ACL graft failure location differs between allografts and autografts.

Background: Between 5 and 20% of patients undergoing ACL reconstruction fail and require revision. Animal studies have demonstrated slower incorporation of allograft tissue, which may affect the mechanism of graft failure. The purpose of this study is to determine the location of traumatic graft failure following ACL reconstruction and investigate differences in failure patterns between autografts and allografts.

Methods: The medical records of 34 consecutive patients at our center undergoing revision ACL reconstruction following a documented traumatic re-injury were reviewed. Graft utilized in the primary reconstruction, time from initial reconstruction to re-injury, activity at re-injury, time to revision reconstruction, and location of ACL graft tear were recorded.

Results: Median patient age at primary ACL reconstruction was 18.5 years (range, 13-39 years). The primary reconstructions included 20 autografts (13 hamstrings, 6 patellar tendons, 1 iliotibial band), 12 allografts (5 patellar tendon, 5 tibialis anterior tendons, 2 achilles tendons), and 2 unknown. The median time from primary reconstruction to re-injury was 1.2 years (range, 0.4 - 17.6 years). The median time from re-injury to revision reconstruction was 10.4 weeks (range, 1 to 241 weeks). Failure location could be determined in 30 patients. In the autograft group 14 of 19 grafts failed near their femoral attachment, while in the allograft group 2 of 11 grafts failed near their femoral attachment (p < 0.02).

Conclusions: When ACL autografts fail traumatically, they frequently fail near their femoral origin, while allograft reconstructions that fail are more likely to fail in other locations or stretch.

Level of evidence: Level III - Retrospective cohort study.