Multiple studies have demonstrated that females have a 4 to 10 higher risk of ACL-injury compared with same-sport males, and up to 4 times higher rate of re-injury or further surgical treatment after they’ve undergone ACL reconstruction.[i] There are several factors that may be responsible, including anatomic, hormonal, and neuromuscular factors, among others.[ii]
Interestingly, sex differences also play a factor in how well a specific graft type tends to function. The hamstring tendons can be small in females, particularly those of smaller stature. This is typically not a problem if the athlete’s stature is also small, but can be more of an issue if the hamstring graft has smaller than a 7-mm diameter in an athlete of larger build.
Bone-patellar tendon-bone (BTB) reconstructions may outperform hamstring autograft (HS) and allograft reconstructions in younger, highly athletic female athletes with respect to lower rates of re-tear during the course of their athletic careers. However, I find that some of these same successfully-treated, athletic young females (and also males) complain a bit about their post-BTB-ACL-reconstructed knees in parenthood years, when kneeling, squatting and crawling after their toddlers is common!
Similarly, it is more common for females to have increased valgus (knock-knees) and femoral torsion (a twist in the femur from hip to knee) compared to males, which can result in patellofemoral maltracking (a mis-alignment of the way the kneecap functions). This is a problem that can be made worse if BTB reconstructions are performed.