New Concepts in Bone Regeneration

There continue to be extensive investigation of new methods for enhancing bone regeneration, motivated primarily by the goal to treat bone loss, critical sized defects, and non-unions in human beings. Such approaches typically include novel biological methods of augmenting bone union, the use of biocompatible materials, or the combination of both biological treatments with biodegradable scaffolds. Thus far such approaches are not commonly employed even in humans and likewise their clinical application in veterinary patients is also uncommon. However, further study and development of such methods does included investigation in animals and ultimately some of these therapies may prove beneficial as well as realistic for use in clinical veterinary medicine.

In terms of biologics for enhancing bone healing, increasing attention is being given to use of ‘common’ biologics such as platelet-rich plasma (PRP), bone marrow aspirate, and ‘stem cell’ therapy. PRP has been consistently shown to provide anabolic growth factors such as transforming growth factor (TGF)-β, vascular endothelial growth factor, and platelet-derived growth factors, all of which can potentially stimulate cellular proliferation. Accordingly, numerous studies have evaluated PRP and its effect on bone healing in animal models of fracture/osteotomy and in people. Some data from animal models provide support for the benefits of PRP in augmenting osseous union and some authors conclude there is sufficient evidence to demonstrate proof of principle. However, other authors conclude that the evidence remains ambiguous as numerous studies, particularly when considering clinical trials in people, fail to provide consistent or convincing evidence of benefit. There are only 2 studies in dogs that the author has been able to acquire and review; one showed a significant benefit of PRP but the other did not. Consequently, the author recently concluded a prospective comparison of PRP for augmenting bone healing using dogs treated with TPLO. Sixty dogs completed the study, 33 having TPLO without PRP and 27 having activated PRP placed in the osteotomy at the time of surgery. All dogs had radiographic and ultrasonographic examinations at 4, 7, and 10 weeks and an MRI at 4 weeks to assess bone healing. There was no significant benefit of PRP on bone healing with any of the associated outcome measures. [...]