Jhb. Geertzen et al., VARIATION IN MEASUREMENTS OF GRIP STRENGTH - A STUDY IN REFLEX SYMPATHETIC DYSTROPHY PATIENTS, Acta orthopaedica Scandinavica, 69, 1998, pp. 4-11
The clinical picture of reflex sympathetic dystrophy (RSD) is characte
rized by a combination of the triad: autonomic, motor and sensory chan
ges. In this study, the grip strength is measured in 29 upper extremit
y RSD patients. We used the generalizability theory to assess the exte
nt of the disagreement or differences (errors in measurement) within o
r between observers and interactions between observer-session and repe
tition of the measurements. The aims of our study were to determine th
e different sources of variation in grip strength tests and the smalle
st detectable differences (SDD) as well as the reliability of upper ex
tremity grip strength tests in RSD patients. The main sources of varia
tion of measurement errors were observer, patient/observer interaction
s and patient/session/observer interaction and a random source. We fou
nd that the generalizability theory is useful for estimating the sourc
es of measurement error. Clinical examinations for muscle strength mea
surements, as a part of a total clinical examination, for example for
a disability payment or worker's compensation in case of RSD patients
should be done by more than one observer in more than one session and
more than once.