151.
Evaluation of Lower-Limb Asymmetries in Mechanical Muscle
Function and Functional Performance of ACL-Patients
Anders Holsgaard-Larsen, Tine Iversholt, Carsten Jensen, Niels Mortensen,
Per Aagaard
Orthopaedic Research Unit, Institute of Clinical Research Odense University
Hospital, University of Southern Denmark; Institute of Sports Science and
Clinical Biomechanic, University of Southern Denmark; Orthopaedic Research
Unit, Institute of Clinical Research, Odense University Hospital, University of
Southern Denmark; Orthopaedic Research Unit, Institute of Clinical Research,
Odense University Hospital, University of Southern Denmark; Institute of
Sports Science and Clinical Biomechanic, Odense University Hospital,
University of Southern Denmark
Background:
Between-limb asymmetry is commonly investigated in
orthopedic patients by use of functional tests. However, mechanistic outcomes
related to mechanical muscle function may provide further insight.
Purpose / Aim of Study:
To investigate limb asymmetry in unilateral jump
performance by means of kinetic and kinematic analysis and mechanical
muscle function in ACL- patients and healthy controls.
Materials and Methods:
The study comprised 23 ACL- reconstructed
(
hamstring-graft) men (ACL, mean age: 27.2 ± 7.5 years, BMI: 25.4 ± 3.2 kg
m-2) 27 ± 7 month post- surgery and 25 healthy matched controls (CON, 27.2
± 5.4 years, 24.1 ± 1.8 kg m-2). Subjects performed (i) bilateral counter
movement jumps (CMJ) and (ii) unilateral single-leg CMJs (6- camera
ViconMX system, 2 AMTI force plates) where maximal jump height, knee
joint range of motion (ROM), peak and mean sagittal knee moments were
analyzed, (iii) one-leg maximal hop for distance, and (iv) maximal unilateral
isometric knee extensor and flexor strength. Asymmetry ratios were calculated
as operated/non-operated leg in ACL-patients, and non- dominant/dominant
leg in controls.
Findings / Results:
CMJ: Asymmetry ratios for ROM differed (p<0.01)
between ACL and CON with both types of CMJ (96.1% vs. 102.6% and
87.0%
vs. 99.9% in bilateral and single-leg CMJs, respectively). Hop for
distance: ACL demonstrated greater (p<0.01) asymmetry for jump length
(92.9%
vs. 98.6%). MVC: Asymmetry in hamstring MVC was greater
(
p<0.001) in ACL than controls (77.4% vs. 101.3%).
Conclusions:
The findings of greater inter-limb asymmetry in ACL subjects,
especially for maximal hamstring muscle strength, have significant clinical
implications since the hamstring muscles are important protagonists to the
ACL. Thus, the present data suggest that an elevated risk for secondary ACL-
rupture and/or risk of osteoarthritis exist in ACL patients.
