A method to quantify the "cone of economy"

Area of Science:

• Biomechanics
• Neurology
• Orthopedics

Background:

• Adult degenerative scoliosis (ADS) alters posture, potentially affecting balance.
• The cone of economy (COE) represents the stable region for upright posture.
• Quantifying balance and energy expenditure in ADS is crucial for understanding and managing the condition.

Purpose of the Study:

• To develop and evaluate a method for quantifying the dimensions of the cone of economy (COE) in adult degenerative scoliosis (ADS) patients.
• To measure the energy expenditure associated with maintaining balance within the COE in ADS patients.
• To compare balance parameters and energy expenditure between ADS patients and matched non-scoliotic controls.

Main Methods:

• A non-randomized, prospective, concurrent control cohort study was conducted.
• Ten ADS patients and ten non-scoliotic volunteers participated.
• Human motion video capture and dynamic surface electromyography were used to measure COE dimensions, center of mass (COM) sway, and muscle activity.

Main Results:

• ADS patients showed significantly greater COM sway in sagittal and coronal directions compared to controls.
• ADS patients exhibited larger COM and head displacements.
• Scoliosis patients demonstrated increased muscle activity in erector spinae and gluteus maximus to maintain static standing.

Conclusions:

• A novel method effectively quantifies COE boundaries, COM displacement, sway, and energy expenditure.
• This objective measurement tool can assist spine care practitioners in patient evaluation.
• The method aids in determining appropriate treatment options and documenting intervention effectiveness.