Danger zone for screw placement in minimally invasive plate osteosynthesis (MIPO) of diaphyseal fractures of forearm: a cadaveric study.

PURPOSES To identify the anatomical relationship between neurovascular structures and screws and to evaluate the danger zone of screw placement during minimally invasive plate osteosynthesis (MIPO) technique following the volar approach for the radius and the subcutaneous approach for the ulna in diaphyseal forearm fractures. METHODS Sixteen cadaveric forearms were fixed with a 3.5-mm, 14-hole, locking compression plate (LCP) using the MIPO technique with a volar approach of the radius. Two locking screws were fixed at each end via two separated incisions, and the remaining ten  screws were inserted percutaneously. The same MIPO technique was performed at the ulna with the subcutaneous approach. The forearms were then dissected to identify any damage to or direct contact between the screws and the radial artery (RA), the superficial branch of the radial nerve (SBRN), the posterior interosseous nerve (PIN), and the dorsal cutaneous branch of the ulnar nerve (DCBUN). The distances from the screws to the structures at risk, as well as the radial and ulnar length, were measured. RESULTS The average lengths of the radius and ulna were 24.74 cm and 25.93 cm, respectively. On the volar aspect of the radius, the danger zones of RA and SRN were between 15.26 and 81.24% of the length of the radius from the radial styloid. The zone of PIN injury at the posterior aspect of the radius was between 41.45 and 81.24% of the length of the radius from the radial styloid. Meanwhile, the danger zone of DCBUN was between 12.21 and 27.23% of the ulnar length from the ulnar styloid. CONCLUSION Based on our study, the percutaneous screw fixation in MIPO for the treatment of diaphyseal fractures of the forearm is a dangerous procedure, especially for the volar approach of the entire radius and the subcutaneous approach of the distal ulna.