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Postural changes after sustained neck muscle contraction in persons with a lower leg amputation
Cyril Duclos1, Régine Roll, Anne Kavounoudias
1Laboratoire de Neurobiologie Humaine, UMR/CNRS 6149, Aix-Marseille Universités, Centre St. Charles, Pole 3C, Case B, 3, Place Victor Hugo, 13331 Marseille Cedex 03, France. cyril.duclos@umontreal.ca
Summary
Lower leg amputation causes asymmetrical weight-bearing. A short neck muscle contraction can alter standing posture in amputees, potentially improving weight distribution on prosthetics.
Area of Science:
- Biomedical Engineering
- Rehabilitation Science
- Human Physiology
Background:
- Lower leg amputation often leads to asymmetrical weight-bearing, negatively impacting amputees' quality of life and increasing joint strain.
- This asymmetrical loading can result in pain, premature joint degeneration, and arthritis in weight-bearing joints.
- Understanding postural adaptations is crucial for improving long-term outcomes for individuals with lower limb amputations.
Purpose of the Study:
- To investigate if individuals with lower leg amputations experience postural post-effects after isometric muscle contraction.
- To determine if these postural changes could potentially enhance weight-bearing distribution on prosthetic limbs.
- To compare postural responses in amputees versus healthy individuals following a controlled muscle contraction.
Main Methods:
- A pilot study involving 15 unilateral lower leg amputees and 17 control subjects.
- Center of Pressure (CP) position was measured during standing (eyes open/closed) before and after a 30-second voluntary isometric lateral neck muscle contraction.
- Measurements were taken 1 and 4 minutes post-contraction to assess postural shifts.
Main Results:
- Postural post-effects, characterized by a Center of Pressure (CP) shift in the medio-lateral plane, were observed in most amputee and control subjects.
- The direction of the CP shift (towards or away from the contraction side) varied among participants.
- Postural changes occurred without an increase in Center of Pressure (CP) velocity, and shift direction remained consistent over time in a subset of amputees.
Conclusions:
- A brief isometric muscle contraction can induce measurable changes in standing posture for individuals with lower leg amputations.
- These postural post-effects may stem from adaptations in the body's postural reference frame in response to proprioceptive input.
- Further research is warranted to explore the therapeutic potential of these findings for improving prosthetic limb integration and function.
