Vascularized Bone Grafting for Reconstruction of Oncologic Defects in the Spine: A Systematic Review and Pooled Analysis of the Literature
Rachel Pedreira, BA1, Charlampos Siotos, MD2, Brian H. Cho, MD2, Stella Seal, MLS2, Hannah M. Carl, BS1, Michelle Seu, BA2, Justin M. Sacks, MD, MBA2.
1Johns Hopkins School of Medicine, Baltimore, MD, USA, 2Johns Hopkins Department of Plastic and Reconstructive Surgery, Baltimore, MD, USA.
PURPOSE: Resection of primary spinal tumors inevitably requires reconstruction of the resultant defect for restoration of spinal column stability. Traditionally, some combination of bone grafting and instrumentation is implemented. However, delayed healing environments are associated with complications including pseudoarthrodesis and failure with use of these modalities. Implementation of vascularized bone grafting (VBG) in lieu of avascular grafts to complement hardware may present a solution to this dilemma. In order to assess the efficacy of and indications for VBG in oncologic spinal reconstruction, we performed a systematic review and pooled analysis of relevant literature.
METHODS: We searched PubMed/MEDLINE, Embase, Cochrane, and Scopus databases for relevant studies published through September 2017, according to PRISMA guidelines. (Figure 1). We performed a pooled analysis of studies with n > 5, to estimate the percentage of overall complications, wound complications, fusion, and reoperation rates using RevMan software.
RESULTS: We identified 21 eligible studies and ultimately executed a pooled analysis of 12. Our analysis indicates an 89% rate of successful union (95% CI: 0.75-1.03) when VBG is employed in spinal reconstruction after primary tumor resection (Figure 2). The associated overall compilation rate was 42% (95% CI: 0.23, 0.61) and reoperation rate was 27% (95% CI: 0.12, 0.41) in the pooled cohort (Figure 3). According to our review only 15 out of a total 209 patients (7.2%) had instrumentation failure and mean time to union was 5.975 months. Overall, consensus in the literature is that introduction of vascularized bone into previously irradiated or infected tissue beds proves advantageous given decreased bone resorption, increased capacity for load bearing, and faster consolidation as compared to other methods. Reported downsides to this technique included longer operative times, potential donor site morbidity, and difficulty in coordinating care to ensure access to a microsurgeon.
CONCLUSION: Our results demonstrate that overall complication rates after use of VBG is not wildly different from those reported in studies using non-VBG for similar spinal reconstructions, however fusion rates are better. In particular 89% fusion is demonstrated in our analysis versus rates ranging from 37-49% in studies using non-VBG. Given these rapid fusion rates and even the possibility of hardware independence, VBG may be particularly useful in reconstructing large defects in patients with longer life expectancies and therefore higher anticipated strain on constructs. This technique is also worth consideration for patients with a history of chemoradiation and/or infection at the site of tumor resection. Our experience supports use of VBG for creating strong, stable spinal constructs, particularly in said higher risk patients.
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