Strength Asymmetry and Landing Mechanics at Return to Sport after Anterior Cruciate Ligament Reconstruction.
OBJECTIVE
Evidence-based quadriceps femoris muscle (QF) strength guidelines for return to sport after anterior cruciate ligament (ACL) reconstruction are lacking. This study investigated the effect of QF strength asymmetry on knee landing biomechanics at the time of return to sport after ACL reconstruction.


METHODS
Seventy-seven individuals (17.4 yr) at the time of return to sport after primary ACL reconstruction (ACLR group) and 47 uninjured control individuals (17.0 yr; CTRL group) participated. QF strength was assessed and quadriceps index was calculated (QI = [involved strength / uninvolved strength] × 100%). The ACLR group was subdivided based on QI: high quadriceps (HQ, QI ≥ 90%) and low quadriceps (LQ, QI < 85%). Knee kinematic and kinetic variables were collected during a drop vertical jump maneuver. Limb symmetry during landing and discrete variables were compared among the groups using multivariate analysis of variance and linear regression analyses.


RESULTS
The LQ group demonstrated worse asymmetry in all kinetic and ground reaction force variables compared to the HQ and CTRL groups, including reduced involved limb peak knee external flexion moments (P < 0.001), reduced involved limb (P = 0.003) and increased uninvolved limb (P = 0.005) peak vertical ground reaction forces and higher uninvolved limb peak loading rates (P < 0.004). There were no differences in the landing patterns between the HQ and CTRL groups on any variable (P > 0.05). In the ACLR group, QF strength estimated limb symmetry during landing after controlling for graft type, meniscus injury, knee pain, and symptoms.


CONCLUSIONS
At the time of return to sport, individuals after ACL reconstruction with weaker QF demonstrate altered landing patterns. Conversely, those with nearly symmetrical QF strength demonstrate landing patterns similar to uninjured individuals. Consideration of an objective QF strength measure may aid clinical decision making to optimize sports participation after ACL reconstruction.
1Division of Physical Therapy, School of Health and Rehabilitation Sciences, Ohio State University, Columbus, OH; 2Division of Sports Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH; 3Sports Medicine Biodynamics Center and Human Performance Laboratory, Cincinnati Children's Hospital Medical Center, Cincinnati, OH; 4Division of Occupational Therapy and Physical Therapy Cincinnati Children's Hospital Medical Center, Cincinnati, OH; 5Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH; 6Department of Physical Therapy, High Point University, High Point, NC; 7Department of Orthopaedic Surgery, University of Cincinnati, Cincinnati, OH; 8Sports Health & Performance Institute, Ohio State University, Columbus, OH; 9Department of Physiology and Cell Biology, Ohio State University, Columbus, OH; 10Department of Orthopaedic Surgery, Ohio State University, Columbus, OH; 11Department of Family Medicine, Ohio State University, Columbus, OH; 12Department of Biomedical Engineering, Ohio State University, Columbus, OH; and 13School of Health and Rehabilitation Sciences, College of Medicine, Ohio State University, Columbus, OH.
Laura C
LC
Schmitt
Mark V
MV
Paterno
Kevin R
KR
Ford
Gregory D
GD
Myer
Timothy E
TE
Hewett
D000293:Adolescent; D000328:Adult; D059549:Anterior Cruciate Ligament Reconstruction; D016022:Case-Control Studies; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D015999:Multivariate Analysis; D053580:Muscle Strength / Q000502:physiology*; D000068958:Return to Sport; D055815:Young Adult