Graft selection for anterior cruciate ligament (ACL) reconstruction remains controversial, despite studies during the past 10 years indicating roughly equivalent clinical outcomes in both short- and long-term follow-up. However, new data in 2012 suggest that allograft should be avoided in athletic patients under the age of 25 years due to an unacceptably high failure rate in this group.
"ACL graft selection is surgeon-dependent — but outcome goals are consistent: Optimize functional results, minimize morbidity and decrease the incidence of revision," explains Mayo Clinic orthopedic surgeon Michael J. Stuart, M.D.
Adds his colleague Cedric J. Ortiguera, M.D.: "There is no perfect graft choice, with advantages and disadvantages to each. Allografts can provide excellent outcomes in the properly chosen patient."
Mayo Clinic-published research demonstrates that handling and sterilization of allografts can have a significant impact on performance, emphasizing that knowing the processing and irradiation parameters of the graft supplier is central to successful outcomes.
At Mayo Clinic Department of Orthopedic Surgery, surgeons use the following approach to inform decision-making and obtain best results from an ACL reconstruction.
In North America and Europe, surgical reconstruction of a ruptured ACL is one of the most common knee procedures. Tears are usually related to rapid pivots and turning movements common in football, soccer and basketball. The only study on the prevalence of ACL injuries in the general population has estimated the incidence as one case in 3,500 people, resulting in 95,000 new ACL ruptures a year, although the actual incidence may be higher.
Approximately 60,000 to 75,000 ACL reconstructions are performed annually in the United States. Data are limited by the absence of any standard surveillance mechanism for the general population. Registries exist for injuries sustained by U.S. college and high school athletes, but these account for a small percentage of the total number of injuries.
Because the ACL is a central stabilizer of the knee, the objective of surgery is to restore knee integrity so the patient can avoid additional injury and return to sports. The ultimate goal of participation in strenuous activity is dependent on graft selection, the surgical procedure and postoperative rehabilitation.
Over the past decade, use of allografts has risen as processing of grafts has improved its safety profile. Commonly used allografts include the semitendinosus, Achilles, hamstring and patellar tendons. The main disadvantages of allografts relate to increased cost, longer incorporation time and secondary sterilization with irradiation that alters the biomechanical properties of the graft.
In addition, performance concerns include allograft elongation and rupture. Most recently, a higher failure rate has been reported in young athletes. In a June 2012 study published in The American Journal of Sports Medicine, 120 young, active adults entering the U.S. Military Academy at West Point as cadets were 7.7 times more likely to experience a graft failure with an allograft ACL reconstruction compared to autograft ACL reconstruction prior to matriculation.
The main advantages of allograft use are lack of donor-site morbidity and suitability for cases requiring multiple ligament reconstruction procedures.
Commonly used autografts include patellar, hamstring (semitendinosis and gracilis) and quadriceps tendons. The disadvantages of autografts include increased postoperative pain and potential complications resulting from graft harvest. Recent data also show that quadrupled hamstring tendons less than 8 millimeters in diameter are associated with an increased risk of failure.
The use of autograft eliminates concerns about allograft contamination, disease transmission and structural compromise from irradiation.