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Got knee pain? Learn about the knees and how to best protect them

Updated: May 2

Knee Anatomy

The knee is a weight-bearing joint composed of the patella, cartilage, ligaments, tendons, and meniscus. It is the “meeting point” for the bones of the leg: the femur (thigh bone), the tibia (the shin), and the fibula.

Bones of the knee

The femur connects the hip to the knee and is a weight-bearing bone. The tibia connects the knee to the ankle. The fibula is shorter than the tibia and runs parallel to the tibia. Lastly, the patella (knee cap) attaches to the quadricep tendon and the patellar ligament. It rests on the end of the femur and protects the knee.

Ligaments of the knee

Ligaments comprise collagen, connective tissue, and elastic fibers that attach bones. The four ligaments in the knee are the Anterior Cruciate Ligament, the Posterior Cruciate Ligament, the Medial Collateral Ligament, and the Lateral Cruciate Ligament.

Anterior Cruciate Ligament (ACL): The ACL is the stabilizing ligament in the knee. It is located in the center of the knee, running from the femur to the tibia. It prevents the tibia from moving in front of the femur and controls the rotation of the knee.

Medial Collateral Ligament (MCL): The MCL keeps the tibia in place. It runs from the top of the tibia to the bottom of the femur. The MCL prevents the knee from collapsing medially.

Posterior Cruciate Ligament (PCL): The PCL runs from the bottom front of the femur to the top back of the tibia. The PCL prevents posterior instability in the knee.

Lateral Cruciate Ligament (LCL): The LCL stabilizes the outside of the knee. It runs from the top of the fibula to the outside of the lower femur.

Menisci of the knee

In the knee, the menisci act as shock absorbers between the femur and the tibia.

Medial Meniscus: The medial meniscus is a crescent-shaped fibrocartilaginous structure that attaches to the top of the tibia.

Lateral Meniscus: The lateral meniscus is another fibrocartilaginous structure found in the knee, located near the outer side of the knee.

Image credits: Comprehensive Orthopaedics, S.C

Common Injuries

  • ACL injury

  • Meniscal Tears

  • Knee Bursitis

  • Patellar Tendinitis

  • Fractures

  • Patellofemoral Knee Syndrome

ACL Injury

An ACL injury is one of the most common knee injuries. It can be a tear or sprain of the anterior cruciate ligament. The injury can be a partial tear or a complete tear of the ligament. ACL injuries are referred to as sprains, of which there are three types:

  • Grade 1: The ligament has been stretched but is still able to keep the joint stable

  • Grade 2: The ligament is injured so that it becomes loose. This is also known as a partial tear.

  • Grade 3: The ligament has been torn in half or pulled off the bone. This is known as a complete tear.

Meniscal Tears

A meniscal tear is a common knee injury that can occur because of a sudden twist of the upper leg while bearing weight.

Knee Bursitis

Knee Bursitis is an overuse injury characterized by the inflammation of the bursa (fluid-filled cushioning sacs) near the knee joint.

Patellar Tendinitis

Patellar Tendinitis is another overuse injury that causes inflammation of the patella tendon.


A knee fracture (or patell