What is the function of the knee joint?

The knee joint’s main functions are to bend and lift (flex and extend), permitting the body to shift positions. The thigh bone (femur) and the shin bone (tibia) meet the kneecap (patella) to form the knee joint. 

Allograft reconstruction rebuilds an ACL-deficient knee with tissue from other parts of the leg.
Allograft reconstruction rebuilds an ACL-deficient knee with tissue from other parts of the leg.

There are four thick bands of tissues (ligaments) that stabilize the knee and keep its movement steady. These include:

  • Medial collateral ligament (MCL)
  • Lateral collateral ligament (LCL)
  • An anterior cruciate ligament (ACL)
  • A posterior cruciate ligament (PCL)
  • ACL prevents the gliding of the knee from back to front and vice versa.

What is the ACL-deficient knee?

An ACL injury is a tear in the anterior cruciate ligament (ACL). Injuries may be mild or severe (ligaments tear completely). Without treatment, the ACL loses its function and creates instability in the joints that result in the friction between the bones, leading to a condition known as a chronic ACL deficiency.

An ACL injury occurs due to:

  • Playing sports
  • Sudden bending or twisting of the knee
  • Falling off a ladder
  • Sudden force hitting the knee

What is allograft reconstruction of ACL-deficient knee?

The ACL-deficient knee can be repaired using an allograft reconstruction technique. Allograft reconstruction utilizes tissue (Achilles, hamstrings, or patellar tendons) obtained from a different donor to reconstruct the ACL-deficient knee. Autograft reconstruction uses tissues obtained from one’s body to repair the defect.

Advantages of using allograft reconstruction over autograft are:

  • Spares recipient’s own tissues (autogenous tissues)
  • Complications of using autogenous tissue can be avoided
  • Incisions are small
  • Short surgical times
  • A larger choice of tissue types and size is possible.
  • Because of all these advantages, allograft reconstruction appears to be the rational choice in repairing an ACL-deficient knee.

How is allograft reconstruction of ACL-deficient knee carried out?

The physician identifies the potential donor. The donor needs to undergo physical examinations as well as blood tests to rule out any underlying conditions. Tissues or grafts can be taken from the donor site in sterilized conditions. 

Next, the physician sterilizes the issue by soaking the tissue in antibiotic solution and freeze-dries it for preservation.

The freeze-dried tissue is thawed, which then undergoes the following steps:

  • Revascularization: Restoration of blood supply
  • Cell repopulation: Increase in the number of cells
  • Remodeling: Changing the structure of the grafts to match the recipient’s ACL

Once the remodeling is complete, the grafts appear similar to the recipient’s ACL. The remodeled graft is used to repair the ACL-deficient knee.

What are the complications of allograft reconstruction?

The complications of allograft reconstruction include:

  • Disease transmission
  • Immune response to the implanted grafts
  • High failure rates
  • Donor site complications
  • Infections

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Medically Reviewed on 7/15/2020
References
Medscape Medical Reference
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