Is Aggressive Surgery Always Necessary for Suspected Early-Onset Surgical Site Infection after Lumbar Surgery? A 10-Year Retrospective Analysis.

OBJECTIVE: Surgical site infection (SSI) after spinal surgery is still a persistent worldwide health concern as it is a worrying and devastating complication. The number of samples in previous studies is limited and the role of conservative antibiotic therapy has not been established. This study aims to evaluate the clinical efficacy and feasibility of empirical antibiotic treatment for suspected early-onset deep spinal SSI. METHODS: We conducted a retrospective study to identify all cases with suspected early-onset deep SSI after lumbar instrumented surgery between January 2009 and December 2018. We evaluated the potential risks for antibiotic treatment, examined the antibiotic treatment failure rate, and applied logistic regression analysis to assess the risk factors for empirical antibiotic treatment failure. RESULTS: Over the past 10 years, 45 patients matched the inclusion criteria. The success rate of antibiotic treatment was 62.2% (28/45). Of the 17 patients who failed antibiotic treatment, 16 were cured after a debridement intervention and the remaining one required removal of the internal fixation before recovery. On univariate analysis, risk factors for antibiotic treatment failure included age, increasing or persisting back pain, wound dehiscence, localized swelling, and time to SSI (cut-off: 10 days). Multivariate analysis revealed that infection occurring 10 days after primary surgery and wound dehiscence were independent risk factors for antibiotic treatment failure. CONCLUSION: Appropriate antibiotic treatment is an alternative strategy for suspected early-onset deep SSI after lumbar instrumented surgery. Antibiotic treatment for suspected SSI occurring within 10 days after primary surgery may improve the success rate of antibiotic intervention. Patients with wound dehiscence have a significantly higher likelihood of requiring surgical intervention.

Pathogen detection in suspected spinal infection: metagenomic next-generation sequencing versus culture.

PURPOSE: The aim is to compare the pathogen detection performance of metagenomic next-generation sequencing (mNGS) and the culturing of percutaneous needle biopsy samples obtained from an individual with a suspected spinal infection. METHODS: A retrospective study of 141 individuals with a suspected spinal infection was conducted, and mNGS was performed. The microbial spectra and detection performance between mNGS and the culturing-based method were compared, and the effects of antibiotic intervention and biopsy on the detection performance were assessed. RESULTS: The microorganisms isolated most commonly via the culturing-based method were Mycobacterium tuberculosis (n = 21), followed by Staphylococcus epidermidis (n = 13). The most common microorganisms detected via mNGS were Mycobacterium tuberculosis complex (MTBC) (n = 39), followed by Staphylococcus aureus (n = 15). The difference in the type of detected microorganisms between culturing and mNGS was observed only in Mycobacterium (P = 0.001). mNGS helped identify potential pathogens in 80.9% of cases, which was significantly higher than the positivity rate of 59.6% observed for the culturing-based method (P < 0.001). Moreover, mNGS had a sensitivity of 85.7% (95% CI, 78.4% to 91.3%), a specificity of 86.7% (95% CI, 59.5% to 98.3%), and sensitivity gains of 35% (85.7% vs. 50.8%; P < 0.001) during culturing, while no differences were observed in the specificity (86.7% vs. 93.3%; P = 0.543). In addition, antibiotic interventions significantly lowered the positivity rate of the culturing-based method (66.0% vs. 45.5%, P = 0.021) but had no effects on the results of mNGS (82.5% vs. 77.3%, P = 0.467). CONCLUSION: The use of mNGS could result in a higher detection rate compared to that observed with the culturing-based method in an individual with spinal infection and is particularly valuable for evaluating the effects of a mycobacterial infection or previous antibiotic intervention.

Facile Fabrication of 3D-Printed Porous Ti6Al4V Scaffolds with a Sr-CaP Coating for Bone Regeneration.

To improve osseointegration caused by the stress-shielding effect and the inert nature of titanium-based alloys, in this work, we successfully constructed a strontium calcium phosphate (Sr-CaP) coating on three-dimensional (3D)-printed Ti6Al4V scaffolds to address this issue. The energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) results indicated that the coatings with and without Sr doping mainly consisted of CaHPO4. The bonding strength of Sr doping coating met the required ISO 13 779-4-2018 standard (≥15 MPa). The in vitro results suggested that the Sr-CaP-modified Ti6Al4V scaffolds were found to effectively promote mice bone-marrow stem cell (mBMSC) adhesion, spreading, and osteogenesis. The in vivo experiments also showed that the Sr-CaP-modified Ti6Al4V scaffolds could significantly improve bone regeneration and osseointegration. More importantly, Sr-doped CaP-coated Ti6Al4V scaffolds were found to accelerate bone healing in comparison to CaP-coated Ti6Al4V scaffolds. The Sr-CaP-modified Ti6Al4V scaffolds are considered a promising strategy to develop bioactive surfaces for enhancing the osseointegration between the implant and bone tissue.

In Vitro Study of Degradation and Cytocompatibility of Ceramics/PLA Composite Coating on Pure Zinc for Orthopedic Application.

Zinc and its alloys are considered to be next-generation materials for fabricating absorbable biomedical devices. However, cytotoxicity has been reported to be associated with rapid degradation. To address these issues, a composite coating (PLA/Li-OCP) consisting of CaHPO4 conversion coating (Ca-P) and polylactic acid (PLA) decorated with Li-octacalcium phosphate particles was constructed on pure zinc. The immersion tests showed that the presence of Ca-P coating and PLA/Li-OCP coating on pure zinc could reduce the pH value. Compared with Ca-P coating, the introduction of the PLA/Li-OCP film on the Ca-P-coated samples could enhance the corrosion resistance, and there was one order of magnitude decrease in the corrosion current density. The cytocompatibility assay suggested that the PLA/Li-OCP coating favored the cell viability and upregulated the expression of related osteogenic-genes including RUNX2, OCN, and BMP. Therefore, the presence of the PLA/Li-OCP coating on pure zinc could effectively improve the degradation rate and cytocompatibility of pure zinc.

Finite Element Assessment of the Screw and Cement Technique in Total Knee Arthroplasty.

BACKGROUND: The screw and cement technique is a convenient method used to rebuild medial tibial plateau defects in primary total knee arthroplasty (TKA). The objective of this study was to perform a finite element assessment to determine the effect of different numbers of screws on the stability of TKA and to determine whether differences exist between two different insertion angles. METHOD: Six tibial finite element models with defects filled with screws and cement and one model with defects filled only with cement were generated. Contact stresses on the surface of cancellous bone in different areas were calculated. RESULTS: Compared to the cement-only technique, the stress on the border of cancellous bone and bone cement decreased by 10% using the screw and cement technique. For bone defects with a 12% defect area and a 12-mm defect depth, the use of 1 screw achieved the greatest stability; for those with a 15% defect area and a 20-mm defect depth, 2 screws achieved the greatest stability. CONCLUSIONS: (1) The screw and cement technique is superior to the bone cement-only technique. For tibial defects in which the defect area comprises a large percentage but the depth is less than 5 mm, the screw and cement technique is recommended. (2) Vertical screws can achieve better stability than oblique screws. (3) Screws should be used in moderation for different defects; more is not always better.

Comparison of the Pull-Out Strength between a Novel Micro-Dynamic Pedicle Screw and a Traditional Pedicle Screw in Lumbar Spine.

OBJECTIVE: This study aimed to investigate the strength of a novel micro-dynamic pedicle screw by comparing it to the traditional pedicle screw. METHODS: Forty-five lumbar vertebrae received a traditional pedicle screw on one side and a micro-dynamic pedicle screw on the other side as follows (traditional group vs micro-dynamic group): 15 vertebrae underwent instant pull-out testing; 15 vertebrae underwent 5000-cyclic fatigue loading testing; and 15 vertebrae underwent 10,000-cyclic fatigue loading testing and micro-computed tomography (micro-CT) scanning. The peek pull-out force and normalized peek pull-out force after instant pull-out testing, 5000-cyclic and 10,000-cyclic fatigue loading testing were recorded to estimate the resistance of two types of screws. Bone mineral density was recorded to investigate the strength of the different screws in osteoporotic patients. And the semidiameter of the screw insertion area on micro-CT images after fatigue were compared to describe the performance between screw and bone surface. RESULTS: The bone mineral density showed a weak correlation with peek pull-out force (r = 0.252, P = 0.024). The peek pull-out force of traditional pedicle screw after 10,000-cyclic fatigue loading were smaller than that of instant pull-out test in both osteoporotic (P = 0.017) and healthy group (P = 0.029), the peek pull-out force of micro-dynamic pedicle screw after 10,000-cyclic fatigue loading was smaller than that in instant pull-out test in osteoporotic group (P = 0.033), but no significant difference in healthy group (P = 0.853). The peek pull-out force in traditional group and micro-dynamic group underwent instant pull-out testing (P = 0.485), and pull-out testing after 5000-cyclic fatigue loading testing (P = 0.184) did not show significant difference. However, the peek pull-out force in micro-dynamic group underwent pull-test after 10,000-cyclic fatigue loading testing was significantly greater than that measured in traditional group (P = 0.005). The normalized peek pull-out force of traditional groups underwent instant pull-out testing, pull-out test after 5000-cyclic and 10,000-cyclic fatigue loading testing significantly decreased as the number of cycles increased (P < 0.001); meanwhile, the normalized peek pull-out force of micro-dynamic groups remained consistent regardless of the number of cycles (P = 0.133). The semidiameter after the fatigue loading test of the traditional screw insertion area was significantly larger than that of the micro-dynamic screw insertion area (P = 0.013). CONCLUSION: The novel micro-dynamic pedicle screw provides stronger fixation stability in high-cyclic fatigue loading and non-osteoporotic patients versus the traditional pedicle screw, but similar resistance in low-cycle fatigue testing and osteoporotic group vs the traditional pedicle screw.

Alkaline-phosphatase triggered self-assemblies enhances the anti-inflammatory property of methylprednisolone in spinal cord injury.

Methylprednisolone sodium phosphate (MP) is an anti-inflammatory corticosteroid which is used in the treatment of spinal cord injury (SCI), however the overdose of MP has toxic effects Therefore it is prerequisite to develop novel approaches to overcome the side effects of MP and enhance its efficacy. In the present work, we have developed alkaline phosphatase (ALP) trigger self-assembly system of oligopeptides to physically entrap and locally deliver MP. The synthesis of Nap-Phe-Phe-Tyr(H2PO3)-OH (1P) was achieved using solid phase peptide synthesis and was characterized using mass spectroscopy. The 1P is a hydrogelator, which in presence of ALP self-assembles to form the hydrogel. During the self-assembly of 1P, MP was physically entrapped without losing the physical strength of hydrogel as revealed in the rheology study. The consistency of this hydrogel and the structure was characterized using circular dichroism. The MP was released from the hydrogel in a sustain manner and 80% of the drug release was observed at 120 h. The MP + 1P were non-toxic to the cells at lower concentration however toxicity increases with the increase in concentration of MP. Further, the in-vivo administration of MP + 1P significantly reduces the pro-inflammatory cytokines and the histological analysis revealed improvement in the SCI. In conclusion, it could be stated that the synthesis of 1P for the delivery of MP provides the novel opportunity in for the treatment of SCI.

Association between lumbar sacralization and increased degree of vertebral slippage and disc degeneration in patients with L4 spondylolysis.

OBJECTIVEThe aim of this study was to evaluate the effect of lumbar sacralization on the level of vertebral slip and disc degeneration in patients with L4 spondylolysis.METHODSThe authors analyzed data from 102 cases in which patients underwent surgical treatment for L4 spondylolysis and spondylolisthesis at their institution between March 2007 and September 2016. Lumbar sacralization was characterized by the presence of pseudarthrosis and/or bony fusion between the L5 transverse process and sacrum, and the type of lumbosacral transitional vertebra (LSTV) was evaluated with the Castellvi classification. The amount of vertebral slippage was measured using the Taillard technique and Meyerding grade. Degeneration of the L4-5 segment was quantified using the Pfirrmann and Modic classifications. Patients were divided into 2 groups based on the presence or absence of sacralization, and the amount of vertebral slip and degeneration of the L4-5 segment was compared between groups.RESULTSLumbar sacralization was present in 37 (36%) of 102 patients with L4 spondylolysis. The LSTV was type IIa in 10 cases, type IIb in 7, type IIIa in 2, and type IIIb in 18. The levels of vertebral slip and disc degeneration in the group of patients with sacralization were significantly greater than in the group without sacralization. No significant difference was found between the 2 groups with respect to Modic changes.CONCLUSIONSThe increased stability between a sacralized L5 and the sacrum may predispose the L4-5 segment to greater instability and disc degeneration in patients with L4 spondylolysis.

Anterior Transdiscal Axial Screw Fixation for Subaxial Cervical Spine: A Biomechanical Study.

OBJECTIVE: To evaluate stability of anterior transdiscal axial screw (ATAS) fixation for anterior instrumentation and to compare with standard anterior cervical decompression and fusion and plate (ACDFP) fixation in human subaxial cervical spine. METHODS: Flexibility tests were conducted on 7 cadaveric specimens (C5-T1) in an intact and injured state and instrumented with ACDFP fixation, ATAS fixation, and ACDFP plus ATAS fixation at the C6-7 segment after section of the anterior and posterior longitudinal ligaments and discectomy. A pure moment of ±2.0 N-m was applied to the specimen in flexion-extension, lateral bending, and axial rotation. Range of motion (ROM) and neutral zone were calculated for the C6-7 segment. RESULTS: ROM was reduced significantly compared with the intact or injured condition for 3 configurations under all motions. ATAS fixation resulted in similar ROM in C6-7 compared with ACDFP fixation in flexion (2.7° vs. 2.6°, P = 0.419), extension (2.7° vs. 2.1°, P = 0.152), and lateral bending (4.6° vs. 4.2°, P = 0.295) but larger ROM in axial rotation (6.1° vs. 5.3°, P = 0.014). When combined with an anterior plate, ATAS fixation reduced ROM to 1.2° in flexion, 1.1° in extension, 3.3° in lateral bending, and 3.8° in axial rotation, which were significantly smaller than ACDFP or ATAS fixation alone. CONCLUSIONS: ATAS fixation is a biomechanically effective alternative or supplemental method of anterior fixation in subaxial cervical spine.

[Association of vitamin D receptor gene polymorphisms with susceptibility to bone and joint tuberculosis in Chinese Han population].

OBJECTIVE: To investigate the association between vitamin D receptor (VDR) gene Apa I polymorphism and the susceptibility to bone and joint tuberculosis in Chinese Han population. METHODS: Between May, 2015 and June, 2016, 100 patients with bone and joint tuberculosis and 100 healthy volunteers were recruited concomitantly in Heyuan Hospital of Traditional Chinese Medicine. Vitamin D receptor gene Apa I polymorphisms in these subjects were analyzed using SNaPshot. RESULT: The genotype frequencies of Apa I-AA, Apa I-Aa and Apa I-aa were 51%, 41%, and 8% in the case group and 33%, 55%, and 12% in the control group, respectively, showing significant differences between the two groups (P<0.05). The genotype of Apa I-AA was significantly higher in the case group with an odds ratio (OR) of 2.073 (95% CI: 1.142-3.763). CONCLUSION: The Apa I polymorphisms of the VDR gene are associated with the susceptibility to bone and joint tuberculosis in Chinese Han population, and individuals with a Apa I-AA genotype are at greater risks to develop bone and joint tuberculosis.

Anatomic Study of Anterior Transdiscal Axial Screw Fixation for Subaxial Cervical Spine Injuries.

Anterior transdiscal axial screw (ATAS) fixation is an alternative or supplement to the plate and screw constructs for the upper cervical spine injury. However, no existing literatures clarified the anatomic feasibility of this technique for subaxial cervical spine. Therefore, the objective of this study was to evaluate the anatomical feasibility and to establish guidelines for the use of the ATAS fixation for the subaxial cervical spine injury.Fifty normal cervical spines had radiographs to determine the proposed screw trajectory (the screw length and insertion angle) and the interbody graft-related parameters (the disc height and depth, and the distance between anterior vertebral margin and the screw) for all levels of the subaxial cervical spine. Following screw insertion in 8 preserved human cadaver specimens, surgical simulation and dissection verified the feasibility and safety of the ATAS fixation.Radiographic measurements showed the mean axial screw length and cephalic incline angle of all levels were 41.2 mm and 25.2°, respectively. The suitable depth of the interbody graft was >11.7 mm (the distance between anterior vertebral margin and the screw), but <17.1 mm (disc depth). Except the axial screw length, increase in all the measurements was seen with level up to C5-C6 segment. Simulated procedure in the preserved specimens demonstrated that ATAS fixation could be successfully performed at C2-C3, C3-C4, C4-C5, and C5-C6 levels, but impossible at C6-C7 due to the obstacle of the sternum. All screws were placed accurately. None of the screws penetrated into the spinal canal and caused fractures determined by dissecting the specimens.The anterior transdiscal axial screw fixation, as an alternative or supplementary instrumentation for subaxial cervical spine injuries, is feasible and safe with meticulous surgical planning.

[Fabrication of a new composite scaffold material for delivering rifampicin and its sustained drug release in rats].

OBJECTIVE: To fabricate a new composite scaffold material as an implant for sustained delivery of rifampicin and evaluate its performance of sustained drug release and biocompatibility. METHODS: The composite scaffold material was prepared by loading poly(lactic-co-glycolic) acid (PLGA) microspheres that encapsulated rifampicin in a biphasic calcium composite material with a negative surface charge. The in vitro drug release characteristics of the microspheres and the composite scaffold material were evaluated; the in vivo drug release profile of the composite scaffold material implanted in a rat muscle pouch was evaluated using high-performance liquid chromatography. The biochemical parameters of the serum and liver histopathologies of the rats receiving the transplantation were observed to assess the biocompatibility of the composite scaffold material. RESULTS: The encapsulation efficiency and drug loading efficiency of microspheres were (56.05±5.33)% and (29.80±2.88)%, respectively. The cumulative drug release rate of the microspheres in vitro was (94.19±5.4)% at 28 days, as compared with the rate of (82.23±6.28)% of composite scaffold material. The drug-loaded composite scaffold material showed a good performance of in vivo drug release in rats, and the local drug concentration still reached 16.18±0.35 µg/g at 28 days after implantation. Implantation of the composite scaffold material resulted in transient and reversible liver injury, which was fully reparred at 28 days after the implantation. CONCLUSION: The composite scaffold material possesses a good sustained drug release capacity and a good biocompatibility, and can serve as an alternative approach to conventional antituberculous chemotherapy.

Is duration of preoperative anti-tuberculosis treatment a risk factor for postoperative relapse or non-healing of spinal tuberculosis?

PURPOSE: This study evaluated the relationship between spinal TB postoperative recurrence or non-healing and duration of preoperative anti-TB treatment (ATT). METHODS: From January 2004 to January 2013, patients who underwent surgery for spinal TB and met this study's inclusion criteria were retrospectively reviewed. Observed parameters were age, sex, initial ESR, preoperative ESR, degree of ESR change, initial CRP, preoperative CRP, degree of CRP change, duration of preoperative ATT, surgical approach, presence of internal fixation, location of spinal lesion, number of involved segments, duration of operation, and intraoperative blood loss. The data were analyzed by univariate and multivariate analyses for spinal TB recurrence or non-healing to determine related risk factors. RESULTS: A total of 223 patients met the inclusion criteria. There were 84 female and 139 male patients with a mean age of 42.2 years (range 2-85 years). The follow-up period was 18-72 months (average 28.7 months). Among 223 patients observed, 23 patients had postoperative relapse or non-healing (10.3 %) during the follow-up period. Statistical analysis indicated that the location of a spinal lesion was significantly associated with postoperative relapse or non-healing. Risk of postoperative relapse or non-healing in thoracolumbar TB was 2.524-fold (95 % CI 1.026-6.580) that of lumbosacral TB. CONCLUSIONS: Duration of preoperative ATT may not be a risk factor for postoperative recurrence or non-healing of spinal TB. Junctional zones such as the lumbosacral and thoracolumbar junction have a higher recurrence rate than non junctional.

Clinical outcomes after decompressive laminectomy for symptomatic ossification of ligamentum flavum at the thoracic spine.

Ossification of the ligamentum flavum (OLF) is a rare disease that causes acquired thoracic spinal canal stenosis and thoracic myelopathy. The aim of this study was to investigate clinical outcomes of symptomatic thoracic OLF treated using posterior decompressive laminectomy. We retrospectively analyzed the medical records of 22 patients who underwent posterior decompressive laminectomy for symptomatic thoracic OLF. The surgical results were evaluated using the modified Japanese Orthopaedic Association (JOA) scoring system and Hirabayashi recovery rate. The intensity of pain was evaluated using a visual analog scale (VAS). The mean duration of follow-up was 35.6months. The mean JOA score was significantly improved at final follow-up (9.18±standard deviation of 1.53 points [range, 6-11 points]) compared with before surgery (5.64±2.04 points [range, 3-9 points]) (P<0.001). The mean Hirabayashi recovery rate was 65.49% (range, 20-100%). Recovery outcomes were excellent in nine patients, good in eight patients, fair in four patients and unchanged in one patient. No patient was classified as deteriorated. The VAS scores were 2.82±3.08 before surgery and 0.59±1.05 at final follow-up (P=0.001). Surgical complications, which resolved after appropriate and prompt treatment, included dural tear in five patients, cerebrospinal fluid leakage in one patient, immediate postoperative neurologic deterioration in one patient, epidural hematoma in one patient, and wound infection in one patient. Our findings suggest that posterior decompressive laminectomy is an effective treatment for symptomatic thoracic OLF and provides satisfactory clinical improvement, but surgery for thoracic OLF is associated with a relatively high incidence of complications.

Computed Tomographic Morphometric Analysis of Pediatric C1 Posterior Arch Crossing Screw Fixation for Atlantoaxial Instability.

STUDY DESIGN: A CT-based study of pediatric atlas. OBJECTIVE: The aim of this study was to identify morphometric patterns and dimensions of the pediatric C1 posterior arch to establish guidelines for the posterior arch crossing screw (PACS) fixation. SUMMARY OF BACKGROUND DATA: The PACS fixation is an alternative or supplement to the C1 lateral mass screw or pedicle screw constructs. However, the anatomic feasibility of this technique has not been well documented in the pediatric population. METHODS: A total of 123 pediatric patients were assigned into 6 groups based on age at an interval of 3 years. The C1 posterior arch unsuited to PACS fixation was classified as type 1 with synchondrosis, and type 2 without synchondrosis. Three subtypes of type 2 were included: the underdeveloped tubercle, the flat arch, and the undersized tubercle (height < 7 mm or width < 3.5 mm), respectively. The C1 posterior tubercle height and arch width, the projected PACS length and angle were measured, respectively. RESULTS: There were 19 patients of type 1 and 68 patients of type 2. Type 1 was mostly found in patients under age 3 years, whereas type 2 was largely observed in patients older than 4 years. The tubercle size was the most limiting variable for successful PACS placement. The PACS fixation was feasible for 42% patients over age 7 years and only 5% patients under age 6 years. The posterior tubercle height increased with age, whereas the tubercle width, the PACS length, and axial-plane angle increased with age up to 12 years. The PACS length was between 16 and 18 mm with the angle between 18° and 23° for patients over age 7 years. CONCLUSION: The PACS fixation was anatomically feasible in patients over age 7 years, but contraindicated in patients under age 6 years. Pediatric patients for the PACS fixation should be assessed before surgery. LEVEL OF EVIDENCE: 4.

Photothermal ablation of bone metastasis of breast cancer using PEGylated multi-walled carbon nanotubes.

This study investigates therapeutic efficacy of photothermal therapy (PTT) in an orthotropic xenograft model of bone metastasis of breast cancer. The near-infrared (NIR) irradiation on Multi-Walled Carbon Nanotubes (MWNTs) resulted in a rapid heat generation which increased with the MWNTs concentration up to 100 µg/ml. MWNTs alone exhibited no toxicity, but inclusion of MWNTs dramatically decreased cell viability when combined with laser irradiation. Thermographic observation revealed that treatment with 10 µg MWNTs followed by NIR laser irradiation resulted in a rapid increase in temperature up to 73.4±11.98 °C in an intraosseous model of bone metastasis of breast cancer. In addition, MWNTs plus NIR laser irradiation caused a remarkably greater suppression of tumor growth compared with treatment with either MWNTs injection or NIR irradiation alone, significantly reducing the amount of tumor-induced bone destruction. All these demonstrate the efficacy of PTT with MWNTs for bone metastasis of breast cancer.

Feasibility and trajectory study of anterior transarticular crossing screw placement for atlantoaxial joint instability: a cadaveric study and description of a novel technique.

PURPOSE: In unique clinical situations where C1-C2 anterior transarticular screw (ATS) fixation is not available or has failed, an anterior transarticular crossing screw (ATCS) with transcorporal pathway of the screws inside the contralateral promontory of C2 may enhance the stabilization and achieve atlantoaxial arthrodesis. The present study was to describe a novel technique of ATCS fixation for atlantoaxial joint instability and its applied anatomy, and compared it with ATS fixation method. METHODS: Direct measurements using digital calipers and a goniometer were conducted on 30 pairs of dried human C1 and C2 vertebrae. The ATS and ATCS with screws (Φ 4.0 mm) were performed on 11 fresh cervical spine specimens. The screw lengths in the C1 and C2, and screw entry angles of the ATS and ATCS were measured, respectively. Cadaver specimens were dissected to observe the incidence of violation to the important structures surrounding the ATS and ATCS fixation technique. RESULTS: There was enough osseous space for ATCS placement. The lateral and incline angle of the ATCS was 36.2° and 28.7°, respectively. Screw purchase in C2 of the ATCS (25.6 mm) was greater than that of the ATS (11.4 mm). The ATCS C1 purchase (14.8 mm) was similar to the ATS C1 purchase (14.9 mm). No violation to the vertebral artery groove, the spinal canal or the atlanto-occipital joint was observed after the ATCS placement. CONCLUSION: Anterior transarticular crossing screw is a feasible and viable option for atlantoaxial fixation in selected cases. This technique achieved remarkable longer screw purchase and could enhance the atlantoaxial stability.

[Structural characteristics and biocompatibility of a new nano-Ta-Ti alloy rod fabricated by laser melting technique].

OBJECTIVE: To evaluate the structural characteristics and biocompatibility of a novel nano-Ta-Ti alloy rod for its potential application in internal fixation. METHODS: Ta coating of a Ti alloy rod with nano-Ta (tantalum) powder was performed using laser melting with symmetrical grooves repleted with nano-Ta powder along the whole length. The microstructure of the cross section of Ta-Ti alloy rod, pore diameter and components of the coating were analyzed using scanning electron microscopy. The influence of this nano-Ta-Ti alloy on proliferation and differentiation of MC3T3-E1 cells was evaluated by MTT cytotoxicity test and ALP activity test. RESULTS: Under scanning electron microscope, the Ta-coating surface presented with a gross porous (200-300 µm) structure with dense fusion between Ta particles, and no new element was produced after laser melting. Biocompatibility evaluation showed that Ti alloys with and without Ta coating both promoted the proliferation of MC3T3-E1 cells, but the coated alloy showed better performance and obviously promoted the differentiation of the osteoblasts. CONCLUSION: Alloying between Ta and Ti can be accomplished successfully by laser melting technique, and the alloy obtained has ideal surface structure and good biocompatibility.

Esophageal perforation related to anterior cervical spinal surgery.

Esophageal perforation is an uncommon but potentially fatal complication of anterior cervical spinal surgery. This study aimed to investigate the diagnosis and treatment of cervical esophageal perforation related to spinal surgery. Among 1097 consecutive cases of anterior cervical spinal surgery that were managed at our institution over a 20 year period, five patients with esophageal perforation were identified. We performed a retrospective review of the diagnoses and treatment of esophageal perforation in these five patients as well as another patient who was transferred from another hospital. The esophageal perforations in all six patients were recognized during the early postoperative period. All patients presented with neck pain, dysphagia, odynophagia, coughing, fever and incision swelling and drainage. Diagnosis was confirmed by one or several of the following methods: contrast swallow study; endoscopy; cervical radiographs; or oral methylene blue. Nasogastric tube, intravenous antibiotics, enteral and parenteral nutrition, and open drainage were conducted in all patients. The wound was debrided in three patients, while two had implant removal and primary suture of the perforation. Five patients had a good recovery with healing of the esophagus, while one patient died due to severe pneumonia. The early diagnosis of esophageal perforation related to cervical spinal surgery relies on clinical suspicion and efficient investigation. The selection of appropriate treatment options, which include esophageal rest, antibiotic administration, nutrition support, wound debridement, open drainage, and surgical repair, largely depends on when the perforation is recognized. Early diagnosis and prompt management of this complication are likely to result in a good clinical outcome.

[Biomechanical study on effect of polymethylmethacrylate augmentation on cervical stability after anterior cervical interbody fusion].

OBJECTIVE: To evaluate the effect of polymethylmethacrylate (PMMA) augmentation on cervical stability after anterior cervical interbody fusion (ACIF) before and after fatigue. METHODS: Twelve porcine cervical spines (C3-7) were subjected to testing angular displacement parameters, including the range of motion (ROM), neutral zone (NZ), and elastic zone (EZ), in nondestructive flexion and extension, right/left lateral bending, and left/right rotation on Motion Analysis motion capture system and MTS-858 servo-hydraulic testing machine. Intact cervical spines served as control group (group A); one-level discectomy and fusion was performed with anterior plate fixation based on group A as group B; flexion and extension, left/right lateral bending (5 000 cycles) fatigue testing based on group B as group C; the augmentation screw channel was used based on group C as group D; and flexion and extension, left/right lateral bending fatigue testing were performed based on group D as group E. RESULTS: The ROM, NZ, and EZ in group A were significantly different from those in other groups (P < 0.05) at flexion/extension, left/right bending, and left/right rotation. The ROM, NZ, and EZ in group B were significantly smaller than those in group C (P < 0.05) in flexion/extension, left/right bending, and left/right rotation, but there was no significant difference when compared with group D (P > 0.05). The ROM and NZ in flexion/extension and the EZ in flexion in group B were significant smaller than those in group E (P < 0.05), but there was no significant difference in the other indexes (P > 0.05). The ROM, NZ, and EZ in group C in flexion and extension, left/right lateral bending, and left/right rotation were significantly higher than those in groups D and E (P < 0.05). The ROM and NZ in flexion and extension and left/right lateral bending, and the ROM in left/right rotation, and the EZ in flexion and extension, right bending, and left/right rotation in group D were significantly smaller than those in group E (P < 0.05), but there was no significant difference in the other indexes (P > 0.05). CONCLUSION: PMMA augmentation can significantly increase the instant cervical stability and provide a biomechanics basis in cervical anterior plate fixation.