JUDGMENTS OF THE PRESENCE OF ABERRANT MOVEMENT
ICF category	Measurement of impairment of body function – pain in back; pain in lower limb; mobility of several joints; and control of complex voluntary movements
Description	“Aberrant movement” includes the presence of any of the following: Painful arc with flexion or return from flexion, instability catch, Gower sign, and reversal of lumbopelvic rhythm
Measurement method	Painful arc with flexion or return from flexion is positive if the patient reports pain during movement but not at the end ranges of the motion. Instability “catch” is positive when patient deviates from straight-plane sagittal movement during flexion and extension. Gower sign is positive if the patient needs to utilize “thigh-climbing” on return from flexion, specifically the hands push against the anterior thighs in a sequential distal to proximal manner to diminish the load on the low back when returning to the upright position from a forward bent position. Reversal of lumbopelvic rhythm is positive if the patient, upon return from a forward bent position, suddenly bends his/her knees to extend hips shifting pelvis anterior as he/she returns to the standing position.
Nature of variable	Categorical
Units of measurement	Present/absent
Measurement properties	Observation of aberrant movements has demonstrated moderate to good reliability (k=0.60) for aberrant movement; and variable for individual tests (k = 0 to 0.69) with painful arcs being most reliable (k = 0.61 to 0.69)146 in 3 pairs of physical therapy raters evaluating 63 consecutive subjects currently experiencing LBP and with a previous history of LBP.