CT ankle joint is a radiological method of examining the articulation area of the foot and shin bones by obtaining layered images followed by multiplanar and three-dimensional reconstruction of images. Allows you to study the articular surfaces of the tibia and talus bones, the articular gap, vessels, muscles, ligaments and tendons of the ankle. CT is informative in the diagnosis of fractures of the bones forming the joint, soft tissue injuries, foreign bodies, degenerative (arthrosis) and inflammatory (arthritis) processes, rheumatic changes, osteomyelitis. It is used to control the fusion of bone fragments and the results of surgical interventions. In some cases, contrast enhancement may be required.
Indications
One of the main indications for CT ankle joint are injuries – fractures of the ankles (one-, two- and three-ankle), less often of the talus, distal tibia and fibula. Conventional radiography sometimes does not provide exhaustive information about the direction of the fracture line and the nature of the displacement of fragments, in such cases, computer tomography is resorted to. Degenerative lesions of articular cartilage (osteoarthritis) can also be a reason for CT. Pain of unclear origin, swelling and redness of the joints also sometimes become indications for this study, since in some cases traditional radiography is unable to detect pathological changes. CT of the joint is actively used to control the fusion of fractures, to assess the effectiveness of treatment after orthopedic interventions. Modern equipment allows you to take pictures of both one and both joints (depending on the indications).
Contraindications
There are few contraindications to the procedure, since it is a non-invasive and relatively safe study. An absolute contraindication is pregnancy, especially in the early stages – due to radiation exposure and possible complications associated with it. Also, excessive obesity (due to the limited load capacity of the equipment), childhood and some neurological diseases are considered restrictions for CT. The use of X-rays during examination in childhood is undesirable, in addition, young children are not always able to remain motionless during the study. The latter problem is also relevant for patients with hyperkinesis. The list of contraindications is expanded if the tomography is performed with the introduction of contrast – such a procedure is prohibited for kidney diseases, allergies to contrast agents and damage to the endocrine system.
Preparation
Before the examination, traditional radiography is usually prescribed in various projections, if there are doubts about the diagnosis or more information is needed (for example, before surgery), then they resort to computed tomography. Special measures for the preparation of CT ankle joint does not require, when using contrast, it is advisable to refrain from eating for several hours before the procedure.
Methodology of conducting
The patient should take off his shoes and lie down on the CT scanner table. Some models of devices provide for fixing the legs during the procedure – this increases its accuracy, since the slightest movements lead to “blurring” of the picture. Then the scanning begins directly, which, when examining the entire area (the lower part of the shin, the joint and the upper part of the foot) takes about 5-7 minutes, about the same amount of time is spent on computer processing of the results. The duration of the procedure does not depend on whether one or both legs are being examined. Then the resulting images are interpreted, recorded on digital media or on film.
Interpretation of results
The conclusion is prepared by a doctor of X-ray diagnostics. In case of violation of the integrity of the bone, defects will be clearly visible on the CT ankle joint, except in the rarest cases when the fracture line is exactly in the axial plane. However, such fractures are very clearly visible on a conventional radiograph, so their diagnosis is not difficult. The resulting images also reveal thinning and defects of articular cartilage corresponding to osteoarthritis and other degenerative processes. Dislocations of the ankle joint on a CT scan are manifested as a change in the configuration of the articular gap and the position of the bones relative to each other.
If the purpose of CT was preoperative preparation (for example, for severe fractures), then the orthopedic surgeon studies the images and the conclusion. After surgery, a second CT scan may be prescribed to evaluate the results of the operation and monitor the recovery process.
Advantages
Other modern diagnostic methods, such as magnetic resonance imaging (MRI), are also used to detect pathology of the ankle joint. However, due to the anatomical features of this part of the body (a significant amount of bone and a relatively small number of soft tissues), the use of CT ankle joint in most cases turns out to be more appropriate. In addition, MRI cannot be used to control bone fusion after orthopedic operations accompanied by the installation of metal pins or spokes. The latter also create difficulties during CT (form unwanted artifacts due to illumination), but this problem can be corrected by special data processing and some other methods.
