Interbody Implants Research Articles

Predictability in Achieving Target Intervertebral Lordosis Using Personalized Interbody Implants.

Lumbar lordosis distribution has become a pivotal factor in re-establishing the foundational alignment of the lumbar spine. This can directly influence overall sagittal alignment, leading to improved long-term outcomes for patients. Despite the wide availability of hyperlordotic stock cages intended to achieve optimal postoperative alignment, there is a lack of correlation between the lordotic shape of a cage and the resultant intervertebral alignment. Recently, personalized spine surgery has witnessed significant advancements, including 3D-printed personalized interbody implants, which are customized to the surgeon's treatment and alignment goals. This study evaluates the reliability of 3D-printed patient-specific interbody implants to achieve the planned postoperative intervertebral alignment. This is a retrospective study of 217 patients with spinal deformity or degenerative conditions. Patients were included if they received 3D-printed personalized interbody implants. The desired intervertebral lordosis (IVL) angle was prescribed into the device design for each personalized interbody (IVL goal). Standing postoperative radiographs were measured, and the IVL offset was calculated as IVL achieved minus IVL goal. In this patient population, 365 personalized interbodies were implanted, including 145 anterior lumbar interbody fusions (ALIFs), 99 lateral lumbar interbody fusions (LLIFs), and 121 transforaminal lumbar interbody fusions. Among the 365 treated levels, IVL offset was 1.1° ± 4.4° (mean ± SD). IVL was achieved within 5° of the plan in 299 levels (81.9%). IVL offset depended on the approach of the lumbar interbody fusion and was achieved within 5° for 85.9% of LLIF, 82.6% of transforaminal lumbar interbody fusions and 78.6% of ALIFs. Ten levels (2.7%) missed the planned IVL by >10°. ALIF and LLIF levels in which the plan was missed by more than 5° tended to be overcorrected. This study supports the use of 3D-printed personalized interbody implants to achieve planned sagittal intervertebral alignment. Personalized interbody implants can consistently achieve IVL goals and potentially impact foundational lumbar alignment.

Tomographic Assessment of Fusion Rate, Implant-Endplate Contact Area, Subsidence, and Alignment With Lumbar Personalized Interbody Implants at 1-Year Follow-Up.

Incongruity between irregularly shaped vertebral endplates and the uniform surfaces of stock interbody fusion cages has been identified as contributing to cage subsidence, pseudarthrosis, and unpredictable alignment. Advances in manufacturing techniques have driven the development of personalized interbody cages (PICs) that can match individual endplate morphology and provide the exact shape and size needed to fill the disc space and achieve the planned correction. This study used computed tomography (CT) imaging to evaluate the implant-endplate contact area, fusion, subsidence, and achievement of planned alignment correction in patients receiving PIC devices. This retrospective study included patients treated for adult spinal deformity at a single site and implanted with PIC devices at L4 to L5 or L5 to S1 for segmental stabilization and alignment correction, who received 1-year postoperative CT images as part of their standard of care. An evaluation using 3-dimensional thin-section scans was conducted. Implant-endplate contact and signs of fusion were assessed in each CT slice across both endplates. The degree of subsidence as well as measures of segmental and global lumbar alignment were also assessed. Fifteen patients were included in the study, with a mean age of 68.2 years. Follow-up ranged between 9 and 14 months. Twenty-six total lumbar levels were implanted; 20 with PIC devices via the anterior lumbar interbody fusion approach, 2 with stock cages via the anterior lumbar interbody fusion approach, and 4 with PIC devices via the transforaminal lumbar interbody fusion approach. CT analysis of PIC-implanted levels found an overall implant-endplate contact area ratio of 93.9%, a subsidence rate of 4.5%, a fusion rate of 100%, and satisfactory segmental and global lumbar correction compared with the preoperative plan. PIC implants can provide nearly complete contact with endplate surfaces regardless of the individual endplate morphology. Subsidence, fusion, and alignment assessments in this tomographic study illustrated results consistent with the benefits of a personalized interbody implant.

Mismatch Between Pelvic Incidence and Lumbar Lordosis After Personalized Interbody Fusion: The Importance of Preoperative Planning and Alignment in Degenerative Spine Diseases.

Emerging data have highlighted the significance of planning and aligning total and segmental lumbar lordosis with pelvic morphology when performing short-segment fusion with the goal of reducing the risk of adjacent segment disease while also decreasing spine-related disability. This study evaluates the impact of personalized interbody implants in restoring pelvic incidence-lumbar lordosis (PI-LL) mismatch compared with a similar study using stock interbody implants. This multicenter retrospective analysis assessed radiographic pre- and postoperative spinopelvic alignment (PI-LL) in patients who underwent 1- or 2-level lumbar fusions with personalized interbody implants for degenerative (nondeformity) indications. The aim was to assess the incidence of malalignment (PI-LL ≥ 10°) both before and after fusion surgery and to determine the rate of alignment preservation and/or correction in this population. There were 135 patients included in this study. Of 83 patients who were aligned preoperatively, alignment was preserved in 76 (91.6%) and worsened in 7 (8.4%). Among the 52 preoperatively malaligned patients, alignment was restored in 23 (44.2%), and 29 (55.8%) were not fully corrected. Among patients who were preoperatively aligned, there was no statistically significant difference in either the "preserved" or "worsened" groups between stock devices and personalized interbody devices. In contrast, among patients who were preoperatively malaligned, there was a statistically significant increase in the "restored" group (P = 0.046) and a statistically significant decrease in the "worsened" groups in patients with personalized interbodies compared with historical stock device data (P < 0.05). Compared with a historical cohort with stock implants, personalized interbody implants in short-segment fusions have shown a statistically significant improvement in restoring patients to normative PI-LL. Using 3-dimensional preoperative planning combined with personalized implants provides an important tool for planning and achieving improvement in spinopelvic parameters.

P280. Predictability in achieving target lordosis using personalized interbody implants – a comparative analysis by approach

P280. Predictability in achieving target lordosis using personalized interbody implants – a comparative analysis by approach

The contribution of E3D imaging integrated with robotic navigation: analysis of the first 80 consecutive posterior spinal fusion cases

Eighty consecutive complex spinal robotic cases utilizing intraoperative 3D CT imaging (E3D, Group 2) were compared to 80 age-matched controls using the Excelsius robot alone with C-arm Fluoroscopic registration (Robot Only, Group 1). The demographics between the two groups were similar—severity of deformity, ASA Score for general anesthesia, patient age, gender, number of spinal levels instrumented, number of patients with prior spinal surgery, and amount of neurologic compression. The intraoperative CT scanning added several objective factors improving patient safety. There were significantly fewer complications in the E3D group with only 3 of 80 (4%) patients requiring a return to the operating room compared to 11 of 80 (14%) patients in the Robot Only Group requiring repeat surgery for implant related problems (Chi squared analysis = 5.00, p = 0.025). There was a significant reduction the amount of fluoroscopy time in the E3D Group (36 s, range 4–102 s) compared to Robot only group (51 s, range 15–160 s) (p = 0.0001). There was also shorter mean operative time in the E3D group (257 ± 59.5 min) compared to the robot only group (306 ± 73.8 min) due to much faster registration time (45 s). A longer registration time was required in the Robot only group to register each vertebral level with AP and Lateral fluoroscopy shots. The estimated blood loss was also significantly lower in Group 2 (mean 345 ± 225 ml) vs Group 1 (474 ± 397 ml) (p = 0.012). The mean hospital length of stay was also significantly shorter for Group 2 (3.77 ± 1.86 days) compared to Group 1 (5.16 ± 3.40) (p = 0.022). There was no significant difference in the number of interbody implants nor corrective osteotomies in both groups—Robot only 52 cases vs. 42 cases in E3D group.Level of evidence: IV, Retrospective review.

A Comparison between Structural Allografts and Polyetheretherketone Interbody Spacers Used in Anterior Cervical Discectomy and Fusion: A Systematic Review and Meta-analysis.

Among interbody implants used during anterior cervical discectomy and fusion (ACDF), structural allografts and polyetheretherketone (PEEK) are the most used spacers. Currently, no consensus has been established regarding the superiority of either implant, with US surgeons preferring structural allografts, whereas UK surgeons preferring PEEK. The purpose of this systematic review (level of evidence, 4) was to compare postoperative and patient-reported outcomes between the use of structural allografts PEEK interbody spacers during ACDF. Five electronic databases (PubMed, Embase, Scopus, Web of Science, and Cochrane) were searched for articles comparing the usage of structural allograft and PEEK interbody spacers during ACDF procedures from inception to April 10, 2023. The searches were conducted using the keywords "Spine," "Allograft," and "PEEK" and were performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. Subsequent quality and sensitivity analyses were performed on the included studies. Nine studies involving 1,074 patients were included. Compared with the PEEK group, the structural allograft group had comparable rates of postoperative pseudoarthrosis (p=0.58). However, when stratified according to the number of levels treated, the 3-level ACDF PEEK group was 3.45 times more likely to have postoperative pseudoarthrosis than the structural allograft group (p=0.01). Subsequent postoperative outcomes (rate of subsidence and change in the preoperative and postoperative segmental disc heights) were comparable between the PEEK and structural allograft groups. Patient-reported outcomes (Visual Analog Scale [VAS] of neck pain and Neck Disability Index [NDI]) were comparable. This study showed that for 3-level ACDFs, the use of structural allografts may confer higher fusion rates. However, VAS neck pain, NDI, and subsidence rates were comparable between structural allografts and PEEK cages. In addition, no significant difference in pseudoarthrosis rates was found between PEEK cages and structural allografts in patients undergoing 1- and 2-level ACDFs.

A Comparison between Structural Allografts and Polyetheretherketone Interbody Spacers Used in Anterior Cervical Discectomy and Fusion: A Systematic Review and Meta-analysis.

Among interbody implants used during anterior cervical discectomy and fusion (ACDF), structural allografts and polyetheretherketone (PEEK) are the most used spacers. Currently, no consensus has been established regarding the superiority of either implant, with US surgeons preferring structural allografts, whereas UK surgeons preferring PEEK. The purpose of this systematic review (level of evidence, 4) was to compare postoperative and patient-reported outcomes between the use of structural allografts PEEK interbody spacers during ACDF. Five electronic databases (PubMed, Embase, Scopus, Web of Science, and Cochrane) were searched for articles comparing the usage of structural allograft and PEEK interbody spacers during ACDF procedures from inception to April 10, 2023. The searches were conducted using the keywords "Spine," "Allograft," and "PEEK" and were performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. Subsequent quality and sensitivity analyses were performed on the included studies. Nine studies involving 1,074 patients were included. Compared with the PEEK group, the structural allograft group had comparable rates of postoperative pseudoarthrosis (p=0.58). However, when stratified according to the number of levels treated, the 3-level ACDF PEEK group was 3.45 times more likely to have postoperative pseudoarthrosis than the structural allograft group (p=0.01). Subsequent postoperative outcomes (rate of subsidence and change in the preoperative and postoperative segmental disc heights) were comparable between the PEEK and structural allograft groups. Patient-reported outcomes (Visual Analog Scale [VAS] of neck pain and Neck Disability Index [NDI]) were comparable. This study showed that for 3-level ACDFs, the use of structural allografts may confer higher fusion rates. However, VAS neck pain, NDI, and subsidence rates were comparable between structural allografts and PEEK cages. In addition, no significant difference in pseudoarthrosis rates was found between PEEK cages and structural allografts in patients undergoing 1- and 2-level ACDFs.

Ten-Year Risk of Recall of Novel Spine Devices.

Observational epidemiological study. This study's primary objective was to examine the risk of recall for novel spine devices over time. Secondarily, we sought to analyze interbody fusion and vertebral body replacement (VBR) devices (corpectomy cages) as a risk factor for recall. The recall risk of a novel spine device over time has not been reported. In addition, FDA regulations were lowered for interbody fusion devices to enter the market in 2007. As well, VBR implants were recently approved by the FDA for use in the cervical spine in 2015. Spine devices cleared between January 1, 2008 and December 31, 2018 were identified from the FDA's 510(k) database. All recall data were collected from the database in January 2021 to provide a 2-year minimum follow-up for a recall to occur. Product labels were used to classify interbody fusion and VBR devices. Cumulative incidence function was conducted to compare the overall risk of recall for FDA-cleared spine devices, and the hazard ratio determined for VBR and all other devices versus interbody implants during the study period. A total of 2384 spine devices were cleared through 510(k) in the study period. The hazard of recall at 5 years was 5.3% (95% CI: 4.4%-6.2%) and 6.5% (95% CI: 5.4%-7.7%) at 10 years. No significant difference in recall risk was identified for interbody fusion and VBR devices. The risk of recall at 5 and 10 years of a novel spine device is about half the 12% rate reported for orthopedic devices in general. Despite lowered FDA regulations for interbody fusion devices and recent approval for VBR device use in the cervical spine, no increased risk of recall was detected. Further research is necessary to explain the reason for the lower risk of recall with spine devices. 4.

Analysis of Personalized Interbody Implants in the Surgical Treatment of Adult Spinal Deformity.

Multicenter cohort. A report from the International Spine Study Group (ISSG) noted that surgeons failed to achieve alignment goals in nearly two-thirds of 266 complex adult deformity surgery (CADS) cases. We assess whether personalized interbody spacers are associated with improved rates of achieving goal alignment following adult spinal deformity (ASD) surgery. ASD patients were included if their surgery utilized 3D-printed personalized interbody spacer(s) and they met ISSG CADS inclusion criteria. Planned alignment was personalized by the surgeon during interbody planning. Planned vs achieved alignment was assessed and compared with the ISSG CADS series that used stock interbodies. For 65 patients with personalized interbodies, 62% were women, mean age was 70.3 years (SD = 8.3), mean instrumented levels was 9.9 (SD = 4.1), and the mean number of personalized interbodies per patient was 2.2 (SD = .8). Segmental alignment was achieved close to plan for levels with personalized interbodies, with mean difference between goal and achieved as follows: intervertebral lordosis = .9° (SD = 5.2°), intervertebral coronal angle = .1° (SD = 4.7°), and posterior disc height = -0.1mm (SD = 2.3mm). Achieved pelvic incidence-to-lumbar lordosis mismatch (PI-LL) correlated significantly with goal PI-LL (r = .668, P < .001). Compared with the ISSG CADS cohort, utilization of personalized interbodies resulted in significant improvement in achieving PI-LL <5° of plan (P = .046) and showed a significant reduction in cases with PI-LL >15° of plan (P = .012). This study supports use of personalized interbodies as a means of better achieving goal segmental sagittal and coronal alignment and significantly improving achievement of goal PI-LL compared with stock devices.

Early radiographic outcomes after anterior cervical discectomy and fusion with anatomic versus lordotic cages

BackgroundAnterior cervical discectomy and fusion (ACDF) interbody implants are shaped anatomically, with a convex superior aspect, or lordotically, with an angle and flat surfaces. However, the effect of implant shape on cervical sagittal balance (CSB) is not well described. MethodsOf the 192 cases reviewed from 2018 to 2019, 118 were included with matching pre- and postoperative imaging. Cases were categorized by interbody implant type (anatomic or lordotic) and number of levels fused (1-level, 2-level, etc.). SurgiMap was used to measure cervical lordosis (CL), C2–C7 sagittal vertical axis (cSVA), T1 slope (T1S), and T1S minus CL (T1S-CL) on pre- and postoperative imaging. Pre- and postoperative parameters were compared within and between each cohort. Change in CL (ΔCL), cSVA (ΔcSVA), and T1S-CL (ΔT1S-CL) were calculated as the difference between pre- and postoperative values and were compared accordingly (1) anatomic versus lordotic and (2) 1-level versus 2-level versus 3-level fusion. ResultsThirty-nine (33.1%), 57 (48.3%), and 22 (18.6%) cases comprised the anatomic, lordotic, and mixed (anatomic and lordotic) groups, respectively. ACDFs improved CL and T1S-CL by 5.71° (p<.001) and 3.32° (p<.01), respectively. CL was improved in the lordotic (5.27°; p<.01) and anatomic (4.57°; p<.01) groups, while only the lordotic group demonstrated improvement in T1S-CL (3.4°; p=.02). There were no differences in ΔCL (p=.70), ΔcSVA (p=.89), or ΔT1S-CL (p=.1) between the groups. Two- and 3-level fusions improved CL by 7.48° (p<.01) and 9.62° (p<.01), and T1S-CL by 4.43° (p<.01) and 5.96° (p<.01), respectively. ConclusionsOverall, ACDFs significantly improved CL and T1S-CL however, there were no differences in CSB correction between the anatomic and lordotic groups. Two- and 3-level fusions more effectively improved CL (vs. single-level) and T1S-CL (vs. 3-level). These results suggest that implants should continue to be personalized to the patient's anatomy, however, future research is needed to validate these findings and incorporate the effects of preoperative deformities.

Development of a novel PLDLA/β-TCP composite-based biodegradable anterior cervical plate and screw system.

We investigated the effectiveness and safety of a new composite-based biodegradable anterior cervical plate/screw (ACPS) system for the anterior cervical discectomy and fusion (ACDF) fixation. A biocomposite in combination with 30 wt% β-tricalcium phosphate (β-TCP; a biodegradable ceramic having osteoconductive ability) and 70 wt% poly-l/d-lactide copolymer (PLDLA; a biodegradable polymer) was developed and used in the ACPS device, comprising one plate and four screws for fixation. Based on a literature review, a clinically required period of performance maintenance was set as 16 weeks, and to verify the performance for a period of 16 weeks or more, the test was conducted for 26 weeks. Following ISO 13781:2017 testing protocols, an in vitro degradation test was performed to verify the performance and evaluate the decomposition characteristics of the biodegradable ACPS system. Using an animal model as a preclinical investigation, the prepared ACPS device was implanted into five mongrel dogs weighing over 30 kg to evaluate the detachment prevention effect of the ACPS system on polyether ether ketone (PEEK) cage after ACDF. By week 26, the molecular weight was decreased by 45.35% for the plate and 52.56% for the screw; the bending strength of the plate was decreased by approximately 26.2% when compared with the initial stage. The torsional yield strength and pullout strength of the screw was increased by 52.31% and 5.3%, respectively by week 2 and then subsequently decreased until week 26. No detachment or dislocation of the inserted PEEK cage was observed for 26 weeks in vivo study. These findings recommend that the ACPS system might be a promising biodegradable tool for the fixation of interbody implants and supporting the fusion in an ACDF model. Furthermore, additional clinical trials are planned for the future.

Are all Cages Created Equal? Analysis of Cervical Cage Malfunctions Using FDA MAUDE Database.

Retrospective case series. To characterize failure rates of cervical cages based on manufacturer and design characteristics using the nationwide database of reported malfunctions. The Food and Drug Administration (FDA) aims to ensure the safety and efficacy of cervical interbody implants postimplantation; however, intraoperative malfunctions may be overlooked. The FDA's Manufacturer and User Facility Device Experience database was queried for reports of cervical cage device malfunctions from 2012 to 2021. Each report was categorized based on the failure type, implant design, and manufacturer. Two market analyses were performed. First, "failure-to-market share indices" were generated by dividing the number of failures per year for each implant material by its yearly US market share in cervical spine fusion. Second, "failure-to-revenue indices" were calculated by dividing the total number of failures per year for each manufacturer by their approximate yearly revenue from spinal implants in the US. Outlier analysis was performed to generate a threshold value above which failure rates were defined as greater than the normal index. In total, 1336 entries were identified, and 1225 met the inclusion criteria. Of these, 354 (28.9%) were cage breakages, 54 (4.4%) were cage migrations, 321 (26.2%) were instrumentation-related failures, 301 (24.6%) were assembly failures, and 195 (15.9%) were screw failures. Poly-ether-ether-ketone implants had higher failure by market share indices for both migration and breakage compared with titanium. Upon manufacturer market analysis, Seaspine, Zimmer-Biomet, K2M, and LDR exceeded the failure threshold. The most common cause of implant malfunction was breakage. Poly-ether-ether-ketone cages were more likely to break and migrate compared with titanium ones. Many of these implant failures occurred intraoperatively during instrumentation, which underscores the need for FDA evaluation of these implants and their accompanying instrumentation under the appropriate loading conditions before commercial approval.

Revision Reconstruction of the Cervical Spine in a Patient With Early Deep Surgical Site Infection Complicated by Angular Kyphosis: Case Report and Review

Background. Deep surgical site infection (DSSI) is one of the most severe complications in spinal surgery. The timing and nature of DSSI are the determining criteria in the choice of treatment tactics. The uniqueness of the clinical observation is the combination of early DSSI, epidural abscess and angular kyphotic deformity formed after a course of conservative antibacterial therapy in a patient who underwent surgery for degenerative-dystrophic disease of the cervical spine. Correction of angular kyphosis, removal of fractured vertebrae, interbody implants and three-column cervical reconstruction were performed in one surgical session.&#x0D; Case presentation. A 57-year-old patient was admitted to the clinic after staged surgical interventions on the cervical spine for multilevel degenerative stenosis of the spinal canal. The primary surgical interventions were complicated by DSSI in the early period after the second surgery with formation of angular kyphosis of the cervical spine. The patient underwent revision one-stage reconstructive intervention to correct the deformity, decompress the spinal canal, and three-column reconstruction of C3-7 segments. Long-term follow-up showed persistent reduction of pain syndrome, improved quality of life and absence of recurrence of DSSI.&#x0D; Conclusion. The presented case illustrates the possibilities of one-stage revision three-column cervical spine reconstruction for correction of sagittal profile, decompression of intracanal neural structures and ensuring stability of operated segments. Use of DSSI treatment algorithms based on Prinz V. and Vajkoczy P. classification contributes to the selection of the optimal tactics of patient management.

The effect of expandable versus static lordotic interbody implants in minimally invasive spine surgery: patient reported outcomes, sagittal alignment, and restoration of disc height and foraminal height.

Pain and disability due to age-related spinal disorders are increasing due to a more active population placing greater demands on their musculoskeletal system. For patients requiring surgery, spinal fusion is typically indicated. Interbody fusion cages improve fusion rates and restore lordosis, disc height, and foraminal height. Static cages are offered in multiple conformations to account for anatomic variability; however, they have issues related to implant subsidence and loss of lordosis. Expandable cages were developed to address these drawbacks. Patients treated with either static or expandable transforaminal lumbar interbody fusion devices (ProLift® Expandable Spacer System) for the treatment of spondylolisthesis, degenerative disc disease, spinal stenosis, disc herniation, or degenerative scoliosis at L4-L5 or L5-S1 were chosen from retrospective data. Outcomes included radiographic and spinopelvic changes, patient-reported outcomes, and incidence of non-union and revision surgery. One hundred patients were included (Static: 50; Expandable: 50). Demographics between groups were similar, with some differences in comorbidities and spinal disease diagnosis. Radiographically, changes in disc height, foraminal height, and lordosis were significantly improved in the Expandable group up to 2 years (P<0.001). Improvements in patient reported outcomes were more favorable in the Expandable group. In patients who underwent transforaminal lumbar spinal fusion via minimally invasive surgery, the Expandable device group demonstrated significantly improved radiographic and patient reported outcomes compared to a static cage over 2 years.

Letter: Arthrodesis With Titanium Implants: A Different Picture.

ABBREVIATION: DECT Dual-energy computed tomography. To the Editor: Psuedoarthrosis is a commonly known complication of trying to achieve solid body spinal fusion (arthrodesis) in the setting of spine surgery. Although recent advances in spinal surgery instrumentation, imaging, biologics, and management have occurred, it is still a prominent complication with significant morbidity and high cost burden.1 Deciding when to operate on these patients is variable and is primarily dependent on clinician gestalt regarding degree of intervention, physical examination findings, and the presence or lack of boney bridge formation across interbody implantation. Complicating this matter even further is the presence of psuedoarthrosis in the setting of no clinical symptoms. As it stands, computed tomography (CT) is the gold standard for detecting the presence of psuedoarthrosis. When evaluating multiple modalities of imaging for effectiveness in evaluating psuedoarthrosis, Peters et al found the pooled CT odds ratio to be highest in comparison with other modalities such as flexion/extension radiography, magnetic resonance, and scintigraphy. Furthermore, the authors went on to cite several instances in the literature where psuedoarthrosis was not detected through radiographic means but was detected by unveiling motion between adjacent segments.2 Although CT imaging may be a useful tool in imaging operated vertebrae with polyetheretherketone, carbon fiber, metal alloy, or other radiolucent implants, it can be less than reliable in titanium implants which often display significant artifact. Similar artifacts are seen on magnetic resonance imaging, posing an obstacle for thorough postoperative evaluation. Altogether, these findings illustrate the necessity of alternative modalities to better evaluate arthrodesis in the setting of spine surgery using titanium implants. Dual-energy CT (DECT) may prove a step in the right direction for evaluating psuedoarthrosis. In opposition to conventional CT imaging which uses a single image set, DECT uses 2 separate x-ray photon energy spectra; thus, allowing the interrogation of different attenuation properties at different energies.3 Artifact secondary to metal prosthesis (ie, titanium spinal interbody implants) typically occurs when low-energy photons within a polychromatic x-ray beam scatter radiation and abut image quality. Using DECT, these low-energy photons are removed; thus, limiting artifact. As of now, artifact in conventional CT is a major limitation in the evaluation of arthrodesis because initial boney bridge formation can be subtle or absent. To date, several articles have investigated the use of DECT in the setting of spinal fusion. Zeng et al4 in a retrospective review of 40 patients who underwent DECT after lumbar internal fixation found superior image quality with metal artifact reduction compared with conventional methods. Srinivasan et al5 in a retrospective review analyzing transpedicular screw interfacing noted the beneficial effects of metallic streak artifact reduction alongside better visualization of the hardware-bone interface. To our knowledge, there have been no prospective studies that study the differences between DECT and non-DECT images of the same patients. Several radiological fusion scales exist for the grading and measurement of fusion including a quantitative scale such as CT-Hounsfield Unit and qualitative scales such as the Lenke, Bridwell, and Brantigan, Steffe, Fraser scales.6,7 However, these are limited in that they are significantly dependent on subjective interpretation by an individual clinician and limited in their utility in assessment of titanium implants that present with significant artifact. Taken together, these findings highlight the need for a novel, quantized scale for assessing fusion with titanium implants using DECT.

Management of deep surgical site infections of the spine: a Canadian nationwide survey.

Deep surgical site infections after spinal instrumentation represent a significant source of patient morbidity and poorer outcomes. Given lack of evidence or guidelines on the variety of procedural options in the management of deep spine surgical site infections, the purpose of this survey was to document and investigate the use of these techniques across Canada. A 34-question survey evaluating surgical techniques for irrigation and debridement in postoperative thoracolumbar infection was distributed to Canadian adult spine surgeons. Results were analyzed qualitatively, and comparisons by specialty, years of training, and number of cases were completed using Fischer's exact tests. We defined consensus as >70% agreement. We received 53 responses (62% response rate) from a comprehensive sample of Canadian adult spine surgeons. There was a consensus to retain hardware (80%) and interbody implants (93%) in acute infection, to retain interbody implants in chronic/recurrent infection (71%), and application of topical antibiotics in recurrent infection (85%). There was consensus on the use of absorbable suture to close fascia in acute (83%) and chronic (87%) infection. Eighty-five percent of surgeons used nonabsorbable materials such as Nylon or staples for skin closure in chronic infection, however, there was no consensus in acute infection. Surgeons varied significantly in type, volume and pressure of fluids, adjuvant solvents, graft management, use of topical antibiotics acutely, and the use of negative pressure wound therapy. Partial hardware exchange was controversial. Additionally, specialty or surgeon experience had no impact on management strategy. This survey demonstrates significant heterogeneity amongst Canadian adult spine surgeons regarding key steps in the surgical management of deep instrumented spine infection, concordant with scarce literature addressing these steps.

A method for determining the optimal technique of surgical intervention in patients with post-traumatic kyphotic deformity of the thoracolumbar spine in the late period of spinal injury.

Introduction. Spinal fractures account for 63.6 cases per 100,000 populations. Of these, the largest number falls on the Th10-L2 zone. Regardless of the choice of treatment tactics in the early period of spinal injury, a vast number of patients continue to complain of local pain and deformity. In these patients, surgical treatment may be indicated. At the preoperative stage, the operating surgeon faces the problem of choosing an intervention of sufficient volume.The aim of the study was to determine the optimal amount of corrective surgical interventions in patients with kyphotic deformity that has developed as a result of a vertebral fracture.Methods. Patients with a medical history of vertebral compression fracture and local kyphotic deformity greater than 11 degrees were enrolled in a single-centre, prospective, experimental study. All patients were divided into three groups according to the studied algorithm. Patients in group A underwent two-stage surgical treatment with corporectomy, implantation of a mesh interbody implant, and posterior transpedicular fixation from two approaches. Group B patients underwent one-stage surgical treatment with corporectomy and implantation of a mesh interbody implant from a single approach. Patients of group C underwent corrective vertebrotomy without the use of a mesh implant. The degree of deformity correction, the traumatism of surgical intervention, the stability of the metal structure, the formation of a bone block, and changes in the functional status of the patient were assessed. Patients were followed up for 24 months after surgical treatment.Results. The study was completed by 114 patients. Surgical treatment options used allowed achieving good results in the correction of deformity in all groups, in groups B and C the traumatism of the operation was significantly (p=0.05) lower than in group A. A bone block was formed in all study groups. It is important to note that patients in group B had transient radicular pain in the early postoperative period, which probably associated with the traction of neural structures during the installation of an interbody mesh implant.Conclusion. Application of the presented algorithm allowed us to achieve comparable beneficial results in patients of all study groups, however, a small sample and the absence of control subgroups do not allow us to extrapolate the study results to the entire population.

Радиологические результаты поясничного моносегментарного спондилодеза 360° у пациентов с изменениями Modic

Introduction A cascade of degenerative spine changes affects the structures including vertebral endplates and bodies of adjacent vertebrae that can be visualized on MRI imaging as Modic changes. The aim of the study was to assess the role of changes in the endplates and adjacent vertebral bodies in radiological results of monosegmental posterior lumbar interbody fusion (PLIF) in patients with degenerative lesions of the spine. Material and methods The design of the study was a monocenter retrospective comparative cohort study. The radiological results of PLIF performed in combination with transpedicular screw fixation for 122 patients with Modic changes in adjacent endplates and adjacent vertebral bodies were evaluated for interbody fusion, subsidence of interbody implants, segmental angle, interbody space height. The followup period was 1-2 years. Results Complete interbody fusion was seen in 94.4 % of Modic type 0 and in 77.3 % of Modic type II changes. Interbody cage subsidence occurred in 38.9 % Modic type I, 22.7 % in Modic type II, 9.1 % in Modic type III and in 11.3 % Modic type 0 changes. A significant decrease in the segmental angle was found in all types of Modic changes (p &lt; 0.05) at 1-2 years with the greatest decrease noted in Modic type I (p = 0.000438). A significant decrease in the interbody space height was noted in all groups (p &lt; 0.05) with the greatest decrease seen in Modic type I changes (p = 0.000438) and the minimum decrease noted in Modic type III changes (p = 0.000438). Discussion The role of the endplates and adjacent vertebral bodies in the results of surgical treatment was evident, and more research is needed to explore the sort of this relationship. Conclusions Modic changes in the endplates and adjacent red bone marrow showed a significant relationship with the radiological outcomes of monosegmental PLIF. The interbody fusion Tan grade I and Tan grade II was more common for Modic type 0 and less common for Modic type II changes. Subsidence of interbody implants was more common for Modic type I and less common for Modic type III changes (9.1%). Postoperative loss of interbody space height and segmental correction was common for Modic type I.

Feasibility of Machine Learning in the Prediction of Short-Term Outcomes Following Anterior Cervical Discectomy and Fusion

Increased emphasis is being placed on efficiency and resource utilization when performing anterior cervical discectomy and fusion (ACDF), and accurate prediction of complications is increasingly important to optimize care. This study aimed to compare predictive models for postoperative complications following ACDF using machine learning (ML) models based on traditional comorbidity indices. In this retrospective case series, the American College of Surgeons National Surgical Quality Improvement Program database was queried between 2011 and 2017 for all elective, primary ACDF cases. Levels of surgery, use of interbody implants, and graft selection were calculated by procedural codes. Six ML algorithms were constructed using available preoperative and intraoperative features. The overall dataset was randomly split into training (80%) and validation (20%) subsets wherein the training subset optimized the model, and the validation subset was evaluated for accuracy. ML models were compared with models constructed from American Society of Anesthesiologists classification and frailty index alone. There were 42,194 ACDF cases eligible for inclusion. Mean age was 47.7 ± 11.6 years, body mass index was 30.4 ± 6.7, and levels of operation were 1.6 ± 0.7. ML algorithms uniformly outperformed comorbidity indices in predicting complications. Logistic regression ML algorithm was the best performing for predicting any adverse event (area under the curve [AUC] 0.73), transfusion (AUC 0.90), surgical site infection (AUC 0.63), and pneumonia (AUC 0.80). Gradient boosting trees ML algorithm was the best performing for predicting extended length of stay (AUC 0.73). ML algorithms modeled the development of postoperative adverse events with superior accuracy to that of comorbidity indices and may guide preoperative clinical decision making before ACDF.

Impact of surface roughness and bulk porosity on spinal interbody implants.

Spinal fusion surgeries are performed to treat a multitude of cervical and lumbar diseases that lead to pain and disability. Spinal interbody fusion involves inserting a cage between the spinal vertebrae, and is often utilized for indirect neurologic decompression, correction of spinal alignment, anterior column stability, and increased fusion rate. The long-term success of interbody fusion relies on complete osseointegration between the implant surface and vertebral end plates. Titanium (Ti)-based alloys and polyetheretherketone (PEEK) interbody cages represent the most commonly utilized materials and provide sufficient mechanics and biocompatibility to assist in fusion. However, modification to the surface and bulk characteristics of these materials has been shown to maximize osseointegration and long-term stability. Specifically, the introduction of intrinsic porosity and surface roughness has been shown to affect spinal interbody mechanics, vascularization, osteoblast attachment, and ingrowth potential. This narrative review synthesizes the mechanical, in vitro, in vivo, and clinical effects on fusion efficacy associated with introduction of porosity in Ti (neat and alloy) and PEEK intervertebral implants.