Knee Fractures

Causes of knee fractures

There are many possible causes of knee fractures. Traumatic accidents, such as direct impact to the knee during a vehicle collision, sporting injuries or tripping and falling heavily onto your knee are among the primary reasons for knee fractures in younger people. Stress fractures can occur if you make repeated movements that put your knee joint under strain, such as repetitive running or jumping. In older people, a condition called osteoporosis that weakens the bones can heighten the risk of knee fractures. These are called pathological fractures. Where you sustain a clean break, we call it a non-displaced fracture which means the broken bones are still correctly positioned. However, if you have a displaced fracture the bones have been jolted out of alignment and require re-aligning before the break can heal. With a comminuted fracture the bones have shattered into several pieces. An open fracture is where the broken bone has pierced the skin surface. The risk of infection is particularly high with this type of knee fracture.

A patella fracture is a broken kneecap which is normally caused by a heavy blow to your patella. This type of fracture is a serious injury that can be extremely painful and make it impossible to walk or straighten your knee. There is a high risk of complications, including post-traumatic arthritis, chronic pain and ongoing muscle weakness. Depending on the cause of the fracture your patella may develop a hairline fracture, break cleanly into two (stable patella fracture), become displaced (displaced patella fracture) or shatter into pieces (comminuted patella fracture). The cartilage covering the patella can also be damaged, leading to the possibility of post-traumatic arthritis.

Symptoms of knee fractures

Symptoms can vary depending on the location and severity, but most knee fractures are painful and cause swelling of the knee joint and bruising. You may not be able to put weight on the affected leg or be able to bend and straighten the knee. It may be impossible to walk and your knee joint may be visibly deformed or misaligned. If you have a comminuted fracture, you may feel a grinding sensation in the joint caused by shattered piece of bone rubbing against each other. With an open fracture, you will have an open wound and may be able to see fragments of bone.

If you fracture your patella (kneecap), you may be able to feel broken pieces of bone beneath your skin. You will often be unable to walk or straighten your leg and your knee joint may appear bruised and swollen.

Diagnosis of knee fractures

While some fractures are immediately obvious, others will only be confirmed following an X-ray which will reveal any breaks or displacement in the bones. You will be assessed for signs of hemarthrosis, which is where damaged blood vessels bleed into the spaces of the joint, leading to potentially serious complications.

Treatment of knee fractures

Depending on the type of fracture, you will normally need to wear a cast or splint to keep the knee straight and prevent movement in the joint while the bones heal. If the broken bones have become displaced or you have sustained a comminuted fracture, you will need surgery to realign the bones and pin them back into place. Your orthopaedic surgeon will fix the bones in place with plates, screws or pins. Tiny piece of bone may have to be removed if they are too small to pin. If you have developed hemarthrosis, you may need a procedure called aspiration to draw excess fluid out of the damaged joint to reduce swelling. Open fractures will require immediate surgery to reduce the risk of infection.

You will be given painkillers to help manage the pain of a knee fracture. A physiotherapist will be able to recommend a programme of exercise to help prevent stiffness in your knee and to strengthen the thigh muscles. It is important to follow this programme to support yourself to rehabilitate and make a good recovery.

Outcomes of treatment for knee fracture

How well you recover from a knee fracture will depend on the type and extent of the fracture, the type of treatment you receive and your rehabilitation programme. Your age, fitness and general state of health will also play a part in determining how well you recover. Your orthopaedic surgeon may recommend lifestyle changes to help protect your knee and reduce the risk of further injury.