Is distal locking screw necessary for intramedullary nailing in the treatment of humeral shaft fractures? A comparative cohort study.

The gold standard for intramedullary nailing (IMN) in humeral shaft fracture treatment is bipolar interlocking. The aim of this study was to compare clinical and radiographic outcomes in two cohorts of patients treated with IMN with or without distal interlocking. We hypothesized that there was no significant difference between isolated proximal interlocking and bipolar interlocking in terms of consolidation and clinical results. One hundred twenty-one acute humeral shaft fractures were retrospectively included in group WDI (without distal interlocking screw, n = 74) or in group DI (with distal interlocking screw, n = 47). One hundred six patients (87.60%) could be verified by an X-ray, and 63 (52.07%) could be examined clinically. Fracture union at 6 months was the primary outcome, and the second was the final clinical outcome for shoulder and elbow after at least 6 months of follow-up. Pain, operating time, and radiation time were also analyzed. The two groups were not significantly different for population, fractures, or immobilization duration. No significant difference was found for bone union (WDI 89.06% vs DI 83.33%, p = 0.51), shoulder or elbow functional outcomes, or pain. However, there were significant differences in advantage to the WDI group for operating time (WDI 63.09 ± 21.30 min vs DI 87.96 ± 30.11 min, p < 0.01) and fluoroscopy time (WDI 59.06 ± 30.30 s vs DI 100.36 ± 48.98 s, p < 0.01). Thus, it seems that there were no significant differences between proximal unipolar and bipolar interlocking for humeral shaft fractures in terms of consolidation and clinical outcomes. WDI avoided the additional operating time and fluoroscopy time and risks linked to DI.