What Are the Most Common Knee Injuries?

Reviewed on 12/22/2020

What is a knee injury?

 Knee injuries can happen at any age. The most common types of knee injuries are stress fractures, dislocation, ACL injury, meniscal tearing, and tendonitis.
Knee injuries can happen at any age. The most common types of knee injuries are stress fractures, dislocation, ACL injury, meniscal tearing, and tendonitis.

The knee is the largest and one of the most complex joints in the body. Whether you’re moving or sitting throughout the day, your knees can experience heavy wear and tear, so it’s important to take good care of them. 

Three large bones come together to form the knee joint: The femur, the tibia, and the patella. Each one is covered at the ends with a cushioned, elastic material called cartilage that works like a shock absorber. 

These bones are additionally supported by two muscle groups: The hamstrings at the back of the thigh, and the quadriceps at the front of the thigh. 

Although knee injuries can happen to anyone, some activities and demographics are higher risk than others, such as: 

  • Athletes, especially in high-impact sports
  • Runners, especially if wearing improper footwear 
  • People who are overweight
  • People who sit too long in uncomfortable positions

Knee injuries left untreated can potentially lead to a number of complications, like: 

Understanding the signs of a serious knee injury can help you know when it’s time to seek treatment from a health professional.

Signs of a knee injury

The first sign of a knee injury that most people feel is pain. Though the pain may be severe, often there is only a very mild stiffness or discomfort around the knee joint, especially while making certain repetitive motions with it. 

Other important warning signs of a serious knee injury include: 

Pain while climbing stairs

Pain while climbing up the stairs is indicative of a torn meniscus, whereas pain while going down the stairs is a sign your kneecap is pushing painfully against the femur bone in the leg


Some kinds of swelling can stop you from bearing weight on your knee or bending it at all, whereas you may have no problem whatsoever walking in other cases. Either way, a swollen knee shouldn’t be ignored. 

Immediate pain

Sometimes the injury shows itself right away, such as a sharp pain in the middle of exercising. In this case, the pain and swelling will happen immediately, suggesting a torn ligament or even a bone fracture has occurred. 

Gradual pain

Some injuries appear a few hours or even days after the injury actually took place. An overuse injury, for example, develops little by little in response to prolonged pressure and is often a sign of cartilage or meniscal tearing. 

Some more signs to look for are: 

  • Redness
  • Bruising
  • Popping sounds
  • Feeling unstable

Seek medical attention if you notice any of these symptoms. 


Slideshow: Exercises for Knee Osteoarthritis and Joint Pain See Slideshow

Types of knee injuries

Some kinds of knee pain go away with a little rest, but some injuries are more serious. The most common types of knee injuries are: 

Stress fractures

Fractures can happen with any bone in the knee joint. They can occur as a result of trauma, but osteoporosis can also cause fractures. 


The bones of the knee joint may sometimes fall completely or partially out of alignment. Some people, due to their specific bone structure, may be more prone to this kind of injury than others. The most common cause of knee dislocation is trauma.

Anterior cruciate ligament (ACL) injury

Athletes who often quickly change direction or jump will often have ACL injuries. Many hear it "pop" when the ligament is either torn or strained.

Meniscal tearing

The menisci are two cartilages that protect the joint from stress as you walk. Though the menisci are often damaged during sports activity, they can also wear down as a result of aging or arthritis


Tendonitis in the knees is sometimes known as"jumper’s knee" because it often affects athletes who jump regularly. There are two tendons involved in the knee joint, around the quadriceps and patellar bones, and both can be stretched, torn, or worn down with time.

Diagnosing knee injuries

Doctors have many tools at their disposal to aid in the diagnosis of knee injuries. For instance, they’ll often collect your medical history and ask you questions about your activity level. X-rays, ultrasounds, and MRI scans can also provide a clear picture of your knee joint for an accurate diagnosis. 

Treatments for knee injuries

Some mild knee injuries are treated using the R.I.C.E. method, which stands for rest, ice, compression, and elevation. 

Other cases may require physical therapy to strengthen the joint and restore its range of motion. Surgery is reserved for the most serious knee injuries and may be either minimally invasive or involve a total replacement of the joint.


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