The little finger superficialis--clinical investigation of its anatomic and functional shortcomings.

Based on clinical experience in the treatment of isolated injury to the little finger profundus tendon, we hypothesized that the little finger superficialis is functionally deficient in a significant portion of the population. Five hundred twenty-six normal hands were examined using the standard superficialis test and a subset of two hundred four normal hands were again examined using a modified superficialis test. We found that 33.8% of the little finger superficialis tendons in the normal population could not achieve normal range of flexion at the proximal interphalangeal joint (PIP) when submitted to the standard superficialis test. When the ring finger was allowed to flex along with the little finger, many of the previously deficient appearing fingers achieved near normal PIP joint flexion; however, 15.7% of the population still showed significant superficialis deficiency in the little finger. This portion of the population risks complete loss of flexion at both interphalangeal joints in the event of isolated profundus disruption in the little finger.