Risk of Radial Nerve Injury in Anterolateral Humeral Shaft Plating.

PURPOSE: The purpose of this study was to evaluate and compare the risk of iatrogenic radial nerve injury between arm positionings of 45° and 60° abduction in anterolateral humeral plating using a 4.5-mm narrow dynamic compression plate. METHODS: Fifty-six humeri of cadavers in the supine position with 45° of arm abduction were exposed through the anterolateral approach. A hypothetical fracture line was marked at the middle of the humerus, and a precontoured ten-hole 4.5-mm narrow dynamic compression plate was applied and fixed to the anterolateral surface. After the fixation, the radial nerve was exposed through a triceps-splitting approach. Screws in contact with or which had penetrated the radial nerve were deemed to be injuries. Then, the screws and plate were removed, the arm changed to the 60° arm abduction position, and the steps of applying the plate and inserting the screws were followed as in the 45° arm abduction step. RESULTS: The screws which could potentially injure the radial nerve were those of the second to sixth screw holes in both the 45° and 60° of arm abduction positions. The incidences of iatrogenic radial nerve injury of the second to sixth screw holes in the 45° position were 5.36%, 39.29%, 80.36%, 60.71%, and 10.71%, respectively, and at the 60° position were 5.36%, 53.57%, 83.93%, 60.71%, and 7.14%, respectively. There were no statistically significant differences in risk of injury between the two positions in all screw holes (all P-values > 0.05). DISCUSSION: In anterolateral humeral shaft fixation, arm abduction position did not affect the risk of iatrogenic radial nerve injury, with the main risk from certain screw holes. The surgeon should be careful in screw insertion, especially at the fourth and fifth screw holes. LEVEL OF EVIDENCE: IV; cadaveric study.

The risk of iatrogenic radial nerve and/or profunda brachii artery injury in anterolateral humeral plating using a 4.5 mm narrow DCP: A cadaveric study.

INTRODUCTION: Fixation of humeral shaft fractures with a plate and screws can endanger the neurovascular structure if proper care is not taken. No studies to our knowledge have studied the risk of iatrogenic radial nerve and/or profunda brachii artery (RNPBA) injury from each screw hole of a 4.5 mm narrow dynamic compression plate (narrow DCP). The purpose of this study is to evaluate the risk of RNPBA injury in anterolateral humeral plating with a 4.5 mm narrow DCP. MATERIAL AND METHODS: 18 humeri of 9 fresh-frozen cadavers in the supine position were exposed via the anterolateral approach with 45 degrees of arm abduction. A hypothetical fracture line was marked at the midpoint of each humerus. A precontoured ten-hole 4.5mm narrow DCP was applied to the anterolateral surface of the humerus using the fracture line to position the center of the plate. All screw holes were drilled and screws inserted. The cadaver was then turned over to the prone position with 45 degrees of arm abduction, and the RNPBA exposed. The holes through in which 100% of the screw had contact with or penetrated the RNPBA were identified as dangerous screw holes, while lesser percentages of contact were defined as risky. RESULTS: The relative distance ratios of the entire humeral length from the lateral epicondyle of the humerus to the 4th, 3rd, 2nd and 1st proximal holes were 0.64, 0.60, 0.56 and 0.52, respectively. The most dangerous screw hole was the 2nd proximal, in which all 18 screws had contacted or penetrated the nerve, followed by the risky 1st (12/18), 3rd (8/18) and 4th (2/18) holes. CONCLUSION: In humeral shaft plating with the 4.5mm narrow DCP using the anterolateral approach, the 2nd proximal screw hole carries the highest risk of iatrogenic radial nerve and/or profunda brachii artery injury.