What is the MRI of the knee joint, how do they show the MRI of the knee joint?
The knee joint is the most vulnerable in the human musculoskeletal system. That is why the diagnosis of knee injuries is an actual problem of traumatology. An ideal method of visualizing the knee joint is magnetic resonance imaging( MRI).With it, you can diagnose various injuries, from ligament ruptures to bone fractures. What is an MRI of the knee joint? How is tomography done? In these matters it is necessary to understand.
Anatomy of the knee joint
This compound is the largest in the human body. The bone bases of the knee are the femoral and tibia, as well as the patella. The fibula has nothing to do with the joint. The surfaces of the bones forming the joint are covered with cartilage. Thanks to it, the frictional force is reduced and ease of movement is ensured.
At the distal end of the femur, there are two condyles - lateral( smaller) and medial( larger).They have a rounded shape. The condyle is also at the proximal end of the tibia. They are relatively flat. Between the articulating surfaces there are menisci( external and internal) - crescent cartilages. They stabilize the knee, perform the role of shock absorber in it.
In the knee joint, several ligaments are selected to ensure its stability:
- tibial( medial) collateral;
- peroneal( lateral) collateral;
- front cross-shaped;
- posterior cruciate.
The knee also includes tendons. Before considering the MRI of the knee joint, which it shows, it is worth noting that the tendon of the quadriceps muscle most often is damaged. Its rupture is caused by an unexpected contraction of the muscle. Sometimes injuries of the dense and broad tendon or of the ootibial tract are diagnosed. This structure is a strong lateral dynamic knee joint stabilizer.
Indications for MRT
Damage to knee structures is observed quite often. The specialists are mainly addressed by young people who lead an active lifestyle and engage in sports. Before the help, doctors conduct magnetic resonance imaging. This is an accurate and reliable method of diagnosing various injuries.
MRI of the knee joint has definite indications. These include:
- possible damage to collateral and cruciate ligaments;
- violation of the integrity of menisci or tendons;
- suspected of fracture;
- pain in the knee;
- specification of information obtained due to radiography.
Contraindications to the
study "What will the MRI of the knee and foot show?"- a question that all people may not be able to answer, because this diagnostic method has contraindications:
- the presence of an electrocardiostimulator( artificial pacemaker) whose function may be impaired due to the research;
- metal clips attached to the blood vessels, capable of shifting due to the action of the magnetic field;
- severe patient condition;
- ferromagnetic implants, due to which the images are not quite correct, the results of the research are distorted;
- pregnancy before the 12th week.
From this list it is worth highlighting claustrophobia. It is not an absolute contraindication. When a patient develops a fear of closed and tight spaces, sedative therapy or shallow anesthesia is used.
study How the MRI of the knee joint is performed is an actual topic for people who are assigned this procedure. So, before performing magnetic resonance imaging, the patient is offered to change into special clothes. You can stay in your things, if they do not have any metal buttons, lightning. Before research also it is necessary to remove all ornaments, glasses, watches, remove keys from pockets, mobile phone.
Scan is performed when the patient is lying down on the back. The human feet are placed in the device. During the study, the injured leg is in the radio frequency coil. A healthy limb is parallel to it. Under the leg being examined, a small roller is inserted. It is necessary for the best visualization of cruciate ligaments.
If there are suspicions of a tumor, then contrast magnetic resonance imaging is performed. Before the study, a special substance is injected into the patient's vein. It is necessary for the MRI of the knee joint to show a neoplasm.
MRI Anatomy of the Knee Joint
It is important to know that it will show the MRI of the knee joint in order to make the correct diagnoses. Here is the characteristic of the main components of the knee:
- Normally, the anterior cruciate ligament on T2-VI and T1-VI looks like a black structure with a homogeneous low-intensity signal. The posterior cruciate ligament on images obtained as a result of MRI is visualized as a well-defined homogeneous black strand.
- The tibial and tibial collateral ligaments normally give a homogeneous low-intensity signal to the T2-VI and T1-VI.
- Normal menisci on T2-VI and T1-VI are visualized as homogeneously hypo-intensive structures( up to black ones) with central bundles of nerves and vessels. The contours of the meniscus are clear, the surface is uniform.
- Tendons tend to have a very low signal. They may not even give it at all in images weighted by T1 and T2.
- Articular cartilage is characterized by a low signal intensity on T2-VI and an average signal intensity at T1-VI.
Damage to the ligaments of the
The most frequently injured ligament is the anterior cruciate. What will the MRI of the knee joint show if this structure is damaged? At break, the intensity of the signal within the ligament increases. There may be a discontinuity or a lack of a normal signal. With fresh injuries it is difficult to conclude on the results of MRI on the presence or absence of a rupture, because with a trauma the ligament increases in size( there is edema).
Collateral ligament injury can be a complete rupture, partial tearing and an intra-connective rupture. If the tibial collateral ligament proves to be damaged, its thickening will be observed. Areas of signal increase will appear. This is what will show the MRI of the knee in the first day. In the future, these areas will disappear due to the absorption of excess fluid in the area of injury by surrounding tissues.
Fractures of the peroneal collateral ligament are diagnosed, as a rule, extremely rarely. Such traumas are combined with massive fractured fractures of the condyle of the tibia, loss of surrounding soft tissues.
In the injuries of these knee structures, the images obtained in the sagittal and coronal planes are considered the most informative. To assess what MRT shows the knee joint and make a diagnosis, doctors pay attention to the following characteristics:
- the size of the meniscus;
- their configuration, the nature of the signal;
- the thickness and depth of the changed signal;
- localization of changes within the meniscus.
There are several degrees of meniscus damage:
- The first degree is an expressed central degeneration. In the course of magnetic resonance imaging, changes are detected within the meniscus. They are manifested by the increased intensity of the signal.
- The second degree is a widespread central degeneration. Inside the meniscus, a wider area of increased signal intensity is visualized. The third degree is the tearing of the meniscus. Inside the meniscus, an increased intensity of the signal is detected. The contour of the intraarticular space is broken. Sometimes the position of fragments of the meniscus changes.
Damage to the tendon
The examination of the tendon of the knee joint is performed in the sagittal and axial planes. In the first one, the changes are more clearly visualized. The presence of lesions is confirmed if the following MR-signs are detected during magnetic resonance imaging:
- effusion in the tendon sheath( response to excessive congestion) or edema in the peritendinous synovial tissue( in those areas where there is no envelope);
- thickening or thinning of the tendon;
- signal change( in case of degenerative pathology in the central zone of the tendon, longitudinally directed radiance is observed, for which a hyperintense signal is characteristic for T1-VI);
- complete rupture of the tendon( a thickening of scraps of the tendon with a recorded signal intensity and a wavy contour is recorded).
One of the most common injuries is fractures of the bones that form the knee joint. With true fractures, a linear decrease in the signal with a rupture of the cortical bone is observed. Sometimes fragments move. There may be hemarthrosis - a hemorrhage into the joint cavity. It appears on the T1-weighted image with a higher signal than the serous fluid.
Special attention should be paid to chronic( chronic) fractures, because some people do not seek help from specialists after getting the damage. Such injuries are characterized by hypo-intensive, non-uniform changes with signs of sclerosis of fibrous tissue and bone marrow space.
It is worth considering and contusion lesions( bruises) of the bone. What does the knee MRI show in these cases? With these injuries, there is limited intraosseous edema. It is characterized by a weak diffuse signal decrease on the T1-weighted image and an increase in its intensity on a T2-weighted image. The pathological signal can persist for 3-10 months.
In conclusion, it should be noted that the knee joint is injured most often. One of the best methods for diagnosing various lesions is magnetic resonance imaging. It has several advantages. First, this study is very informative. It allows specialists to assess the condition of bones and soft tissues. Secondly, magnetic resonance imaging is harmless for patients( in the absence of contraindications).That is why MRI of the knee joint is prescribed for children and adults.