Pathology Around the Knee

Tumours

Thankfully malignant tumours around the knee are very rare. Bone tumours occur mostly in people under the age of 20 and tumours of muscle occur mostly in middle aged people. Rarely secondary tumours from other tumours such as breast, thyroid, kidney, prostate and lung cancer can grow in the bones around the knee. These secondary tumours are most common in elderly patients.

The treatment of any tumour in bone or muscle is performed in regional centres due to the rarity of the condititon.

Quadriceps weakness

Following any injury to the knee, but especially one in which the knee has swelled up, the quadriceps muscles are inhibited and they rapidly diminish in bulk. This diminution of size and power can occur very rapidly and if the quadriceps become weak beyond a certain point then the knee may begin to feel unstable and pain may be felt around and behind the kneecap. Quadriceps weakness may also occur due to chronic disease that cause pain such as osteoarthritis affecting the patello-femoral joint.

The treatment for this is hard work with your physiotherapist who will show you the best exercises to build muscle. Unfortunately, although quadriceps wasting can occur in days, it can take weeks to rebuild the strength in this muscle group as overdoing the exercises initially may lead to more pain and further inhibition.

Posterior cruciate ligament injury

The posterior cruciate ligament (PCL) is the major restraint of backwards movement of the shin bone (tibia) on the thigh bone (femur). It is a very large ligament and is a major stabiliser of the knee. A blow to the shin while the knee is flexed or a hyperextension injury can cause a PCL rupture.

Not all isolated PCL ruptures require reconstruction due to the fact that “secondary” restraints can compensate for it’s loss but if other structures in the knee are damaged as well, reconstruction may be necessary.

Plicas

Plicas are remnants of tissue from when the knee was developing and are seen as crescenteric bands of tissue within the lining of the knee. Small plicas are normal within the knee but large plicas can get pinched in the knee, normally in the patello-femoral joint. This causes inflammation and pain. The inflammation can lead to a thickening of the plica making it more likely to be pinched. Arthroscopic removal of the plica resolves the symptoms.

Athletes that do repetitive deep flexion and extension movements of the knee, such as cyclists, and people who kneel at work are most likely to suffer from plicas.

Patello-femoral problems (general)

Symptoms from behind or around the kneecap (anterior knee pain) are extremely common. They can be caused by a multitude of conditions from flat feet to patello-femoral arthritis. Anterior knee pain is generally felt when the knee is flexed under pressure such as walking downstairs, squatting and kneeling. Young women (12-20) are particularly susceptible to anterior knee pain due to a condition called chondromalacia patellae in which the cartilage behind the kneecap softens.

The treatment of anterior knee symptoms is dependent on the cause of the symptoms. To reach a diagnosis investigations such as X-rays, MR scan and bone scans may be necessary although simple clinical examination by a knee surgeon may often give the diagnosis.

Patello-femoral arthritis

Arthritis of the joint behind the kneecap typically causes pain at the front of the knee that is worse when walking up, but especially down, stairs. This is because during this action the kneecap takes a force across it equivalent to 5x your body weight. Pain from the patello-femoral joint may also be felt behind the knee. Often the joint can be felt to grind (crepitus) and crack. It commonly affects people who kneel a lot in the course of their work. It can also follow patellar fractures.

If the pain is severe enough, an arthroscopic debridement (“clean-up”) may improve the symptoms and injections may be appropriate in the early stages. If the arthritis is advanced, a patello-femoral joint replacement may be required.

Patellar tendinitis

Patellar tendinitis is a common condition in athletes, especially in athletes whose sport includes jumping. The symptoms are generally a sharp pain just below the kneecap and there is generally a tender spot to touch.

Frequently this condition can be successfully treated by non-operative methods but in cases resistant to this form of treatment, surgery is required to excise a small piece of the kneecap. This operation can be performed arthroscopically (keyhole). The success rate, however, is only about 80%.

Patellar maltracking

As the name suggests, this is when the kneecap (patella) does not run properly in the groove on the front of the knee (trochlear). There are many causes for this including muscle imbalance in the quadriceps, maldevelopment of the trochlear or patella, malrotation of the femur and foot pathology. The main symptom of maltracking is pain but severe maltracking may be the underlying cause for recurrent patellar dislocation. Chronic maltracking over many years may lead to patello-femoral arthritis.

The treatment for patellar maltracking is addressed to it’s underlying cause and treatments range from physiotherapy and insoles to major reconstructive surgery.

Patellar fracture

Patellar fractures are generally caused by a direct blow to the front of the knee although they can also be caused by an over-energetic contraction of the quadriceps muscle during sporting activities. The knee swells up rapidly, especially at the front of the knee over the kneecap. Walking is normally impossible and in most cases it will prove impossible to straight leg raise.

Most significant patellar fractures will require accurate reconstruction and fixation.

Patello-femoral arthritis may occur following a patellar fracture.