The scientific basis of vascularized bone grafts: Models and perfusion assessments, a systematic review.

Vascularized bone grafts (VBGs) are assumed to have advantages over non-VBGs, including preservation of cell viability and accelerated osteogenesis. Indications include the reconstruction of large bone defects, poor vascularity and previous radiation. However, clinical evidence supporting their superiority is limited. A return to the basic science of animal and cadaver models seems appropriate. This systematic review focuses on perfusion assessment in studies on VBGs. Only by understanding the vascular anatomy and ensuring bone perfusion is truly maintained in VBGs, can we expect to find differences to non-VBGs in subsequent experiments. A systematic review was performed according to the PRISMA checklist. In February 2025, MEDLINE via PubMed, Embase, and the Cochrane Library databases were systematically searched for studies presenting animal or cadaver anatomical models of VBGs. Exclusion criteria were: language other than English, missing full-text publication, systematic reviews, prefabrication and tissue engineering, anatomical descriptions of bone grafts without perfusion assessments. Inclusion criteria were: original research on VBGs in animals or cadavers assessed by contrast agents, bone graft perfusion models. Out of 520 initially identified publications, 25 studies were included. Disagreements on the eligibility of articles were resolved by discussion with a senior author. Pedicled and free VBGs from various anatomical sites were examined, covering indications, contraindications, benefits, and limitations. Several perfusion assessment techniques were employed, including histology, CT, MRI, technetium-based scintigraphy, near-infrared fluorescence imaging (NIRFI), angiography, radioactive microspheres, and fluorochrome bone labeling (FBL). Histology helps confirm viable osteocytes, while FBL and conventional as well as CT-angiography provide insight into vascular integrity. Meanwhile, scintigraphy and MRI offer indirect perfusion markers but demonstrate high false-positive rates. NIRFI seems accurate intraoperatively but is of limited use postoperatively. Advantages and disadvantages of each method are explored. Reliable perfusion assessment is crucial in research on VBGs and requires a multimodal approach. Future research should standardize models and timing of perfusion assessment while accounting for confounding factors such as spontaneous neoangiogenesis and considering pitfalls of each modality.