Increased Risk of Graft Failure after ACL Reconstruction in Young Female Athletes with Hamstring Grafts

OBJECTIVES: The incidence of second anterior cruciate ligament (ACL) injury after ACL reconstruction (ACLR) and return to sport (RTS) in a young, active population is likely between 25-33% with the greatest risk in the first 12 months after RTS. Although the use of allograft tissue in young athletes has been reported to result in increased risk of graft failure, differences in graft and contralateral ACL injury risk between patients who receive a hamstrings (HS) autograft and bone-patellar tendon- bone (BTB) autograft has yet to be reported in a young, athletic population. The tested hypothesis was that the relative risk (RR) of ipsilateral graft failure would be higher in young, active patients who receive an ACLR with a hamstrings graft, while the RR of contralateral ACL injury would be higher in patients who receive and ACLR with a BTB autograft. METHODS: One hundred thirty-nine subjects (99 female/40 male) with a mean age of 16.9±2.0 years old (range: 13-25 y/o) underwent ACLR with either a HS autograft (n=79) or a BTB autograft (n=60) and were released to return to pivoting/cutting sport. These patients were enrolled in a prospective, observational cohort study and were tracked for incidence of 2(nd) ACL after ACLR for a median of 73 months. Thirty-four (24.5%) suffered a 2(nd) ACL injury. Fisher’s exact tests were used to determine whether graft choice (HS vs. BTB) was associated with risk of either ipsilateral graft failure or contralateral ACL injury. Sub-group analyses by sex were also conducted. RESULTS: Patients who underwent ACLR with HS graft (n=79) sustained 14 ipsilateral tears and 6 contralateral ACL injuries. Patients who received an ACLR with BTB (n=62) sustained 2 ipsilateral tears and 12 contralateral ACL injuries (Table 1). Patients who received an ACLR with HS graft were 6 times more likely (RR=6.2; 95% CI: 1.4-28.7) to suffer a graft failure after RTS than the BTB group. In the first 12 months after RTS, the HS graft patients were nearly 10 times (RR=9.5; 95% CI: 1.2-76.1) more likely to suffer an ipsilateral graft failure. Patients with a HS graft were 3 times less likely (RR=0.33; 95%CI: 0.12-0.935) to suffer a contralateral ACL injury and nearly 7 times less likely (RR=0.15, 95%CI: 0.031-0.709) to suffer a contralateral ACL injury in the first 12 months after RTS compared to the BTB group. When the cohort was divided by sex, females with HS grafts were significantly more likely to sustain a graft failure in the first 12 months after RTS (p=0.008) and by final follow-up (p=0.002) compared to females with BTB graft. Females with HS grafts were 3 times less likely (RR=0.30; 95%CI: 0.095-0.943) to suffer a contralateral ACL injury than females with BTB graft and 6 times less likely (RR=0.17; 95%CI: 0.034-0.846) to suffer contralateral ACL injury in the first year after RTS. Males demonstrated no significant difference in ipsilateral or contralateral injury risk based on graft type. CONCLUSION: Young, active females who return to pivoting and cutting sports after ACLR with HS autograft are at greater risk to suffer a graft failure and reduced risk to suffer a contralateral ACL injury compared to females who undergo ACLR with BTB graft tissue. No significant differences in 2(nd) ACL injury risk based on graft type were observed in the male patients.