Comparison of the clinical effectiveness of Bone Morphogenic Protein (BMP)-2 and-7 in the adjunct treatment of lower limb nonunions

Background: Substantial evidence exists demonstrating the individual effectiveness of both rhBMP-2 and -7 in the treatment of nonunions, data comparing the clinical effectiveness of adjunct rhBMP-2 and 7 remains scarce. Therefore, we examined our large single-center case series to compare the clinical effectiveness of both rhBMP-2 and -7 in non-union therapy aiming to answer: - Does a certain type of BMP have an advantageous effect on radiological outcome of applied lower limb non-union therapy? - Does application of a certain type of BMP have an advantageous effect on radiological outcome of infected lower limb nonunions? - Are there any additional risk factors associated with inferior outcome in context with an adjunct BMP treatment? Hypothesis: Both BMPs have the same effect on the radiological outcome of surgically treated lower limb nonunions. Patients and methods: Single-center retrospective database analysis of a case series of patients with lower limb long bone nonunions receiving either a one- or two-stage (Masquelet-) procedure based on the diamond concept with application of rhBMP-2 or -7. The diamond concept summarizes core factors that need to be present to achieve bone healing. In particular, these factors relate to the optimization of the mechanical ( stability) and biological environment (sufficient osteogenic and angiogenic cells, osteoconductive scaffolds and growth factors). All medical data from patients that received surgical treatment between 01/01/2010 and 31/12/2016 were assessed. In total, 356 patients were treated with BMPs and 156 patients 18 years or older with non-union of their tibia or femur having a follow-up of at least 1 year were included. Consolidation in context with type of rhBMP was compared and the influence of relevant risk factors assessed. Results: Consolidation rate was significantly higher in patients treated with rhBMP-2 (rhBMP-2: 42/46 (91%) vs. rhBMP-7: 64/110 ( 58%); p < 0.001). In particular, application of rhBMP-2 increased the likelihood of consolidation for tibial nonunions (OR 32.744; 95%CI: 2.909-368.544; p = 0.005) and when used in two-stage therapy (OR 12.095; 95% CI: 2.744-53.314; p = 0.001). Furthermore, regression modeling revealed a higher correlation between application of rhBMP-2 and osseous consolidation in infected nonunions (OR 61.062; 95% CI: 2.208-1688.475; p = 0.015) than in aseptic nonunions (OR 4.787; 95% CI: 1.321-17.351; p = 0.017). Risk factors negatively influencing the outcome of non-union treatment in context with rhBMPs were identified as active smoking (OR 0.357; 95% CI: 0.138-0.927; p = 0.024), atrophic nonunion (OR 0.23; 95% CI: 0.061-0.869; p = 0.030), higher BMI (OR 0.919; 95% CI: 0.846-0.998; p = 0.046) and a larger defect size (OR 0.877; 95% CI: 0.784-0.98; p = 0.021). Discussion: Patients who received rhBMP-2 for the treatment of tibial nonunions and as part of the two-stage treatment had a significantly higher rate of healing compared to patients treated with rhBMP-7 regardless of infection. (C) 2018 Elsevier Masson SAS. All rights reserved.