The humeral bone is subject to torsional forces. In case of displaced shaft fractures, internal fixation remains the standard of care. This retrospective two-center study assessed the fracture union rate and complications after dual 3.5 mm locking compression plate (LCP) fixation using an anterolateral approach. Over a 9-year period, 38 patients underwent surgery in two centers. They had a mean age of 53.7 years (15-97, +/- standard deviation (SD) 26) and there were three open fracture cases (7.9 %). The dominant side was affected in 21 cases (55.3 %) and there were 11 polytrauma patients (29 %). Mean operative time was 78 min (40-124, +/- 19.8 SD). Patients were treated with dual 3.5 mm LCP fixation (6 screws on either side of the fracture line, anterolateral approach without a tourniquet). The first two orthogonal views showing at least 3 cortical bridges out of 4 determined fracture healing, as assessed by two independent raters. Pre- and postoperative complications were tabulated. Clinical outcomes included range of motion (ROM) and return to activities, while functional outcomes were assessed with the Disability of the Arm Shoulder and Hand (DASH), the Constant score, the Subjective Shoulder Score (SSV) and the Mayo Elbow Performance Score (MEPS). Minimum follow-up was 1 year. Four patients were given a shoulder immobilizer to wear for 3 weeks; immediate mobilization was the standard of care for the other patients. Fracture union was achieved in all cases within a mean of 11.7 weeks (6-28 +/- 7.1 SD) without any heterotopic ossification of the brachialis muscle. There were eight patients with preoperative radial nerve palsy and two cases of postoperative palsy. There was one surgical site infection (2.6 %). Return to work for active patients was possible in 87 % of cases within a mean of 23 weeks (6-72 +/- 11 SD). The Constant score was 84.6 (35-100, +/- 13.4 SD), the SSV score was 80.7 (60-100, +/- 8.2 SD), the DASH score was 13.5 (0-38.3, +/- 8.8 SD) and the MEPS score was 85 (55-100, +/- 11.9 SD). Traditional fixation methods provide little control over torsional forces, leading to non-union rates between 3 % and 12 % and delayed union (12 to 20 weeks). The simplicity of the technique described here, and the short operative time, may help explain the low infection rate. Dual plate fixation makes it possible to use more screws and allows nerve exploration and decompression in case of preoperative nerve palsy. Dual plate fixation to treat humeral shaft fractures is a simple and reliable technique.
