Knee Fracture: Diagnosis, Classification and Treatment

Knee fracture or fractures of the knee joint can include the following

• fractures of the lower end of femur
• fractures of the upper end of tibia
• fractures of the patella

Here on this page we will know about fractures of the lower end of femur that are called Supracondylar and Intercondylar femur fractures.
The lower end of the femur bone is broad and forms two curved structures that are called condyles. The one located on the inner side is called medial condyle and the one on the outer side is called lateral condyle. In the front the condyles are united with each other. Behind they are separated by a space called the intercondylar notch.
The supracondylar area of the femur is the part that lies between the condyles and the shaft of the femur. Intercondylar area is the part between the two condyles.
In young adults these fractures result from high energy injuries such as road traffic accidents. In the elderly they occur following a minor fall with the knee joint flexed in weak osteoporotic bone.
Symptoms include the following

• Patient will give a history of a fall or accident.
• Severe pain and swelling will be present.
• Deformity is seen in the thigh or knee.
• Inability to lift the leg and inability to walk.
• The ankle and the toes can be moved freely unless there is a neuro-vascular injury along with the fracture.

In elderly people there may not be much pain and swelling. History of injury may also be vague. Inability to walk and lift the leg should alert us to the possibility of a fracture.
Diagnosis of the fracture can be easily made with x rays of the knee joint taken in two planes. At times it is difficult to understand the fracture pattern on x rays. In such conditions if is advisable to get a CT scan with three dimensional reconstruction of the fractured knee. This greatly helps in planning of definitive treatment.
These fractures are classified in three types based on the pattern of the fracture. They can be

• Extra-articular or supracondylar in which the fracture does not extend to the knee joint line.
• Partial-articular or condylar in which the fracture extends to the knee joint line but part of the condyles remain attached to the femur shaft.
• Complete-articular or intercondylar in which the fracture extends to the knee joint line but the condyles are completely separated from the femur shaft.

Treatment of knee fracture is decided by the classification of the fracture along with the degree of displacement, which can be either displaced or un-displaced.
All un-displaced knee fractures can be treated by a groin to toe plaster cast. This cast is applied for a period of 6 to 12 weeks depending on the age and general condition of the patient. Early removal of the cast followed by the application of knee brace is advisable. This allows movement of the knee while maintaining fracture alignment. When to remove the cast and apply the knee brace has to be decided by the treating doctor.
During cast treatment it is essential to repeat x rays every 10 to 15 days as these fractures can displace within the cast. Maintaining fracture alignment in a cast is more difficult in obese people.
All displaced fractures are treated surgically. Surgical fixation of the fracture can be done with either screws only, a plate and screws or a nail.

• Extra-articular or supracondylar fractures are usually treated with a nail.
• Partial-articular or condylar fractures are usually treated with screws only.
• Complete-articular or intercondylar fractures are usually treated with plate and screws.

Common complications seen with knee fracture include the following

• Loss of knee movement. This is seen more in partial-articular and complete-articular fractures, delay in surgery and after cast immobilization.
• Non-union or failure of the fracture to unite. This is seen more in the extra-articular or supracondylar fractures.
• Arthritis of the knee joint following fracture healing in a wrong position or due to damage of knee joint cartilage at the time of injury.
• Infection
• Deep-vein thrombosis

Frequently Asked Questions

How much time does it take for the fracture to heal?Most fractures heal enough within 8 to 12 weeks so as to allow walking.
How can loss of knee movement be prevented?
Loss of knee movement can be prevented by

• Stable and strong surgical fixation of the fracture allowing early postoperative mobilization of the knee joint.
• Meticulous handling of the skin and muscles around the knee during surgery so as to minimise scar tissue formation.

How long does it take to reach the activity and strength level as before the fracture?
Any fracture results in muscular weakness, and muscles take time to recover. For quick recovery stimulating the muscles in a organised and goal oriented way is essential.With out physiotherapy it can take 8 months to a year to reach the the pre-fracture level of muscle power and agility.
If you want to return quickly to the pre fracture level of activity following a knee fracture you need an intensive physiotherapy program.


This above is a CT scan of a young male showing a complete articular knee fracture. This fracture was sustained in a motor cycle accident. The patella bone was fractured in multiple pieces and so had to be removed. The remaining femur pieces were stabilized with a locking plate and screws as shown in the x ray below.


The x ray shown below is of a 70 year old male with severe osteoporosis and a extra-articular fracture that he sustained when he slipped on the way to the bathroom. When I first examined him there wasn't much swelling and he was not complaining of much pain. His inability to lift the limb alerted me to the possibility of a fracture. He was treated by the insertion of a titanium nail. A knee brace was used in the post-operative period.