Anterior Cruciate Ligament Reconstruction in Young Females: Patellar versus Hamstring Tendon Autografts

OBJECTIVES: Female athletes are two to eight times more likely to suffer a primary ACL tear than males. Although ACL reconstruction can successfully return many athletes to their pre-injury sports, re-injury to the ipsilateral or contralateral knee can occur in over 20% of young athletes. Both female sex and younger age have been shown to be risk factors for graft failure. The optimal graft choice for this high-risk population of young female athletes remains unknown and poorly studied. We compared the clinical outcomes in young female patients who underwent ACL reconstruction at our institution using bone-patellar tendon-bone (BTB) and quadrupled hamstring (HS) autografts. METHODS: Female patients aged 15-25 who underwent primary ACL reconstruction at our institution between January 2012 and May 2015 using either BTB or HS autograft were included in our review. Patients were further sub-divided into 2 age groups, 15-20 and 20-25. Patients with a prior history of ACL injury to either knee, or those with multiligament injury were excluded. Graft choice and fixation method were documented from a review of operative records. Medical records were reviewed to document the occurrence of chondral, meniscal or ligamentous injury to the ipsilateral or contralateral knee in the first two years following ACL reconstruction. Comparisons were made using the chi-square test with statistical significance set at p < 0.05. RESULTS: A total of 256 females were included in our review with 175 in the BTB group and 81 in the HS group. There was no difference between the groups with regards to average age or time to follow-up. The majority of patients in both groups, 80% of the BTB group and 77.8% of the HS group, were between the ages of 15-20. Interference screw fixation was used in all BTB cases and 63.0% of HS cases. In the remainder of HS cases, femoral suspension and tibial screw (27.2%), and femoral cross-pins and tibial screw (9.9%) were used. In our series, 22.2% of hamstring grafts were augmented with allograft due to inadequate size. Overall, graft re-tear occurred in 6.9% of BTB patients and 12.3% of HS patients [p=0.16]. Contralateral ACL tear occurred in 7.4% of BTB patients and 6.2% of HS patients [p=0.72]. Sub-group analysis showed that 75% of BTB and 100% of HS graft re-tears occurred in females aged 15-20. Within this group, there was a significantly lower rate of graft re-tears in the BTB group (6.4%) when compared to the HS group (15.9%) [p=0.04]. Allograft augmentation was used in four of the ten HS grafts that re-tore. The risk of failure with hamstring augmentation with allograft (4/18, 22.2%) was higher than that of hamstring autograft alone (6/63, 9.5%), but this difference was not significant [p=0.18]. CONCLUSION: The results of our study indicate that BTB autograft led to fewer graft re-tears compared to HS autograft following ACL reconstruction in female patients aged 15-20. However, this difference was not observed in females aged 20-25. Thus, further investigation regarding optimal graft choice is warranted in this age group.