Knee cap (patella-femoral) problems

Knee cap (patella) is a small bone in front of the knee, and can be easily felt. It runs in a groove in front of the lower end of the thigh bone.  It improves mechanical efficiency of the knee, and is particularly useful in getting up from sitting position, and in going up and down the stairs.

There are two main problems affecting the patella.  One, anterior knee pain due to damage to the undersurface of the patella (chondromalacia), and the other patella instability.In the earlier, the patient presents with pain, and In the latter, the patella has a tendency to jump out of its groove.

Chondromalacia patella

Chondromalacia refers to softening of the articular cartilage covering the back of the knee cap. This disorder occurs most often in young adults particularly ladies, and can be caused by injury, overuse, patellamalalignmentor muscle weakness. The damage may range from a slightly abnormal surface of the cartilage to a surface that has been worn away to bare bone. Chondromalacia related to injury occurs when a blow to the knee cap tears off a small piece of cartilage with a piece of bone (osteochondral fracture).

Frequently Asked Questions

Q 1. How does one know that he has chondromalacia?

ANS 1: The most frequent symptom is a dull pain around or under the knee cap that worsens when climbing down stairs or hills. A person may also feel pain when climbing stairs or in activities such as getting up from sitting position. On examination often a crepitus can be felt by a hand on the patella.

Q 2. How is chondromalacia treated?

ANS 2: Patients with chondromalacia should perform exercises to strengthen thigh muscles. If this does not improve the condition, you may need arthroscopic surgery to smoothen the surface of the cartilage and “wash out” the cartilage fragments that cause the joint to catch during bending and straightening. In more severe cases, surgery may be necessary to correct the angle of the knee cap and relieve friction.

Q 3. What is Patella instability?

ANS 3: This is a spectrum of diseases where the knee cap (patella) in not well fitted in the groove in which it tracks. The instability, in its most classic form presents as dislocation of the patella where the patient can tell exactly what happens, i.e., the knee cap came out.  In more subtle varieties, actual dislocation my not occur, but the patient has a tendency to lose control over the knee. Often the only symptom of patella instability is pain, in which cases,astute clinical examination may be the only way to diagnosis.

Q 4. What is the treatment of recurrent dislocation of patella?

ANS 4: Treatment depends upon the cause.  Often the cause is simply an injury where the thigh muslces so contract that they pull out the patella, rupturing the ligaments holding it in place. In such cases, if repeated dislocation occurs, best is to reconstruct the torn ligament (MPFL reconstruction). In other cases, dislocation is a result of some manufacturing defect in the formation of the knee. This may be in the form of too highly placed patella, deformity of the leg helping the patella to jump out etc. In this type of patella dislocation, success of the operation is dependent on precisely identifying the manufacturing defect and correcting it.