Your clients probably have runner's knee if their knee cap hurts during long runs or when walking down stairs. Oddly, bicycling doesn't seem to flare it up and may even help some who suffer with this troublesome condition.

In 2001, Long Beach, California's VA Hospital (1) released a study that sheds some light on why runners are far more likely to suffer knee pain than cyclists. When most people run, they land on the outside bottom of the foot and roll inward toward the big toe (pronation). Their research demonstrated that the amount of inner twisting of the lower leg during running is related to how straight the knee is. (Fig. 2)

Apparently, bending the knee decreases internal tibial rotation and lessens rubbing of the patella against the femoral head. As a result, many manual therapists have begun advising their clients suffering from runner's knee to integrate bicycle training to avoid 'flare-ups'. Since bicycle training prevents complete knee extension, it seems to lessen patellofemoral pain.

A movement cue I've found helpful for relieving patellofemoral pain and many other lower quadrant problems is to ask the client to strongly contract their ipsilateral G-max upon heel strike during walking or running. The firing of G-max causes co-contraction of biceps femoris which prevents complete knee extension. This simple, but powerful, exercise strengthens and helps balance anti-gravity foot and ankle muscles (tibialis anterior/peroneus longus) of the Stirrup Spring System (SSS).

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What's Tight?

Flexibility deficits in the hip's external rotators, hamstrings, quadriceps, and gastrocnemius-soleus muscle groups may also contribute to abnormal patellofemoral biomechanics. Figure 3 demonstrates a nice external rotator release from my newly released 6-DVD set. Assessing asymmetry is a critical part of fixing patellofemoral disorders. Ask your seated client to contract the quadriceps while you observe the timing of the vastus medialis and lateralis contractions. Normally they fire simultaneously which balances the quadriceps' action on the patella. In clients presenting with anterior knee pain and patellofemoral malalignment, it is not unusual to see the vastus lateralis fire before vastus medialis. Place your index fingers on each muscle if you're not sure which is firing first.

Corrections for unbalanced quadriceps contraction must be treated globally and should include myofascial and joint mobilization to all lower quadrant structures (pelvis, hips, knees, ankles and feet) to improve coordination and restore firing order. Home strengthening exercises for vastus medialis and hip abductors using TheraBand® elastic straps or tubing are simple, fun and very helpful.

Summary:
The jury is out on the exact causes of this common condition, but some of the factors believed to be the main culprits are: overuse or repetitive weight-bearing activities, such as running, walking up & down steps or hills and uneven surfaces, arch variations - flat or high arches, wider hips & knock-knees (known as the Q angle), and medial quadricep muscle weakness

TQ Lee, BY Yang, MD Sandusky, PJ McMahon. Lee TQ, The effects of tibial rotation on the patellofemoral joint: Journal of Rehabilitation Research and Development, 2001

Predisposing Factors
1. Abnormal biomechanics:
excessive foot pronation
internal femoral torsion (squinting patella)
increased Q angle

2. Soft tissue tightness:
hamstringso iliotibial band (TFL)
gastrocnemius
lateral retinaculum
vastus lateralis

3. Muscle weakness:
vastus medialis
hip abductors/especially gluteus medius/minimus