Biomechanical Testing of an Olecranon Osteotomy Nail

INTRODUCTION Comminuted distal humerus fractures often require large access to the distal humerus for anatomic reconstruction of the joint surface. In these cases an olecranon osteotomy is usually performed, allowing the triceps muscle to be moved out of the way with clear access to the distal humerus. After fixing the distal humerus, the olecranon is often fixed with two k-wires inserted longitudinally down the ulna and a tension band in a figure of eight, or with a 6.5mm cancellous screw and tension band. These olecranon fixations are commonly associated with complications like k-wire migration, hardware prominence, increased fracture gaps, or non-unions, all requiring secondary operations. Some papers report up to a 70%-80% re-operation rate. The olecranon osteotomy nail (Figure 1) provides a number of advantages over current fixation methods. First, the nail is drilled for, inserted, and cross-locked in the bone prior to creating the osteotomy at a position distal to the location of the osteotomy. After the distal humerus is fixed, an end cap is simply inserted through the predrilled hole in line with the nail, reducing the olecranon and creating compression across the osteotomy, ensuring an anatomic reduction. This also allows for quick realignment and fixation of the loose fragment, instead of the secondary operation required to fix the olecranon after fixing the distal humerus, saving OR time. Second, the locking holes in the nail are oblique to each other and the anatomic axis of the ulna. This unique design prevents the nail from moving within the medullary canal to prevent toggle and ensure anatomic reduction of the olecranon fragment. Third the locking screws used to lock the nail in place incorporate a threaded head that bites into the near cortex and sits flush with the surface. It also bottoms out on the nail taking up additional clearance between the nail and the screw, preventing toggle of the nail in the canal, and ensuring anatomic reduction. Since the screws sit flush with the surface of the ulna there should be no hardware prominence, and no risk of hardware migration.