[Motion characteristics of motorized knee splints]

Area of Science:

• Biomechanics
• Rehabilitation Engineering
• Medical Device Technology

Background:

• Accurate kinematic replication is vital for motor-assisted limb rehabilitation.
• Existing motor devices vary in their ability to precisely mimic human joint motion.
• Quantifying device-limb motion congruence is essential for device selection.

Purpose of the Study:

• To assess the kinematic accuracy of eight motor devices during passive limb motion.
• To introduce a quantitative metric, the "device quotient" (DQ), for evaluating motion congruence.
• To identify motor devices that accurately transform set motion ranges to limb joints.

Main Methods:

• Determined X-Y coordinates of hip, knee, and ankle joints for both the limb and device.
• Calculated joint center distances and limb/device flexion angles.
• Introduced the "device quotient" (DQ) to quantify motion transformation efficiency.

Main Results:

• Only two of eight devices demonstrated near-harmonic motion transfer.
• These two devices achieved high "device quotient" (DQ) values for knee (65-100) and hip (27-63).
• Superior performance correlated with the ability to adjust the hip joint's center of rotation.

Conclusions:

• Adjustable hip joint centers are critical for achieving accurate device-limb motion congruence.
• Most motor devices exhibit significant discrepancies in motion transfer.
• The "device quotient" provides a valuable metric for assessing motor device performance in rehabilitation.