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Patella Fracture: Causes, Diagnosis and Treatment

Patella fracture is a injury the involves the patella bone which is located in the front of the knee joint. While sitting on a chair put your hands over your knees. The roughly round to triangular bone that you feel is your patella.

The patella is a sesamoid bone.This means that it is located within a tendon.

It would good to first check out the Knee anatomy before proceeding further so that you may get a better understanding of patella fracture. (skip this if you have already done so)

The tendon of the quadriceps muscle forms an expansion as it crosses the knee joint. The patella bone is located in the centre of this tendon. Extending from the lower pole of the patella is the patellar tendon that attaches to the tibial tuberosity.

Function of the patella is to

increase the leverage of the quadriceps muscle
protect the quadriceps and patellar tendons

Fractures of the patella are more common in males between the age of 20 to 50 years. They are caused by

direct injuries such as falling on the knee or road traffic accidents
indirect injuries from sudden contraction of the quadriceps muscle

Symptoms include

pain
swelling over the knee; swelling may be mild or absent in hairline or undisplaced fractures
inability to walk; sometimes patient may be able to walk with difficulty in these fractures
inability to extend the knee against gravity (raise the leg straight) may be present
in hairline fractures the only symptom may be tenderness over the patella bone
swelling develops rapidly in displaced (fragments separated) fractures of the patella as blood fills up the knee joint

Diagnosis is by x rays of the knee joint. X rays will help in the classification of the fracture. Skyline view x rays may be required sometimes.

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$x ray of comminuted patella fracture$ This x ray of patella fracture shows 3 pieces of bone, but during surgery there were 4 pieces. One piece was of cartilage. In the x rays below, taken 6 weeks after surgery, the same fracture was fixed by stainless steel wires and is healing well.

$patella fracture$ $patella fracture$

Classification is according to the pattern of the fracture.

Transverse in which the fracture occurs through the mid line dividing the bone into two parts upper and lower.
Longitudinal in which there is a vertical split in the bone
Lower or upper pole fractures
Comminuted fractures in which there are multiple pieces
Osteochondral fractures that involve the cartilage

$patella fracture classification$

Classification of patella fracture is also according to the separation of the bone fragments.

Displaced fractures in which the bone fragments are separated
Undisplaced fractures in which the bone fragments are not separated

Treatment depends upon the following factors

fracture is displaced or undisplaced
you are able or unable to lift your leg straight against gravity

Treatment includes the following methods

ankle to groin plaster cast
surgery which includes the following

fracture is aligned and fixed with stainless steel wires or screws called tension band wiring
few fracture fragments are removed and the remaining bone is stitched with the tendon called partial patellectomy
all the fracture fragments are removed and the tendon ends are stitched together called total patellectomy

Undisplaced fractures in which it is possible to lift the leg against gravity are treated with a plaster cast.

Undisplaced fractures in which it is not possible to lift the leg against gravity are treated by tension band wiring.

Transverse or longitudinal displaced fractures require surgery in which the fracture is fixed by wires or screws.

Communited fractures (multiple pieces) require ,partial patellectomy.

Severely communited fractures may require total patellectomy if they are un-salvageable.

Latest trend is to attempt to save as much of the patella as possible even in fractures with multiple bone pieces by gently holding the pieces in proper position and fixing them with flexible and stiff wires.

Complications include

stiffness of the knee joint
infection
arthritis

$patella fracture lower pole$ This is a x ray of a patient with a fracture of the lower pole of patella. In the following x ray you can see the same fracture treated by tension band wiring method. $patella fracture lower pole$