By Jordana Bieze Foster
Several studies presented in early June at the American College of Sports Medicine (ACSM) annual meeting in Denver add to the growing body of research suggesting some biomechanical deficits linger for a year after anterior cruciate ligament reconstruction (ACLR), even in athletes who have been cleared to return to sports.
The findings underscore several aspects of the ongoing discussion among researchers and clinicians regarding ways to reduce rates of subsequent ACL injuries in athletes: the need to refine rehabilitation goals and strategies after ACLR, to reevaluate existing return-to-sports criteria, and to investigate more closely the question of how much time is really required for complete ACL healing.
Symmetry between the reconstructed limb and the contralateral limb is often used to determine an athlete’s readiness to return to sports, but three ACSM presentations reported significant between-limb asymmetries during the first year following unilateral ACLR.
Researchers from Virginia Polytechnic Institute and State University in Blacksburg analyzed movement and loading symmetry during a vertical stop-jump task in 23 adolescent athletes (14 girls), all of whom were cleared to return to sports six months after ACLR and discontinued physical therapy at that time.
They found significant between-limb asymmetries for knee extension moment, peak vertical ground reaction force, and impulse at 12 months after ACLR; symmetry improvements that were seen between four and six months appeared to plateau after that time.
“There’s still something we’re leaving on the table during therapy that we need to be focusing on,” said Robin M. Queen, PhD, an associate professor of biomedical engineering and mechanics at Virginia Tech and director of the university’s Kevin P. Granata Biomechanics Laboratory.
Researchers from Children’s Hospital Los Angeles also found that between-limb asymmetries persisted when assessed six to 10 months after ACLR in adolescent athletes, despite improvement relative to an assessment between three and six months after ACLR.
In 24 athletes (14 girls), the investigators found that asymmetries in sagittal plane kinematics and kinetics during a vertical drop-jump landing improved between the two visits but remained statistically significant at the second visit.
Although rehab after ACLR tends to focus on the magnitude of maximum force generation as an outcome measure, a study from the University of Wisconsin-Madison (UWM) supports the increasingly popular belief that rate of force development may also be important.
In 18 collegiate athletes (10 women) an average of seven months removed from ACLR, investigators analyzed rate of force development in the quadriceps, hamstrings, and gluteal muscles during a countermovement jump and a treadmill run, and found significant between-limb asymmetries.
“Our findings suggest we should consider rapid force activation during rehabilitation after ACLR,” said Daniel Cobian, PhD, DPT, CSCS, a postdoctoral scholar in the university’s Department of Orthopedics and Rehabilitation Science, who presented his group’s findings at the ACSM meeting. “Rate of force development may be more related to real-world activity than maximum force.”
Fear of reinjury, which can impede rehabilitation and return to sports after ACLR, also appears to have effects on biomechanics years after surgery, according to another UWM study.
Investigators used the Tampa Scale of Kinesiophobia-11 to assess 59 female adolescents with a history of unilateral ACLR (mean time from surgery 25.5 months), and divided them into tertiles for high, medium, and low fear of injury. Those in the highest tertile demonstrated stiffer jump-landing hip and knee mechanics than those in the lower tertiles.
“We need to try to identify fear of injury during rehab and implement interventions,” said Stephanie Trigsted, PhD, ATC, an athletic trainer and doctoral candidate in the Department of Kinesiology-Biomechanics, who presented the findings at the ACSM meeting.
Queen RM, Miller TK. Limb asymmetry during anterior cruciate ligament reconstruction recovery. Med Sci Sports Exerc 2017;49(5 Suppl 1):S373.
Katzel M, Pace JL, Mueske N, et al. Biomechanical asymmetries in drop jump improve during rehabilitation following ACL reconstruction in adolescents. Med Sci Sports Exerc 2017;49(5 Suppl 1):S373-374.
Cobian DG, Knurr KA, Stiffler MR, et al. Reduced rates of quadriceps activation during running and jumping in collegiate athletes post-ACL reconstruction. Med Sci Sports Exerc 2017;49(5 Suppl 1):S374.
Trigsted SM, Post E, Schaefer D, et al. The effect of fear of reinjury on biomechanics during a jump landing following ACL reconstruction. Med Sci Sports Exerc 2017;49(5 Suppl 1):S374.