Introduction The radial nerve is at risk in arthroscopic elbow surgery and there are reports of significant nerve injury, particularly with arthroscopic synovectomy or arthroscopic capsulectomy for the stiff elbow. This study was aimed to further define the relationship of the radial nerve to the elbow joint.

Methods Magnetic Resonance Imaging studies of 23 elbows with minimal or no pathology were used to measure the distance of the radial nerve from the border of the radial head and the position of the nerve relative to the bony landmarks of the elbow joint.

Results The radial nerve or its branches were found to lie on average 6.6 mm from the border of the radial head (range 3 to 9 mm) and in an arc of 64° antero-lateral to the radial head. At the level of the radial head the nerve was not separated from capsule by muscle in 12 of the 23 elbows.

Conclusions Care should be taken in the insertion of antero-lateral portals in elbow arthroscopy as the position of the radial nerve and its branches is variable. Arthroscopic synovectomy and capsulectomy should be carried out above the level of the radial head where the nerve is protected by brachialis to avoid permanent damage to the radial nerve.