ACL reconstruction is one of the most commonly performed procedures in orthopedic practice. Young athletes sustain ACL injuries requiring reconstruction at alarming rates. The ratio of ACL rupture in female athletes is three times more likely than in their male counterparts (Sutton, 2013). Additionally, females postoperatively are 15 times more likely to rupture the reconstructed knee within the first year, as compared to their male counterparts (Sutton, 2013).
In a meta-analysis of ACL reconstruction choices for reconstruction options, such as graft selection, graft position, fixation types, rehabilitation course and long-term postoperative outcomes, little difference exists in outcomes between males and females despite the anatomic and other acknowledged differences. But with a cost of reconstruction procedures at one billion dollars annually in the US, efforts have turned to reducing the rates of ACL injury through risk factor identification and prevention strategies.
Due to anatomic disparities between the sexes, females are predisposed to ACL injury. Factors such as an increased quadriceps angle, smaller ACL cross-sectional area and a smaller intercondylar notch width are possible reasons for the predisposition to injury seen in female athletes. Additionally, female athlete’s tendency to land with the knees in insufficient flexion, with a greater than normal valgus and external rotation, caused an increase in risk of ACL injury. Hewitt, in 2010, noted decreased neuromuscular control of the trunk causing increased “valgus torques” in females.
Newer models focus on the genetic difference between males and females, with three genes noted to affect ACL stability based on ACL biopsy results and PCR (polymerase chain reaction) technology (Johnson, 2015). In this study Johnson studied biopsy samples of young athletes with non-contact ACL injuries. It was found that two genes (ACAN (Aggregan) and FOMD ( fibromodulin)) were up-regulated in females and integral in the ACL matrix. A third gene (WISP2) was downregulated and involved an increase in collagen turnover and production in the ACL matrix of females, perhaps a contributor to the weakness in the composition of the ACL in females, making them more apt to rupture.
The literature about surgical considerations given to females at the time of reconstruction are somewhat ambiguous. More recent and larger literature reviews of studies comparing outcomes of female and male ACL reconstruction subjects demonstrated no significant differences in surgical outcomes (John, 2014). Other authors suggested that special surgical considerations be practiced among female athletes, due to the narrowed intercondylar notch.
Due to anatomic and potential genetic predisposing factors, females are at an increased risk of ACL rupture. In light of these differences, and the lack of impact as regards surgical technique improving outcomes of female athletes, prevention has taken an increasingly important role. The American Academy of Orthopedic Surgeons has formulated what is termed the Appropriate Use Criteria or AUC, guiding a prescribed prevention strategy to prevent ACL injury. According to the academy, these AUC’s have been more effective in female versus male athletes. The AAOS also have “return to play” criteria established by evidence-based guidelines, to decrease re-injury rates in female athletes, who have undergone ACL reconstruction.
The Appropriate Use Criteria include the following preventative measures to reduce ACL injury:
A female who has suffered one ACL injury or reconstruction is considered “high risk". Therefore re-injury to the surgical knee, as well as the opposite knee and in consideration of this classification, rehabilitative guidelines and “return to play” guidelines are very different than that of the female athlete who has not encountered an ACL injury and reconstruction. Overall, given the anatomic, and perhaps genetic differences that research has borne out, these preventive measures, according to the literature, are more effective in females versus males.
School and athletics trainers are key to training young females to jump and land safely.
"We recommend that serious attention be given to instituting similar training programmes in women's teams where jumping and landing put the ACL at risk, in order to reduce cost both in terms of medical care and personal suffering. Specifically hamstrings-to-quads ratio should be optimised to protect the ACL." - Frank Noyes
Jeffrey Jackson MD, Melanie Morschaer MD et al. Genetic differences between ruptured ACL ligaments in young female and male athletes. Journal of the American Academy of Orthopedics, March 2014 375-390
Karen Sutton MD, JM Bullock MD. Anterior Cruciate Ligament Rupture: Differences between males and females. Jan 2013 Vol 21 no 1 41-50
Timothy Hewitt Ph.D.. Et al. Why women have an increased risk of ACL injury. American Journal of Sports Medicine Feb 2006 Vol 34 (2) 299-311
J Ryan MD, Robert Magnusssen et al ACL Reconstruction: Do outcomes differ by sex? A systematic review. Journal of Bone and Joint Surgery 2014 Mar 19 96 (6)507-512.
ACL Injury Reduction for Female Athletes Part 1 - YouTube Video on Strength (w/ Rachel DeMita)
ACL Injury Reduction for Female Athletes Part 2 - YouTube Video on Landing (w/ Rachel DeMita)
ACL Injury Reduction for Female Athletes Part 3 - YouTube Video on Footwork (w/ Rachel DeMita)
ACL Injury Reduction for Female Athletes Part 4 - YouTube Video on Mobility (w/ Rachel DeMita)