Nail dynamization for delayed union and nonunion in femur and tibia fractures following intramedullary nailing: A systematic review and meta-analysis.

PURPOSE: This study aims to evaluate the efficacy of nail dynamization in patients with delayed union and nonunion of femur and tibia shaft fractures following intramedullary nailing, and systematically analyze the associated factors to guide surgeons.

METHODS

A comprehensive search of PubMed, EMBASE, and Cochrane Library databases was conducted to identify relevant studies. We screened the literature based on the eligibility criteria, extracted relevant data, and assessed the quality of the included studies. A single-arm meta-analysis using a random-effects model was conducted to estimate overall union rates, while meta-regression and subgroup analyses explored sources of heterogeneity and contributing factors. Sensitivity analyses were used to assess result stability.

RESULTS

11 studies consisting of 318 patients met the inclusion criteria. The pooled union rate after nail dynamization was 77.2 % with significant heterogeneity. Meta-regression identified the time of dynamization, the method of dynamization, and Fracture Healing Index (FHI) as critical factors affecting union rates. Subgroup analysis revealed that dynamization within 6 months, preserving the dynamic locking screw, and an FHI >1.17 were significantly associated with higher union rates.

CONCLUSION

Nail dynamization is an effective treatment for delayed union and nonunion of femur and tibia shaft fractures following intramedullary nailing. Early dynamization (within 6 months), preserving the dynamic locking screw, and ensuring an FHI >1.17 are crucial strategies for maximizing union rates.