What Are Your Expected Results After ACL Reconstruction?
The short answer is I expect the results to be similar between allografts and autografts. In my mind, the expectation that the results of allograft anterior cruciate ligament (ACL) reconstruction are similar to autograft ACL reconstruction must be a prerequisite for its inclusion in the informed consent discussion as a potential graft option for primary ACL reconstruction.
That being said, studies looking at allografts admittedly have shown high failure rates.1-3 These studies suffer from poor study design, are not comparative in nature, and include sterilization techniques that often do not reflect the most current scientific knowledge. Roberts et al looked at freeze-dried, ethylene oxide–sterilized, bone-patellar tendon-bone allografts in 44 consecutive patients who underwent ACL reconstruction.2 At 2-year follow-up, 8 cases of graft failure (18%) were confirmed arthroscopically. Pritchard et al looked at long-term follow-up of anterior cruciate ligament reconstruction using freeze-dried fascia lata allografts in 40 patients at an average of 134.5 months.3 To the best of the authors’ knowledge, no patients underwent a revision ACL reconstruction, although 19% fit the criterion for patient-reported failure (complaints of at least partial giving way episodes) and 7.7% had more than 5-mm side-to-side difference with KT-1000 arthrometer manual maximum testing. However, follow-up was not obtained on half of the subjects (49%); hence, lack of follow-up limits the ability to draw inferences from this study.
Contrary to many other studies showing higher graft failure rates for allografts, a study by Kustos et al showed similar graft failure rates for primary ACL reconstruction with fresh frozen, nonirradiated bone-tendon-bone (BTB) allograft and BTB autograft using the same surgical technique and postoperative rehabilitation.4 In this retrospective clinical assessment, the groups were similar in age and activity level at baseline and at a mean follow-up of 38 months; both groups had similar (less than 4%) rates of revision ACL reconstruction; and there was no disease transmission attributed to the use of allografts.
In a quest to find the best available evidence on this topic, a literature search of manuscripts comparing bone-tendon-bone allografts to bone-tendon-bone autografts was performed. Using the keywords auto$.mp, allo$.mp, and Anterior Cruciate Ligament/ or acl.mp, Medline and EMBASE were searched (1950 to May 2007). Inclusion criteria were minimum 2-year follow-up, comparative study design, and the use of clinically relevant outcomes (Lysholm score, instrumented laxity, anterior knee pain, and/or graft failure). All studies were required to be level III or greater evidence and thus level IV studies were excluded. In the end, 8 studies, 4 level II and 4 level III, qualified based on the inclusion and exclusion criteria.1,5-11 One comparative study by Gorschewsky et al was subsequently excluded due to the type of sterilization technique used.1 The authors looked at the Tutoplast allograft, irradiated with 1.5 Mrad and subject to acetone solvent drying, versus the autologous patellar tendon in 201 patients (75% follow-up) at 2 years and 186 (69% follow-up) at 6 years following anterior cruciate ligament reconstruction. Failure rates were 20.6% at 2 years and 44.7% at 6 years for allograft patients, compared to 4.8% and 5.9%, respectively, for autograft patients. It is important to mention that the sterilization technique, acetone solvent drying, does not reflect current practices.
The following results are based on pooled data from the remaining 7 manuscripts comparing lower dose irradiation (less than 2.5 mRad) bone-tendon-bone allograft to autograft. Of the 6 studies that used instrumented measures of laxity, there were no significant differences between groups. Of the 5 studies that included the Lysholm, no differences were observed between allograft and autograft. Among the 5 studies that reported graft failure, the pooled bone-tendon-bone allografts failure was 5% to 6% compared with 1% to 2% for autografts. This slightly higher failure rate may be acceptable in many circumstances, especially if the patient understands this and still wishes to choose an allograft as his preferred graft option for other reasons. A high-quality randomized trial is necessary to determine whether there is a significant difference among allograft and autograft.
1. Gorschewsky O, Klakow A, Riechert K, Pitzl M, Becker R. Clinical comparison of the Tutoplast allograft and autologous patellar tendon (bone-patellar tendon-bone) for the reconstruction of the anterior cruciate ligament: 2- and 6-year results. Am J Sports Med. 2005;33:1202-1209.
2. Roberts TS, Drez D, Jr, McCarthy W, Paine R. Anterior cruciate ligament reconstruction using freeze-dried, ethylene oxide-sterilized, bone-patellar tendon-bone allografts. Two year results in thirty-six patients. Am J Sports Med. 1991;19:35-41.
3. Pritchard JC, Drez D, Jr., Moss M, Heck S. Long-term followup of anterior cruciate ligament reconstruction using freeze-dried fascia lata allografts. Am J Sports Med. 1995;23:593-596.
4. Kustos T, Balint L, Than P, Bardos T. Comparative study of autograft or allograft in primary anterior cruciate ligament reconstruction. Int Orthop. 2004;28:290-293.
5. Barrett G, Stokes D, White M. Anterior cruciate ligament reconstruction in patients older than 40 years: allograft versus autograft patellar tendon. Am J Sports Med. 2005;33:1505-1512.
6. Chang SK, Egami DK, Shaieb MD, Kan DM, Richardson AB. Anterior cruciate ligament reconstruction: allograft versus autograft. Arthroscopy. 2003;19:453-462.
7. Harner CD, Olson E, Irrgang JJ, Silverstein S, Fu FH, Silbey M. Allograft versus autograft anterior cruciate ligament reconstruction: 3- to 5-year outcome. Clin Orthop. 1996;Mar(324):134-144.
8. Kleipool AE, Zijl JA, Willems WJ. Arthroscopic anterior cruciate ligament reconstruction with bone-patellar tendon-bone allograft or autograft. A prospective study with an average follow up of 4 years. Knee Surg Sports Traumatol Arthrosc. 1998;6:224-230.
9. Peterson RK, Shelton WR, Bomboy AL. Allograft versus autograft patellar tendon anterior cruciate ligament reconstruction: a 5-year follow-up. Arthroscopy. 2001;17:9-13.
10. Saddemi SR, Frogameni AD, Fenton PJ, Hartman J, Hartman W. Comparison of perioperative morbidity of anterior cruciate ligament autografts versus allografts. Arthroscopy. 1993;9:519-524.
11. Victor J, Bellemans J, Witvrouw E, Govaers K, Fabry G. Graft selection in anterior cruciate ligament reconstruction—prospective analysis of patellar tendon autografts compared with allografts. Int Orthop. 1997;21:93-97.