TY - JOUR
T1 - ACL deficiency affects stride-to-stride variability as measured using nonlinear methodology
AU - Moraiti, Constantina
AU - Stergiou, Nicholas
AU - Ristanis, Stavros
AU - Georgoulis, Anastasios D.
N1 - Funding Information:
Acknowledgments The authors gratefully acknowledge the support from the NIDRR (HI33G040118), NIH (K25HD047194), and the Nebraska Research Initiative to Dr Nicholas Stergiou.
PY - 2007/12
Y1 - 2007/12
N2 - Previous studies suggested that the small fluctuations present in movement patterns from one stride to the next during walking can be useful in the investigation of various pathological conditions. Previous studies using nonlinear measures have resulted in the development of the "loss of complexity hypothesis" which states that disease can affect the variability and decrease the complexity of a system, rendering it less able to adjust to the ever changing environmental demands. The nonlinear measure of the Lyapunov Exponent (LyE) has already been used for the assessment of stride-to-stride variability in the anterior cruciate ligament (ACL) deficient knee in comparison to the contralateral intact knee. However, there is biomechanical evidence that after ACL rupture, adaptations are also present in the contralateral intact knee. Thus, our goal was to investigate stride-to-stride variability in the ACL deficient knee as compared to a healthy control knee. Seven subjects with unilateral ACL deficiency and seven healthy controls walked at their self-selected speed on a treadmill, while three-dimensional knee kinematics was collected for 80 consecutive strides. A nonlinear measure, the largest LyE was calculated from the resulted knee joint flexion-extension data of both groups. Larger LyE values signify increased variability and increased sensitivity to initial conditions. Our results showed that the ACL deficient group exhibited significantly less variable walking patterns than the healthy control. These changes are not desirable because they reflect decreases in system's complexity, which indicates narrowed functional responsiveness, according to the "loss of complexity hypothesis." This may be related with the increased future pathology found in ACL deficient patients. The methods used in the present paper showed great promise to assess the gait handicap in knee injured patients.
AB - Previous studies suggested that the small fluctuations present in movement patterns from one stride to the next during walking can be useful in the investigation of various pathological conditions. Previous studies using nonlinear measures have resulted in the development of the "loss of complexity hypothesis" which states that disease can affect the variability and decrease the complexity of a system, rendering it less able to adjust to the ever changing environmental demands. The nonlinear measure of the Lyapunov Exponent (LyE) has already been used for the assessment of stride-to-stride variability in the anterior cruciate ligament (ACL) deficient knee in comparison to the contralateral intact knee. However, there is biomechanical evidence that after ACL rupture, adaptations are also present in the contralateral intact knee. Thus, our goal was to investigate stride-to-stride variability in the ACL deficient knee as compared to a healthy control knee. Seven subjects with unilateral ACL deficiency and seven healthy controls walked at their self-selected speed on a treadmill, while three-dimensional knee kinematics was collected for 80 consecutive strides. A nonlinear measure, the largest LyE was calculated from the resulted knee joint flexion-extension data of both groups. Larger LyE values signify increased variability and increased sensitivity to initial conditions. Our results showed that the ACL deficient group exhibited significantly less variable walking patterns than the healthy control. These changes are not desirable because they reflect decreases in system's complexity, which indicates narrowed functional responsiveness, according to the "loss of complexity hypothesis." This may be related with the increased future pathology found in ACL deficient patients. The methods used in the present paper showed great promise to assess the gait handicap in knee injured patients.
KW - Anterior cruciate ligament deficiency
KW - Gait analysis
KW - Nonlinear methods
KW - Stride-to-stride variability
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U2 - 10.1007/s00167-007-0373-1
DO - 10.1007/s00167-007-0373-1
M3 - Article
C2 - 17828526
AN - SCOPUS:36348981143
SN - 0942-2056
VL - 15
SP - 1406
EP - 1413
JO - Knee Surgery, Sports Traumatology, Arthroscopy
JF - Knee Surgery, Sports Traumatology, Arthroscopy
IS - 12
ER -