It may not seem obvious, but the hip and knee share the femur bone. The knee does not work in isolation, and improving hip function may be the answer to a painful knee.
In physical therapy we tend to think of tendonitis and degenerative joint disease in terms of a victim and culprits. Many patients will arrive in my office complaining of a painful knee (victim), and it is my job to identify the underlying biomechanical dysfunction (culprits).
For various reasons, hips tend to become restricted and weak. When your hip is no longer accepting the proper loading during activities such as descending stairs or transitioning from sit to stand, your knee may attempt to take on that extra load and become the victim.
If the local bully came to your house every morning just to step on your big toe, this victim would inevitably become red, swollen, and irritated with an inflammatory process. You could go to your medical practitioner who might diagnose you with some sort of "toeitis."
Any number of treatments could be prescribed such as medication, injections, ultrasound, or cold laser, but unless we somehow stop the culprit from stepping on your toe, we are unlikely to make any long-term progress on curing your "toeitis." Instead of focusing on your inflamed toe, we should take a critical look at what factors are creating a situation where there is increased stress on your toe.
Patellofemoral pain syndrome (runner's knee) is generally thought to be excessive stress of the knee cap on the groove of the femur. You can think of this as a train running on a track, with excessive wear on the outside rail of a turn. Most people complain of pain just under the kneecap, especially during activities such as descending stairs.
Studies have shown that hip position has a tremendous influence on how much pressure is on the knee cap during functional activities. Many times we see a weak hip allow the knee to dip toward the midline during a squat. While the patient will complain of kneecap pain, the real culprit is that the hip is not adequately positioning the knee for loading.
The hip should be the knee's best friend. It has the largest muscle mass of the body, and thus has the greatest responsibility to support the knee. The key to decreasing inflammation at the knee may be to take stress off of it by stretching and strengthening your hip. Your physical therapist can help you figure out if your hip motion is limited, and how to best strengthen and stretch the hip without irritating the knee.
As your hip mobility and stability improve, your knee will thank you.
Feeling better? Stay strong at a fitness class.