Axially vascularised mandibular constructs: Is it time for a clinical trial?

Applying regenerative therapies in the field of cranio-maxillofacial reconstruction has now become a daily practice. However, regeneration of challenging or irradiated bone defects following head and neck cancer is still far beyond clinical application. As the key factor for sound regeneration is the development of an adequate vascular supply for the construct, the current modalities using extrinsic vascularization are incapable of regenerating such complex defects. Our group has recently introduced the intrinsic axial vascularization technique to regenerate mandibular defects using the arteriovenous loop (AVL). The technique has shown promising results in terms of efficient vascularization and bone regeneration at the preclinical level. In this article, we have conducted a narrative literature review about using the AVL to vascularize tissue-engineering constructs at the preclinical level. We have also conducted a systematic literature review about applying the technique of axial vascularization in the field of craniofacial regeneration. The versatility of the technique and the possible challenges are discussed, and a suggested protocol for the first clinical trial applying the AVL technique for mandibular reconstruction is also presented.

Enhancing mandibular bone regeneration and perfusion via axial vascularization of scaffolds.

OBJECTIVE: Reconstruction of large and complex bone segments is a challenging problem facing maxillofacial surgery. The majority of current regenerative approaches rely on extrinsic vascularization, which is deficient after cancer ablation and irradiation. The aim of the study was to investigate the efficacy of intrinsic axial vascularization of synthetic bone scaffolds in the management of critical-size mandibular defects. MATERIALS AND METHODS: Scaffold-guided mandibular regeneration in two groups of adult male goats was compared. Only the scaffolds of the second group were axially vascularized via in situ embedding of an arteriovenous loop through microsurgical anastomosis of facial vessels. After 6 months of follow up, both groups were compared through radiological, biomechanical, histological and histomorphometric analysis. RESULTS: The axially vascularized constructs have showed significantly more central vascularization (p = 0.021) and markedly enhanced central bone formation (p = 0.08). The biomechanical characteristics were enhanced, but the difference between both groups was not statistically significant (p = 0.98). CONCLUSIONS: Axially vascularized synthetic mandibular grafts show better vascularization at their central regions, permitting more efficient bone regeneration. CLINICAL RELEVANCE: The encouraging results of the proposed technique could be of benefit in optimizing the reconstruction of large critical-size bone defects.