Lindsey Vonn and the ACL dilemma
When skiing superstar Lindsey Vonn recently announced her withdrawal from the Winter Olympics, she demonstrated that reconstructing the torn anterior cruciate ligament of a world-class athlete has its unique problems.
While I have no personal information about Lindsey’s case and no criticism of the excellent care she received, as a former orthopedic surgeon to the U.S. Olympic ski team, I am all too familiar with the issues as stake.
These issues are:
The patient: World-class athletes push themselves and their recovering tissues to extremely high levels. While in some cases this accelerates healing, in other cases the speed of healing is just not fast enough for the patient’s patience. On the one hand, the Olympics occur just once every four years and an athlete’s moment is fleeting. Yet on the other hand, exposing healing tissues to forces that exceed their strength leads to tissue failure. Finding the balance between too soon and too late is the art form of the sports medicine orthopedic surgeon’s life.
Comprehensive diagnosis: Accurate diagnosis of the ACL injury involves understanding the associated injuries as well. Injuries to the knee sustained at high speed usually injure multiple tissues. One commonly missed injury is the posterolateral corner of the knee.
Another injury often not picked up in initial exams is a meniscus cartilage tear. Failure to recognize, repair or reconstruct these injuries leaves the knee without its normal stabilizing and shock-absorbing tissues. If an ACL reconstruction fails, it can be due to failure of these secondary tissues. Employing new techniques to repair each of the torn tissues is critical to the quality of the outcome.
We are biased toward repair and replacement of the meniscus tissue now that we have data to show that even small losses of meniscus tissue can lead to large increases in force concentration in the knee and can result in early arthritis. During the same surgical intervention as the ACL reconstruction, we reconstruct the posterolateral corner and repair or replace the meniscus whenever they are also injured. However, each of the repairs can slow down the recovery.
Graft choice: A world-class skier uses their hamstrings and quadriceps at extremely high levels of force and precision. Holding an edge on an icy slope at 60 mph uses every muscle fiber. Choosing which tissue to use to rebuild the ACL is a significant dilemma. Most commonly, surgeons have preferred to harvest tissue from one part of the knee and transfer it to the ruptured ACL to provide a new graft.
However, in my opinion, by using the patella tendon or the hamstring, the patient suffers from weakness of the quadriceps or flexor muscles for years — and often permanently — after the harvest. If that tissue ruptures again, the choices are limited still further.
For me, the best choice is donor tissue, and a particular kind of donor tissue: only young, healthy tissue called bone-patellar tendon–bone has properties that are similar to the patient’s own tissue. In addition, surgeons need to carefully select the right tissue bank. Processing of the tissues to reduce infection may also reduce their biomechanical properties and methods have not been standardized across the donor tissue banks. Unfortunately, the perfect tissue for an ACL reconstruction is in limited supply. (In the near future, this dilemma may be solved by the use of young, healthy strong pig tissue.)
Technique: Surgical precision at placing the ACL in the exact anatomic location has been shown to have a major impact on the long-term stability of the knee. Slight errors in placement have dire consequences. Older techniques using two incisions and rear entry guides have actually been shown to be more accurate in a wider variety of knees than some of the newer single-incision techniques. Surgeon experience and skill really does matter.
Rehabilitation: Vonn and many other world-class skiers rehab their knee and their entire body to a level most people will never know. But even that level of dedication is not enough to protect the healing ACL soon after surgery.
While superb rehab will lead to much more normal feeling knees and successful ACL reconstructions, superb healing is what is needed. Our research institute and others are working on new ways to speed healing so the window of failure is narrower. The secrets may lie in stem cell and growth-factor insertion into the tissues and the use of stronger animal tissues. The challenge is that every top athlete will want to return to full sports tomorrow. Our goal is to return them safely and fitter, faster and stronger.