In NMES for reducing glenohumeral joint subluxation, which electrode arrangement best increases current density over the supraspinatus?

• A. Large electrode over supraspinatus
• B. Small electrode over supraspinatus, large electrode over deltoid
• C. Small electrode over deltoid
• D. Large electrode over deltoid

Answer: (B)

Current density is higher under smaller electrodes because density equals current divided by electrode area. Using a small active electrode over the supraspinatus concentrates the stimulation right where you want to recruit that muscle, increasing the likelihood of a strong, targeted contraction. Pairing it with a large dispersive electrode over the deltoid provides a return path and spreads the remaining current away from the target area, further concentrating the nerve activation under the small supraspinatus electrode. This focused activation helps stabilize the humeral head and reduce glenohumeral subluxation. Larger electrodes over the supraspinatus or small/large electrodes over the deltoid would dilute the current density at the target, making activation of the supraspinatus less selective and less effective.