KNEE
Anterior cruciate ligament (ACL) tears are one of the most common injuries of the knee seen in orthopedics practices around the country. In general, most ACL tears do not heal on their own and therefore if a patient is indicated for surgery the majority of ACL tears are reconstructed, which means using different types of substitute tissue or graft to create a new ligament. There has been recent advancements in orthopedics with ACL repair instead of reconstruction for specific types of ACL tears including primary repair and augmented repair with Bridge-enhanced ACL repair (BEAR) that have shown promise but long term study results are still pending compared to the abundance of long term studies on reconstruction.
There are four main types of ACL grafts, three autografts (your own tissue):
1) bone patellar bone (BTB)
2) hamstring (HT)
3) quadriceps tendon (QT) and
4) multiple types of allografts (cadaver tissue). Allograft options include tibialis anterior and posterior, Achilles, hamstrings, and patellar tendon. The perfect graft does not exist as each graft has its own benefits and limitations. Ultimately, graft choice should be an individualized informed decision with the patient and surgeon, based off the patient age, activity level, job, goals and surgeon familiarity/experience with graft technique. Surgeon recommendation does have a major impact on patient choice.1
The goals, type of work, type of sport, and age of the patent should be taken into account when discussing graft options. Studies indicates that the risk of graft failure is increased in young active patient when allograft is used compared to autograft ACL reconstructions. This risk begins to reduce and become similar as patients approach 40 years of age and beyond. 2-4
Bone patella bone (BTB) autograft involves taking bone from the inferior patella (kneecap) and tibial tubercle (shin) with a strip of the patellar tendon in between. This graft option is encouraged for young, athletic patients due to its rigid fixation, bone-to-bone healing and highly successful studied outcomes. This graft is not recommended for growing kids due to risk of the bone block causing growth plate closure. Advantages included bone to bone healing for which is thought to be stronger and faster than soft tissue to bone healing in the ACL tunnels. 5
Disadvantages include risk of patella fracture, lateral knee numbness, damage to patellar cartilage, and possibly persistent extensor mechanism weakness. A common compliant after BTB is anterior knee pain with kneeling at donor site which can become an issues for certain types of jobs or sport requiring some form of kneeling. 6,7
Hamstring (HT) autografts are harvested off their distal insertion at the knee and is an all soft tissue graft. Donor site pain may be less with hamstring autograft than BTB and may be better for patients with prior anterior knee pain, participation in certain sports, and/or work/activities that require kneeling. Given this all soft tissue graft, it can be use in ACL reconstruction in growing kids as it can pass through growth plate with less risk of growth disturbance. Disadvantages include possible injury to superficial sensory nerve, possible hamstring weakness and slower soft tissue tunnel healing.
Quadriceps tendon (QT) autograft is the last of the autograft options and has been increasing in popularity. This graft can be 1) all soft tissue or 2) soft tissue with bone from the superior pole of the patella. All soft tissue QT grafts may be used in growing kids ACL reconstruction similar to HT grafts. Anterior knee pain is less compared to BTB and similar to HT. 8 Therefore, this graft may be better in certain sports, and/or work/activities that require kneeling. Disadvantages included possible quadriceps/extensor mechanism weakness, patella fracture if harvesting bone plug, and slower soft tissue tunnel healing if all soft tissue graft is used.
There are many allograft options including tibialis anterior and posterior tendons, Achilles tendon, semitendinosus tendon, and allograft BTB. Allograft offers the benefits of decrease surgical pain for the patient with less surgical time, possibly fewer or smaller incisions, and less potential for post op knee stiffness.9 Disadvantages include higher graft failure rates especially in young active patients and slower graft/bone tunnel healing compared to autograft. All allografts undergo extensive testing however there is a potential risk of inflammatory reaction and disease transmission, although both are extremely rare. 10
Comparing different graft types can be difficult. Given the multiple variables when comparing graft options, it is difficult to support one option over the other based off the current literature as all have acceptable results. Despite the differences, all three autograft options have had excellent and comparable clinical outcomes. Based on recent literature, there seems to be no differences in rupture rates between these three autografts. 8 Allograft has been shown to have a higher graft failure rate compared to autograft in young, active patients, however, acceptable results have been seen in older, less active patients. Therefore, the decision on graft choice depends on many factors, including the surgeon’s preference/experience with graft type, patient's age, activity level, sport, work and goals. Ultimately, the patient preferences after an informed discussion with the surgeon should determine the graft choice.
1. Cheung SC, Allen CR, Gallo RA, et al. Patients’ attitudes and factors in their selection of grafts for anterior cruciate ligament reconstruction. Knee 2012;19(1): 49–54.
2. Kaeding CC, Pedroza AD, Reinke EK, et al. Risk factors and predictors of subsequent ACL injury in either knee after ACL reconstruction: prospective analysis of 2488 primary ACL reconstructions from the MOON cohort. Am J Sports Med 2015;43:1583–90.
3. Maletis GB, Chen J, Inacio MC, et al. Age-related risk factors for revision anterior cruciate ligament reconstruction: a cohort study of 21,304 patients from the Kaiser Permanente anterior cruciate ligament registry. Am J Sports Med 2015; 44:331–6.
4. Bottoni, Craig R., Eric L. Smith, James Shaha, Steven S. Shaha, Sarah G. Raybin, John M. Tokish, and Douglas J.Rowles. Autograft versus allograft anterior cruciate ligament reconstruction: a prospective, randomized clinical study with a minimum 10-year follow-up. The American journal of sports medicine 43, no. 10 (2015): 2501-2509.
5. Rodeo SA, Arnoczky SP, Torzilli PA, Hidaka C, Warren RF: Tendon-healing in a bone tunnel: A biomechanicaland histological study in the dog. J Bone Joint Surg Am 1993;75:1795-1803.
6. Freedman KB, D’Amato MJ, Nedeff DD, Kaz A, Bach BR Jr: Arthroscopic anterior cruciate ligament reconstruction: A metaanalysis comparing patellar tendon and hamstring tendon autografts. Am J Sports Med 2003;31:2-11.
7. 10. Aune AK, Holm I, Risberg MA, Jensen HK, Steen H: Four-strand hamstring tendon autograft compared withpatellar tendon-bone autograft for anterior cruciate ligament reconstruction: A random ized study with two-year follow up. Am J Sports Med 2001;29:722-728
8. Mouarbes D, Menetrey J, Marot V, Courtot L, Berard E, Cavaignac E: Anterior cruciate ligament reconstruction: A systematic review and meta-analysis of outcomes for quadriceps tendon autograft versus bone-patellar tendon-bone and hamstring-tendon autografts. Am J Sports Med 2013.
9. Mariscalco MW, Magnussen RA, Kaeding CC, Hewett TE, Flanigan DC. Use of irradiated and non-irradiated allograft tissue in anterior cruciate ligament reconstruction surgery: a critical analysis review. JBJS Rev 2:2 2014.
10. Jackson DW, Grood ES, Goldstein JD, et al: A comparison of patellar tendon autograft and allograft used for anterior cruciate ligament reconstruction in the goat model. The American journal of sports medicine, 1993. 21(2), 176-185.
