path of instantaneous center of rotation


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path of instantaneous center of rotation

Abbreviation: PICR
The plotted trajectory of the axis of rotation of a joint through its entire range of movement. The center of rotation moves due to translation, the accessory gliding or sliding motion that accompanies the rotation. The fact that this is instantaneous infers that the PICR is not constant, but changes with the moment.

Patient care

Deviation from the ideal PICR for any joint may result from muscle strength or length imbalance, internal joint derangement, or joint capsule restriction. These conditions may occur because of previous joint surgery, scar tissue, traumatic injury, or simply from aging, and may affect the quality, quantity, efficiency, or pain of joint movement and gait mechanics. Physical therapists try to improve their patients’ awareness of their center of gravity and of shifts that can throw this off balance by employing balance exercises and posture training. Correct patient positioning for bed or chair rest should be practiced by all health care providers, as asymmetry can affect the patient’s comfort and lead to further joint concerns over time. An orthotist or prosthetist measuring and fitting a patient for any joint brace must consider the desired PICR, as the brace must allow the joint to move through full PICR. If proper joint movement is restricted, the device could lead to further pathology.

See also: path