The knee is a complex pivotal hinge joint that connects the bones in the upper and lower leg, comprised of muscle, ligaments, tendons, and the meeting of four bones: the femur, tibia, fibula, and patella. It is the largest joint in the body.  Read More
Of Interest
Written and medically reviewed by the Healthline Editorial Team
Co-developed by:

In Depth: Knee

The knee is a complex joint that moves straight backward as well as twists slightly from side to side. 

The knee is the meeting point of the femur in the upper leg and the tibia in the lower leg. The fibula, the other bone in the lower leg, is connected to the joint but is not directly affected by the hinge joint action. Another bone, the patella or kneecap, is at the center of the knee.

Two concave pads of cartilage called menisci disperse the friction created at the meeting of the ends of the tibia and femur.

There are also several key ligaments that connect these bones. The four key ligaments of the knee are:

  • Anterior cruciate ligament (ACL)
  • Medial collateral ligament (MCL)
  • Lateral collateral ligament (LCL)
  • Posterior cruciate ligament (PCL)

Damage to the ACL, such as a tear, is a common knee injury among athletes. Severe injuries to this important ligament typically involve reconstructive surgery

Another common sporting injury is pulling or straining the hamstring tendons, two groups of string-like connective tissues at the back of the knee and thigh that connect some of the major muscles of the knee.

A dislocated kneecap is yet another common knee condition. The kneecap slides along a groove in the femur as the knee bends. It is held in place by a ligament at the bottom and a tendon on top. Those connect to the femur and tibia. Sometimes, due to numerous complications, the kneecap comes out of its groove and becomes dislocated. The proper term for this condition is called patellar subluxation. It is most often treatable with bracing and physical therapy.

Knee problems and knee pain are common as the knee is a frequent point of contact during traumatic accidents and is as prone to wear and tear due to its weight-bearing nature. It is also a common site for arthritis pain.

Other knee problems include:

  • Fractured knee cap
  • Torn meniscus
  • Torn ligament
  • Torn hamstring muscle
  • Gout

Debugging Tools

Level: 1
Frame: 1
Toggle Hotspot
VP Data Tool
HexTable json from Steve
Steve's ajax layer update call:
[still on original layer]

Ad values:

adParams['k1']: generalanatomy,knee,8815356

More on BodyMaps

Take a Video Tour

Learn how to rotate, look inside and explore the human body. Take the tour

BodyMaps Feedback

How do you like BodyMaps? How can we improve it? Tell us what you think

Welcome to BodyMaps. Please select a category below that best describes you: