Evaluation of callus formation in distal femur fractures after carbon fiber composite versus stainless steel plate fixation

Introduction Carbon-fiber-reinforced polyetheretherketone (CFR) composite plates have a more favorable stress modulus than stainless steel (SS) plates that may confer an advantage to bridge plating. The purpose of this study was to compare callus formation after CFR and SS plating of distal femur fractures. Methods A retrospective review identified distal femoral fractures treated with CFR ( n = 10) and SS ( n = 21) plate fixation. Callus formation was measured using the modified Radiographic Union Score for Tibia (mRUST) at 3- and 6-month follow-up by three orthopedic trauma surgeons. Loss of alignment, implant failure, and revision surgeries were reviewed. Results At 3 months, the mRUST in the CFR and SS groups was 9.0 (range, 6.3–12.3) and 6.9 (range, 4.3–11.7), respectively ( p = 0.01). At 6 months, the mRUST in the CFR and SS groups was 11.4 (range, 7.7–16.0) and 10.5 (range, 6.0–15.7), respectively ( p = 0.3). CFR and SS groups had a loss of fracture alignment in 1 (10%) and 1 (5%) patient, respectively ( p = 0.5), and an unplanned revision surgery in 0 (0%) and 3 (15%) patients, respectively ( p = 0.2). All three revisions surgeries in the SS group were for nonunion repair. Conclusions Treatment of distal femur fractures with CFR versus SS plating resulted in greater callus formation at 3 months. At 6 months, there was no difference in callus formation between groups. A larger series of patients is necessary to determine if the observed early increased callus formation confers a benefit to clinical outcomes. Level of evidence Therapeutic level III.