The safety of percutaneous screw placement in reverse shoulder arthroplasty for fracture: A cadaveric study

Background Cementless reverse shoulder arthroplasty (RSA) with percutaneous locking screw fixation is an increasingly utilized option for treatment of proximal humerus fractures. The safety of percutaneous screw placement in the humerus has not been well established. This study aims to evaluate the proximity of the axillary and radial nerves to percutaneous screw trajectories in RSA. Methods A humeral fracture stem with percutaneous locking screws was implanted into six male cadaveric specimens. Screw holes were over-drilled, and distances from trocars and drill bits to the axillary and radial nerves were measured using precise calipers. Results The drill bit was an average of 5.43 mm from the axillary nerve exiting the proximal cross-lock hole, with direct nerve penetration in one specimen. At the distal cross-lock hole, the drill bit was 1.45 mm from the radial nerve and pierced it in two specimens. The middle cross-lock hole showed no proximity to either nerve. Arm rotation did not affect these distances. Discussion The axillary and radial nerves are near the proximal and distal locking screws in RSA fracture stems with cross-locking options. Surgeons should exercise caution when placing these screws to reduce nerve injury risk. Further clinical studies are needed to validate these findings.