Strength assessment in postpolio syndrome: validity of a hand-held dynamometer in detecting change.
OBJECTIVE
To investigate the validity, the intraexaminer and interexaminer reproducibility, and the ability to detect change of a hand-held dynamometer (HHD) in strength measurements in former polio subjects.


METHODS
HHD measurement of knee extensor strength was compared with the criterion standard of a chair dynamometer measurement in 49 subjects. The "break" method was used for HHD measurements. Reproducibility was studied for six lower extremity muscle groups in 28 subjects. The measurements were performed by one experienced and one inexperienced examiner on two separate occasions, with an interval of 1 week. The examiners were blinded to each other's and to previous results.


METHODS
University hospital.


METHODS
Volunteer sample of former polio subjects.


RESULTS
For knee extension, the forces that could be measured with the HHD were limited to approximately 200N. Although the intraclass correlation coefficients were high (.75 to .98), the 95% limits of agreement between measurements showed large intervals for differences between two measurements (ratio intervals ranging from .76-1.52 to .52-2.77). The intraexaminer reproducibility for the experienced examiner was superior to that of the inexperienced examiner. The reproducibility of the inexperienced examiner showed systematic bias, with significantly higher strength values for the second session measurement of three muscle groups.


CONCLUSIONS
The device has good validity in the lower force range. However, because the agreement between measurements was poor, it has limited ability to detect a change in muscle strength. Therefore, this method is unable to detect small changes in lower extremity muscle strength in former polio patients.
Nollet
F
F
Department of Rehabilitation Medicine, Academic Medical Center, University of Amsterdam, The Netherlands.
Beelen
A
A
D002983:Clinical Competence / Q000592:standards; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D007866:Leg / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology; D015588:Observer Variation; D010808:Physical Examination / Q000295:instrumentation* / Q000379:methods; D016262:Postpoliomyelitis Syndrome / Q000150:complications*; D016684:Prone Position; D015203:Reproducibility of Results; D016037:Single-Blind Method; D016683:Supine Position; D013997:Time Factors