RESUMO
OBJECTIVE: Dynamization has already been described as a secondary intervention for delay unions of tibial shaft fractures treated with intramedullary nailing. Although it's a common procedure, it is not widely supported in the literature. The purpose of this study was to determine the union rate of nail dynamization in cases of delayed union of diaphyseal tibial fractures, and assess the effect of fracture morphology on union rates. MATERIALS AND METHODS: We retrospectively analyzed a series of 199 consecutive tibial shaft fractures. We recorded the dynamization rate, period from nailing to dynamization, nailing to the union, the fracture pattern (according to AO/ASIF and whether it was closed or open), the callus diameter before dynamization (fracture healing index; FHI) and union/failure rates. RESULTS: Out of a total of 199 fractures treated during the study period, 41 (20.6%) were dynamized. After applying inclusion and exclusion criteria, 39 patients with 39 fractures were included in the study. The mean time from nailing to dynamization was 18.4 ± 7.2 weeks. The union rate was 92.3% (n = 36) over a mean time of 14.1 ± 5.6 weeks as from dynamization. The overall failure rate was 6.7% (n = 3). There was no significant association between failure and AO/ASIF classification (p > 0.05) or fracture exposure (X 2 = 0.19; p = 0.66). The pre-dynamization FHI of ≥ 1.17 was significantly associated with consolidation (p < 0.05). CONCLUSION: In cases of delayed union of tibial fractures, dynamization offered a high union rate associated with pre-dynamization FHI, while fracture morphology did not affect the failure rate.