Relationship between axillary nerve and percutaneously inserted proximal humeral locking plate: a cadaver study.

Objective: The aim of this study was to investigate the relationship between the axillary nerve and the percutaneously inserted proximal humeral locking plate and to evaluate the risk of axillary nerve injury during percutaneous plate insertion.

Methods: The study included 50 shoulders of 25 fresh frozen cadavers. A 5 cm incision was made from the anterolateral border of the acromion to the arm and a 5-hole 3.5-mm proximal humeral plate was inserted. The axillary nerve was then dissected. Plate holes which crossed the axillary nerve were noted. The distance between the axillary nerve and the lateral edge of the acromion and the length of the arm were measured and their relations evaluated with a correlation test.

Results: The average arm length was 319 mm. The average distance between the axillary nerve and the lateral edge of the acromion was 60 mm. There was a significant correlation between the arm length and acromion-axillary nerve distance (p<0.05). The plate was inserted under the deltoid fascia in all shoulders except one. There were no axillary nerve lesions. In 1 case, the distal end of the plate was inserted in the deltoid muscle. No constant relationship between the plate holes and the axillary nerve was detected.

Conclusion: There is a risk of axillary nerve injury during percutaneous plate insertion. It must be ensured that the plate is inserted under the deltoid fascia during the surgery. The axillary nerve must be visible during application of the screws due to the impossibility of knowing which holes cross the axillary nerve.