If you’ve been told you have injured your anterior cruciate ligament, you’re certainly not alone. The ACL is the most commonly injured ligament in the knee.
The ligament is the main guide wire that runs through the middle of the knee, acting as a stabilizer. It is often injured in skiing, soccer, football, basketball and twisting sports. While minor injuries to the ACL may heal on their own without surgery, the majority of people will unfortunately develop unstable knees after rupturing the cruciate ligament and will require reconstruction surgery if they want to have stable, sports-active knees.
Injuries to the ACL are often accompanied by other injuries around the knee, such as tears in the meniscus cartilage, which is the shock-absorbing cushion in the knee joint, or damage to the articular cartilage, the covering of the joint. It is extremely important to make an accurate, early diagnosis after a knee ligament injury to discover exactly what has been damaged.
Failure to spot additional damage to the knee can result in a failed surgical repair of the ACL. We use a combination of a physical examination, X-rays and a high-quality magnetic-resonance image to study both the ligament and the associated damage to the knee joint. ACL injuries should be repaired or reconstructed as soon as possible to prevent the damage to the meniscus and articular cartilage that comes from an unstable knee.
A partially torn ACL can sometimes be repaired without being removed. If, however, the ACL is damaged to the point where it needs to be replaced, surgeons have a choice about whether to use a patient’s own tissue from his or her patellar tendon or hamstrings (autograft) or instead use donor tissue from a tissue bank (allograft). This choice is hotly debated in the orthopedic community.
Some, myself included, argue that robbing Peter to pay Paul is not an effective treatment since moving a patient’s own tissue from one place to another weakens the knee and permanently increases the risk of arthritis. The outcomes of donor tissue procedures have been excellent, except a reported higher incidence of rupture in young people, though it is unclear if that was due to the type of allograft used.
We’re not convinced by the studies that limit allograft use because they include all kinds of donor tissue in their research: from both young and old donors; from many different areas such as hamstrings, Achilles tendons and patella tendons; and from both registered and unregistered tissue banks. With every year of age after age 20, tissue strength degrades by 1 percent. So an older donor’s tissue is not nearly as good as tissue from a young donor. Additionally, the Achilles tendon is designed to stretch when you walk. This makes the Achilles a poor choice for a ligament replacement that is designed not to stretch. Our results using donor patellar tendons from donors younger than 40 years old have been better than our results from using the patient’s own tissue.
Other factors determining the success of an ACL repair or reconstruction are the surgical technique and the skill used to accurately place the ligament. The No. 1 cause of ACL repair failure is poor placement of the ligament by the surgeon. Finally, it comes down to the patient. Those who commit to a rigorous rehabilitation program, focusing on full range of motion of the knee and full-body fitness, do the best.
Advancements in ACL surgery are extremely exciting. We have been investigating the use of pig tissue that soon may augment or replace the use of human tissue. A European study of 60 patients comparing pig ligs to human donor tissue is getting excellent results. A U.S. Food and Drug Administration-approved wide clinical trial will commence soon.
Dr. Kevin R. Stone is an orthopedic surgeon at The Stone Clinic and chairman of the Stone Research Foundation in San Francisco. He pioneers advanced orthopedic surgical and rehabilitation techniques to repair, regenerate and replace damaged cartilage and ligaments. For more info, visit www.stoneclinic.com.