Timing of Radiographic Healing for Distal Femur Fractures Treated With Intramedullary Nails.

Area of Science:

• Orthopedic Surgery
• Trauma Surgery
• Radiology

Background:

• Distal femur fractures are complex injuries requiring precise management.
• Assessing radiographic union is crucial for determining treatment success and preventing complications.
• The modified Radiographic Union Scale for Tibia (mRUST) is a tool used to evaluate fracture healing.

Purpose of the Study:

• To profile modified Radiographic Union Scale for Tibia (mRUST) scores over time in distal femur fractures treated with intramedullary nails.
• To identify predictors of radiographic union timing and delayed progression in these fractures.

Main Methods:

• Multicenter retrospective cohort study involving ten Level I Trauma Centers.
• Included patients with distal femur fractures (OTA/AO 33A and 33 C) treated with intramedullary nails, with a minimum 1-year follow-up.
• Analyzed mRUST scores at 3, 6, and 12 months postoperatively, using ROC analysis and multivariable models to identify predictors.

Main Results:

• A 3-month mRUST score ≤8 predicted reoperation with 99% negative predictive value.
• Tobacco use (1.2 months longer) and open fractures (1.4 months longer) were associated with delayed radiographic union.
• Chronic kidney disease predicted delayed progression of fracture healing (P < 0.01).

Conclusions:

• A 3-month mRUST score >8 suggests a high likelihood of avoiding reoperation for nonunion in distal femur fractures.
• Tobacco use and open fractures prolong radiographic union time.
• Chronic kidney disease necessitates adjusted expectations and management strategies due to delayed radiographic progression.