Peripheral nerve damage that results in lost segments requires surgery, but currently available hollow scaffolds have limitations that could be overcome by adding internal guidance support. A novel solution is to use filaments of absorbable metals to supply physical support and guidance for nerve regeneration that then safely disappear from the body. Previously, we showed that thin filaments of magnesium metal (Mg) would support nerve regeneration. Here, we tested another absorbable metal, zinc (Zn), using a proprietary zinc alloy with 2% iron (Zn-2%Fe) that was designed to overcome the limitations of both Mg and pure Zn metal. Non-critical-sized gaps in adult rat sciatic nerves were repaired with silicone conduits plus single filaments of Zn-2%Fe, Mg, or no metal, with autografts as controls. After seventeen weeks, all groups showed equal recovery of function and axonal density at the distal end of the conduit. The Zn alloy group showed some improvements in early rat health and recovery of function. The alloy had a greater local accumulation of degradation products and inflammatory cells than Mg; however, both metals had an equally thin capsule (no difference in tissue irritation) and no toxicity or inflammation in neighboring nerve tissues. Therefore, Zn-2%Fe, like Mg, is biocompatible and has great potential for use in nervous tissue regeneration and repair.

In vivo use of biodegradable magnesium (Mg) metal can be plagued by too rapid a degradation rate that removes metal support before physiological function is repaired. To advance the use of Mg biomedical implants, the degradation rate may need to be adjusted. We previously demonstrated that pure Mg filaments used in a nerve repair scaffold were compatible with regenerating peripheral nerve tissues, reduced inflammation, and improved axonal numbers across a short—but not long—gap in sciatic nerves in rats. To determine if the repair of longer gaps would be improved by a slower Mg degradation rate, we tested, in vitro and in vivo, the effects of Mg filament polishing followed by anodization using plasma electrolytic oxidation (PEO) with non-toxic electrolytes. Polishing removed oxidation products from the surface of as-received (unpolished) filaments, exposed more Mg on the surface, produced a smoother surface, slowed in vitro Mg degradation over four weeks after immersion in a physiological solution, and improved attachment of cultured epithelial cells. In vivo, treated Mg filaments were used to repair longer (15 mm) injury gaps in adult rat sciatic nerves after placement inside hollow poly (caprolactone) nerve conduits. The addition of single Mg or control titanium filaments was compared to empty conduits (negative control) and isografts (nerves from donor rats, positive control). After six weeks in vivo, live animal imaging with micro computed tomography (micro-CT) showed that Mg metal degradation rates were slowed by polishing vs. as-received Mg, but not by anodization, which introduced greater variability. After 14 weeks in vivo, functional return was seen only with isograft controls. However, within Mg filament groups, the amount of axonal growth across the injury site was improved with slower Mg degradation rates. Thus, anodization slowed degradation in vitro but not in vivo, and degradation rates do affect nerve regeneration.

Background: Correction of adult spinal deformity (ASD) using the Roussouly classification, SRS-Schwab classification, or the global alignment and proportion (GAP) score is associated with reduced mechanical complications. However, the benefit of combining these frameworks is unclear. Methods: This study included ASD patients undergoing corrective surgery (2018–2023). Patients were classified as Roussouly “Match” or “Mismatch” based on concordance with their theoretical type, and well-aligned subgroups were defined as sagittal vertical axis ≤5 cm, pelvic incidence–lumbar lordosis ≤10°, or a GAP score ≤6. The primary outcome assessed was mechanical complications. Results: Among 174 patients, overall Roussouly classification-matched patients showed no significant differences in mechanical complications compared to mismatched patients. In addition, no significant differences were found between matched and mismatched patients within each subgroup. These findings persisted after adjustment for demographic and comorbidity factors. Conclusion: In ASD patients already well-aligned by established sagittal parameters, Roussouly matching does not provide additional reduction in mechanical complications. Therefore, surgical planning could prioritize key sagittal alignment targets, while future studies should evaluate whether additional alignment strategies improve broader patient outcomes.

Background: Factors influencing opioid prescribing include provider type, clinical experience, regional patterns, and institutional affiliation. This study compared the rates of chronic opioid prescriptions being given to older adults undergoing long-segment posterior lumbar fusions in academic versus nonacademic centers. Methods: Out of 20,719 patients aged ≥65 years who underwent posterior lumbar instrumentation involving 3–12 thoracolumbar levels (2010–2022), we created two matched groups that included 3,904 patients each. Patients were stratified according to whether they were treated in academic versus nonacademic centers. Matching included the utilization of 1:1 demographic and clinical factors and analyzed for opioid prescribing patterns at 3–6, 6–12, and 12–24 months postoperatively. Results: We found that patients operated on in nonacademic centers showed significantly lower odds of receiving codeine-based opioids at 3–6 and 6–12 months postoperatively. Conversely, at 12–24 postoperative months, these patients had increased odds of receiving noncodeine-based, strong, and moderate opioids versus academic center patients. Conclusion: For two cohorts of 3904 adults over 65 years of age undergoing 3–12 level thoracolumbar instrumented fusions, academic centers prescribed more opioids initially postoperatively, while nonacademic centers demonstrated higher long-term usage.

Background: Despite the high volume of posterior cervical fusions performed annually, the impact of academic versus non-academic hospital status on postoperative complications and readmissions requires clarification. Methods: A retrospective analysis was conducted to identify patients who underwent posterior cervical instrumentation from 2010 to 2022. Patients were grouped by academic or non-academic treatment setting. Propensity score matching controlled for age, gender, race, and comorbidities. Outcomes assessed included surgical and medical complications at 30 and 90 days, pseudoarthrosis or mechanical failure at 1–2 years, and readmission rates. Results: After matching, 4,344 patients per cohort demonstrated no significant differences in surgical complications or medical complications at 30 days and 90 days. Similarly, no significant difference was found in pseudoarthrosis or mechanical failure rates at 1–2 years postoperatively. However, non-academic centers had significantly higher readmission odds at 30 (Odds ratio [OR] = 2.325) and 90 days (OR = 2.232). Conclusion: Patients undergoing posterior cervical instrumentation at non-academic centers experience similar surgical, medical, and mechanical complication rates compared to academic centers. However, significantly higher readmission rates for non-academic centers may indicate significant variations in postoperative care.