Superficial Femoral Artery Reactivity In Young Adults With Previous ACL Injury

Anterior cruciate ligament (ACL) injuries are a common sports injury, impacting 100,000-200,000 athletes annually. One in three people with an ACL injury will develop osteoarthritis (OA) within ten years. OA contributes to decrements in vascular function, an antecedent to cardiovascular disease (CVD), and subsequently CVD risk by 50%. It is unknown whether ACL injury per se is associated with early-onset vascular dysfunction. PURPOSE: To evaluate blood vessel reactivity as a proxy measure of vascular function in the injured and uninjured lower limbs of young adults with previous ACL injury and compare that to the lower limbs of young adults without a history of ACL injury. METHODS: Doppler ultrasound was used to capture blood vessel reactivity as superficial femoral arterial flow-mediated dilation (FMD) following 5 minutes of upper leg flow occlusion using a thigh cuff, shear during reactive hyperemia measured as the area under the curve of flow velocity following cuff release, and low-flow mediated constriction (L-FMC) as the change in diameter measured during cuff occlusion. Measures were completed on the right and left lower limbs in 15 participants (women = 10, age = 20 years, body mass index [BMI] = 23.8 kg/m2) with previous ACL injury (ACL group) and 22 participants (women = 9, age = 22 years, BMI = 24.0 kg/m2) without previous ACL injury (CON group). A one-way ANOVA was used to compare FMD, FMD/shear and L-FMC across limbs in the ACL group and the CON group. Data are presented as mean ± standard deviation. RESULTS: There were no differences in FMD across limbs (ACL injured leg: 6.49 ± 4.74%, ACL uninjured leg: 9.01 ± 4.70%, CON leg1: 8.16 ± 5.08%, CON leg2: 9.26 ± 6.14%, p = 0.43). There were no differences in FMD/shear across limbs (ACL injured leg: 0.013 ± 0.01, ACL uninjured leg: 0.010 ± 0.01, CON leg1: 0.010 ± 0.01, CON leg2: 0.013 ± 0.01, p = 0.35). Finally, there were no differences in L-FMC across limbs (ACL injured leg: 0.21 ± 0.14%, ACL uninjured leg: 0.23 ± 0.23%, CON leg1: 0.066 ± 0.22%, CON leg2: 0.027 ± 1.04%, p = 0.66). CONCLUSION: Lower limb vascular reactivity was similar between injured and uninjured limbs in young adults with previous ACL injury and similar to young adults without previous ACL injury. Unlike OA which has been shown to cause vascular damage, our results suggest that ACL injury may not cause vascular dysfunction.