Relation between the finger positions used in the precision and partial power grips and the regional prevalence of osteoarthritis.

The correlation between digital flexion angles used in the precision and partial power grips and the reported regional prevalence of osteoarthritis was studied by goniometric measurement of six female subjects using the grips in 40 preselected activities. Normal interphalangeal ranges were determined by goniometric measurement in 20 normal female subjects. Both grips show a highly significant inverse correlation between mean flexion at each joint and the local prevalence of osteoarthritis. The conflict between these data implicating underuse and those supporting the theory of overload can be reconciled by postulating that primary and secondary osteoarthritis arise from different mechanisms. The former may be bifactorial, with incomplete use initiating the process and cartilage loading determining the rate of progress.