Does double distal locking reduce non-union rates in intramedullary nailing for humeral shaft fracture?

Introduction: Intramedullary nailing is one of the surgical treatments for humeral shaft fracture. Non-union is a common complication, with rates of 10-20%. The objective of this study was to compare non-union in humeral shaft fractures treated by intramedullary nailing with double distal locking, single distal locking or no locking.

Hypothesis: Nailing with double distal locking decreases non-union rates compared to single or no locking.

Material and methods: This single-center retrospective comparative study included 87 patients with closed humeral shaft fracture without neurologic deficit treated by anterograde intramedullary nailing: group 1 (double locking): 15 fractures; group 2 (single locking): 63 fractures; group 3 (no locking): 9 fractures. Non-union was defined as absence of radiographic callus at 6 months without clinical pain. The primary endpoint was non-union rate per group. The secondary endpoints were Constant score at 6 months, and postoperative use of non-steroidal anti-inflammatory drugs (NSAIDs).

Results: There were no significant differences in non-union rate: 20.0% in group 1, 20.3% in group 2, and 0% in group 3 (p=0.32). Constant score at 6 months was significantly different between the 3 groups (p=0.01). Group 2 used more NSAIDs than the other groups (39.1% vs. 20.0% in group 1 and 33.3% in group 3; p=0.37).

Discussion: Non-union rates were similar regardless of distal locking for closed humeral shaft fractures without neurologic deficit treated by intramedullary nailing. Nevertheless, patients in the double locking group had higher Constant scores at 6 months, probably related to greater stability of fixation, allowing more efficient rehabilitation.

Level of evidence: III; retrospective comparative study.