Functional index: a numerical expression of post-traumatic wrist function.

Accurate functional assessment is an essential part of the analysis of managing fractures. A new technique for the measurement of the wrist's function is described. Observations of a wrist's performance are made using three devices. A dynanometer records movement while acting against a resistive torque. Angular and rotational movement at the wrist is measured using a three-dimensional goniometer. A vigorometer is used to assess the strength of grip. The three derived measurements give a functional index for each patient. Eighty-nine patients sustaining fractures at the wrist were seen at the time of trauma and at an assessment clinic 6 months later. Statistical analysis has shown that all three measurements are necessary to assess function. A functional index has applications in clinical work and research.