Introduction #
A Knee X-ray is a simple imaging test that uses a very small amount of radiation to create pictures of the bones that form the knee joint. It is one of the most frequently requested tests when patients complain of knee pain, stiffness, swelling, or after an accident that may have caused injury.
Although CT and MRI scans now provide clearer views of soft tissues like ligaments and cartilage, the plain Knee X-ray is still the first choice in many cases. This is because it is quick, widely available, cost-effective, and particularly good at showing bone-related problems.
This article breaks down the main reasons doctors request a Knee X-ray, what the test involves, and what you can expect from it.
Why might I need a Knee X-ray? #
Some common situations where a Knee X-ray is ordered include:
• Possible fractures or breaks after a fall or accident
• Ongoing knee pain, swelling, or stiffness
• Suspected dislocation of the knee joint
• To check for signs of arthritis or joint wear-and-tear
• Evaluation of bone infections or suspected tumors
• Assessing abnormal alignment (knock-knees or bow-legs)
• Monitoring recovery after surgery or treatment for fractures
What does a Knee X-ray show? #
The test gives images of the main bones that make up the knee joint:
– Lower end of the femur (thigh bone)
– Upper end of the tibia (shin bone)
– Patella (kneecap)
– The space where these bones meet (joint space)
– Sometimes, the fibula and nearby structures are also visible
It does not clearly show soft tissues like ligaments, cartilage, and tendons. For those, doctors may recommend MRI or ultrasound.
Do I need to prepare before the test? #
No special preparation is needed. You may be asked to remove jewellery, clothing with zippers or buttons, or any objects around the knee that could interfere with the images.
Always inform your doctor or Radiographer if you are pregnant or suspect you may be pregnant.
Is a Knee X-ray safe in pregnancy? #
If necessary, yes. Because the knee is far away from the abdomen, the developing baby is less likely to be affected. However, X-rays are generally avoided during pregnancy unless essential. If the test must be done, protective shielding is applied to reduce exposure.
What types of Knee X-ray views are taken? #
To get a full picture, images are usually taken from different angles, such as:
• AP (anteroposterior) view: Shows the joint from front to back
• Lateral view: Side image showing bone alignment and patella position
• Oblique view: Angled image for more detail
• Sunrise/Merchant view: Focused view of the kneecap and its joint space
• Weight-bearing views: Taken while standing to evaluate joint space narrowing, especially in arthritis cases
Is the procedure painful or invasive? #
No. The test is painless and non-invasive. The only mild discomfort may come from holding your knee in certain positions for a few seconds while the images are taken.
How long does it take? #
Most Knee X-rays are completed in about 5 to 10 minutes, depending on the number of views required.
What can doctors detect from a Knee X-ray? #
Your doctor may be looking for:
• Broken bones or cracks in the knee
• Dislocations or abnormal bone positioning
• Early or advanced arthritis (e.g., narrowed joint spaces or bone spurs)
• Bone tumors, cysts, or unusual growths
• Signs of infection in the bone
• Abnormal or uneven bone growth in children
Can a Knee X-ray detect every knee problem? #
No. While it is very useful for bone conditions, Knee X-rays cannot show cartilage injuries, ligament tears, or soft tissue problems. If these are suspected, an MRI or ultrasound may be advised.
How often can I have a Knee X-ray? #
There is no set limit. Knee X-rays are performed only when needed. Although the radiation exposure is very low, it’s best to avoid unnecessary scans.
Conclusion #
A Knee X-ray is a fast, safe, and effective way to examine bone and joint problems in the knee. It remains a reliable first step in diagnosis and can guide doctors on whether further imaging or treatment is necessary.
Is a Knee X-ray good for my arthritis, and why? #
Yes. A Knee X-ray is one of the best first-line tests for arthritis. It shows changes in the joint that suggest arthritis, such as:
– Narrowing of the joint space (due to cartilage wear)
– Formation of bone spurs (osteophytes)
– Changes in bone shape or alignment
– Signs of joint damage from long-standing disease
Although an X-ray cannot show cartilage directly, the space between the bones gives an indirect clue about cartilage health. For a more detailed look at soft tissues like cartilage, ligaments, or early inflammatory changes, your doctor may recommend an MRI.