The relationship between hip-abductor strength and the magnitude of pelvic drop in patients with low back pain.
BACKGROUND
It has been theorized that a positive Trendelenburg test (TT) indicates weakness of the stance hip-abductor (HABD) musculature, results in contralateral pelvic drop, and represents impaired load transfer, which may contribute to low back pain. Few studies have tested whether weakness of the HABDs is directly related to the magnitude of pelvic drop (MPD).


OBJECTIVE
To examine the relationship between HABD strength and MPD during the static TT and during walking for patients with nonspecific low back pain (NSLBP) and healthy controls (CON). A secondary purpose was to examine this relationship in NSLBP after a 3-wk HABD-strengthening program.


METHODS
Quasi-experimental.


METHODS
Clinical research laboratory.


METHODS
20 (10 NSLBP and 10 CON).


METHODS
HABD strengthening.


METHODS
Normalized HABD strength, MPD during TT, and maximal pelvic frontal-plane excursion during walking.


RESULTS
At baseline, the NSLBP subjects were significantly weaker (31%; P = .03) than CON. No differences in maximal pelvic frontal-plane excursion (P = .72), right MPD (P = 1.00), or left MPD (P = .40) were measured between groups. During the static TT, nonsignificant correlations were found between left HABD strength and right MPD for NSLBP (r = -.32, P = .36) and CON (r = -.24, P = .48) and between right HABD strength and left MPD for NSLBP (r = -.24, P = .50) and CON (r = -.41, P = .22). Nonsignificant correlations were found between HABD strength and maximal pelvic frontal-plane excursion for NSLBP (r = -.04, P = .90) and CON (r = -.14, P = .68). After strengthening, NSLBP demonstrated significant increases in HABD strength (12%; P = .02), 48% reduction in pain, and no differences in MPD during static TT and maximal pelvic frontal-plane excursion compared with baseline.


CONCLUSIONS
HABD strength was poorly correlated to MPD during the static TT and during walking in CON and NSLBP. The results suggest that HABD strength may not be the only contributing factor in controlling pelvic stability, and the static TT has limited use as a measure of HABD function.
Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
Karen D
KD
Kendall
Christie
C
Schmidt
Reed
R
Ferber
D000328:Adult; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005260:Female; D006621:Hip Joint / Q000503:physiopathology*; D006801:Humans; D017116:Low Back Pain / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010388:Pelvis / Q000503:physiopathology*; D018709:Statistics, Nonparametric; D016138:Walking / Q000502:physiology