Carpal tunnel syndrome impairs thumb opposition and circumduction motion.
BACKGROUND
Carpal tunnel syndrome is associated with sensory and motor impairments resulting from the compressed and malfunctioning median nerve. The thumb is critical to hand function, yet the pathokinematics of the thumb associated with carpal tunnel syndrome are not well understood.


OBJECTIVE
The purpose of this study was to evaluate thumb motion abnormalities associated with carpal tunnel syndrome. We hypothesized that the ranges of translational and angular motion of the thumb would be reduced as a result of carpal tunnel syndrome.


METHODS
Eleven patients with carpal tunnel syndrome and 11 healthy control subjects voluntarily participated in this study. Translational and angular kinematics of the thumb were obtained using marker-based video motion analysis during thumb opposition and circumduction movements.


RESULTS
Motion deficits were observed for patients with carpal tunnel syndrome even though maximum pinch strength was similar. The path length, normalized by palm width of the thumb tip for the patients with carpal tunnel syndrome was less than for control participants (opposition: 2.2 palm width [95% CI, 1.8-2.6 palm width] versus 3.1 palm width [95% CI, 2.8-3.4 palm width], p < 0.001; circumduction: 2.2 palm width [95% CI, 1.9-2.5 palm width] versus 2.9 palm width [95% CI, 2.7-3.2 palm width], p < 0.001). Specifically, patients with carpal tunnel syndrome had a deficit of 0.3 palm width (95% CI, 0.04-0.52 palm width; p = 0.022) in the maximum position of their thumb tip ulnarly across the palm during opposition relative to control participants. The angular ROM also was reduced for the patients with carpal tunnel syndrome compared with the control participants in extension/flexion for the metacarpophalangeal (opposition: 34° versus 58°, p = .004; circumduction: 33° versus 58°, p < 0.001) and interphalangeal (opposition: 37° versus 62°, p = .028; circumduction: 41° versus 63°, p = .025) joints.


CONCLUSIONS
Carpal tunnel syndrome disrupts kinematics of the thumb during opposition and circumduction despite normal pinch strength.


CONCLUSIONS
Improving understanding of thumb pathokinematics associated with carpal tunnel syndrome may help clarify hand function impairment associated with the syndrome given the critical role of the thumb in dexterous manipulation.
Hand Research Laboratory, Department of Biomedical Engineering, Cleveland Clinic, 9500 Euclid Avenue, ND20, Cleveland, OH, 44195, USA.
Tamara L
TL
Marquardt
Raviraj
R
Nataraj
Peter J
PJ
Evans
William H
WH
Seitz
Zong-Ming
ZM
Li
D000328:Adult; D001696:Biomechanical Phenomena; D002349:Carpal Tunnel Syndrome / Q000175:diagnosis / Q000503:physiopathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology*; D008875:Middle Aged; D016059:Range of Motion, Articular; D013933:Thumb / Q000294:innervation* / Q000503:physiopathology*; D014741:Video Recording