What is a torn ACL/ MCL? What is a torn meniscus?

- answered by Staff at Marina Del Rey Hospital on 24th November 2016

A torn anterior cruciate ligament (ACL), a torn medial collateral ligament (MCL), and a torn meniscus are very common injuries regarding the knee. They appear during sports activities that involve twisting, bending or fast changing of direction.

The knee bones are connected to each other by four major ligaments: two cruciate and two collateral ligaments.

Cruciate ligaments are located inside of the knee, one in the front (anterior) and one in the back (posterior), crossing each other in an X shape. These ligaments are employed in the back and forth movements of the knee. ACL refers to the anterior cruciate ligament.

Collateral ligaments are situated on the sides of the knee, one on the inner side (medial) and one on the outer side (lateral). These ligaments are used in the sideways movements of the knee. MCL is the medial collateral ligament.

The ACL has a diagonal position inside the knee. It connects the shinbone (tibia) to the thighbone (femur) and ensures a proper rotation of the knee. This ligament can tear if the shinbone and thighbone twist in different directions, which often happens during sports or accidentally. It can be partially or completely torn. A partial tear can be treated by protecting the knee with a brace and using crutches, as well as by undergoing physical therapy to rehabilitate the knee’s functions. If, however, a complete tear occurred, it will not generally be repaired with sutures, as it may fail over time. A severely damaged ACL is commonly reconstructed surgically using a graft which is collected from another tendon or ligament in the leg. During the intervention, the torn ACL is removed and the graft is subsequently attached through the holes made by the surgeon in the tibia and femur. After the graft is inserted through the holes, it will be held in place with screws. Finally, incisions are closed with stitches after the procedure is completed. Regular physical therapy is necessary after surgery to regain the normal range of motions and strengthen the knee.

The MCL is located on the inner side of the knee. It connects the shinbone to the tibia and ensures the strength and stability of the knee joint. This ligament can be torn if there is a direct blow to the outer side of the knee which pushes the knee inwards. A partially torn MCL can heal naturally over time with bracing and physical therapy, while a completely torn MCL requires surgery. If the tear occurred in the middle of the ligament, the surgeon will stitch the two parts together. If the ligament has detached from the bone, the surgeon will reattach it using larger sutures, anchors or metal screws.

The meniscus is the knee cartilage. There are two menisci cartilages (lateral and medial) inside the knee joint, which are situated between the tibia and the femur. These cartilages protect the knee joint, functioning as rubbery shock absorbers. The meniscus can be damaged or torn when there is direct pressure on it following a forced rotation or twist. Another cause of meniscus tears is degeneration, which occurs due to aging or accompanies joint conditions such as arthritis. Mild meniscus tears often heal naturally, without intervention. For a severely torn meniscus, however, surgery is necessary. Arthroscopic surgery involves three methods for the treatment of a torn meniscus:

  • meniscectomy, which removes the damaged meniscus
  • meniscus repair, during which the torn cartilage pieces are reconnected by sutures
  • cartilage transplant from another part of the knee

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