Polymeric Nanoparticles Enable mRNA Transfection and Its Translation in Intervertebral Disc and Human Joint Cells, Except for M1 Macrophages.

Chronic lower back pain caused by intervertebral disc degeneration and osteoarthritis (OA) are highly prevalent chronic diseases. Although pain management and surgery can alleviate symptoms, no disease-modifying treatments are available. mRNA delivery could halt inflammation and degeneration and induce regeneration by overexpressing anti-inflammatory cytokines or growth factors involved in cartilage regeneration. Here, we investigated poly(amidoamine)-based polymeric nanoparticles to deliver mRNA to human joint and intervertebral disc cells. Human OA chondrocytes, human nucleus pulposus (NP) cells, human annulus fibrosus (AF) cells, fibroblast-like synoviocytes (FLS) and M1-like macrophages were cultured and transfected with uncoated or PGA-PEG-coated nanoparticles loaded with EGFP-encoding mRNA. Cell viability and transfection efficiency were analyzed for all cell types. Nanoparticle internalization was investigated in FLS and M1-like macrophages. No significant decrease in cell viability was observed in most conditions. Only macrophages showed a dose-dependent reduction of viability. Transfection with either nanoparticle version resulted in EGFP expression in NP cells, AF cells, OA chondrocytes and FLS. Macrophages showed internalization of nanoparticles by particle-cell co-localization, but no detectable expression of EGFP. Taken together, our data show that poly (amidoamine)-based nanoparticles can be used for mRNA delivery into cells of the human joint and intervertebral disc, indicating its potential future use as an mRNA delivery system in OA and IVDD, except for macrophages.

How a broken vertebra can lead to a fatal hemorrhage: a case report.

BACKGROUND: Unintentional falls are common among the elderly and given the expected increase of the aging population, these falls contribute to a high number of admissions to the emergency department. Relatively low-energy trauma mechanisms can lead to serious injuries in the elderly, with contributing factors being comorbidities, medication use and degenerative abnormalities. CASE PRESENTATION: A 94-year-old female suffered an unintentional fall at home. Upon arrival of the ambulance at her house she was hemodynamically stable and mobilized to the gurney with assistance. During primary survey at the emergency department, her blood pressure and oxygen saturation decreased, she was not able to move her legs anymore and lost consciousness. A full-body CTA was performed, which showed a fracture through the vertebral body of L2 with significant dislocation and a large active bleeding of the corpus, extending to the retroperitoneum and the epidural space. Despite resuscitation, her vital signs deteriorated and given the severe abnormalities on CTA, it was decided to discontinue further treatment, after which she deceased. The performed CTA and an x-ray from 2016 suggested diffuse idiopathic skeletal hyperostosis, which might have contributed to the severity and instability of the vertebral fracture. Mobilization after the fall might have increased the dislocation of the fracture. The use of oral anticoagulants worsened the subsequent bleeding and the extension to the epidural space caused the paralysis of the legs. CONCLUSIONS: It is important to be aware of the possible serious consequences of unintentional falls in the elderly population and to provide strict immobilization of the spinal column until proper imaging.

The Evidence for the Use of Osteobiologics in Hybrid Constructs (Anterior Cervical Discectomy and Fusion and Total Disc Replacement) in Multilevel Cervical Degenerative Disc Disease: A Systematic Review.

STUDY DESIGN: Systematic review. OBJECTIVE: Examine the clinical evidence for the use of osteobiologics in hybrid surgery (combined anterior cervical discectomy and fusion (ACDF) and total disc replacement (TDR)) in patients with multilevel cervical degenerative disc disease (DDD). METHODS: PubMed and Embase were searched between January 2000 and August 2020. Clinical studies investigating 18-80 year old patients with multilevel cervical DDD who underwent hybrid surgery with or without the use of osteobiologics were considered eligible. Two reviewers independently screened and assessed the identified articles. The methodological index for non-randomized studies (MINORS) tool and the risk of bias (RoB 2.0) assessment tool were used to assess risk of bias. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) was used to evaluate quality of evidence across studies per outcome. RESULTS: Eleven studies were included. A decrease in cervical range of motion was observed in most studies for both the hybrid surgery and the control groups consisting of stand-alone ACDF or TDR. Fusion rates of 70-100% were reported in both the hybrid surgery and control groups consisting of stand-alone ACDF. The hybrid surgery group performed better or comparable to the control group in terms of adjacent segment degeneration. Studies reported an improvement in visual analogue scale for pain and neck disability index values after surgery compared to preoperative scores for both treatment groups. The included studies had moderate methodological quality. CONCLUSIONS: There is insufficient evidence for assessing the use of osteobiologics in multilevel hybrid surgery and additional high quality and controlled research is deemed essential.

Gait alterations in patients with adult spinal deformity.

Background: Adult spinal deformity patients (ASD) experience altered spinal alignment affecting spatiotemporal parameters and joint kinematics. Differences in spinal deformity between patients with symptomatic idiopathic scoliosis (ID-ASD) and patients with "de novo" scoliosis (DN-ASD) may affect gait characteristics differently. This study aims to compare gait characteristics between ID-ASD, DN-ASD, and asymptomatic healthy matched controls. Methods: In this observational case-control study, ID-ASD (n = 24) and DN-ASD (n = 26) patients visiting the out-patient spine clinic and scheduled for long-segment spinal fusion were included. Patients were matched, based on age, gender, leg length and BMI, with asymptomatic healthy controls. Gait was measured at comfortable walking speed on an instrumented treadmill with 3D motion capture system. Trunk, pelvic and lower extremities range of motion (ROM) and spatiotemporal parameters (SPT) are presented as median (first and thirds quartile). Independent t-test or Mann-Whitney U test was used to compare ID-ASD, DN-ASD and controls. Statistical Parametric Mapping (independent t-test) was used to compare 3D joint kinematics. Results: DN-ASD patients walk with increased anterior trunk tilt during the whole gait cycle compared with ID-ASD patients and controls. ID-ASD walk with decreased trunk lateroflexion compared with DN-ASD and controls. DN-ASD showed decreased pelvic obliquity and -rotation, increased knee flexion, and decreased ankle plantar flexion. ID-ASD and DN-ASD displayed decreased trunk, pelvic and lower extremity ROM compared with controls, but increased pelvic tilt ROM. ID-ASD patients walked with comparable SPT to controls, whereas DN-ASD patients walked significantly slower with corresponding changes in SPT and wider steps. Conclusions: DN-ASD patients exhibit distinct alterations in SPT and kinematic gait characteristics compared with ID-ASD and controls. These alterations seem to be predominantly influenced by sagittal spinal malalignment and kinematic findings in ASD patients should not be generalized as such, but always be interpreted with consideration for the nature of the ASD.

Methodology and application of three-dimensional technology for brace design and production for treatment in patients with adolescent idiopathic scoliosis: a scoping review protocol.

INTRODUCTION: Conservative treatment for adolescent idiopathic scoliosis (AIS) using bracing has proven to be effective at reducing curve progression. However, variation in brace design and lack of brace specificity hamper clinical treatment outcomes as well as the predictability and comparison hereof. To overcome this, recent technological developments aim to generate transparent and objective criteria for brace manufacturing by applying computer-aided design software and additive manufacturing to produce braces for scoliosis treatment. Yet, the extent of its applicability and clinical implementation are to be determined. This study will identify and map the available evidence for the methodology and application of three-dimensional technology for the design and production of clinical braces used for treatment in patients with AIS. METHODS AND ANALYSIS: This scoping review will be conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews. This scoping review will consider studies on methodology of three-dimensional technological methodology and applications that have been or are currently being applied in brace treatment of AIS. The following databases will be searched: MEDLINE, Web of Science, Cochrane Database of Systematic Reviews and Embase (OVID). Search limits will be applied; for example, only articles written in the English language published after 2000 will be included. The retrieved articles will be screened independently by two researchers. A third researcher will be consulted in case of disagreement. Data from relevant articles will be independently extracted by two researchers and presented in a tabular manner accompanied by a descriptive narration. ETHICS AND DISSEMINATION: Considering the nature of the study, no ethical approval needed to be requested. The study result will be submitted to a peer-reviewed journal.

Biomechanical evaluation of different semi-rigid junctional fixation techniques using finite element analysis.

BACKGROUND: Proximal junctional failure is a common complication attributed to the rigidity of long pedicle screw fixation constructs used for surgical correction of adult spinal deformity. Semi-rigid junctional fixation achieves a gradual transition in range of motion at the ends of spinal instrumentation, which could lead to reduced junctional stresses, and ultimately reduce the incidence of proximal junctional failure. This study investigates the biomechanical effect of different semi-rigid junctional fixation techniques in a T8-L3 finite element spine segment model. METHODS: First, degeneration of the intervertebral disc was successfully implemented by altering the height. Second, transverse process hooks, one- and two-level clamped tapes, and one- and two-level knotted tapes instrumented proximally to three-level pedicle screw fixation were validated against ex vivo range of motion data of a previous study. Finally, the posterior ligament complex forces and nucleus pulposus stresses were quantified. FINDINGS: Simulated range of motions demonstrated the fidelity of the general model and modelling of semi-rigid junctional fixation techniques. All semi-rigid junctional fixation techniques reduced the posterior ligament complex forces at the junctional zone compared to pedicle screw fixation. Transverse process hooks and knotted tapes reduced nucleus pulposus stresses, whereas clamped tapes increased nucleus pulposus stresses at the junctional zone. INTERPRETATION: The relationship between the range of motion transition and the reductions in posterior ligament complex and nucleus pulposus stresses was complex and dependent on the fixation techniques. Clinical trials are required to compare the effectiveness of semi-rigid junctional fixation techniques in terms of reducing proximal junctional failure incidence rates.

The economic and societal burden associated with adolescent idiopathic scoliosis: A burden-of-disease study protocol.

Background: Adolescent idiopathic scoliosis (AIS) has an estimated general population prevalence of 2% to 3%. The impact of adolescent idiopathic scoliosis (AIS) on the patients' experienced quality of life and psychological well-being and the resulting societal burden are increasingly recognized. However, there is limited knowledge on the economic burden of AIS. This cross-sectional, prevalence-based, bottom-up approach burden of disease study aims to determine the impact associated with adolescent idiopathic scoliosis in terms of the cost-of-illness and health-related quality of life from a societal perspective in the Netherlands. Methods: Persons diagnosed with AIS or parents of a child with AIS that are willing and able to answer the questionnaires will be eligible to participate. Patients will be included consecutively between June until January 2023. Costs and self-perceived health-related quality of life will be estimated using 3 steps: identification, measurement and valuation. To assess the costs associated with AIS the institute for Medical Technology Assessment - Medical Consumption Questionnaire and the institute for Medical Technology Assessment - Productivity Cost Questionnaire will be used. To assess the HRQoL of adult AIS patients the EuroQol 5-dimensions or EuroQol 5-dimensions Youth questionnaire for children under the age of 12 and the Scoliosis Research Society-22 revised questionnaire will be considered. Discussion: This is the first study in this field. It will help raise awareness for AIS and wider support for both the patient community and informal care takers among healthcare professionals and policymakers. Major strengths of this study will be the use of mostly validated, standardized questionnaires. Limitations include the cross-sectional and retrospective nature of the study design.

Predictors of poor outcome following lumbar spinal fusion surgery: a prospective observational study to derive two clinical prediction rules using British Spine Registry data.

PURPOSE: Lumbar spinal fusion surgery (LSFS) is common for lumbar degenerative disorders. The objective was to develop clinical prediction rules to identify which patients are likely to have a favourable outcome to inform decisions regarding surgery and rehabilitation. METHODS: A prospective observational study recruited 600 (derivation) and 600 (internal validation) consecutive adult patients undergoing LSFS for degenerative lumbar disorder through the British Spine Registry. Definition of good outcome (6 weeks, 12 months) was reduction in pain intensity (Numerical Rating Scale, 0-10) and disability (Oswestry Disability Index, ODI 0-50) > 1.7 and 14.3, respectively. Linear and logistic regression models were fitted and regression coefficients, Odds ratios and 95% CIs reported. RESULTS: Lower BMI, higher ODI and higher leg pain pre-operatively were predictive of good disability outcome, higher back pain was predictive of good back pain outcome, and no previous surgery and higher leg pain were predictive of good leg pain outcome; all at 6 weeks. Working and higher leg pain were predictive of good ODI and leg pain outcomes, higher back pain was predictive of good back pain outcome, and higher leg pain was predictive of good leg pain outcome at 12 months. Model performance demonstrated reasonable to good calibration and adequate/very good discrimination. CONCLUSIONS: BMI, ODI, leg and back pain and previous surgery are important considerations pre-operatively to inform decisions for surgery. Pre-operative leg and back pain and work status are important considerations to inform decisions for management following surgery. Findings may inform clinical decision making regarding LSFS and associated rehabilitation.

Predicting Survival in Patients Presenting With Spinal Epidural Metastases: The Limburg Spinal Metastasis Score.

BACKGROUND: Patients with spinal epidural metastases (SEM) often experience a reduction in ambulatory status and, thus, the quality of life. Predicting which patients will benefit from a surgical intervention remains a challenge. Life expectancy is an essential factor to be considered in surgical decision-making, although not the only one. Prediction models can add value in surgical decision-making. The goal of this study was to develop and internally validate a novel model (Limburg spinal metastases score [LSMS]) and compare the predictive value with 2 commonly used models: modified Bauer score and Oswestry Spinal Risk Index (OSRI). METHODS: We retrospectively analyzed 144 consecutive patients who underwent surgical decompression for SEM in our centers between November 2006 and December 2020. Clinical and surgical parameters were evaluated. The novel prediction model was based on multivariate analysis and was internally validated. External validation of the 2 most commonly used prediction models was performed. RESULTS: The median survival was 17 months, 55.7% of the immobile patients regained ambulation postoperatively. In 50 patients (34.7%), at least 1 complication occurred within 30 days after surgery. The LSMS consists of 4 parameters: primary tumor type, Karnofsky performance score, presence of visceral metastases, and presence of multiple spinal metastases. Bootstrap internal validation of the model developed on this cohort yielded an optimism-corrected c-statistic of 0.75 (95% CI: 0.71-0.80). The c-statistic of the OSRI score and the Bauer score was 0.69 (95% CI: 0.64-0.74) and 0.67 (95% CI: 0.62-0.72), respectively. CONCLUSION: The LSMS consists of 4 parameters to assist surgical decision-making for patients with SEM. The score is easy to use and appears more accurate in our population in comparison with previous existing models. CLINICAL RELEVANCE: A novel prediction model was developed to aid in surgical decision-making for patients with spinal epidural metastases.

Preoperative community based functional high intensity interval training (f-HIIT) with high-risk patients opting for lumbar spinal fusion: a pilot study.

PURPOSE: To determine the feasibility, safety and preliminary effectiveness of preoperative functional high-intensity interval training (f-HIIT) for high-risk patients undergoing LSF. MATERIALS AND METHODS: High-risk patients eligible for elective 1-3 level LSF were included. Feasibility and safety of the preoperative f-HIIT program was determined by measuring participation and attrition rates, training adherence, adverse events, reached training intensity and preoperative progression in physical fitness. Preliminary effect of the preoperative f-HIIT program was estimated on time to postoperative functional recovery and length of hospital stay (LoS) between high-risk patients who did and did not participate in the prehabilitation program. RESULTS: Eleven out of 23 high-risk patients opted to participate in the f-HIIT program, which was safe and feasible, as no adverse events occurred and only one out of 74 sessions was missed (1.4%). Trained high-risk patients improved their physical fitness with 21.2% on average and obtained faster time to functional recovery compared to matched untrained patients (median 4.5 vs 7.5 days; p = 0.013). No effect was seen on LoS (median 7 vs 8 days (p = 0.58)). CONCLUSIONS: The preoperative f-HIIT program is feasible, safe and shortened time to postoperative functional recovery in patients who underwent LSF.Implications for rehabilitationPreoperative high-intensity interval training is safe and feasible for high-risk patients opting for lumbar spinal fusion.In a relatively small sample the study shows preoperative high-intensity interval training could reduce time to functional recovery in high-risk patients opting for lumbar spinal fusion.

[Low back pain in daily clinical practice; article for education and training purposes]. / Lagerugpijn.

Low back pain is a very common reason for patient visits to a general practitioner or medical specialist. It is associated with a negative effect on daily living and high costs of care. The differential diagnosis of low back pain is extensive, and usually no specific cause can be identified. In such a case, we speak of non-specific low back pain. In this article, we present practical pointers to recognising specific causes of low back pain and answer some frequently-asked questions regarding the diagnosis and treatment of low back pain.

Immediate patient perceptions following lumbar spinal fusion surgery: semi-structured multi-centre interviews exploring the patient journey and experiences of lumbar fusion surgery (FuJourn).

PURPOSE: To understand the patient journey to Lumbar Spinal Fusion Surgery (LSFS) and patients' experiences of surgery. METHODS: Qualitative study using interpretive phenomenological analysis. Adult participants following LSFS were recruited from 4 UK clinical sites using purposive sampling to ensure representation of key features (e.g. age). Semi-structured interviews informed by a piloted topic guide developed from the literature were audio-recorded and transcribed verbatim. Framework analysis for individual interviews and then across participants (deductive and inductive) identified emerging themes. Trustworthiness of data analyses was enhanced using multiple strategies (e.g. attention to negative cases). RESULTS: Four emerging themes from n = 31 patients' narratives were identified: decision for surgery, coping strategies, barriers to recovery and recovery after surgery. Decision for surgery and recovery after surgery themes are distinguished by the point of surgery. However, barriers to recovery and coping strategies are key to the whole patient journey encompassing long journeys to surgery and their initial journey after surgery. The themes of coping strategies and barriers to recovery were inter-related and perceived by participants as parallel concepts. The 4 multifactorial themes interacted with each other and shaped the process of an individual patient's recovery. Factors such as sporadic interventions prior to surgery, time-consuming wait for diagnosis and surgery and lack of information regarding recovery strongly influenced perceptions of outcome. CONCLUSION: Patient driven data enables insights to inform research regarding surgery/rehabilitation through depth of understanding of the patient journey. Awareness of factors important to patients is important; ensuring that patient-driven data informs research and patient care.

Effectiveness and cost-effectiveness of dynamic bracing versus standard care alone in patients suffering from osteoporotic vertebral compression fractures: protocol for a multicentre, two-armed, parallel-group randomised controlled trial with 12 months of follow-up.

INTRODUCTION: Patients with osteoporosis may suffer from a fracture after minimal trauma. Osteoporotic vertebral compression fractures (OVCFs) are among the most common fractures, often leading to substantial pain. There is a need for evidence-based conservative treatment to aid in the management of OVCFs. The objective of this randomised controlled trial (RCT) is to evaluate the effectiveness and cost-effectiveness of dynamic bracing in addition to standard care for improving quality of life (QoL) in patients suffering from an OVCF. METHODS AND ANALYSIS: Ninety-eight postmenopausal women from two academic and four community hospitals with a recent symptomatic thoracolumbar OVCF will be randomised into either the standard care or dynamic bracing group. In the dynamic bracing group, the Spinova Osteo orthosis will be used in addition to standard care. Standard care comprises pain control with analgesics, physical therapy and osteoporosis medication. The primary outcome parameter is QoL 1 year after inclusion, as measured by the Quality of Life Questionnaire of the European Foundation for Osteoporosis (QUALEFFO-41). Secondary outcome parameters are pain, pain medication used, functional disability, sagittal spinal alignment, recurrence rate of OVCFs and physical activity in daily life. A trial-based economic evaluation consisting of both cost-effectiveness analysis and cost-utility analysis will be performed based on empirical data obtained in the RCT. A process evaluation will assess the feasibility of dynamic bracing. All outcomes will be assessed at baseline, 6 weeks, 3 months, 6 months, 9 months and 12 months. ETHICS AND DISSEMINATION: Ethical approval has been granted by the Medical Ethics Committee, University Hospital Maastricht and Maastricht University (METC azM/UM) (NL74552.068.20/METC 20-055). Patients will be included only after verification of eligibility and obtaining written informed consent. Results will be disseminated via the Dutch National Osteoporosis Patient Society and via publications and conferences. TRIAL REGISTRATION NUMBER: NL8746.

Assessment of need for hemostatic evaluation in patients taking valproic acid: A retrospective cross-sectional study.

INTRODUCTION: Valproic acid (VPA) is a frequently prescribed anti-epileptic drug. Since its introduction side effects on hemostasis are reported. However, studies show conflicting results, and the clinical relevance is questioned. We aimed to determine the coagulopathies induced by VPA in patients who undergo high-risk surgery. The study results warrant attention to this issue, which might contribute to reducing bleeding complications in future patients. METHODS: Between January 2012 and August 2020, 73 consecutive patients using VPA were retrospectively included. Extensive laboratory hemostatic assessment (including platelet function tests) was performed before elective high-risk surgery. Patient characteristics, details of VPA treatment, and laboratory results were extracted from medical records. RESULTS: 46.6% of the patients using VPA (n = 73) showed coagulopathy. Mainly, platelet function disorder was found (36.4%). Thrombocytopenia was seen in 9.6% of the patients. Data suggested that the incidence of coagulopathies was almost twice as high in children as compared to adults and hypofibrinogenemia was only demonstrated in children. No association was found between the incidence of coagulopathies and VPA dosage (mg/kg/day). CONCLUSION: A considerable number of patients using VPA were diagnosed with coagulopathy, especially platelet function disorder. Further prospective studies are needed to confirm the need for comprehensive laboratory testing before elective high-risk surgery in these patients.

Instrumentation Techniques to Prevent Proximal Junctional Kyphosis and Proximal Junctional Failure in Adult Spinal Deformity Correction: A Systematic Review of Clinical Studies.

STUDY DESIGN: Systematic review. OBJECTIVES: To summarize the results of clinical studies investigating spinal instrumentation techniques aiming to reduce the postoperative incidence of proximal junctional kyphosis (PJK) and/or failure (PJF) in adult spinal deformity (ASD) patients. METHODS: EMBASE and Medline® were searched for articles dating from January 2000 onward. Data was extracted by 2 independent authors and methodological quality was assessed using ROBINS-I. RESULTS: 18 retrospective- and prospective cohort studies with a severe or critical risk of bias were included. Different techniques were applied at the upper instrumented vertebra (UIV): tethers in various configurations, 2-level prophylactic vertebroplasty (2-PVP), transverse process hooks (TPH), flexible rods (FR), sublaminar tapes (ST) and multilevel stabilization screws (MLSS). Compared to a pedicle screw (PS) group, significant differences in PJK incidence were found using tethers in various configurations (18% versus 45%, P = 0.001, 15% versus 38%, P = 0.045), 2-PVP (24% vs 36%, P = 0.020), TPH (0% vs. 30%, P = 0.023) and FR (15% versus 38%, P = 0.045). Differences in revision rates for PJK were found in studies concerning tethers (4% versus 18%, P = 0.002), 2-PVP (0% vs 13%, P = 0.031) and TPH (0% vs 7%, P = n.a.). CONCLUSION: Although the studies are of low quality, the most frequently studied techniques, namely 2-PVP as anterior reinforcement and (tensioned) tethers or TPH as posterior semi-rigid fixation, show promising results. To provide a reliable comparison, more controlled studies need to be performed, including the use of clinical outcome measures and a uniform definition of PJF.

Early bone ingrowth and segmental stability of a trussed titanium cage versus a polyether ether ketone cage in an ovine lumbar interbody fusion model.

BACKGROUND CONTEXT: Lumbar interbody fusion is an effective treatment for unstable spinal segments. However, the time needed to establish a solid bony interbody fusion between the two vertebrae may be longer than twelve months after surgery. During this time window, the instrumented spinal segment is assumed to be at increased risk for instability related complications such as cage migration or subsidence. It is hypothesized that the design of new interbody cages that enable direct osseointegration of the cage at the vertebral endplates, without requiring full bony fusion between the two vertebral endplates, might shorten the time window that the instrumented spinal segment is susceptible to failure. PURPOSE: To quantify the bone ingrowth and resulting segmental stability during consolidation of lumbar interbody fusion using two different cage types. STUDY DESIGN: Preclinical ovine model. METHODS: Seven skeletally mature sheep underwent bi-segmental lumbar interbody fusion surgery with one conventional polyether ether ketone (PEEK) cage, and one newly developed trussed titanium (TT) cage. After a postoperative time period of 13 weeks, non-destructive range of motion testing, and histologic analysis was performed. Additionally, sample specific finite element (FE) analysis was performed to predict the stability of the interbody fusion region alone. RESULTS: Physiological movement of complete spinal motion segments did not reveal significant differences between the segments operated with PEEK and TT cages. The onset of creeping substitution within the cage seemed to be sooner for PEEK cages, which led to significantly higher bone volume over total volume (BV/TV) compared with the TT cages. TT cages showed significantly more direct bone to implant contact (BIC). Although the mean stability of the interbody fusion region alone was not statistically different between the PEEK and TT cages, the variation within the cage types illustrated an all-or-nothing response for the PEEK cages while a more gradual increase in stability was found for the TT cages. CONCLUSIONS: Spinal segments operated with conventional PEEK cages were not different from those operated with newly developed TT cages in terms of segmental stability but did show a different mechanism of bone ingrowth and attachment. Based on the differences in development of bony fusion, we hypothesize that TT cages might facilitate increased early segmental stability by direct osseointegration of the cage at the vertebral endplates without requiring complete bony bridging through the cage. CLINICAL SIGNIFICANCE: Interbody cage type affects the consolidation process of spinal interbody fusion. Whether different consolidation processes of spinal interbody fusion result in clinically significant differences requires further investigation.

Local bone metabolism during the consolidation process of spinal interbody fusion.

INTRODUCTION: Although computed tomography (CT) can identify the presence of eventual bony bridges following lumbar interbody fusion (LIF) surgery, it does not provide information on the ongoing formation process of new bony structures. 18F sodium fluoride (18F-NaF) positron emission tomography (PET) could be used as complementary modality to add information on the bone metabolism at the fusion site. However, it remains unknown how bone metabolism in the operated segment changes early after surgery in uncompromised situations. This study aimed to quantify the changes in local bone metabolism during consolidation of LIF. MATERIALS AND METHODS: Six skeletally mature sheep underwent LIF surgery. 18F-NaF PET/CT scanning was performed 6 and 12 weeks postoperatively to quantify the bone volume and metabolism in the operated segment. Bone metabolism was expressed as a function of bone volume. RESULTS: Early in the fusion process, bone metabolism was increased at the endplates of the operated vertebrae. In a next phase, bone metabolism increased in the center of the interbody region, peaked, and declined to an equilibrium state. During the entire postoperative time period of 12 weeks, bone metabolism in the interbody region was higher than that of a reference site in the spinal column. CONCLUSION: Following LIF surgery, there is a rapid increase in bone metabolism at the vertebral endplates that develops towards the center of the interbody region. Knowing the local bone metabolism during uncompromised consolidation of spinal interbody fusion might enable identification of impaired bone formation early after LIF surgery using 18F-NaF PET/CT scanning.

Biomechanical Evaluation of Semi-rigid Junctional Fixation Using a Novel Cable Anchor System to Prevent Proximal Junctional Failure in Adult Spinal Deformity Surgery.

STUDY DESIGN: A porcine cadaveric biomechanical study. OBJECTIVE: To biomechanically evaluate a novel Cable Anchor System as semi-rigid junctional fixation technique for the prevention of proximal junctional failure after adult spinal deformity surgery and to make a comparison to alternative promising prophylactic techniques. SUMMARY OF BACKGROUND DATA: The abrupt change of stiffness at the proximal end of a pedicle screw construct is a major risk factor for the development of proximal junctional failure after adult spinal deformity surgery. A number of techniques that aim to provide a gradual transition zone in range of motion (ROM) at the proximal junction have previously been studied. In this study, the design of a novel Cable Anchor System, which comprises a polyethylene cable for rod fixation, is assessed. METHODS: Ten T6-T13 porcine spine segments were subjected to cyclic 4 Nm pure-moment loading. The following conditions were tested: uninstrumented, 3 level pedicle screw fixation (PSF), and PSF with supplementary Cable Anchors applied proximally at 1-level (Anchor1) or 2-levels (Anchor2), transverse process hooks (TPH), and 2-level sublaminar tapes (Tape2). The normalized segmental range of motion in the junctional zone was compared using one-way analysis of variance and linear regression. RESULTS: Statistical comparison at the level proximal to PSF showed significantly lower ROMs for all techniques compared to PSF fixation alone in all movement directions. Linear regression demonstrated a higher linearity for Anchor1 (0.820) and Anchor2 (0.923) in the junctional zone in comparison to PSF (1-level: 0.529 and 2-level: 0.421). This linearity was similar to the compared techniques (TPH and Tape2). CONCLUSION: The Cable Anchor System presented in this study demonstrated a gradual ROM transition zone at the proximal end of a rigid pedicle screw construct similar to TPH and 2-level sublaminar tape semi-rigid junctional fixation constructs, while providing the benefit of preserving the posterior ligament complex.Level of Evidence: 5.

The Effect of Bolus Vitamin D3 Supplementation on Distal Radius Fracture Healing: A Randomized Controlled Trial Using HR-pQCT.

Vitamin D is an important factor in bone metabolism. Animal studies have shown a positive effect of vitamin D3 supplementation on fracture healing, but evidence from clinical trials is inconclusive. A randomized controlled trial was performed to assess the effects of vitamin D3 supplementation on fracture healing using HR-pQCT-based outcome parameters. Thirty-two postmenopausal women with a conservatively treated distal radius fracture were included within 2 weeks postfracture and randomized to a low-dose (N = 10) and a high-dose (N = 11) vitamin D intervention group receiving a 6-week bolus dose, equivalent to 700 and 1800 IU vitamin D3 supplementation per day, respectively, in addition to a control group (N = 11) receiving no supplementation. After the baseline visit 1-2 weeks postfracture, follow-up visits were scheduled at 3-4, 6-8, and 12 weeks postfracture. At each visit, HR-pQCT scans of the fractured radius were performed. Cortical and trabecular bone density and microarchitectural parameters and microfinite element analysis-derived torsion, compression, and bending stiffness were assessed. Additionally, serum markers of bone resorption (CTX) and bone formation (PINP) were measured. Baseline serum levels of 25OHD3 were <50 nmol/L in 33% of all participants and <75 nmol/L in 70%. Compared with the control group, high-dose vitamin D3 supplementation resulted in a decreased trabecular number (regression coefficient ß: -0.22; p < 0.01) and lower compression stiffness (B: -3.63; p < 0.05, together with an increase in the bone resorption marker CTX (B: 0.062; p < 0.05). No statistically significant differences were observed between the control and low-dose intervention group. In conclusion, the bolus equivalent of 700 U/day vitamin D3 supplementation in a Western postmenopausal population does not improve distal radius fracture healing and an equivalent dose of 1800 IU/day may be detrimental in restoring bone stiffness during the first 12 weeks of fracture healing. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Overall survival nomogram for patients with spinal bone metastases (SBM).

•Demographic features are essential for a more personalize survival prediction of spinal bone metastasis (SBM).•Women have a relatively better survival chance than men before 75 years, while men have better survival after this age.•SBM survival is not dependent on the number of spinal metastases.