Validity of pulp-to-palm distance as a measure of finger flexion

This study investigated the validity of pulp-to-palm distance measures as clinical indicators of finger flexion capacity. Pulp-to-palm distance and goniometry of the metacarpophalangeal, proximal interphalangeal and distal interphalangeal joints were measured by a single tester in 50 patients with abnormal digital flexion using a computerized hand assessment system. The correlation between pulp-to-palm distance measurements and total finger flexion measures obtained by goniometry, was moderate (r=-0.46 and -0.51). This indicates that the measures are not interchangeable. The relationship between an upper extremity disability score (DASH) and restricted motion was stronger for the goniometric measurements (r=0.45, P<0.01) than for the pulp-to-palm distance measurements (r<0.30, P>0.01). Both types of range of motion measurements were able to discriminate between minimal and substantial upper extremity disability. Further methodological evaluation is required to support the use of pulp-to-palm distance measures as an outcome indicator.