Ligaments and Bursae of the Knee

Bones and cartilage make up the knee’s structure but without ligaments and bursae the knee would be unable to bend properly. Ligaments stabilize and strengthen the knee and bursae provide padding so the tendons of the knee joint move freely.

Ligaments

The following ligaments help to stabilize the knee joint.

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  • Patellar ligament: This ligament runs from the patellar apex to the tibial tuberosity.

  • Lateral collateral ligament: Also known as the fibular collateral ligament, this strong, rounded band of ligament runs from the lateral epicondyle of the femur to the lateral part of the head of the fibula.

  • Medial collateral ligament: Also called the tibial collateral ligament, this strong, flat ligament runs from the medial epicondyle of the femur to the medial surface of the tibia and attaches to the medial meniscus.

  • Oblique popliteal ligament: This ligament starts behind the medial condyle of the tibia and runs superiorly and laterally to attach to the posterior part of the joint capsule.

  • Arcuate popliteal ligament: This ligament starts from the posterior part of the fibular head and runs superiorly and medially to the posterior part of the knee joint.

  • Anterior cruciate ligament: The ACL starts from the anterior part of the intercondylar area of the tibia and runs superiorly, posteriorly, and laterally. It attaches to the posterior, medial side of the lateral condyle of the femur. The ACL prevents the tibia from sliding forward on the femur.

  • Posterior cruciate ligament: The PCL starts at the posterior intercondylar area of the tibia and runs superiorly and anteriorly (medial to the ACL) to attach to the anterior part of the lateral side of the medial condyle of the femur. The PCL prevents the tibia from sliding backward on the femur.

  • Coronary ligaments: These ligaments are part of the joint capsule. They attach the menisci to the tibial condyles.

  • Transverse ligament: This ligament runs across the anterior intercondylar area and attaches to the menisci anteriorly.

  • Posterior meniscofemoral ligament: This ligament attaches the lateral meniscus to the posterior cruciate ligament and the medial condyle of the femur.

The bursae

The knee joint contains the following bursae, which are fluid-filled sacs that help tendons glide over the bones and other tendons:

  • Suprapatellar bursa: Between the femur and the quadriceps femoris tendon

  • Popliteus bursa: Between the tendon of the popliteus muscle and the lateral condyle of the tibia

  • Pes anserine bursa: Between the tendons of the sartorius, gracilis, and semitendinosus muscles (and the medial (tibial) collateral ligament

  • Gastrocnemius bursa: Between the tendon of the medial head of the gastrocnemius muscle and the joint capsule

  • Semimembranosus bursa: Between the tendon of the medial head of the gastrocnemius muscle and the tendon of the semimembranosus muscle

  • Subcutaneous prepatellar bursa: Between the anterior surface of the patella and the skin that covers it

  • Subcutaneous infrapatellar bursa: Between the tibial tuberosity and the skin

  • Deep infrapatellar bursa: Between the patellar ligament and the anterior part of the tibia

Bursitis of the knee is an inflammation of any of those eight bursae, resulting in pain and tenderness of the knee, swelling, and a warm feeling when you touch the area. The bursae can become irritated by frequent kneeling, direct trauma to the knee, or falling on the knee too often. Bacterial infections and arthritis can also lead to bursitis. Treatment may include medications for pain relief, antibiotics if infection is present, specific exercises, and possibly surgery.

A sprain is an injury to a ligament. Because the knee is fairly vulnerable to injury, knee sprains are fairly common, and most involve the medial or lateral collateral ligaments or the cruciate ligaments (and sometimes a collateral ligament and a cruciate ligament are damaged in the same injury).

Knee sprains are graded on their severity:

  • A mild sprain is simply a stretched ligament, which usually heals just fine on its own.

  • A moderate sprain involves some tearing of the ligament. Treatment includes rest, ice, and specific exercises.

  • A severe sprain may include a complete rupture of a ligament, which usually means surgical repair is necessary.

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