Why a surgically treated humeral shaft fracture became a nonunion: review of 11 years in two trauma centers.

Aim: The aim of this study was to evaluate nonunion causes of surgically treated humeral shaft fractures in two different trauma centers.

Methods: A total of 327 cases of humeral shaft fractures were treated in 11 years in two trauma centers. We retrospectively reviewed in detail some factors in order to understand the reasons for nonunion: (1) fracture type, according to the AO classification, (2) grade of open fracture, according to Gustilo-Anderson, (3) timing, (4) reduction and (5) fixation.

Results: We observed 19 nonunions, 10 women and 9 men, with an average age of 57 years. Fractures were 1 A1 case, 2 A2 cases, 4 B2 cases, 6 B3 cases, 2 C1 cases, 1 C2 case and 3 C3 cases. Three cases had a simple fracture with two fragments; all the other were comminuted. Fifteen cases were closed, four open. The major criticalities observed were fracture comminution, exposure, unstable fixation and bone resorption. All 19 patients with nonunion underwent surgical fixation with compression plate and frozen cortical bone graft. A 4.5 LCP plate was used in 17 cases. The remaining 2 cases had an anatomical site-specific proximal humeral 3.5-mm LCP plate (Synthes, Paoli, PA, USA). In 17 patients, the nonunion healed: 15 cases treated with a 4.5 straight plate, and 2 cases with an anatomical site-specific proximal humeral 3.5 mm LCP plate, at a mean of 5 months. In 2 cases, consolidation was not reached.

Conclusions: We believe that humeral diaphyseal fractures should be treated surgically to avoid many complications. Our retrospective analysis indicates that factors that lead to a fixation failure are fracture comminution, open fracture, unstable fixation. The 19 nonunions treated with compression plating and frozen bone graft demonstrated consolidation in almost 90% of the cases.