Sometimes people complain of pain from an unknown origin and state that “I really didn’t do anything” to hurt that area. For those who suffer from Patellofemoral Pain syndrome, known as PFPS for short, that is usually the case. The patella, commonly referred to as the kneecap, can be a source of pain for some people with no real cause of injury. It is usually caused when the patella fails to function properly due to one or a variety of reasons and can causes soft tissue irritation to the front of the knee, eventually causing significant pain, swelling, and structural damage to the kneecap and areas surrounding it.
In order to understand why such a small bone can cause so much pain you have to understand how important the patella is in maintaining proper functioning of the knee. The patella is the “connecter” for the large quadriceps muscle group on the front of the upper leg (or femur bone) to the lower leg (tibia bone) that allows you to pull your lower leg up to make your entire leg fully straighten. In order to do so, the patella actually moves in a little cavity or groove of the upper leg bone, which are both covered in a smooth cartilage, which allows smooth transition of this movement.
However, sometimes this movement is disrupted by one or more of a variety of reasons and causes damage of soft tissues around the front of the knee. In this case, most people a gradual onset of a dull, aching pain around their patella, usually on the top or outside of the knee where it connects to the lower portion of the femur and sometimes noticeable swelling is apparent. Some people report aching pain described behind the kneecap as well. People who experience PFPS note increased difficulty walking up/down stairs, kneeling, squatting, or sitting prolonged periods of time due to the stress these activities place on the patella directly, incorrect pulling of the patella by the quadriceps muscle, improper movement of the patella through the femur’s groove. Other’s report catching or crunching of the knee when bending the knee, for example going down stairs or performing a sitting/standing motion, which can be cause by improper tracking of the patella through the femoral groove.
So, what causes PFPS? Well, it’s actually hard to say. PFPS can be caused by many different sources, both that are modifiable and nonmodifiable. Here’s a list of
the most common ways people develop PFPS:
Faulty Vastus Medialis Oblique (VMO): There
are four muscles that compose your quadriceps muscles, one being the smaller
vastus medialis oblique and towards the middle, lower portion of your leg. The
vastus lateralis is on the outside portion of your leg. Both of these muscles
connect to the quadriceps tendon, or the tendon the directly attaches to the
patella. These muscles are meant to pull the patella synergistically, or at the
same time. However, sometimes the timing can be off, and the vastus lateralis
can pull the patella first, causing the patella to drag towards the outside of
the leg and roughly along the edge of the groove of the femur, causing
significant knee pain.
Muscle Weakness/Imbalance: Like I have stated in previous blogs, the whole body is a chain, so weakness/tightness at one area significantly impacts another. Muscle weakness at the hip and knee especially can cause other muscles to become over worked and tight which can potentially cause abnormal alignment of the knee.
Similarly, muscle imbalances of the knee especially can cause faulty pulling of
the patella. The vastus lateralis muscle is normally significantly larger than
the vastus medialis muscle. However, if this imbalance becomes too apparent the
lateralis will “out pull” the medialis, similarly to a faulty VMO.
Malalignment of Patella/Knee/Flat Feet: Structural variations can
also cause PFPS. Patella Baja, or a patella that is normally higher than usual,
places abnormal stress on the patella as it rubs with the lower portion of the
thigh where the groove is especially shallow. Also, malalignment of the knee in
an extreme valgus or “knock-kneed” position also causes increased friction of
the patella on the lower leg even in a resting position due to the abnormality
it causes. Having flat feet can also put the knee at an extreme valgus angle
due to the lower extremity once again being a chain.
In most cases, PFPS should initially be treated with RICE: Rest, Ice, Compression, and Elevation. This will help decrease pain, inflammation, and rest the area around the knee. The cause of the individual’s PFPS will determine the resulting treatment. If
strength, muscle imbalances and weakness are the key, physical therapy is a
great way to strengthen weaker muscles, stretch tighter muscles, and correct
the way the quadriceps pull the patella. In a faulty VMO case, strengthening
and stabilization exercises, as well as using muscular re-education in the form
of electrical stimulation, can re-educate the firing patterns between the two
muscles in order to produce a more normal contraction of the quadriceps. Depending
on the malalignment issue the problem may be corrected with strengthening and
stretching, orthotics, bracing, taping, and in some severe cases surgical
realignment may be necessary.
To prevent possible PFPS, it is important to easy to complete measures you can do
almost every day. Try to stay in shape, including strengthening and stretching of the back, hip, knee, and ankle musculature. It is also important to increase your training routine gradually as a sudden heavy increase in the load of exercise could cause great muscle compensations and imbalances. Lastly, use proper running shoes when doing any physical activity to avoid and potential affects that may cause pain up the chain.
