Intraoperative assessment of wrist extensor muscle force.

Surgical restoration of hand grasp in the patient with spinal cord injury at the sixth cervical level often involves use of one of the two radial wrist extensors. Because the loss of the remaining wrist function would be devastating, it is important to establish techniques for quantitatively predicting postoperative function before tendon transection. An in situ method has been developed for determining muscle strength during tendon transfer surgery. Buckle transducers are placed on the tendons of the extensor carpi radialis brevis and longus for simultaneous measurement of strength of each individual muscle during voluntary and/or electrically stimulated extension of the wrist. The measured strength of the extensor carpi radialis brevis is examined to determine whether sufficient wrist extension torque would remain if the long wrist extensor is transferred. This technique allows accurate measurement of the force developed in any voluntarily activated muscle that has a long tendon of insertion.