Cervical Disc Arthroplasty: Rationale, Designs, and Results of Randomized Controlled Trials.

BACKGROUND: This review outlines clinical data and characteristics of current Food and Drug Administration (FDA)-approved implants in cervical disc replacement/cervical disc arthroplasty (CDR/CDA) to provide a centralized resource for spine surgeons. METHODS: Randomized controlled trials (RCTs) on CDR/CDA were identified using a search of the PubMed, Web of Science, and Google Scholar databases. The initial search identified 69 studies. Duplicates were removed, and the following inclusion criteria were applied when determining eligibility of RCTs for the current review: (1) discussing CDR/CDA prosthesis and (2) published within between 2010 and 2020. Studies without clinical data or that were not RCTs were excluded. All articles were reviewed independently by 2 authors, with the involvement of an arbitrator to facilitate consensus on any discrepancies. RESULTS: A total of 34 studies were included in the final review. Findings were synthesized into a comprehensive table describing key features and clinical results for each FDA-approved CDR/CDA implant and are overall suggestive of expanding indications and increasing utilization. CONCLUSIONS: RCTs have provided substantial evidence to support CDR/CDA for treating single- and 2-level cervical degenerative disc disease in place of conventional anterior cervical discectomy and fusion. CLINICAL RELEVANCE: This review provides a resource that consolidates relevant clinical data for current FDA-approved implants to help spine surgeons make an informed decision during preoperative planning.

The influence of modifiable risk factors on short-term postoperative outcomes following cervical spine surgery: A retrospective propensity score matched analysis.

BACKGROUND: Modifiable risk factors (MRFs) represent patient variables associated with increased complication rates that may be prevented. There exists a paucity of studies that comprehensively analyze MRF subgroups and their independent association with postoperative complications in patients undergoing cervical spine surgery. Therefore, the purpose of this study is to compare outcomes between patients receiving cervical spine surgery with reported MRFs. METHODS: Retrospective analysis of the Nationwide Readmissions Database (NRD) from the years 2016 and 2017, a publicly available and purchasable data source, to include adult patients undergoing cervical fusion. MRF cohorts were separated into three categories: substance abuse (alcohol, tobacco/nicotine, opioid abuse); vascular disease (hypertension, dyslipidemia); and dietary factors (malnutrition, obesity). Three-way nearest-neighbor propensity score matching for demographics, hospital, and surgical characteristics was implemented. FINDINGS: We identified 9601 with dietary MRFs (D-MRF), 9654 with substance abuse MRFs (SA-MRF), and 9503 with vascular MRFs (V-MRF). Those with d-MRFs had significantly higher rates of medical complications (9.3%), surgical complications (8.1%), and higher adjusted hospital costs compared to patients with SA-MRFs and V-MRFs. Patients with d-MRFs (16.3%) and V-MRFs (14.0%) were independently non-routinely discharged at a significantly higher rate compared to patients with SA-MRFs (12.6%) (p<0.0001 and p = 0.0037). However, those with substance abuse had the highest readmission rate and were more commonly readmitted for delayed procedure-related infections. INTERPRETATION: A large proportion of patients who receive cervical spine surgery have potential MRFs that uniquely influence their postoperative outcomes. A thorough understanding of patient-specific MRF subgroups allows for improved preoperative risk stratification, tailored patient counseling, and postoperative management planning. FUNDING: None.

Regional gene therapy for bone healing using a 3D printed scaffold in a rat femoral defect model.

At the present time there are no consistently satisfactory treatment options for some challenging bone loss scenarios. We have previously reported on the properties of a novel 3D-printed hydroxyapatite-composite material in a pilot study, which demonstrated osteoconductive properties but was not tested in a rigorous, clinically relevant model. We therefore utilized a rat critical-sized femoral defect model with a scaffold designed to match the dimensions of the bone defect. The scaffolds were implanted in the bone defect after being loaded with cultured rat bone marrow cells (rBMC) transduced with a lentiviral vector carrying the cDNA for BMP-2. This experimental group was compared against 3 negative and positive control groups. The experimental group and positive control group loaded with rhBMP-2 demonstrated statistically equivalent radiographic and histologic healing of the defect site (p > 0.9), and significantly superior to all three negative control groups (p < 0.01). However, the healed defects remained biomechanically inferior to the unoperated, contralateral femurs (p < 0.01). When combined with osteoinductive signals, the scaffolds facilitate new bone formation in the defect. However, the scaffold alone was not sufficient to promote adequate healing, suggesting that it is not substantially osteoinductive as currently structured. The combination of gene therapy with 3D-printed scaffolds is quite promising, but additional work is required to optimize scaffold geometry, cell dosage and delivery.

Evaluating the Standardized Letter of Recommendation Form in Applicants to Orthopaedic Surgery Residency.

INTRODUCTION: A standardized letter of recommendation (SLOR) form for orthopaedic surgery residency programs has recently been adopted for use, but it has not been scientifically evaluated. The purpose of this study is to investigate the usefulness of the SLOR form in the selection process. METHODS: All SLOR forms submitted to our institution over a single application cycle were extracted and analyzed. The United States Medical Licensing Examination Step 1 scores, grades in clinical rotations, Alpha Omega Alpha status, and the number of publications were recorded for each applicant. Correlations were calculated with Spearman rho, and inter-rater reliability was evaluated by calculating intraclass correlation coefficients. RESULTS: One thousand one hundred thirty-seven SLOR forms were analyzed for 513 applicants. There was substantial rank inflation with the SLOR form; the majority (92%) of applicants were rated as either ranked to match or in the top one-third of their rank list. Objective applicant factors such as grades and Step 1 scores demonstrated a very weak to nonexistent correlation with the summative rank (rho 0.07 to 0.13, P ≤ 0.012). Poor inter-rater reliability was observed with the intraclass correlation coefficient ranging from 0.22 to 0.33 (P < 0.001). CONCLUSIONS: The usefulness of the SLOR form is limited by the very high ratings observed for all questions, and in particular, the final summative rank. Measures to reduce rank inflation must be implemented to improve the discriminant ability of the SLOR form, and if this cannot be accomplished, perhaps the form should be abandoned. LEVEL OF EVIDENCE: Level III Retrospective.