Is nail dynamization beneficial after twelve weeks - An analysis of 37 cases.

Purpose: Although nail dynamization in femoral and tibial fractures is an effective method of promoting healing, its role beyond twelve weeks is still not clear. It is usually done two to three months following interlocking nailing. This study was done to evaluate the efficacy of late dynamization (after 12 weeks) and factors affecting union.

Materials and methods: In this retrospective study, thirty seven patients who underwent dynamization for reamed intramedullary interlocking nails of femur (18) and tibia (20) after twelve weeks from index surgery and with a minimum followup of six months were included. Fracture healing index was calculated using predynamization radiographs. Radiographic union was defined as osseous bridging of three cortices on followup radiographs. Dynamization failure was defined as fractures not showing progressive increase in callus on followup radiographs and those that required secondary intervention.

Results: Mean age of patients at time of injury was 35.92 years (range: 16-63) with males (86.8%) predominating. Mean time to dynamization from index surgery was 19.11 weeks (range-12-36). Thirty one fractures (81.5%) went onto union after dynamization of which twelve were femoral and nineteen were tibial fractures. Mean time to union after dynamization was 6 months. Communited fractures (6-21) showed poor results with delayed dynamization compared to other anatomical types which was statistically significant (P = 0.05). Predynamization FHI of more than 1.18 had 83% sensitivity and 72% specificity in predicting fracture healing after dynamization.

Conclusion: Late dynamization is still beneficial in promoting healing in femoral and tibial fractures. Communited fractures showed poor results with dynamization. Predynamization FHI was an important predictor of fracture healing.