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Kanzaki H1, Takahashi T1, Nagase T1, Minamisawa T1, Makabe H1, Akatsuka S1, Nakanowatari T1, Yoshida S2, Ihashi K3
1Yamagata Prefectural University of Health Science, Physical Therapy, Yamagata, Japan, 2Graduate School of Yamagata Prefectural University of Health Sciences, Physical Therapy, Yamagata, Japan, 3Fukushima Medical University, Preparing Section for New Faculty of Medical Science, Fukushima, Japan
Background: In clinical practice, a knee orthosis is applied to patients with sway of the knee joint, muscle weakness, deformation, pain, or other characteristics. During normal walking, the knee joint performs articulation in a large range: 60-70 deg. Therefore, limiting the knee joint motion invites many biomechanical changes as compensation, producing a large change in the movement of the center of mass (COM) during walking. Walking with poor mechanical efficiency is expected to occur. Nevertheless, few reports of studies have described biomechanical changes caused by knee extension position fixation during walking.
Purpose: To examine biomechanical changes during walking by fixing the unilateral knee joint in the extension position using a knee orthosis.
Methods: We examined 12 healthy adults (7 female, 5 male ; 20-21 years old; 56.6 ± 4.0 kg body weight; 164.8 ± 6.6 cm height). A knee orthosis (T-SCOPE premier; Breg, Inc.) was used to fix the knee joint. Patients were then asked to walk (1) without a knee orthosis, (2) with a knee orthosis, but with unrestricted knee joint motion, or (3) with a knee orthosis and with the knee joint fixed at the extension position. Kinematic and kinetic data were collected using a three-dimensional motion analysis system (MX T20, VMS; Vicon Motion Systems) and four force plates (Kistler Instruments AG) while patients walked at a comfortable speed. Three-dimensional displacements of COM were computed through integration of force plate data. As the index of the mechanical efficiency of walking, we used the work required to move 1 kg of body weight 1 m and the energy exchange rate of potential energy and kinetic energy. Using an average of three trials for each walking parameter, we compared results obtained among conditions using repeated measures analysis of variance or Friedman´s test.
Results: With knee fixation, the range of pelvic anterior-posterior tilt, rotation, and lateral tilt of the trunk to the left side were increased significantly. Actually, COM displacement in all directions increased significantly, but the mechanical efficiencies of walking were significantly high. During knee fixation, a significant decrease occurred in the positive work produced respectively by the right knee and hip joint during the right leg stance phase and the early right swing phase.
Conclusion(s): Results suggest that knee joint fixation displaced the COM and increased pelvis and trunk motion during walking, but the walking mechanical efficiency increases because of decreased positive work by the knee and hip joint on the fixed knee side. Mechanical efficiency was enhanced probably because of external forces by the knee orthosis substituting for knee joint work and because cooperative movement of the pelvis and the trunk compensated work by the hip joint.
Implications: Results of this study show biomechanical effects of wearing a knee orthosis and suggest implications for the use of prostheses and long leg orthoses, and the stiff knee, as seen in hemiplegia or osteoarthritis of the knee. These findings are expected to be useful for elucidating the walking mechanisms of patients with limited knee movement.
Keywords: Fixation of knee extension position, biomechanics, gait analysis
Funding acknowledgements: This research was supported by JSPS Kakenhi Grant Number 15K01421.
Purpose: To examine biomechanical changes during walking by fixing the unilateral knee joint in the extension position using a knee orthosis.
Methods: We examined 12 healthy adults (7 female, 5 male ; 20-21 years old; 56.6 ± 4.0 kg body weight; 164.8 ± 6.6 cm height). A knee orthosis (T-SCOPE premier; Breg, Inc.) was used to fix the knee joint. Patients were then asked to walk (1) without a knee orthosis, (2) with a knee orthosis, but with unrestricted knee joint motion, or (3) with a knee orthosis and with the knee joint fixed at the extension position. Kinematic and kinetic data were collected using a three-dimensional motion analysis system (MX T20, VMS; Vicon Motion Systems) and four force plates (Kistler Instruments AG) while patients walked at a comfortable speed. Three-dimensional displacements of COM were computed through integration of force plate data. As the index of the mechanical efficiency of walking, we used the work required to move 1 kg of body weight 1 m and the energy exchange rate of potential energy and kinetic energy. Using an average of three trials for each walking parameter, we compared results obtained among conditions using repeated measures analysis of variance or Friedman´s test.
Results: With knee fixation, the range of pelvic anterior-posterior tilt, rotation, and lateral tilt of the trunk to the left side were increased significantly. Actually, COM displacement in all directions increased significantly, but the mechanical efficiencies of walking were significantly high. During knee fixation, a significant decrease occurred in the positive work produced respectively by the right knee and hip joint during the right leg stance phase and the early right swing phase.
Conclusion(s): Results suggest that knee joint fixation displaced the COM and increased pelvis and trunk motion during walking, but the walking mechanical efficiency increases because of decreased positive work by the knee and hip joint on the fixed knee side. Mechanical efficiency was enhanced probably because of external forces by the knee orthosis substituting for knee joint work and because cooperative movement of the pelvis and the trunk compensated work by the hip joint.
Implications: Results of this study show biomechanical effects of wearing a knee orthosis and suggest implications for the use of prostheses and long leg orthoses, and the stiff knee, as seen in hemiplegia or osteoarthritis of the knee. These findings are expected to be useful for elucidating the walking mechanisms of patients with limited knee movement.
Keywords: Fixation of knee extension position, biomechanics, gait analysis
Funding acknowledgements: This research was supported by JSPS Kakenhi Grant Number 15K01421.
Topic: Human movement analysis; Musculoskeletal; Orthopaedics
Ethics approval required: Yes
Institution: Yamagata Prefectural University of Health Science
Ethics committee: The ethical board of Yamagata Prefectural University of Health Science
Ethics number: Ethics Committee approval number: 1512-18
All authors, affiliations and abstracts have been published as submitted.
