Bioengineered Anterior Cruciate Ligaments

Other Unique Engineering Ideas
Anterior cruciate ligaments are frequently torn in sports injuries and traffic accidents, resulting in pain and severe limitations on mobility. Unfortunately a simple repair by suturing the torn ligament together again is not effective.

1.  Description

2. Why

3. How

4. Future Trends

5. Related Links

Useful Links: knee joint

Description

An anterior cruciate ligament is one of two ligaments (the other being the posterior cruciate ligament) that cross in the middle of a knee joint and act to prevent the bones in the knee from sliding forward and backward relative to each other.The function of the ACL is to provide stability to the knee and minimize stress across the knee joint:

  • It restrains excessive forward movement of the lower leg bone (the tibia) in relation to the thigh bone (the femur).
  • It limits rotational movements of the knee.

It is one of the most important of four strong ligaments connecting the bones of the knee joint. It is often injured. Ligaments are strong, dense structures made of connective tissue that stabilize a joint. They connect bone to bone across the joint.

Why

A tear to the anterior cruciate ligament (ACL) results from overstretching of this ligament within the knee.

  • It's usually due to a sudden stop and twisting motion of the knee, or a force or "blow" to the front of the knee.
  • The extent of the tear can be a partial or a complete tear.
  • Individuals experiencing a tear to the ACL may or may not feel a pop at the time of the injury.
  • It is often injured together with other structures inside the knee joint.
  • After the initial injury, the knee may swell and become painful.
  • Instability or a sensation the knee is "giving out" may be a major complaint following this injury.

Often, but not always, depending on a person's activity level, a torn ACL needs to be fixed. A successful repair involves completely replacing the torn ligaments.By making it possible to grow replacement anterior cruciate ligaments that structurally and functionally resemble natural ones more closely than do totally synthetic replacements, the method could create new opportunities for full or nearly full restoration of functionality in injured knees.Moreover, this finding can be generalized to nonmechanical (e.g., chemical and electromagnetic) stimuli that are experienced in vivo by tissues of interest and, hence, the method can be modified to incorporate such stimuli in the ex vivo growth of replacements for the various tissues mentioned above.

How

In the method for growing bioengineered tissues that is used in surgical replacement of damaged anterior cruciate ligaments. The histomorphological properties of a bioengineered tissue grown in vitro from pluripotent cells within a matrix are affected by the direct application of mechanical force to the matrix during growth generation.During the growth process, the matrix is subjected to a combination of tension, compression, torsion, and shear stresses via movement of one or both of the anchors. The work was done by Gregory Altman, David L. Kaplan, Ivan Martin, and Gordana Vunjak-Novakovic of Massachusetts Institute of Technology for Johnson Space Center.Typical requirements are:

  • A bioreactor tube within which the growth process takes place and
  • An apparatus that operates under computer control to generate the required motions.
  • Examining the mechanical stress, biochemical and cell-immobilization methods, and cell differentiation, as applicable to the production of the variety of tissues.

Optimally, the stresses should mimic those to which the anterior cruciate ligament is subjected in vivo during normal activity. The bioengineered ligament produced by this method is characterized by a cellular orientation and/or matrix crimp pattern in the direction of the applied mechanical forces, and by the production of collagen type I, collagen type III, and fibronectin proteins along the axis of mechanical loading. The ligament thus produced contains fiber bundles arranged in a helical pattern.The method is also adaptable to the growth of bioengineered replacements for other ligaments (e.g., other knee ligaments as well as those in the hands, wrists, and elbows) and to the production of tissues other than ligaments, including cartilage, bones, muscles, and blood vessels.

Future Trends

The new bioengineered anterior cruciate ligament (ACL) replacement could provide a new treatment option for the more than 200,000 Americans who rupture their ACLs annually. The next step will be to test the scaffold in large animals such as sheep or goats, and that he is looking for corporate partners to help commercialize his invention.

Keywords

Anterior cruciate ligament, bioengineered, injured sports stars, pluripotent cells.

Related Articles

Related Links