Interventions to minimize blood loss and transfusion risk in spine surgery: A narrative review.

Blood loss is an inevitable reality of spine surgery. Excessive loss is associated with increased morbidity and mortality and is frequently combated with allogeneic blood transfusions. Transfusions themselves are associated with increased morbidity, including circulatory overload, lung injury, and acute kidney injury. It is therefore incumbent upon the practicing spine surgeon to be aware of evidence-based interventions capable of reducing blood loss and the risk of transfusion. Here we review the available literature and make recommendation based upon the available evidence.

Radiographic and clinical outcomes of silicate-substituted calcium phosphate (SiCaP) bone grafts in spinal fusion: Systematic review and meta-analysis.

Pseudarthrosis continues to affect a nontrivial proportion of spine fusion patients. Given its ties to poorer patient outcomes and high reoperation rates, there remains great interest in interventions aimed at reducing the rates of nonunion. Recently, silicate-substituted calcium phosphate (SiCaP) bone grafts have been suggested to improve fusion rates, yet there exists no systematic review of the body of evidence for SiCaP grafts. Here, we present the first such review along with a meta-analysis of the effect of SiCaP bone grafts on fusion rates. Using the PubMed, Embase, and Web of Science databases, we queried the English-language literature for all studies examining the effect of SiCaPs on spinal fusion. Primary endpoints were: 1) radiographic fusion rate at last follow-up and 2) postoperative improvements in Visual Analog Scale (VAS) pain scores and Oswestry Disability Index (ODI) at last follow-up. Meta-analyses were performed for each endpoint using random effects. Ten articles (694 patients treated with SiCaP bone grafts) were included. Among SiCaP-treated patients, 93% achieved radiographic fusion (range: 79-100%), with comparable rates across subgroups. Meta-analysis of the three randomized controlled trials demonstrated no difference in fusion rates between SiCaP-treated patients and patients receiving grafts with recombinant human bone morphogenetic protein-2 (rhBMP-2) (OR: 1.11; p = 0.83). Patients treated with SiCaP bone grafts experienced significant improvements in VAS back pain (-3.3 points), VAS leg pain (-4.8 points), and ODI (-31.6 points) by last follow-up (p < 0.001 for each). Additional high-quality research is needed to evaluate the relative cost-effectiveness of SiCaP bone grafts in spinal fusion.

A retrospective cohort analysis of the effects of renin-angiotensin system inhibitors on spinal fusion in ACDF patients.

BACKGROUND CONTEXT: Recently, preclinical and clinical studies suggest an association between renin-angiotensin system (RAS) blockers and bone healing, particularly in the context of osteoporotic bone fractures. PURPOSE: To determine the correlation between the use of RAS inhibitors and fusion outcomes and neurologic status in anterior cervical discectomy and fusion (ACDF) surgery. STUDY DESIGN: Retrospective observational study. PATIENT SAMPLE: Patients who underwent ACDF for degenerative disorders. OUTCOME MEASURES: Spinal fusion status and neurologic function (modified Japanese Orthopedic Association [mJOA] and Nurick grading scales). METHODS: A retrospective chart review was performed, including 200 patients who underwent ACDF for degenerative disorders with 1-year minimum follow-up. Demographic data, comorbidities, antihypertensive medication, neurologic examination, and fusion status were collected. Spinal fusion was assessed via plain cervical x-ray, resorting to dynamic radiographs and/or computer tomography (CT) in cases of uncertainty. Preoperative mJOA and Nurick scores and recovery rates were calculated to determine neurologic status. RESULTS: Of the 200 patients (42.5% females, 57.5% males, median age of 53.7 years), 82 hypertensive patients were identified. Seventy-seven (93.9%) were taking antihypertensive medication as follows: 36.4% angiotensin-II receptor blockers (ARBs), 35.1% angiotensin-converting enzyme inhibitors (ACEIs), and the remaining patients were taking other medication. In the analysis of fusion rates, patients treated with ARBs exhibited a higher fusion rate, while those treated with ACEIs displayed a lower fusion rate compared to untreated nonhypertensive patients (p = .04 and .02, respectively). The difference in fusion rates between ARBs and ACEIs was also significant, with the former displaying higher rates (p < .001). Smoking exhibited a negative correlation with spinal fusion (p < .001). In the multivariate analysis, ARBs remained an independent factor for successful fusion (p = .02), while smoking remained a risk factor for failed fusion (p = .002). In the neurologic examination, ACEIs, hypertension status, and older age correlated with lower modified Japanese Orthopedic Association (mJOA) recovery rates (p = .001, <.001, and <.001, respectively) in the univariate analysis. CONCLUSIONS: In ACDF patients, we observed that ARBs were associated with higher fusion rates. Conversely, ACEIs and smoking were related to failed fusion. Prospective case-control studies are needed to confirm these RAS inhibitors effects on spinal fusion.