Anterior Knee Pain
Pain over the front of the knee is an exceptionally common symptom described to knee surgeons. Unfortunately it is a relatively non-specific symptom and its cause can be very difficult to ascertain.
Frequently patients complain of pain felt over the front of the knee, associated with clicking, clunking or grinding noises. The pain is worse on sitting for any period of time (the so-called ‘cinema knee’) or on going up and especially down stairs. A sensation of the knee giving way is not uncommon but this is usually preceded by pain and is due to reflex inhibition of the quadriceps muscles. A significant proportion of adolescents, particularly female, complain of anterior knee pain at some point.
Anterior knee pain can result from:
- Damage/degeneration of the articular (surface) cartilage – sometimes referred to as chondromalacia patellae
- Maltracking of the patella (see Patellar Instability)
- Previous trauma, such as fracture of the patella or patellar dislocation
- Abnormal plica – a fold of the synovium (joint lining membrane) which can become enlarged and interfere with the patella during knee movement
- Patellar tendinitis due to impingement of the lower part of the patella with the patellar tendon
- Miscellaneous conditions where no knee abnormality can be found e.g. foot alignment problems which cause the knee to be abnormally loaded during normal activity
The first priority of management is to identify those patients who have a structural cause for their pain, which can be treated surgically, from those who have symptoms but with no identifiable cause. These latter patients rarely respond well to surgery.
Plain X-rays may show evidence of degenerative arthritis or tilting of the patella within the trochlea. Evidence of a developmental abnormality (dysplasia) may suggest that the cause is maltracking of the patella and instability.
MRI scans are useful in excluding other causes of pain such as cartilage tears or ligament injuries; they can also show degeneration of the cartilage in the patellofemoral joint.
When patella maltracking and instability are suspected, tracking studies can be performed to measure how the patella moves as the knee bends.
Where surgery is not indicated:
Lifestyle changes such as weight loss and avoidance of activities that cause pain usually help.
Physiotherapy is also often of use. However, dedicated knee physiotherapists are required as specialised treatment regimes may be necessary to alter specific muscle imbalances.Orthotic insoles may be used to correct foot problems. Pain clinics can often provide symptomatic relief when surgery is not appropriate.
Where surgery is indicated:
Arthroscopy can be undertaken to remove unstable areas of cartilage damage, resect symptomatic synovial plicas, assess the tracking of the patella and if necessary perform a lateral release to improve tracking. In addition, removing the lowermost part of the patella gives excellent pain relief in cases of patellar tendinitis. This can be done arthroscopically.Patellar realignment can be performed if there is significant patellar instability. Patellofemoral replacement (a form of knee replacement) can be used for isolated end-stage patellofemoral arthritis that is unresponsive to other treatments.