Kneecap pain

(Patella Femoral Syndrome or Chondromalacia patella or Lateral tracking patella syndrome.)

What is Chondromalacia Patella? Why do you get pain under the kneecaps?

Chondro means cartilage, malacia means softening and patella is the anatomical name for the kneecap. This is the term used for the cartilage that is damaged and causing pain.  Lateral tracking is the motion where the kneecap pulls off line and causes the irritation of the cartilage.

The patella or kneecap has a V shaped outcropping on the back of it. The bottom end of the femur or thighbone has a V shaped groove on the front. The two main muscles that work the kneecap lie on the front of the thigh.  They should pull the kneecap straight up and down the groove when everything is working well.

The underlying problem in chondromalacia patella lies with is the physics of the angle of pull of those two muscles. In certain circumstances, the outside muscle can pull a lot more strongly than the inside one and so ends up doing a lot of work and getting stronger. The inner one cannot contribute as it should and rests when it ought to be working. When this happens, the kneecap gets pulled off course in its groove, irritating and wearing away cartilage on one side. The podiatrist will check your knee for this sign by having you move your kneecap within the groove.  If the patella moves sideways (or “tracks laterally”), you will be able to see it for yourself once you know what you are looking for.

The pain of chondromalacia patella is usually described as being on the edges of the kneecap or up and under it. Often there is a feeling of fullness below the kneecap that comes from the swelling inside the joint. Sometimes,  a structure called the retinaculum  also gets sore in a more widespread area.  This tissue  holds the kneecap in place and comes under stress when the kneecap wants to pop out of its groove.  The discomfort from this happens around 2-3 cm (an inch) below the kneecap off the inside edge.

Kneecap moves to poor alignment when the foot rolls in or pronates.

Who gets Chondromalacia Patella?

Patella cartilage pain is definitely more prevalent in women and girls.  In females, the hips are wider than in males and the thigh bone has to angle inwards towards the knee. The kneecap is contained within the tendon of the quadriceps muscles on the front of the thigh.  When the thigh bone is angled, a line drawn between the upper and lower attachments of these muscles will pass to the outside edge of the kneecap.  When they contract, there is a large force pulling the kneecap off course laterally (to the outside) in its groove. In pronators, which are people whose feet roll in, not only are the feet affected but the whole leg will rotate inwards towards knock knee. This has the same affect as described above for females. This means that men can experience these effects.  It also means that women who pronate are likely to be the worst sufferers. The angles shown in the pictures above will help explain this.

What is the treatment for lateral tracking patella syndrome ?

Two things are necessary to treat this problem. In the short term, good reduction in pain can be achieved within 10 days by strengthening the weak inner quadriceps muscle. To do so, avoid doing big ‘gym style’ knee extensions, as this will force the strong muscle to do most of the work and get stronger still. The best exercise is a subtle one but very easy to do. You will be shown exactly how at your consultation. In the longer term, shoe inserts called orthotics are usually required to stop the foot from pronating and the leg from rotating inwards. This rotation is quite difficult to control, needing a perfectly fitting orthotic that works well in the transverse (rotation) plane. For this reason, one-size-fits-all insoles from sport shops or chemists that primarily function in the sagittal (arch lowering) plane are not suitable.

What happens in chondromalacia patella without treatment?

Without treatment, the kneecap cartilage will continue to ache and will wear unevenly. Ultimately, this is what brings about a good proportion of knee replacement surgery. Cartilage that is removed unevenly can wear into a distinct ridge, resulting in a clicking sound as you walk. Tiny pieces of cartilage that are ground off stay floating in the joint fluid of the knee and make crunching noises as you walk, particularly on stairs. Earlier treatment with orthotic devices will generally lead to a better result.  If the knee is already significantly worn, the podiatrist may be able to use use orthotics to move the current friction on the knee cartilage to a less worn part of the surface.