Computerised Tomography (CT Scan)

Computerised Tomography (CT Scan)

Investigations

CT scanning is a very useful option for detailed bone imaging. Soft tissues can be seen on CT scan, but are nowhere near as informative as MR scanning. CT scans do involve the use of radiation, and basically involves taking very fine x-rays through the knee, which are then compiled to generate images in different planes through the knee joint. Once again, it can be used to generate three-dimensional images to provide further information. CT scanning is very good at imaging intra-articular, complex fracture patterns prior to surgical fixation. CT scanning is also frequently used to image the chest and abdomen in addition to musculoskeletal imaging.

CT scans can also be used to find patellofemoral mal-alignment. In the position of the merchant’s view, the patella is usually already engaged with the trochlea. To show true malalignment, it is ideal to have the patella not engaged within the trochlea and this can only be done at lesser degrees of knee flexion and in order to do this, plain x-rays are no use, but a CT scan be taken in varying degrees of flexion from 0 to 45° as required. The degree of tilt and subluxation can then be evaluated with reference to the posterior condyles of the femur. The CT also provides excellent anatomical assessment of the femoral trochlea and patella morphological features.