Bernatz, James T.

Study Design Retrospective Cohort Study. Objectives To determine if 3D printed porous titanium (Ti) cages compared to non-porous polyetheretherketone (PEEK) cages predicted improved fusion rate or clinical outcomes after transforaminal lumbar interbody fusion (TLIF). Methods All adult patients who underwent one- and two-level TLIF for degenerative conditions by a single surgeon at an academic center between 2017-2021 were retrospectively identified. Patients were dichotomized into porous Ti and non-porous PEEK interbody cage groups. Fusion status was assessed by at 6-months and 1-year postoperatively by CT Bridwell scale and flexion/extension X-Rays. Postoperative complications (CT-based subsidence, adjacent segment disease, reoperation rates) and interval changes in lumbar radiographic alignment at short- and long-term follow-up were determined. Univariate and multivariate analysis compared patient and surgical factors, fusion rates, alignment, and complications across interbody groups. Results A total of 136 patients with 169 unique fusion levels (125 Ti cages, 44 PEEK cages) met the inclusion/exclusion criteria. Ti relative to PEEK interbodies had significantly decreased surface area and increased height and lordosis. Ti cage use was associated with greater subsidence ( P < 0.001) but did not independently predict maximum subsidence on regression ( P = 0.109). In the overall cohort, there were no significant differences in fusion rates or lumbopelvic alignment between interbody groups. Reoperation (Ti: 10.9% vs PEEK: 28.6%, P = 0.026) and reoperation for pseudoarthrosis (Ti: 2.0% vs PEEK: 11.4%, P = 0.038) was significantly more likely in the PEEK relative to the Ti group. Conclusions Use of 3D printed porous Ti cages relative to non-porous PEEK cages may mitigate pseudoarthrosis related reoperation after TLIF.

Study Design: Retrospective observational study of consecutive patients Objective: The purpose of the study was to evaluate VBQ as a predictor of interbody subsidence and to determine threshold values that portend increased risk of subsidence. Summary of Background Data: Many risk factors have been reported for the subsidence of interbody cages in anterior cervical discectomy and fusion (ACDF). MRI Vertebral Bone Quality (VQB) is a relatively new radiographic parameter that can be easily obtained from preoperative MRI and has been shown to correlate with measurements of bone density such as DXA and CT Hounsfield Units. Methods: All patients who underwent 1- to 3-level ACDF using titanium interbodies with anterior plating between the years 2018 and 2020 at our tertiary referral center were included. Subsidence measurements were performed by 2 independent reviewers on CT scans obtained 6 months postoperatively. VBQ was measured on pre-operative sagittal T1 MRI by 2 independent reviewers, and values were averaged. Results: Eight-five fusion levels in 44 patients were included in the study. There were 32 levels (38%) with moderate subsidence and 12 levels with severe subsidence (14%). The average VBQ score in those patients with severe subsidence was significantly higher than those without subsidence (3.80 vs. 2.40, P<0.01). A threshold value of 3.2 was determined to be optimal for predicting subsidence (AUC=0.99) and had a sensitivity of 100% and a specificity of 94.1% in predicting subsidence. Conclusions: VBQ strongly correlates with the subsidence of interbody grafts after ACDF. A threshold VBQ score value of 3.2 has excellent sensitivity and specificity for predicting subsidence. Spine surgeons can use VBQ as a readily available screening tool to identify patients at higher risk for subsidence. Level of Evidence: Level—IV

Study Design: This was a retrospective chart review. Objective: The objective of this study was to compare the effect of teriparatide on Hounsfield Units (HU) in the cervical spine, thoracic spine, lumbar spine, sacrum, and pelvis. Second, to correlate HU changes at each spinal level with bone mineral density (BMD) on dual-energy x-ray absorptiometry (DXA). Summary of Background Data: HU represent a method to estimate BMD and can be used either separately or in conjunction with BMD from DXA. Materials and Methods: A retrospective chart review included patients who had been treated with at least 6 months of teriparatide. HU were measured in the vertebral bodies of the cervical, thoracic, and lumbosacral spine and iliac crests. Lumbar and femoral neck BMD as measured on DXA was collected when available. Results: One hundred twenty-five patients were identified for analysis with an average age of 67 years who underwent a mean (±SD) of 22±8 months of teriparatide therapy. HU improvement in the cervical spine was 11% (P=0.19), 25% in the thoracic spine (P=0.002), 23% in the lumbar spine (P=0.027), 17% in the sacrum (P=0.11), and 29% in the iliac crests (P=0.09). Lumbar HU correlated better than cervical HU with BMD as measured on DXA. Conclusions: Teriparatide increased average HU in the thoracolumbar spine to a proportionally greater extent than the cervical spine. The cervical spine had a higher baseline starting HU than the thoracolumbar spine. Lumbar HU correlated better than cervical and thoracic HU with BMD as measured on DXA.