VARIATION IN MEASUREMENTS OF GRIP STRENGTH - A STUDY IN REFLEX SYMPATHETIC DYSTROPHY PATIENTS

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.