I had an email last week from a relatively new runner asking who they should see for their knee pain. I asked if they twisted, fell, or jammed their knee or if it was just a wear and tear injury? They confided that as they increased their mileage and distance, their knee pain started to increase. New shoes helped, but didn't fix their nagging pain. Sounds like a biomechanical problem to me! But it could still be a traumatic injury they can't remember...especially if they were out dancing on tables on a Friday night ... Just kidding!
Seriously, mechanically induced knee pain is extremely common in runners. A good analogy is that if you need a tire realignment on your car, the struts can wear out. In fact, you may have no acute foot and ankle problems at all and they can still be the cause of your symptoms.
The best way to assess a runner's knee problem is to start with a sports medicine orthopedist who can rule-out a primary knee problem, like a tear in the meniscus (cartilage), ligaments or tendons. If a primary knee problem is ruled-out, but you just keep having this nagging pain; or if your tendonitis keeps recurring in spite of being compliant with physical therapy and rest; it's time to look elsewhere for the cause.
Your feet affect the function of all their contiguous structures or in English, everything they are connected to. Yes, your feet can even cause back and neck pain!
How? Your feet affect your postural control. Postural control is the ability to maintain the body's center of mass over the supportive foot, a.k.a. being able to keep your balance. Often, balance or proprioception is lost in patients with chronic foot and ankle instability from an underlying congenital foot type. This leads to lack of postural control which leads to knee, hip and back pain a.k.a. postural symptoms. Many studies have concluded that a functional orthotic reduces postural sway and improves stability, therefore reduces further injury in patients with congenital or acquired foot and ankle instability.
How is biomechanical knee pain treated? A complete biomechancial exam can help to assess how to realign your feet and lower extremities. Functional orthotics can be made to precisely fix your foot deformities and functional abnormalities.
Bottom line, if your knee pain is chronic and you have ruled out a primary knee problem, look to your support structures known as your feet.