Bird, Justin E.

Abstract Oxygen deprivation within large or poorly vascularized bone defects remains a key barrier to successful regeneration, especially during the early postimplantation period before vascular ingrowth. Here, the development of COSnPPOD (CaO 2 –Silica NP Platform for Osteogenic Development) is reported, a visible light digital light processing‐printed hydrogel scaffold that integrates oxygen‐releasing nanoparticles (NPs) within a Primitive‐type triply periodic minimal surface architecture. The scaffold combines a gelatin methacrylate‐poly(ethylene glycol) diacrylate matrix with calcium peroxide (CaO 2 )‐loaded hollow silica NPs, enabling localized, short‐term oxygen release while preserving structural fidelity. COSnPPOD scaffolds demonstrate favorable degradation kinetics, tunable stiffness, and increased protein adsorption in vitro. In a preosteoblast model, COSnPPOD maintains cell viability and supports osteogenic gene expression without cytotoxic effects. While overall gene expression is comparable to controls, a 16‐fold increased expression of phosphoprotein 1 (Spp1) suggests scaffold‐driven activation of matrix remodeling pathways. In vivo, COSnPPOD scaffolds enhance bone regeneration in a murine calvarial defect model, with significantly greater bone formation and collagen deposition than untreated defects and hydrogel controls. Additionally, vascular endothelial growth factor immunostaining is increased within the defect, consistent with a proangiogenic response, and no systemic toxicity is observed. These findings establish COSnPPOD as a promising scaffold system that combines sustained oxygenation with biomimetic geometry to support localized bone regeneration.

Study Design Survey study. Objectives The purpose of this study was to characterize the utility of 3D printed patient specific anatomic models for the planning of complex primary spine tumor surgeries. Methods A survey of individual members of an international study group of spinal oncology surgeons was performed. Participants were provided a clinical vignette, pathologic diagnosis, and pre-operative imaging for three primary spinal oncology cases. Study participants provided a free text surgical plan for resection and were then presented an associated 3D printed model for each case and asked to re-evaluate their surgical plan. Results Ten spinal oncology surgeons participated in the study, representing nine institutions across five countries. Four of the surgeons (40%) made significant changes to their surgical plan after reviewing the 3D models, including sacrifice of an additional nerve root to obtain negative margins, sparing an SI joint that was originally planned for inclusion in the en bloc resection, adjusting the location of osteotomy cuts, changes to the number of surgical stages and/or staging order, and preservation of neurology that was originally planned for sacrifice. The overall impression of the 3D models was positive, with 90% of the participants stating they found the 3D model useful in developing a surgical plan. Conclusions Surgical planning for resection of primary spinal column tumors is challenging and time intensive. 3D printed patient specific surgical models may be an additional tool that can augment surgical planning and execution by improving the chance of accomplishing surgical resection goals and minimizing morbidity.

OBJECTIVE The purpose of this study was to analyze risk factors for sacral fracture following noninstrumented partial sacral amputation for en bloc chordoma resection. METHODS A multicenter retrospective chart review identified patients who underwent noninstrumented partial sacral amputation for en bloc chordoma resection with pre- and postoperative imaging. Hounsfield units (HU) were measured in the S1 level. Sacral amputation level nomenclature was based on the highest sacral level with bone removed (e.g., S1 foramen amputation at the S1–2 vestigial disc is an S2 sacral amputation). Variables collected included basic demographics, patient comorbidities, surgical approach, preoperative radiographic details, neoadjuvant and adjuvant radiation therapy, and postoperative sacral fracture data. RESULTS A total of 101 patients (60 men, 41 women) were included; they had an average age of 69 years, BMI of 29 kg/m2, and follow-up of 60 months. The sacral amputation level was S1 (2%), S2 (37%), S3 (44%), S4 (9%), and S5 (9%). Patients had a posterior-only approach (77%) or a combined anterior–posterior approach (23%), with 10 patients (10%) having partial sacroiliac (SI) joint resection. Twenty-seven patients (27%) suffered a postoperative sacral fracture, all occurring between 1 and 7 months after the index surgery. Multivariable logistic regression analysis demonstrated S1 or S2 sacral amputation level (p = 0.001), combined anterior–posterior approach (p = 0.0064), and low superior S1 HU (p = 0.027) to be independent predictors of sacral fracture. The fracture rate for patients with superior S1 HU < 225, 225–300, and > 300 was 38%, 15%, and 9%, respectively. An optimal superior S1 HU cutoff of 300 was found to maximize sensitivity (89%) and specificity (42%) in predicting postamputation sacral fracture. In addition, the fracture rate for patients who underwent partial SI joint resection was 100%. CONCLUSIONS Patients with S1 or S2 partial sacral amputations, a combined anterior–posterior surgical approach, low superior S1 HU, and partial SI joint resection are at higher risk for postoperative sacral fracture following en bloc chordoma resection and should be considered for spinopelvic instrumentation at the index procedure.