Recent years have brought significant improvements in anterior cruciate ligament (ACL) reconstruction, allowing surgeons to better address the specific needs of each patient.
As I outlined in my last column, decisions about how to approach an ACL injury depend on the patient's age, size, and plans for continuing sports. These factors also affect the choice of graft materials, whether to use platelet-rich plasma, and the approach to rehabilitation, which are discussed here.
Choice of Autograft Graft Material
The choice of graft material presents a complex challenge. First, there's the choice between autograft and allograft. Second, there's the choice of tendons to be harvested for grafting. Each has some advantages and potential disadvantages.
In autograft materials, the choices are patellar tendon, hamstring tendon (the semitendinosus and gracilis muscles), or quadriceps tendon.
Autologous patellar tendon is extremely durable and has been used for the past 30 years as the gold standard for ACL reconstruction in athletes. The downside is that harvesting this tendon can cause anterior knee pain and a higher incidence of osteoarthritis. I use it in my most competitive athletes who put the greatest stress on the joint.
Using autologous hamstring tendon avoids anterior knee pain. And these tendons are easier to harvest. On the downside, many athletes never quite get back to full strength after this important tendon is harvested. And the injury to the hamstring can cause an imbalance of strength in the joint, increasing the risk for reinjury, especially in females.
Autologous quadriceps tendon has become more popular in the past 2-3 years because it's a thicker tendon; you don't get anterior knee pain from harvesting it, and it doesn't seem to have to the failure rate associated with hamstring tendon. It's also fairly easy to harvest. So it has many of the advantages without the disadvantages.
The obvious advantage of allografts is that they come from cadavers, so harvesting the graft doesn't injure the donor. Allografts may come from a patellar tendon, hamstring tendon, quadriceps tendon, or tendons of the foot. Historically, allografts used in ACL reconstruction have failed at a higher rate than autografts. The biggest factor has been radiation for sterilization, which weakens the graft. Washes, detergents, and vacuum techniques can effectively sterilize the graft without compromising its strength.[1,2]
Considerations for Allograft Material
My choice of allograft graft material varies from one patient to another. First, because I want to match the width of the donor graft to the anatomy of the patient, I look for age matches, when possible.
In younger athletes, a key question is whether the growth plates are wide open. If they are within an inch of cessation of growth, we can treat the athletes as adults. But in youngsters who have wide-open growth plates, we want to stay away from those plates. We can tunnel above or below the growth plates. Or we can do an iliotibial band procedure where we don't make tunnels through the bones at all.[3,4]
Then I consider the patient and the sport. For example, a 275-lb offensive lineman needs the biggest tissue patellar tendon or quadriceps tendon I can get because of the pivoting force exerted on that knee.
On the other hand, a high school athlete who is a hurdler or sprinter needs to use the muscles around the joint to optimal effect, so I don't want to take any of the patient's own tissues. For this athlete, I might consider an allograft.
For a 50-year-old skier, I would probably also use an allograft. Once a patient gets above 30 years of age, I figure I'll pay a big price in stiffness and soreness for any tissue I harvest from the patient. It's like robbing Peter to pay Paul.
By contrast, in a 13-year-old gymnast, whose growth plates are open, I wouldn't want to use a graft that has bone on either side. This would create a bar at the growth plate, stopping the growth. So I might use hamstring autograft, which is just soft tissue, or a similar soft tissue allograft.
In short, in situations where there is more concern about the graft failing, I might use an autograft, but in situations where there is more concern about pain and stiffness, I might go with an allograft. However, because other factors—such as a patient's age and sport—come into play as well, every case is different. As a result, the surgeon's strategy will vary from one patient to another.
Use of Platelet-Rich Plasma
The next consideration is the use of biologics—specifically, platelet-rich plasma. The graft is dead when it goes in. It has to ligamentize and regenerate to provide the support the joint will need. Stem cells gradually inhabit the tissue, regenerating collagen, blood vessels, and other components of a living tendon. In essence, the graft is a scaffold. Preliminary clinical trials have suggested that applying platelet-rich plasma during the reconstructive surgery can enhance this regeneration.
If I had my druthers, I would use platelet-rich plasma in every ACL reconstruction because I believe it offers significant advantages. But few if any health plans cover its use, so I currently only use it in the most challenging situations.
In the future, we may be able to do even better. Martha Murray, MD, an orthopedic surgeon at Children's Hospital of Boston, has successfully repaired ACL injuries in animals using a collagen matrix to attach the ends of the torn ACL rather than removing the torn ACL and replacing it with a graft. Her research suggests that this approach results in an equally strong joint with less risk for osteoarthritis. I'm looking forward to the results of clinical trials for such biologic augmentation opportunities.
The Complex Process of Rehabilitation
The time it takes an athlete to go from the operating room to fully returning to his or her sport depends on the surgeon's readiness to check off a list of improved functions.
Early on, I look at simple measures of strength and range of motion. But when the patient gets between 4 and 6 months from the procedure, my concern is about regaining his or her functions on the field or court. For example, basketball players have to dribble the ball and run in four directions—forward, to both sides, and backward.
At 90 days, basketball players must do the box drill. They have to go to the side of the court and jog down. When they get to the back of the court, they jog to the left, and when they hit the other side of the court, they go backward, then side-shuttle right. They then repeat the process in the other direction. We also have them do layups from both sides.
For soccer players, we set up cones at 10 and 40 yards, and for 20 minutes, they run in a box shape similar to that of basketball players. Each time they run this drill, we ask them to do it a little bit faster.
At the fifth and sixth month after ACL surgery, we start adding other soccer players back into the patient's recuperative training so that the patient can do some noncontact practice with them. Then, as the patient continues to improve, he or she can begin practice against opposing players.
We use similar routines for athletes in other sports.
Just about every athlete who undergoes ACL surgery is able to run within 90 days. The severity of the injury does not seem to correlate with the time to return to play.
Many variables affect the success of rehabilitation; among them, the patient's motivation, the surgeon's knowledge and skill, surgical variables during the procedure, the expertise of the physical therapist, the expertise of the athletic trainer—and whether the patient even has the benefit of a professional trainer.
Even though most athletes are able to play sports after an ACL injury, not all will return to the same level of competition they reached before their injury. Moreover, athletes with ACL injuries have at least a 10-fold increased rate of reinjury to either knee. Thus, we must identify biomechanical susceptibility, loss of control, and weaknesses.
I always consider prevention of reinjury to be my highest priority. So I include as part of the injured athlete's rehabilitation programs such as, in the case of soccer players, Prevent Injury and Enhance Performance (PEP) and Fédération Internationale de Football Association (FIFA) 11+.
Athletes playing for those teams that can provide the best possible rehabilitation treatment will have the highest return-to-play probability. For a high school athlete in an impoverished school, the odds of returning to play may be a lot lower because he or she probably won't have access to a sports medicine specialist and a physical trainer.
In my practice, I try to mitigate these disadvantages by overseeing all aspects of rehabilitation until the athlete has fully recovered and is ready to go back to the field. But it's impossible for an individual surgeon to overcome all of the disparities of our healthcare system. For that reason, I think that we'll continue to see a lot of variability in which athletes return to play for a long time to come.
1.Rappé M, Horodyski M, Meister K, Indelicato PA. Nonirradiated versus irradiated Achilles allograft: in vivo failure comparison. Am J Sports Med. 2007;35:1653-1658. Abstract
2.Tejwani SG, Chen J, Funahashi TT, Love R, Maletis GB. Revision risk after allograft anterior cruciate ligament reconstruction: association with graft processing techniques, patient characteristics, and graft type. Am J Sports Med. 2015;43:2696-2705.
3.Kocher MS, Garg S, Micheli LJ. Physeal sparing reconstruction of the anterior cruciate ligament in skeletally immature prepubescent children and adolescents. J Bone Joint Surg Am. 2005;87:2371-2379. Abstract
4.Al-Hadithy N, Dodds AL, Akhtar KS, Gupte CM. Current concepts of the management of anterior cruciate ligament injuries in children. Bone Joint J. 2013;95-B:1562-1569.
5.Vogrin M, Rupreht M, Crnjac A, Dinevski D, Krajnc Z, Recnik G. The effect of platelet-derived growth factors on knee stability after anterior cruciate ligament reconstruction: a prospective randomized clinical study. Wien Klin Wochenschr. 2010;122(Suppl 2):91-95. Abstract
6.Vavken P, Murray MM. The potential for primary repair of the ACL. Sports Med Arthrosc. 2011;19:44-49. Abstract
7.Paterno MV. Incidence and predictors of second anterior cruciate ligament injury after primary reconstruction and return to sport. J Athl Train. 2015;50:1097-1099.
8.Santa Monica Sports Medicine Foundation. Pep Program. 2016. http://smsmf.org/smsf-programs/pep-program Accessed January 14, 2016.
9.FIFA 11+. What is FIFA 11+? 2011. http://f-marc.com/11plus/home/ Accessed January 14, 2016.
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Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.
Cite this article: Mandelbaum on Grafts, Biologics, and Rehab in ACL Repair. Medscape. Jan 21, 2016.