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Background: Insufficient data exist on bone graft substitute materials efficacy; two thirds lack any clinical data. 1,2 This prospective animal study identified efficacy differences among commercially available materials of several classes. Methods: Historically validated muscle pouch osteoinduction study (OIS) and posterolateral fusion (PLF) were performed in an athymic rat model. Grafting material products implanted were demineralized bone matrix (DBM)based allografts (Accell EVO3, DBX Mix, DBX Strip, Grafton Crunch, Grafton Flex, Grafton Matrix, Grafton Putty, Magnifuse, and Progenix Plus), allografts (OsteoSponge, MinerOss), cellular allograft (Osteocel Plus), ceramics (Mozaik Strip), or activated ceramics (Actifuse ABX Putty, Vitoss BA). After 4 weeks, OIS specimens were evaluated ex vivo by histologic osteoinductivity. After 8 weeks, PLF ex vivo specimens were evaluated for fusion by manual palpation (F MP), radiography (F XR), and histology (F HISTO). Results: OIS: No materials exhibited a rejection reaction on histology. All DBM-based materials exhibited osteoinductive potential as new bone formation at. 88% of implanted sites. One plain allograft (OsteoSponge) formed bone at 25% of sites. No bone formed for one ceramic (Mozaik Strip), three activated ceramics (Actifuse ABX Putty), or one cellular allograft, regardless of human bone marrow aspirate (hBMA) when added. PLF: Among the 10 DBMs, 6 had F MP of 100% (Accell EVO3, DBX Mix, DBX Strip, Grafton Flex, Grafton Putty, Magnifuse), 2 had F MP of 94% (Grafton Crunch, Grafton Matrix), and 2 conditions had F MP of 0% (Progenix Plus, Progenix Plus þ athymic rat iliac crest bone graft [arICBG]). Ceramics (Mozaik Strip), activated ceramics (Actifuse ABX Putty, Vitoss BA), plain allograft (OsteoSponge, MinerOss (PLF study), and cellular allograft (Osteocel Plus) demonstrated 0% F MP. ArICBG demonstrated 13% F MP. Conclusions: Eight DBM-based materials (Accell EVO3, DBX Mix, DBX Strip, Grafton Crunch, Grafton Flex, Grafton Matrix, Grafton Putty, Magnifuse) demonstrated excellent (. 90% F MP) efficacy in promoting fusion via bone healing. Two DBM conditions (Progenix Plus, Progenix Plus þ arICBG) showed no manual palpation fusion (F MP). Systematically, over the 2 studies (OIS and PLF), cellular (Osteocel Plus), plain allografts (OsteoSponge, MinerOss; PLF study), ceramic (Mozaik Strip), and activated ceramics (Actifuse ABX Putty, Vitoss BA) demonstrated poor F MP efficacy (, 10%). Clinical Relevance: When selecting DBMs, clinicians must be cognizant of variability in DBM efficacy by product and lot. While theoretically osteoinductive, cellular allograft and activated ceramics yielded poor in vivo efficacy. Whole allograft and ceramics may provide osteoconductive scaffolding for mixed-material grafting; however, surgeons should be cautious in using them alone. Direct clinical data are needed to establish efficacy for any bone graft substitute.

OBJECTIVE The aim of this study was to identify and discuss operative nuances utilizing image guidance in the surgical management of aggressive sacral tumors. METHODS The authors report on their single-institution, multi-surgeon, retrospective case series involving patients with pathology-proven aggressive sacral tumors treated between 2009 and 2016. They also reviewed the literature to identify articles related to aggressive sacral tumors, their diagnosis, and their surgical treatment and discuss the results together with their own experience. Information, including background, imaging, treatment, and surgical pearls, is organized by tumor type. RESULTS Review of the institutional records identified 6 patients with sacral tumors who underwent surgery between 2009 and 2016. All 6 patients were treated with image-guided surgery using cone-beam CT technology (O-arm). The surgical technique used is described in detail, and 2 illustrative cases are presented. From the literature, the authors compiled information about chordomas, chondrosarcomas, giant cell tumors, and osteosarcomas and organized it by tumor type, providing a detailed discussion of background, imaging, and treatment as well as surgical pearls for each tumor type. CONCLUSIONS Aggressive sacral tumors can be an extremely difficult challenge for both the patient and the treating physician. The selected surgical intervention varies depending on the type of tumor, size, and location. Surgery can have profound risks including neural compression, lumbopelvic instability, and suboptimal oncological resection. Focusing on the operative nuances for each type can help prevent many of these complications. Anecdotal evidence is provided that utilization of image-guided surgery to aid in tumor resection at our institution has helped reduce blood loss and the local recurrence rate while preserving function in both malignant and aggressive benign tumors affecting the sacrum.

Vitamin D plays a significant role in musculoskeletal health by regulating calcium, phosphate, and promoting new bone mineralization. The purpose of this study was to understand the effect of dietary vitamin D on general bone health during peri-operative bone healing via an in vivo dosing study of vitamin D in a rat posterolateral fusion model using autograft. Vitamin D Deficient (DD), vitamin D Insufficient (ID), Control vitamin D (CD), and Hyper-vitamin D (HD) groups were studied. Increasing dietary vitamin D improved quantitative measures of femoral geometry, including femoral strength, stiffness, and density. Femoral biomechanics, cortical thickness, moment of inertia, cross-sectional area, and measures from bone ashing were all greater in the HD group versus the CD. This suggests that additional dietary vitamin D above normal levels during spinal fusion may lead to improvement in bone health. Serum vitamin D levels were also observed to decrease during fusion healing. These results demonstrate that dietary vitamin D improves general bone health in the femur of a rat model during posterolateral spinal fusion. This suggests a role for further clinical evaluation of vitamin D dietary intake during the peri-operative period, with the possibility of avoiding adverse consequences to general bone health. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1435-1443, 2018.

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