X-ray of the knee – what is it? Indications, preparation, appearance, price [EXPLAINED]

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Knee X-ray is one of the most popular diagnostic tests that is performed in the case of suspected damage to the knee joint. They can also be done in the case of indefinite pains in the area of ​​the knee. What does an X-ray examination of the knee look like? We check what are the indications for its performance, as well as how much the knee X-ray costs.

X-ray of the knee – what is it?

Knee X-ray (X-ray examination of the knee joint) is the basic diagnostic test that is used in orthopedics and traumatology. It consists in x-raying the knee joint. Typically, an X-ray is the first examination after an injury to see if there has been any damage to the bone tissue. The test uses X-rays, also called X-rays, as they pass through the body.

Knee X-ray – what is the knee joint made of?

In order to visualize which injuries it is best to perform a knee X-ray, pay attention to the structure of the knee joint that connects the thigh with the lower leg. It is the largest joint in the human body and is also the most vulnerable to injury. Its three most important components are the femur, the tibia, and the patella (navicular bone). The femoral condyles are located on the head of the joint, and the tibial condyles and the articular surfaces of the patella are located on the acetabulum.

The elements of the joint are filled with a joint capsule composed of two layers: a fibrous membrane and a synovial membrane. At their confluence, there is a sub-patella fat body that fills the joint space during movement. The bag is strengthened by ligaments:

1. external ligaments of the knee joint (collateral ligaments, ligaments associated with the patella, ligaments of the posterior surface of the joint capsule);
2. internal ligaments of the knee joint (anterior cruciate ligaments and posterior cruciate ligaments; ligaments associated with the menisci).

There are also two types of meniscus (lateral and medial) in the knee joint between the femur and the tibia.

X-ray of the knee – how much strain is the human knee?

As already mentioned, the human knee is the largest hinge joint that is extremely stressed when performing its basic functions – flexion and rotation. Healthy people burden the knee five times when walking, and even fifteen times during physical activity. In turn, each increase in weight puts additional strain on the knee joints, which is one of the main causes of knee pain, which is often reported by patients to the orthopedist.

Knee X-ray – what can the test show?

X-ray examination of the knee joint is much less imaging than magnetic resonance imaging and ultrasound, but it is enough to show changes within:

1. the thigh bone (possible fracture);
2. tibia;
3. intercondylar eminence;
4. intercondylar fossa;
5. articular surfaces;
6. osteochondral fractures;
7. thickening of soft bones.

Compared to MRI and ultrasound of the knee, X-ray is not able to show soft tissues, including ligament damage. In this case, the most reliable test is the MRI of the knee.

X-ray of the knee – indications for the examination

The main indications for performing a knee X-ray are:

1. knee pain;
2. knee injuries resulting from increased physical activity;
3. knee injuries during a traffic accident;
4. inflammatory changes in the knee joint;
5. suspected fracture of long bones;
6. suspicion of ligament damage;
7. degenerative changes in the knee joint;
8. gout;
9. genetic defects in the knee joint;
10. developmental defects within the knee joint;
11. suspected fracture or dislocation of the patella;
12. inflammatory changes within the tendons;
13. choroba Larsena-Johanssona;
14. Osgood-Schlatter disease;
15. rheumatoid arthritis;
16. neoplastic changes in the knee joint;
17. knee instability.

See also: Traumatic injury of the knee joint

X-ray of the knee – how to prepare for the examination?

The X-ray examination of the knee does not require any preparation from the patient. However, it should be remembered that for its implementation you need a referral from an orthopedist. On the X-ray of the knee joint, you can put on loose sweatpants so that they can be rolled up and at the same time expose the knee. In other cases, the radiologist will ask you to remove your pants, tights, or leggings. In addition, it is a good idea to take your knee medical documentation with you for the examination.

X-ray of the knee – contraindications to the examination

The main contraindication to performing a knee X-ray is pregnancy, especially its first trimester. This is because of the concern that X-rays may damage the fetus during the examination. Therefore, before the examination, women must sign a declaration that they are not pregnant.

X-ray image of the knee joint AP – what is it?

X-ray examination of the knee joint and other structures can be performed in two projections, AP and PA. PA projection works well in healthy patients who can stand. The radiologist is then able to take an image in the posterior anterior and lateral positions. AP projection is indicated for patients with difficulty standing. Then it is best to perform the AP X-ray in the supine position with an anterior-posterior projection.

Knee X-ray – what does the examination look like?

For an X-ray examination of the knee, four projections are needed:

1. anterior-posterior;
2. side;
3. tunnel shot (also called semi-axial projection);
4. axial photo.

The photo is about two knee joints so as to compare them. In addition, it is possible to take a stress photo, which is taken when ligament damage (e.g. lateral cruciate ligament) is suspected. It consists in taking a picture with a simultaneous load on the limb. Such a forced position allows the joint space to be viewed, which helps in introducing appropriate treatment.

1. See also: Jumper’s knee – causes, symptoms, knee treatment method

X-ray of the knee – the price of the test

X-ray examination of the knee joint can be performed under the National Health Fund or in a private facility. An X-ray image of the knee with a description costs about PLN 50. You can also make a patella X-ray, the price of which is also about PLN 50.

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