PATELLA FEMORAL SYNDROME

If you feel pain in the front of the knee, and suspect patella femoral syndrome, check for tenderness on the back of your knee cap.

Examining your own knee for patellar femoral syndrome

Sit with your heel on the floor or on the edge of another chair and your knee fully straightened out. Relax your thigh muscles. Push the knee cap to one side and dig a finger under the protruding edge. Rub against the back of the bone from top to bottom, to see if there is a tender spot.

Now push the knee cap to the other side and repeat the examination there.

Repeat the examination on your other knee, to compare your sides.

Tender spots are quite obvious, and very localized. If you're not sure it isn't likely to be significant tenderness.

Do you have somewhere you can lay one leg out straight close to the edge on top of a low table, while standing on the other leg? In this position practice pulling the knee cap up by contracting the muscle on the front of the thigh. This is unlikely to hurt. Now repeat it with a finger pressing down immediately above the patella. It is often quite surprising how this causes pain in patello-femoral problems.

See below for more details of examination.

Patellar biomechanics

Anatomy, muscles of patellar tracking

The main pull of the thigh Quadriceps muscles, is upwards and outwards. (See Q angle below.)

A little muscle on the inner side (vastus medialis obliquus,)balances this outwards pull.

You can feel it tighten just as you fully straighten your knee. Sit and place a finger just above and to the inner side, of your knee cap. Lift the leg until it is nearly straight then feel the muscle tighten as you fully lift your foot.

The two muscles combined action is a more directly upwards pull on the knee cap.

The lower end of the femur has a higher ridge on the outer side of the groove for the knee cap, which also helps keep the knee cap moving vertically up and down as we walk.

Radiological examination

A "skyline" X-ray view can show if the (Trochlear) groove on the femur is deep enough, but can't show the articular cartilage gristle and may make the groove look better than it is. Thick cartilage may make it more shallow.

A side view of the knee may show a high riding kneecap (patella alta.) The knee cap here may spend most of the time out of the groove and able to move out sideways too much.

Testing for tight hamstring muscles.

Finding tenderness on the back of your patella, almost guarantees the hamstring muscles at the back of the thigh are tight and need stretching.

The reason is that your quadriceps muscle at the front has to work that much harder, to overcome resistance from tight hamstrings. This pushes the knee cap more firmly against your femur.

hamstrings testing and stretching

To test your hamstrings, lay on your back and have someone lift your leg as shown. Do not attempt to help. Your leg should be a dead weight, with all muscles relaxed.

Ideally it should be possible to lift your leg to vertical without discomfort.

Compare the angle attained and the discomfort, on your two sides.

Strengthening vastus medialis obliquus muscle

In patella femoral syndrome, always exercise VMO.

Lift your leg out straight and feel that it is contracting, as mentioned above.

Hold this position for as long as you can, often.

Stretching your hamstring muscles.

You can stretch your hamstrings yourself, standing as in the diagram above, facing along a bench or table edge. Keep both your knees straight. Put your foot up on something and lean forward until you feel slight discomfort in the back of your thigh.

Hold that pose, and watch TV until the discomfort eases, usually about two minutes.

Then you can lean forwards, increasing the stretch to bring back the discomfort, and wait again.

The stretch can be done sitting down, on progressively lower seats, leaning forward to increase the stretch...

hamstrings stretch in seated position

Photograph courtesy of she who must be obeyed. It required some patience to get a picture mostly free of golden retriever.

Your adductors can also be stretched in this way, by swinging the leg back 90 degrees to the side.

More details on painful conditions at the front of your knee (peripatellar pain)

Chondromalacia patellae is the above condition which has progressed to damage of the gristle on your kneecap.

Sit on a bed with this leg up on it, knee slighly bent. With thigh muscles relaxed, you should now be able to wobble your knee cap from side to side and up and down.

Can you feel any crackling or grating as you move the knee cap? Is this movement causing pain?

Osteoarthritis is when the above is accompanied by bony knobbles along the edges of this patello femoral joint, on the edge of your knee cap or of the trochlear groove of your thigh bone here.

X-ray is better at finding these knobbles, if a "skyline" shot is taken, in the plane of the joint.

These conditions are treated as described above for patella femoral syndrome, which should always include correction of foot problems...

Retropatellar contusion

is damage from a direct blow on the knee cap, in an accident. The same tenderness is present, and this will often be the slowest of a person's injuries to resolve. Treat as above also.

The role of foot posture in knee problems (etc etc)

Is the inner side of your foot losing it's arch, and flattening when you stand? This is called excessive "pronation" and it can put strain on your knee, hip and back.

This is commonly important in patella femoral syndrome.

Ideally this should be corrected with exercises , but often orthotic supports are prescribed. These can allow the stretched muscles to regain their normal length while you are strengthening them.


Plica syndrome and retinaculum sprain

The hard lumps beside your kneecap, are the lower end of your thigh bone. If you rub over the surfce here, you may be able to feel the edge of a retinaculum or plica flip under your fingertip, as you roll over it against the bone. It is a bit like a thick thread.

The retinaculum passes down and outwards away from the patella on each side, a plica towards it on the inner side.

The retinaculaum is part of the tendon of the big quadriceps muscle on the front of your thigh. A plica is a fold of the joint lining.

If there is distinct soreness here, as assessment by a musculoskeletal physician is warranted. It may be the cause of knee pain rather than patella femoral syndrome.

The Q angle of your knee

Your Q angle is between a line drawn from the the point of bone on the hip, at the outer end of your groin crease, to the center of your knee cap and a second line drawn from there to your tibial tubercle.

A larger Q angle makes one more prone to patella femoral syndrome.

This angle is bigger in women because of their wider hips. Whatever it is, there is nothing you can do about it anyhow. You work with what you have got. The best work is towards having strong supple muscles.

From patella femoral syndrome back to home pain page

From patella femoral syndrome to adductor stretching



Search

Is there something else you would like to read about?
This search button will bring up anywhere on this site your words are mentioned...


Google

Custom Search



Contact

The contactpage.

The trochlear groove on the lower end of your femur, guides the knee cap as it glides up and down.

Your tibial tubercle is the bump at the top of the shin bone.

If you are interested in a home study course on examination of the spine, please send me your e-mail address by the contact form.