Journal of Orthopaedic Surgery and Research (Apr 2019)

Radiographic and histologic effects of bone morphogenetic protein-2/hydroxyapatite within bioabsorbable magnesium screws in a rabbit model

  • Le Hoang Nam Dang,
  • Yu Kyoung Kim,
  • Seo Young Kim,
  • Kuk Jin Lim,
  • Ken Bode,
  • Min Ho Lee,
  • Kwang Bok Lee

DOI
https://doi.org/10.1186/s13018-019-1143-8
Journal volume & issue
Vol. 14, no. 1
pp. 1 – 10

Abstract

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Abstract Background Hydrogen gas formed by magnesium (Mg) screw corrosion can accumulate around the implant and create bone cysts, long-term osteolysis lesions, and bone healing delay. Thus, several authors currently do not recommend Mg implants for clinical use. In contrast, bone morphogenetic proteins (BMP)-2 have a very strong osteoinductive activity. The purpose of this study was to evaluate the effect of rhBMP-2/hydroxyapatite (HA) inside specially designed Mg cannulated screws in a rabbit femur model for hydrogen gas formation avoidance. Methods Fifteen rabbits underwent randomly different cannulated Mg screw implantation in both distal femora; 30 femora were divided into three groups depending on the materials fill in the cannulated Mg screw: control group (Mg screw with no treatment), HA group (Mg screw with HA), and BMP-2/HA group (Mg screw with a composite BMP-2/HA). Plain radiography, micro-CT, and histological analysis were accomplished, and the ability to release BMP-2 of the screws was evaluated by immersion of both the screw with no treatment and screw with a composite BMP-2/HA into the SBF for up to 7 days. Results X-ray assessment found the gas shadow around the implant was slightly smaller in the BMP-2/HA group than the HA and control groups at 8 weeks. Micro-CT analysis demonstrated statistically significant higher new bone formation in the BMP-2/HA group than the other groups, respectively, which also correlated with a decreased gas volume. Histological analysis showed higher osteointegration between implants and host femurs in the BMP-2/HA group than the HA and control groups at 12 weeks. Conclusions This study indicates that the combination of BMP-2/HA within Mg screws enhances new bone formation and therefore has the potential to decrease the complications of hydrogen gas formation around these implants.

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