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To investigate the biomechanical changes in the development of scoliosis due to intervertebral disc and facet joint degeneration.We enrolled 39 cases of fresh-frozen lumbar spine specimens and underwent CT scanning and 3D reconstruction. An Osirix Dicom imaging system was to assess the degeneration of the intervertebral disc and facet joints, and mechanical loading was conducted using a spine mechanical instrument with the frequency set at plus/minus 7.5 NM, 0.005 Hz. Range of motion (ROM) and neutral zone (NZ) of 39 cadaveric lumbar spines were tested.Degeneration existed in all 39 cases of the lumbar specimens: the Cobb angle10° in 5 cases (degenerative scoliosis (DS) group), between 3° and 10° in 9 cases (pre-degenerative scoliosis (PS) group) and3° in 25 cases (no scoliosis (NS) group). The axial torsion (AT) range of motion (ROMThe AT correlated with intervertebral disc and facet joint degeneration, which might be a mechanic factor in the occurrence and development of degenerative scoliosis.

Background: Effective triage - directing patients with low back pain to appropriate treatment or correct referral - is fundamental to quality care. Without guidelines, a physician's initial decision may lead to unnecessary investigation, unneeded intervention or unwarranted consultation.Methods: To compare the functional outcomes of patients triaged by a classification based on clinical presentation with those of patients selected at the clinicians’ discretion, an insurance-owned hospital network employed forty-seven specially-trained physical therapists, working within participating primary care practices, to classify low back pain patients into specific Patterns of Pain. Between October 2017 and April 2019, the primary care physicians used this classification, derived entirely from the patient's history and physical examination, to direct subsequent treatment for 260 consecutive low back pain patients. Patients with systemic symptoms, recent substantial trauma or non-mechanical diagnoses indicative of spinal infections or possible malignancy were excluded. Functional outcome measures were spinal imaging, opioid use, length of treatment and number of visits, back-related unplanned care, frequency of spinal surgery and back-related episode cost. These were compared with a control group of 256 propensity-matched patients and, for assessing the financial impact, with a historic cohort of 111 previously treated, non-classified patients.Results: Spinal imaging: study group 24.5%; controls 42.2% (P< .001). Narcotic use: study group 4.6%; controls 13.3% (P< .001). Treatment length: study group 62.2 days; controls 74.5 days (P=.10). Treatment visits: study group 1528 visits; controls 2,046 visits (P=.003). Unplanned care: study group 1.9%; controls 12.8% (P< .001). Spine surgery: study group 15.4%; controls 26.2% (P=.005). Episode cost: study group $1453; controls $2334 (P=.005).Conclusions: A well-defined clinically-based triage system produced meaningful reductions in imaging, opioid use, treatment duration, unplanned interventions, surgery and cost of care.

BACKGROUND CONTEXT Osteoimmunology, the study of the relationship between the musculoskeletal system and immune system, has emerged as an important consideration in biomaterial research. Based on the current understanding of the immune system, both the innate and adaptive components, a combination of tests on current design materials in spinal implant devices may help understand potential clinical complications and thus reduce the potential adverse events associated with specific design materials. Studies involving macrophages facilitate the understanding behind the mechanism of fibrous capsule formation anecdotally reported with PEEK implants. The cell studies in combination with larger animal studies help understand the importance of appropriate choice in materials. The combination of results from three separate kinds of studies would potentially weave a better understanding of PEEK fibrous encapsulation around retrieved implanted PEEK devices. It was hypothesized that IL-1β, IL-6, and TNF-α cytokine expression levels results would be different for PEEK and a novel zeolite filled PEEK composite (ZFuze, DiFusion Technologies). PURPOSE The objective of this study was to compare the activation state of macrophages, as determined by selected gene and protein expression profiles, following in vitro exposure to PEEK zeolite and PEEK based spinal interbody devices. Similarly, the immune response measured at the local sites in a large animal study was also studied in order to determine the inflammatory response at the local implanted site. STUDY DESIGN/SETTING In vitro cell culture study in combination with a large animal functional cervical spine model. The large animal model included two instrumented levels with one level implanted with a PEEK interbody cervical cage and the alternate level implanted with a PEEK zeolite composite interbody device. OUTCOME MEASURES The levels of inflammatory cytokines interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α) were quantified in muscle tissue directly anterior to the index level based on the intensity of fluorescence in each slide. For cell-based study, the presence of cytokines was noted as comparable, increased, or slightly increased compared to macrophages of the M0 phenotype. METHODS Mature macrophages were exposed to the following treatments for 24 hours: complete media (M0 control), 20 ng/ml IFN-γ and 100 ng/mL lipopolysaccharide LPS (M1 control), 20 ng/mL interleukin IL-4 (M2 control). For the cytokine challenge study, cells were exposed for 6 hours to 20 ng/ml IFN-γ and 100 ng/mL LPS, washed and then placed in 10% FBS 1% P/S DMEM for 24 hours. After the incubation period at 37°C, cells were washed with sterile PBS and fixed for 30 minutes with 2% paraformaldehyde (PFA) for immunolabeling, or harvested with TRIzol lysis reagent for RNA assessment, respectively. RNA were isolated from 8 × 106 cells using the RNeasy Mini Kit according to the manufacturer's instructions. Isolated RNA concentration was subsequently determined using a NanoDrop spectrophotometer. Reverse transcription of 500 ng of RNA to cDNA were performed via a high-capacity reverse transcriptase kit according to the manufacturer's instructions. SYBR Green gene expression assays were used to determine the relative expression levels of: gapdh, inos, tnf-α, arg1, fizz1, il1β, il6, and gapdh. Skeletally mature Montadale sheep were implanted with PEEK and PEEK zeolite interbody cages at the C2-C3 and C4-C5 index levels and survived to 12 or 26 weeks, as approved by the IACUC Committee. At the time of sacrifice index level functional spinal units (FSU), major organs, lymph nodes, and muscle tissues were collected. Muscle tissue from the spinal column at the operative level was collected and used for a quantitative analysis of various inflammatory markers using immunohistochemistry techniques. Slides were prepared from these spinal tissue samples as well as positive and negative control tissues. Lymph nodes and muscle tissues distant from the surgical site were collected during necropsy and served as the positive and negative controls respectively. RESULTS In vivo expression was normalized to represent a percentage of intensity measured in the negative control. Independent T-test was performed to compare cytokine expression at both 12 and 26 week time points. Expression of IL1-β was found to be significantly lower in PEEK zeolite samples at 12 weeks (M=0.23, SD=0.28) than standard PEEK samples at 12 weeks (M=1.37, SD=0.49) t(8)=-4.582, p=0.002. PEEK zeolite composite samples were also found to have significantly lower IL1-β expression at 26 weeks (M=0.02, SD=0.009) when compared to standard PEEK samples (M=0.60, SD=0.23) t(11)=-6.667, p CONCLUSIONS The macrophage study in combination with larger animal studies help understand the importance of appropriate choice in design materials. With the above strategies in mind, it was possible to conduct in vitro and/or in vivo studies that comprehensively evaluate the macrophage response to a biomaterial. Results of the macrophage study suggest that PEEK-zeolite, but not PEEK, increases the expression at the translational level of an M2-associated marker, Fizz1. Results of protein expression data support the hypothesis that PEEK zeolite promotes a pro-repair M2-like macrophage phenotype. Similarly, the ovine study showed a novel PEEK zeolite composite elicits reduced pro-inflammatory cytokine excretion when compared to standard PEEK implants. Specifically, the tissues surrounding PEEK-zeolite composite implants had significantly lower levels of IL1-β and IL-6. These results may explain the increased bone growth observed in the pilot rabbit study and suggest the new material is well suited for clinical application including spinal implants that benefit from host bone implant apposition. FDA DEVICE/DRUG STATUS Unavailable from authors at time of publication.

Background Interbody fusion cages with integrated fixation components have become of interest due to their ability to provide enhanced post-operative stability and mitigate device migration. A recently approved anterior lumbar interbody fusion cage with integrated fixation anchors has yet to be compared in vitro to a standard polyetheretherketone cage when used in combination with an interspinous process clamp. Methods Twelve human cadaveric lumbar segments were implanted at L4–L5 with a Solus interbody cage (n = 6) or standard polyetheretherketone cage (n = 6) following Intact testing and discectomy. Each cage was subsequently evaluated in all primary modes of loading after supplementation with the following posterior constructs: interspinous process clamp, bilateral transfacet screws, unilateral transfacet screw with contralateral pedicle screws, and bilateral pedicle screws. Range of motion results were normalized to Intact, and a two-way mixed analysis of variance was utilized to detect statistical differences. Findings The Solus cage in combination with all posterior constructs provided significant fixation compared to Intact in all loading conditions. The polyetheretherketone cage also provided significant fixation when combined with all screw based treatments, however when used with the interspinous process clamp a significant reduction was not observed in lateral bending or axial torsion. Interpretation Interbody cages with integrated fixation components enhance post-operative stability within the intervertebral space, thus affording clinicians the potential to utilize less invasive methods of posterior stabilization when seeking circumferential fusion. Interspinous process clamps, in particular, may reduce peri-operative and post-operative comorbidities compared to screw based constructs. Further study is necessary to corroborate their effectiveness in vivo .

Background context Surgical instrumentation used for posterior craniocervical instability has evolved from simple wiring techniques to sophisticated implant systems that incorporate multiple means of rigid fixation for the cervical spine. Polyaxial screws and lamina hooks in conjunction with occipital plating and transitional rods for caudal fixation theoretically allow for fixation points at each vertebra along the posterior aspect of the cervical spine. However, the potential for anatomical constraints to prevent intraoperative instrumentation at the desired vertebral level exists. The biomechanical implications of such “skipped segments” have not been well documented. Purpose The purpose of this study was to determine the biomechanical effects of partial three-point fixation versus sequential fixation at all levels of the cervical spine from the occiput to T1. Study design/setting Fresh frozen human cadaveric cervical spines from the occiput (CO) to T1 were prepared and mounted on a spine simulator. Motion was assessed by a three-dimensional optoelectronic motion measurement system. Kinematic data were collected and range of motion (ROM) was analyzed and reported. Methods Eight human noninstrumented intact spines (Treatment 1) were tested for baseline ROM which was subclassified into axial (CO–C2), upper subaxial (C2–C4), lower subaxial (C4–T1), and total (CO–T1) ROM. Flexion extension, lateral bending, and axial torsion testing with an applied ±3 Nm moment was conducted. The same testing protocol was performed after three-point fixation in which screws were placed at the CO, C4, and T1 (Treatment 2), and also after sequential fixation at all levels from CO through T1 (Treatment 3). Fixation was achieved using an occipital plate, 12-mm lateral mass screws for C3 through C6, and 20-mm lateral mass or pedicle screws were used for C1, C2, C7, and T1. Results Intact spine testing (Treatment 1) showed statistically significant larger ROM for all segments and for overall ROM when compared with both Treatment 2 (partial fixation CO, C4, and T1) and Treatment 3 (sequential fixation at all levels from the occiput to T1). When comparing Treatment 2 with Treatment 3, no significant difference in flexion extension ROM was detected between axial, upper subaxial, lower subaxial, and total overall ROM (p > .05). Lateral bending showed statistically significant increased ROM for Treatment 2 constructs compared with Treatment 3 constructs in total overall lateral bend ROM. For axial rotation, there was significantly increased ROM for Treatment 2 at the lower subaxial segment and total overall ROM (p Conclusions There was no statistical difference between the three-point fixation treatment group and the sequential fixation group in flexion extension bending. Lateral bending and axial rotation demonstrated an increase in total overall ROM with partial fixation compared with fixation at all levels. Axial rotation in particular showed increased mobility in the lower cervical spine for the partial fixation group. In the instance where surgeons are not able to apply sequential fixation at diseased levels, especially for the lower subaxial cervical spine, particular attention to limitation of lateral bending and axial rotation by the use of external orthotics must be considered.

BACKGROUND CONTEXT: Nucleus replacement devices are intended to replace or augment the pathologic intervertebral disc, particularly in the early stages of the degenerative cascade. In order to evaluate the clinical viability of these devices, it is necessary to conduct tests simulating potential failure modes in the physiologic setting in addition to bench-top mechanical device testing and traditional in vitro flexibility evaluation. PURPOSE: To evaluate the compressive failure loads of lumbar functional spinal units (FSU) following augmentation with an injectiable in situ cured hydrogel. STUDY DESIGN/SETTING: In vitro biomechanical study. PATIENT SAMPLE: Twenty-three functional spinal units derived from 12 human lumbar segments. OUTCOME MEASURES: Compressive failure load. METHODS: After screening available specimens for advanced degeneration based on computed tomography scans, 23 lumbar FSU were prepared for testing from 12 full lumbar segments. Each FSU underwent injection with the nucleus augmentation gel and removal of all posterior elements by transection of the pedicles. Eleven FSU were randomly selected to the Annulectomy subgroup and subjected to a circumferential outer annulectomy. Each of the 23 FSU was then subjected to compressive load to failure at a rate of 0.1 mm/sec on a compression load frame (MTS 858 Bionix, Eden Prairie, MN). Specimens were loaded at this constant rate until an increase in load was no longer achieved in spite of further displacement or until axial displacement of 6 mm was reached. The maximum load achieved during testing was defined as the failure load. RESULTS: The average failure load for the specimens in the Annulectomy group was 3761 N (SD 1728, Range [1772, 8156]). The average failure load for the specimens without annulectomy was 4636 N (SD 2142, Range [1557, 9134]). A group-wise t-test was conducted between the two treatment groups, and a significant difference was not detected (p50.29). CONCLUSIONS: Surprisingly a difference in compressive failure load could not be detected between treatment groups in spite of the removal of the entire outer annulus in the Annulectomy group. The predominant mode of failure within the Annulectomy group was extrusion of the native nucleus and/or nucleus augmentation mass through the remaining annulus. Five of the 11 specimens failed in this manner. None of the specimens with a fully intact annulus failed in this mode, but rather, failed by visible fracture of the vertebral body or expulsion of the nuclear mass through the inferior or superior endplate. In order for potential failure modes of nucleus augmentation devices to be fully elucidated, further study investigating device migration and extrusion under various modes of loading must be evaluated. Additionally, further studies investigating the influence of bone density and other degenerative characteristics should be conducted. FDA DEVICE/DRUG STATUS: Hydrogel (Not approved for this indication).