Investigations for knee problems

X-Rays

The most common investigation to be performed are plain X-rays. X-rays are useful for looking at the bones in the knee joint but are not particularly useful for looking at the soft tissue parts of the knee. There are four common views that most knee surgeons would order: a front to back view with the patient standing, a side view, a view with the knee bent to look at the joint behind the kneecap and a view with the knee bent to look in the notch in the femur.

MR Scans

The next most common investigation is an MR (Magnetic Resonance) scan.  These scans are excellent for viewing the soft tissue components of the knee.  They are therefore good to visualise ligamentous injuries and injuries to the meniscal cartilages.  They also reveal bony pathology such as bone bruises, stress fractures and avascular necrosis.

CT Scans

CT (Computed Tomography) scans are less commonly used in the investigation of the knee since the advent of MR scanning.  However they are still very useful when the pathology is of bone and are especially useful in the management of complex fractures around the knee and in assessing the alignment of the knee in patello-femoral problems..  In conjunction with an injection into the joint, CT scans can be used to assess injuries to the lining cartilage of the knee.

Ultrasound scans

Ultrasound scans are sometimes used to investigate pathology of the patellar tendon and also to rapidly assess swellings around the knee.

Nuclear medicine scans

Scans such as technetium and indium scans are useful for the diagnosis of bone infection, occult fractures and tumours.  A small dose of a radioactive substance is injected into a patient and the substance attaches to bone.  In areas of high bone turnover, such as is found in infection, fractures and tumours, more radioactivity collects.  The patient is then scanned with a gamma camera which picks up the radiation and converts the information into a picture.