Safe zone for the posterior interosseous nerve with regard to the lateral and posterior approaches to the proximal radius.

PURPOSE: The posterior interosseous nerve (PIN) is at risk during the posterior and lateral approaches to the proximal radius. We aimed to define a safe zone for these approaches to avoid injury of the PIN and to evaluate their close and changing relationship to the nerve during forearm rotation.

METHODS

The study collective consisted of 50 upper limbs. After performance of the lateral approach, the distance between the tip of the radial head and the PIN's exit point from the supinator (= distance 1) and the shortest interval between the nerve's exit to the radial margin of the ulna (= distance 2) were measured in maximum pronation and supination. Then, the dorsal approach was conducted and again distance 1 and the interval between the distal margin of the anconeus and the nerve's exit point (distance 2) were evaluated (pronation and supination).

RESULTS

There were significantly shorter distances during supination in comparison to pronation. Regarding the lateral approach, distance 1 changed from a mean of 60.3 mm (supination) to 62.7 mm in pronation (p < 0.001). For the dorsal approach, distance 1 decreased significantly (p < 0.001) from 62.9 mm (pronation) to 60.2 mm (supination).

CONCLUSION

Supination during the lateral and dorsal approaches to the proximal radius needs to be avoided to protect the PIN. Furthermore, the nerve appeared at an interval between 45 and 84.1 mm (lateral approach) and 47.5-93.8 mm (dorsal approach), respectively. Therefore, care must be taken at this height during extension of the approaches in a distal direction.