Ligaments are bands of tough, elastic tissue that bind bones together at joints so that they can move. The artificial ligament is primarily used for placement in the knee. There are four ligaments that surround the meniscus, which is a cartilage tissue that helps support the knee when it undergoes tension and torsion. The four ligaments are the anterior cruciate ligament (acl), the posterior cruciate ligament (pcl), the lateral collateral ligament (lcl), and the medial collateral ligament (mcl). An artificial ligament would be used to replace any one of these four ligaments that has been damaged.
The main mechanical connection for the femur and tibia is the ACL Ligament within the knee. The collagen fiber bundles can withstand different stress loads depending on the patient’s age. An average breaking load of a young athletes ACL is around 1700 to 2000 N. Artificial ACLs developed today can withstand loads of around 4,000 N, however it tends to suffer from poor mechanical performance in the long-term.
There are over 60,000 ACL reconstructions performed annually in the US. The success rate for reconstruction is between 75%-95% and failure rate is around 8% due to graft failure or instability.
ACL injuries usually occur within young athletes who participate in sports or activities that place heavy stress on the knees. These sports or activities include football, skiing, soccer, and any activity that requires side-to-side movement or hard cutting movements that stresses the ligaments in the knees.
Artificial ligaments are mainly constructed as woven or braided materials, but have been known to be nonwoven materials as well. As a braided fabric structure, an artificial ligament is gifted with high flexibility, high strength, high durability, and high cover. The fibers used (typically ePTFE, polyester, polyacetal polyethylene, polyethylene, or silk) all have a round cross-section which is ideal for use in this part of the body because it is surrounded by the human tissue in the knee so that the artificial ligament is secured in place; hopefully for the duration of the user’s life. A nonwoven would be used in order to utilize the fibrous mat made of graphite and Teflon to promote tissue growth using the implant.
Knitted fabrics tend to be much more elastic and flexible than any of the other three fabric constructions, woven fabrics boast high abrasion resistance, strength, and cover. Braided fabrics tend to take the advantages of both knitted and woven fabrics to create a highly function fabric.
Artificial ligaments are a “last-resort” type operation. Usually doctors will try to find a way to use ligaments from other parts of the body to repair an ACL, such as the patella tendon or the hamstring tendon. Patients now opt for donor tissue grafts, which usually uses the patellar tendon of a cadaver. All non-surgical treatments would have had to have failed in order for a replacement to be implanted. The primary function of an artificial ligament is to provide mobility while decreasing the pain. Many times, cartilage can be worn out and bone-to-bone contact can be extremely painful. In addition to athletic injuries, osteoarthritis, or degenerative joint disease can be cause for an artificial ligament.
- Allows return to high-level athletic activity
- May protect future damage to the knee cartilage
- Offers a near-normal knee
- Surgery is not 100% effective–some people don’t improve.
- Many activities can be accomplished without an ACL
- There are complications that may occur.