We recorded the preoperative posterior deltoid (PD) and postoperative elbow extensor torque (EET) to determine if it is possible to predict the likely EET following PD transfer.

A custom built device (Troidometer) was used to measure the preoperative torque generated by the PD under maximum isometric contraction with the shoulder at 90° of abduction and the coronal plane and the elbow flexed at 90°. At a minimum of 3 months post surgery the maximum isometric EET was measured again with the Troidometer.

In a total of 17 arms in 9 patients the average preoperative PD was 9.5 Nm and the average post operative EET was 5.4 Nm or 57% of the PD preoperative torque. A paired sample test demonstrated a highly significant decrease (P = 0.001) and a correlation coefficient of 0.8 between the pre and post operative data. If a poor result from a revised transfer is excluded then the average EET is 60% of preoperative torque.

Based on this data it can be predicted that approximately 60% of the pre operative PD torque will postoperatively be converted to EET.