain is often felt when going up or down stairs or squatting.
• A ‘creaking’ under the patella may be noticeable when running.
• Stiffness and swelling around the patella may be present.
• Possible loss of muscle bulk in the quads.
• ‘Puffy’ knees when running. 

Treatment of AKP in runners
Initially treatment is directed toward reducing the inflammation. The physiotherapist may use a number of different treatment modalities to do this, such as: TENS (a method of treating chronic pain by applying electrodes to the skin and passing small electric currents through sensory nerves and the spinal cord, thus suppressing the signal of pain signals), interferential or acupuncture…along with rest from running-related activities that aggravate the problem.

When able, treatment will be directed towards improving the mechanics of the lower limb. For example, implementing a programme of stretching for muscles (such as stretching the retinaculum), along with orthotics as and when necessary. Strengthening of the quadricep muscles is also an important part of the rehabilitation process. This may often be directed toward the VMO, along with restoration of your spatial awareness system (proprioception).

The important message again here is not to ignore your symptoms, and seek the advice of a professional sooner rather than later.