The most common cause of failure after Steindler flexorplasty has been known insufficient power of the transferred muscles. We develop "effective muscle index" which is calculated from the actual strength of each muscle to predict postoperative flexion power of the elbow for preventing the failure of the surgery.

We reviewed 10 patients who received Steindler flexorplasty from Aug. 1983 to Jan. 1997. We calculated "effective muscle index" with power of each transferred muscle, tension fraction2) by Brand, 1981, correction index of the magnitude of transferring muscle and correlated the "effective muscle index" with postoperative elbow flexion power.

Excluding 4 out of total 10 patients who had grade 1 or 2 power of biceps and brachialis, "effective muscle index" has borderline significance with the postoperative flexion power of the elbow (p=0.123).

The authors concluded that the "effective muscle index" is maybe considered as a useful index for predicting the postoperative flexion power of the elbow after Steindler flexorplasty.