The Knee Cap (Patella)

Knee pain due to disorders affecting the kneecap (patella) is very common.  Pain around the kneecap, in active adolescents in particular, is so common that it could be considered as almost normal in sporty teenagers.  In most cases, kneecap pain (anterior knee pain) is self-limiting and would respond to an adjustment in activities and muscle strengthening exercises, however if symptoms persist, further assessment by a physiotherapist or orthopaedic surgeon specialising in knee problems is advisable. 

The following summarises three of the commoner conditions affecting the kneecap in active individuals.

• Anterior knee pain

This describes an aching pain around the kneecap in active adolescents who are usually keen on sports and describe aching of the knee during and after sporting activities.  Usually, the more they play sport the worse the aching becomes and they eventually have to rest from sport to allow the symptoms to settle.  There may also be a variable degree of slight swelling of the knee and symptoms of the knee giving way, or feeling as though it will give way, particularly when going up and down stairs. 

Examination of the knee is very often normal, although there may be a slight swelling within the knee and the muscles may be wasted.  There may also be a degree of tenderness around the kneecap. 

Investigations by taking special X-ray views of the knee may be required if the symptoms persist.

Treatment in almost every case where no specific abnormality is identified, involves modifying activities and working on strengthening exercises to improve the quadriceps muscles which attach to the kneecap. Although attempting to modify teenagers’ activities is a fairly pointless objective in many cases, trying to cut back on the intensity of exercise until the muscle strength improves and then progressively building this up again until they return to their former activity levels, is usually effective.  Medication is rarely required and surgery almost never.  This is usually a self-limiting condition, which will improve as the individual grows and muscle strength improves, but if symptoms persist and recur on returning to activities, further assessment by a knee specialist is advisable.

• Chondromalacia patella

Chondromalacia describes the condition of softening of the surface of the kneecap (articular cartilage).  It is not a clinical diagnosis but is an observation made at the time of surgery.  A degree of change can be staged.  Articular cartilage softens in this way, either due to damage to the kneecap, abnormal pressure on the kneecap due to maltracking when the knee bends, following episodes of patella dislocation (see below), but often the cause of chondromalacia is not clearly understood.

The treatment of chondromalacia patella in the first instance is non-surgical by rehabilitation of the quadriceps muscles, anti-inflammatory medication if there is swelling of the knee and modification of exercises, particularly avoiding excessive knee bending activities, such as hill and stair climbing.  If symptoms persist, a careful clinical assessment is required, which may involve X-rays and scans of the knee and, on occasions, surgical treatment may be necessary to correct abnormal movement of the kneecap over the front of the knee.

• Patella instability

The kneecap can dislocate to the side in an acute traumatic event.  Although this can happen as a single event, some individuals are susceptible to repeated dislocations of the kneecap.  They usually have certain predisposing conditions, particularly hypermobility of their joints (they have a tendency to be “double jointed”); there may be abnormal growth of the leg, usually causing a degree of “knock knee”, which may predispose to the kneecap slipping to the side.  Each dislocation of the patella can damage the surface of the kneecap, resulting in chondromalacia (see above).
In the first instance, patella instability is treated by physiotherapy to strengthen the quadriceps muscles.  In addition, an elasticated brace with padding around the kneecap can be used to hold the kneecap in position. 

If these measures fail to stabilise the kneecap, surgical treatment may be required, which would involve reconstructing the ligament around the kneecap or correcting the way in which the kneecap tracks over the front of the knee when the knee bends.  Following this surgery, further rehabilitation is required to strengthen the quadriceps muscles, but overall the outcome of treatment for patella dislocation is usually very successful, although the recovery period takes at least six months.

RWN’s view

Patello-femoral pain is very common, and in most cases is benign and self-limiting.  Advice on activities and strengthening exercises are usually effective in most cases.  In those individuals who do not get better, careful assessment is required to make sure the kneecap is not “maltracking”.  This term describes abnormal movement of the kneecap over the front of the knee when the knee bends, causing the kneecap to tilt and move to one side, usually the outer side of the knee and result in damage to the under surface of the kneecap (chondromalacia).  Even though physiotherapy may be effective in controlling symptoms, if the condition persists, surgery may be required to improve the tracking.  This will require reconstruction of ligaments or repositioning of the patella over the front of the knee.

After this operation, a great deal of exercises with the physiotherapist will be required.  Surgery is usually very effective, but working very closely with the physiotherapist, in the recovery period is essential.