Artikel
Investigation of screw osseointegration enhancement by extracellular vesicles (EV) and bone morphogenetic protein 2 (BMP-2) in a rat animal model – a novel study design
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Veröffentlicht: | 25. Oktober 2022 |
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Gliederung
Text
Objectives: Particularly in osteoporotic bone, loosening of osteosynthesis material is a well-known problem in clinical practice. This leads to secondary fracture dislocation and non-healing. The aim of this study is to improve the stability of screws inserted into bone by adding Extracellular Vesicles (EVs) or Bone-Morphogenetic-Protein-2 (BMP-2) with alginate (Alg) as a carrier material.
Methods: Operations were performed on 30 rats (Sprague Dawley). These were divided into 3 groups of equal size: Alg only, Alg EV, and Alg BMP-2. To analyze the osseointegration, a novel surgical procedure and biomechanical protocol were established. Here, a diaphyseal fracture was created with a Gigli saw (0.66 mm) and angular stable 5-hole plate osteosynthesis was placed with four 1.5 mm screws. The 4.0mm long proximal and distal screws were placed monocortically in a 2.0mm hole that was too wide, so the screw had no contact area with the surrounding bone. The hole was filled with the substances mentioned above. The 2 screws next to the osteotomy were placed bicortically to stabilize the fracture. After the endpoint was reached 6 weeks postoperatively, µ-CT, and a biomechanics pull-out test and a stiffness analysis were performed.
Results and conclusion: The novel study design and the examinations were well feasible. The µ-CT scan shows significantly more Bone Volume/Tissue Volume in the BMP-2 treated group compared to the EV treated one (*p= 0.0203). The screw-bone contact area was also significantly increased in the BMP-2 treated group compared to the EV treated (**p= 0.0063) group, the contact area was significantly increased in the Alg only group compared to the Alg EV group (*p= 0.0438), too. The biomechanical pull-out test showed a significant increase of the maximal force of the BMP-2 treated group compared to the EV treated one (*p= 0.0240). The stiffness of the BMP-2 treated group was significantly higher compared to the Alg EV group (*p= 0.0414) and the Alg only group (*p= 0.0363).
Figure 1 [Fig. 1]
The results of the µ-CT scans and the biomechanics studies indicate that the use of BMP-2 can improve the osseointegration of osteosynthesis materials. The use of EVs seems to have a rather negative effect on osseointegration in this animal model.