A Novel Three-Dimensional Computational Method to Assess Rod Contour Deformation and to Map Bony Fusion in a Lumbopelvic Reconstruction After En-Bloc Sacrectomy

Introduction: En-bloc resection of a primary malignant sacral tumor with wide oncological margins impacts the biomechanics of the spinopelvic complex, deteriorating postoperative function. The closed-loop technique (CLT) for spinopelvic fixation (SPF) uses a single U-shaped rod to restore the spinopelvic biomechanical integrity. The CLT method was designed to provide a non-rigid fixation, however this hypothesis has not been previously tested. Here, we establish a computational method to measure the deformation of the implant and characterize the bony fusion process based on the 6-year follow-up (FU) data.Materials and Methods: Post-operative CT scans were collected of a male patient who underwent total sacrectomy at the age of 42 due to a chordoma. CLT was used to reconstruct the spinopelvic junction. We defined the 3D geometry of the implant construct. Using rigid registration algorithms, a common coordinate system was created for the CLT to measure and visualize the deformation of the construct during the FU. In order to demonstrate the cyclical loading of the construct, the patient underwent gait analysis at the 6th year FU. First, a region of interest (ROI) was selected at the proximal level of the construct, then the deformation was determined during the follow-up period. In order to investigate the fusion process, a single axial slice-based voxel finite element (FE) mesh was created. The Hounsfield values (HU) were determined, then using an empirical linear equation, bone mineral density (BMD) values were assigned for every mesh element, out of 10 color-coded categories (1st category = 0 g/cm3, 10th category 1.12 g/cm3).Results: Significant correlation was found between the number of days postoperatively and deformation in the sagittal plane, resulting in a forward bending tendency of the construct. Volume distributions were determined and visualized over time for the different BMD categories and it was found that the total volume of the elements in the highest BMD category in the first postoperative CT was 0.04 cm3, at the 2nd year, FU was 0.98 cm3, and after 6 years, it was 2.30 cm3.Conclusion: The CLT provides a non-rigid fixation. The quantification of implant deformation and bony fusion may help understate the complex lumbopelvic biomechanics after sacrectomy.

Does Local Vancomycin Powder Impregnated with Autogenous Bone Graft and Bone Substitute Decrease the Risk of Deep Surgical Site Infection in Degenerative Lumbar Spine Fusion Surgery? - an Ambispective Study

Background:Deep surgical site infection (DSSI) is one of the most challenging complications in lumbar fusion surgery. Few investigations examined the effect of vancomycin powder mixed with ABG and bone substitutes on preventing DSSI in degenerative lumbar fusion surgeries as well as any interference with bony fusion. The aim of the study was to investigate the effects of autogenous bone graft (ABG) along with bone substitutes as a local vancomycin delivery system on preventing DSSI in lumbar instrumented fusion and compared with those who did not use vancomycin powder.Methods: From January, 2015 through December, 2015, a one-year prospective study using vancomycin powder mixed with ABG and bone substitute for degenerative lumbar fusion surgeries as vancomycin (V) group, 1 gm vancomycin for 2 and 3-level, and 2 gm for more than 3-level instrumentation. From December, 2013 through December 2014, patients received degenerative lumbar fusion surgeries without using vancomycin before the vancomycin protocol were retrospectively enrolled as non-vancomycin (NV) group. Vancomycin concentration was checked at post-operative days 1 and 3 for both the serum and drainage. Patients’ demographic data, microbiology reports, fusion status and functional outcomes were evaluated. Results:One hundred and ten patients were enrolled prospectively in the V group, and 86 for the NV group. After an average 41 months follow-up (range, 36-54), 3 patients (3.48%) developed postoperative DSSIs in the NV group, thereby requiring revision surgeries and parenteral antibiotics treatment versus no DSSIs (0%, 0/100) in the V group. (p=0.048). The postoperative serum vancomycin levels were undetectable and no vancomycin related side effects was encountered. The mean vancomycin concentration of drainage at postoperative days 1 and 3 were 517.96 ± 174.4 and 220.14 ± 102.3 mg/mL, respectively. At final follow-up, there was no statistical difference observed in terms of clinical and radiologic outcomes. Conclusions: Our vancomycin protocol may reduce the incidence of DSSI in degenerative lumbar fusion surgery without affecting bony fusion.

Targeting chondrocytes for arresting bony fusion in ankylosing spondylitis

Bony fusion caused by pathological new bone formation manifests the clinical feature of ankylosing spondylitis (AS). However, the underlying mechanism remains elusive. Here we discovered spontaneous kyphosis, arthritis and bony fusion in mature CD4-Cre;Ptpn11f/f mice, which present the pathophysiological features of AS. A population of CD4-Cre-expressing proliferating chondrocytes was SHP2 deficient, which could differentiate into pre-hypertrophic and hypertrophic chondrocytes. Functionally, SHP2 deficiency in chondrocytes impeded the fusion of epiphyseal plate and promoted chondrogenesis in joint cavity and enthesis. Mechanistically, aberrant chondrocytes promoted ectopic new bone formation through BMP6/pSmad1/5 signaling. It is worth emphasizing that such pathological thickness of growth plates was evident in adolescent humans with enthesitis-related arthritis, which could progress to AS in adulthood. Targeting dysfunctional chondrogenesis with Smo inhibitor sonidegib significantly alleviated the AS-like bone disease in mice. These findings suggest that blockade of chondrogenesis by sonidegib would be a drug repurposing strategy for AS treatment.

Is laminoplasty or laminectomy the best strategy for C3 segment in French-door laminoplasty? A systematic review and meta-analysis

Background To compare the clinical outcomes of C3 laminectomy and C3 laminoplasty at the C3 segment during French-door laminoplasty. Methods The Cochrane Library, PubMed, Embase, and Web of Science databases were searched from inception to November 10, 2020 for studies comparing the clinical outcomes of two types of French-door laminoplasty in the treatment of multilevel cervical spondylotic myelopathy (MCSM). Review Manager 5.3 was used to analyze the following outcomes: operative time, intraoperative blood loss, preoperative and postoperative Japanese Orthopaedic Association (JOA) scores, recovery rate, cervical curvature, cervical range of motion (ROM), incidence of axial symptoms (AS), and C2-3 bony fusion rate. Results A total of eight studies involving 776 patients were included; there were 424 patients in the C3 laminectomy group and 352 patients in the C3 laminoplasty group. The results of the meta-analysis showed that the C3 laminectomy group was superior to the C3 laminoplasty group in terms of operative time (P < 0.00001), cervical ROM (P = 0.04), and incidence of AS (P < 0.0001). However, no statistically significant differences between the two groups were noted regarding intraoperative bleeding (P = 0.44), preoperative JOA score (P = 0.57), postoperative JOA score (P = 0.09), recovery rate (P = 0.25), cervical curvature (P = 0.22), and C2-3 bony fusion rate (P = 0.06). Conclusion This meta-analysis demonstrated that both C3 laminoplasty and C3 laminectomy could effectively improve neurological function in patients with MCSM in French-door laminoplasty. However, C3 laminectomy can reduce the operative time, preserve cervical ROM, and reduce the incidence of postoperative AS. Trial registration PROSPERO registration number is CRD42021230798. Date of registration: February 11, 2021.

Radiological and mid- to long-term patient-reported outcome after stabilization of traumatic thoraco-lumbar spinal fractures using an expandable vertebral body replacement implant

Background For the treatment of unstable thoraco-lumbar burst fractures, a combined posterior and anterior stabilization instead of a posterior-only instrumentation is recommend in the current literature due to the instability of the anterior column. Data on restoring the bi-segmental kyphotic endplate angle (BKA) with expandable vertebral body replacements (VBR) and on the mid- to long-term patient-reported outcome measures (PROM) is sparse. Methods A retrospective cohort study of patients with traumatic thoraco-lumbar spinal fractures treated with an expandable VBR implant (Obelisc™, Ulrich Medical, Germany) between 2001 and 2015 was conducted. Patient and treatment characteristics were evaluated retrospectively. Radiological data acquisition was completed pre- and postoperatively, 6 months and at least 2 years after the VBR surgery. The BKA was measured and fusion-rates were assessed. The SF-36, EQ-5D and ODI questionnaires were evaluated prospectively. Results Ninety-six patients (25 female, 71 male; age: 46.1 ± 12.8 years) were included in the study. An AO Type A4 fracture was seen in 80/96 cases (83.3%). Seventy-three fractures (76.0%) were located at the lumbar spine. Intraoperative reduction of the BKA in n = 96 patients was 10.5 ± 9.4° (p < 0.01). A loss of correction of 1.0 ± 2.8° at the first follow-up (t1) and of 2.4 ± 4.0° at the second follow-up (t2) was measured (each p < 0.05). The bony fusion rate was 97.9%. The total revision rate was 4.2%. Fifty-one patients (53.1% of included patients; age: 48.9 ± 12.4 years) completed the PROM questionnaires after 106.4 ± 44.3 months and therefore were assigned to the respondent group. The mean ODI score was 28.2 ± 18.3%, the mean EQ-5D VAS reached 60.7 ± 4.1 points. Stratified SF-36 results (ISS < and ≥ 16) were lower compared to a reference population. Conclusion The treatment of traumatic thoraco-lumbar fractures with an expandable VBR implant lead to a high rate of bony fusion. A significant correction of the BKA could be achieved and no clinically relevant loss of reduction occurred during the follow-up. Even though health related quality of life did not reach the normative population values, overall satisfactory results were reported.

Spinous Process Combined with a Titanium Mesh Cage as a Bone Graft in the Stability Reconstruction of Lumbar or Lumbosacral Spinal Tuberculosis

Background. To investigate the clinical efficacy of one-stage posterior debridement using the spinous process (SP) combined with titanium mesh cages (TMCs) as interbody grafts for the treatment of single-segment lumbar or lumbosacral spinal tuberculosis.Methods. From 2010 to 2018, 69 patients who underwent one-stage posterior debridement using grafts and internal fixation within a single lumbar or lumbosacral segment were included in this study. 12 cases using the SP combined with a TMC (SP+TMC, group A), 30 cases using a TMC only (group B), and 27 cases using allografts (group C) were included. Measurements including operative time, blood loss, hospital stay, visual analogue scale (VAS) score, Oswestry Disability Index (ODI), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), American Spinal Injury Association Impairment (ASIA) grade, final follow-up (FFU) duration and postoperative complications were recorded. Radiological measurements, including the number of segments fixated, the number of pedicle screws used, the Cobb angle, pelvic parameters, and the bony fusion time, were reviewed. All outcomes were analysed using SPSS 25.Results. We found that group A had fewer fixation segments (1.67±0.64 vs 2.81±0.94, pAC<0.01), fewer pedicle screws implanted (5.05±1.29 vs 6.85±1.37, pAC<0.01), a shorter operative time (166.43±44.11 min vs 205.93±51.73 min, pAC<0.01), reduced blood loss (543.81±230.81 ml vs 803.70±446.78 ml, pAC<0.01), and a strikingly lower hospital cost (14710.42±2354.55$ vs 19260.34±3310.75$, pAC<0.01) than group C.Compared to group B, group A had a lower economic cost (16680.23±3614.73$ vs 14710.42±2354.55$, pAB=0.03). There was no significant difference in bony fusion time among the three groups (8.90 ±2.11 months vs 8.60±2.39 months vs 9.59 ±2.04 months, p>0.01). No significant difference was observed with respect to pre- or postoperative ESR and CRP (p>0.01). There was no significant difference among the 3 groups with respect to the ODI, VAS score or ASIA grade during any period. No differences regarding the hospital stay, rate of complications, loss of PI-LL, correction or loss of Cobb angle were observed among the three groups (p>0.01).Conclusion. Our study demonstrates that compared to a TMC or allograft, the use of the SP combined with a TMC as a bone graft is an effective and reliable approach for the surgical management of one-level lumbar or lumbosacral spinal tuberculosis, leading to good restoration of spinal stability. Furthermore, this approach is an economical structural bone grafting method, especially for patients in developing countries or areas.

Is there a difference in the outcomes of anterior cervical discectomy and fusion among female patients with different menopausal statuses?

Background The surgical outcomes of anterior cervical discectomy and fusion (ACDF) in female patients according to menopausal status remain unclear. The objective of this study was to investigate the differences in these outcomes among female patients with different menopausal statuses. Methods Ninety-one patients undergoing single-level or consecutive two-level ACDF with a minimum 12-month postoperative follow-up were included in this study. There were 38 patients in the premenopausal group, 28 patients in the early postmenopausal group, and 25 patients in the late postmenopausal group. The clinical outcomes were evaluated by means of the neck disability index (NDI) scores, Japanese Orthopedic Association (JOA) scores, and visual analog scale (VAS) scores. Radiological parameters included cervical lordosis (CL), the functional spinal unit (FSU) angle, range of motion (ROM) of the total cervical spine, ROM of the FSU, anterior and posterior FSU height, implant subsidence, adjacent segment degeneration (ASD), and Hounsfield unit (HU) values. Results All groups showed significant improvements in their JOA, VAS, and NDI scores (P < 0.05). The differences in preoperative and final follow-up CL, ROM of C2-7, FSU angle, and ROM of FSU were not statistically significant among the three groups (P > 0.05). The anterior FSU height loss rate showed a significant difference (P = 0.043), while there was no difference in the posterior FSU height loss rate (P = 0.072). The fusion rates in the early and late postmenopausal groups were consistently lower than those in the premenopausal group during the follow-up period. All patients had satisfactory outcomes at the final follow-up. Conclusion There were no significant differences in clinical or other related outcomes of single-level or consecutive two-level ACDF in the long term among female patients with different menopausal statuses. However, the early bony fusion rates and anterior FSU height loss rates were poorer in late postmenopausal patients than in premenopausal or early postmenopausal patients. Hence, importance should be attached to the protection of late postmenopausal patients in the early postoperative period to guarantee solid bony fusion.

ACDF Using a Zero Profile Cage Plate for The Management Of Degenerative Cervical Disc Disease, Early Experience From A Middle Eastern Tertiary Hospital.

Background: Management of cervical disc degenerative diseases through anterior cervical decompression and fusion (ACDF) using various implants had been reported, a Zero-p device used as a stand-alone cage plate in ACDF was introduced to offer higher safety and efficacy. In the current prospective cohort study, we aimed at reporting our early experience from a Middle Eastern tertiary hospital after using the Zero profile cage plate in the management of degenerative cervical disc diseases through ACDF by reporting the clinical, radiological outcomes as well as the incidence of complications. Methods: Thirty patients (16 male and 14 female) with a mean age of 47.9 ±10.9 underwent ACDF with Zero-p implant, a total of 43 operated levels (one level in 20 patients, double levels in 7, and multi-levels in 3). Clinical outcomes were evaluated according to VAS to measure the neck and radicular arm pain and neck disability index (NDI). Radiographic bony fusion was assessed according to Pitzen criteria, any perioperative complications were reported, and the presence of dysphagia was assessed according to the Bazaz-Yoo dysphagia index. Results: At a mean follow up of 14.4 ± 2.3 months, all patients obtained radiographic bony fusion, all patients had a significant reduction of neck and radicular arm pain with a mean VAS score of 7.33 and 8.70 preoperatively to 1.73 and 0.27 at 12 months follow-up respectively (p<0.0001), and reduction of NDI from 68.87% preoperatively to 8.60% at 12 months follow-up (p<0.0001). None had dysphagia after six months postoperatively; one patient developed back-out of one of the implant screws that was extracted, and otherwise, no other implant-related complications. Conclusion: the Zero-p implant is a valid alternative to anterior cervical plating after ACDF with a very low incidence of chronic dysphagia and implant-related complications.Level of Evidence Ⅳ

GATA3 is essential for separating patterning domains during facial morphogenesis

Neural crest cells (NCCs) within the mandibular and maxillary prominences of the first pharyngeal arch are initially competent to respond to signals from either region. However, mechanisms that are only partially understood establish developmental tissue boundaries to ensure spatially correct patterning. In the Hinge and Caps model of facial development, signals from both ventral prominences (the caps) pattern the adjacent tissues while the intervening region, referred to as the maxillomandibular junction (the hinge), maintains separation of the mandibular and maxillary domains. One cap signal is GATA3, a member of the GATA family of zinc-finger transcription factors with a distinct expression pattern in the ventral-most part of the mandibular and maxillary portions of the first arch. Here we show that disruption of Gata3 in mouse embryos leads to craniofacial microsomia and syngnathia (bony fusion of the upper and lower jaws) that results from changes in BMP4 and FGF8 gene regulatory networks within NCCs near the maxillomandibular junction. GATA3 is thus a crucial component in establishing the network of factors that functionally separate the upper and lower jaws during development.