Reoperation for Misplaced Pedicle Screws: A Multicenter Retrospective Study.

STUDY DESIGN: A multicenter retrospective analysis. OBJECTIVE: This study aims to investigate reoperation of misplaced pedicle screws (MPSs) after posterior spinal fusion (PSF), focusing on neurological complications. SUMMARY OF BACKGROUND DATA: The management strategy for MPSs and the clinical results after reoperation are poorly defined. MATERIALS AND METHODS: Subjects were 10,754 patients (73,777 pedicle screws) who underwent PSF at 11 hospitals over 15 years. The total number of reoperations for MPS and patient clinical data were obtained from medical records at each hospital. RESULTS: The rate of reoperation for screw misplacement per screw was 0.17%. A total of 69 patients (mean age, 67.4±16.5 yr) underwent reoperation because of 82 MPS. Reasons for reoperation were neurological symptoms (58 patients), contact with vessels (5), suboptimal bone purchase (4), and misplacement recognized during operation (2). Neurological symptoms were the major reason for reoperation in cervical (5/5 screws, 100%) and lumbo-sacral (60/67 screws, 89.6%) regions. Contact with vessels was the major reason for reoperation in the thoracic spine (6/10 screws, 60.0%). We further evaluated 60 MPSs in the lumbo-sacrum necessitating reoperation because of neurological symptoms. The majority of MPSs necessitating reoperation were placed in the lower lumbar spine (43/60 screws, 71.7%). The mean pedicle breach tended to be larger in the incomplete recovery group than in the complete recovery group (6.8±2.4 vs . 5.9±2.2 mm, P =0.146), and the cutoff value resulting in incomplete resolution was 5.0 mm. Multivariate analysis revealed that medial-caudal breaches ( vs . medial breach, odds ratio: 25.8, 95% confidence interval: 2.58-258, P =0.0057) and sensory and motor disturbances ( vs . sensory only, odds ratio: 8.57, 95% confidence interval: 1.30-56.6, P =0.026) were significant factors for incomplete resolution of neurological symptoms. CONCLUSIONS: After reoperation, 70.1% of the patients achieved complete resolution of neurological symptoms. Factors associated with residual neurological symptoms included sensory and motor disturbance, medial-caudal breach, and larger pedicle breach (>5 mm).

Clinical Features and Surgical Outcomes of Lower Lumbar Osteoporotic Vertebral Collapse with Symptomatic Stenosis: A Surgical Strategy from a Multicenter Case Series.

STUDY DESIGN: A retrospective multicenter case series was conducted. PURPOSE: This study was designed to investigate the clinical features and surgical outcomes of lower lumbar osteoporotic vertebral collapse (LL-OVC) with symptomatic stenosis based on various surgical procedures and classify them using the newly developed collapse severity criteria. OVERVIEW OF LITERATURE: The surgical outcomes of LL-OVC with symptomatic stenosis remain unclear. METHODS: We investigated patients who underwent surgical intervention for LL-OVC (L3, L4, and/or L5) with symptomatic foraminal and/or central stenosis from eight spine centers. Only patients with a minimum follow-up duration of 1 year were included. We developed new criteria to grade vertebral collapse severity (grade 1, 0%-25%; grade 2, 25%-50%; grade 3, 50%-75%; and grade 4, 75%-100%). The clinical features and outcomes were compared based on the collapse grade and surgical procedures performed (i.e., decompression alone, posterior lateral fusion [PLF], lateral interbody fusion [LIF], posterior/transforaminal interbody fusion [PLIF/TLIF], or vertebral column resection [VCR]). RESULTS: In this study, 59 patients (average age, 77.4 years) were included. The average follow-up period was 24.6 months. The clinical outcome score (Japanese Orthopaedic Association score) was more favorable in the LIF and PLIF/TLIF groups than in the decompression alone, PLF, and VCR groups. The use of VCR was associated with a high rate of revision surgery (57.1%). No significant difference in clinical outcomes was observed between the collapse grades; however, grade 4 collapse was associated with a high rate of revision surgery (40.0%). CONCLUSIONS: When treating LL-OVC, appropriate instrumented reconstruction with rigid intervertebral stability is necessary. According to our newly developed criteria, LIF may be a surgical option for any collapse grade. The use of VCR for grade 4 collapse is associated with a high rate of revision.

Rapid Spontaneous Resolution of Lumbar Intraspinal Facet Cyst after Lateral Lumbar Interbody Fusion.

INTRODUCTION: Intraspinal facet cysts resistant to conservative treatment are treated surgically. Surgical treatment was generally resection and decompression, but complications of dural tear and recurrence sometimes occurred. We present good clinical results and rapid spontaneous resolution following treatment of five cases of lumbar intraspinal facet cyst after lateral lumbar interbody fusion (LLIF). METHODS: Multicenter series of five cases of lumbar intraspinal facet cyst with segmental instability treated with LLIF. The cross-sectional area (CSA) of the thecal sac and facet cyst on T2-weighted axial magnetic resonance imaging and the distance of facet joint (FJ) gap on axial computed tomography were measured preoperatively and postoperatively. Patient data and clinical and radiographic results were described. RESULTS: Of five patients, one was male and four were female, with an average age of 72.6 (61-76) years. The mean preoperative CSA of facet cyst was 40.09 mm2. In all cases, intraspinal facet cyst resolved within two weeks after LLIF and good clinical results were obtained. The mean CSA of the thecal sac increased from 64.18 mm2 preoperatively to 95.72 mm2 postoperatively. The mean distance of FJ gap increased from 0.8 (0-1.5) mm preoperatively to 3.1 (0.5-6.0) mm postoperatively. CONCLUSIONS: LLIF may be indicated for intraspinal facet cysts with segmental instability.

Incidence and Risk Factors of Anterior Arch Fracture of the Atlas Following C1 Laminectomy Without Fusion.

STUDY DESIGN: A retrospective multicenter study. OBJECTIVE: To identify the incidence of anterior arch fracture (AAF) of the atlas following C1 (first cervical vertebra) laminectomy without fusion, and its risk factors. SUMMARY OF BACKGROUND DATA: C1 laminectomy without fusion is a widely accepted surgical procedure performed to decompress the spinal cord that is compromised at the C1/C2 level, but without instability. Several case series have reported spontaneous AAF following this procedure. However, the incidence of post-laminectomy AAF and its risk factors have not been studied. METHODS: This retrospective study included patients who underwent C1 laminectomy without fusion in any of the four participating institutions between April 2002 and March 2016. The incidence of AAF following C1 laminectomy was determined, and the included patients were grouped into those who developed AAF (AAF group) and those who did not (non-AAF group). Patient demographics and radiographic parameters including subaxial cervical balance on x-ray (C2-7 sagittal vertical axis, C2-7 lordosis, C2-7 coronal cobb angle, and T1-slope), and morphology of the atlas on computed tomography (CT) scan were compared with the AAF and non-AAF groups. RESULTS: Seventy patients who underwent C1 laminectomy without fusion were included in the study. The incidence of AAF was 14.2% (10/70). Multivariate analysis revealed that a large inferior facet angle (IFA, defined as the coronal inclination angle of the C1/2 facet as measured on CT) and the presence of subaxial ankylosis (bony ankylosis below C2 on CT) were independent risk factors for AAF. There were no significant differences in the subaxial cervical balance as measured on x-ray between the AAF and non-AAF groups (P > 0.05). CONCLUSION: The incidence of AAF after C1 laminectomy without fusion is not uncommon. Preoperative assessment using CT may identify patients at high risk of AAF. LEVEL OF EVIDENCE: 4.

Spontaneous anterior arch fracture of the atlas following C1 laminectomy without fusion: A report of three cases and finite element analysis.

BACKGROUND: Only four cases of anterior arch fracture after C1 laminectomy without fusion have been previously reported. Although atlas fractures commonly occur in response to high-energy trauma, no obvious trauma that could cause the fracture was observed in these reported cases. The purpose of this study was to elucidate the biomechanical mechanism of anterior arch fracture of the atlas following C1 laminectomy and present three cases of this fracture. METHODS: Three cases of fracture of the anterior arch of the atlas following C1 laminectomy were retrospectively reviewed. Three atlas models (an intact model, a laminectomy model, and a transverse ligament-resected model) were created from computed tomography data of each case using a three-dimensional finite element method. Axial load was applied on the superior facet to mimic four conditions (neutral, flexion, extension, lateral bending). The distribution of von Mises stress in the anterior arch and the displacement of the posterior arch were compared among the three models. RESULTS: In all three cases, the anterior arch fracture clinically occurred after C1 laminectomy despite there being no obvious inciting trauma. During the finite element analysis, increased stress was observed in all postures of the laminectomy model as compared with the intact model. The stress-concentrated location observed in the finite element model was consistent with the fracture sites that were clinically observed. In terms of loading condition, much higher stress was observed in extension and lateral bending as compared with other postures. There were no significant differences in stress distribution between the laminectomy model and the transverse ligament-resected laminectomy model. CONCLUSIONS: Stress distribution concentrates in the anterior arch after C1 laminectomy, leading to fracture of the anterior arch despite no inciting trauma. There may be more frequent occult fractures observed after C1 laminectomy than has been reported. Therefore, surgeons should recognize anterior arch fracture as a possible complication of C1 laminectomy without fusion.

Correlation between reduced susceptibility to disinfectants and multidrug resistance among clinical isolates of Acinetobacter species.

BACKGROUND: The aim of this study was to investigate the susceptibility profiles to disinfectants and antimicrobial agents of 283 non-repetitive Acinetobacter clinical isolates obtained in 97 Japanese hospitals in March 2002. METHODS: Susceptibility profiles of the above isolates to four disinfectants, six antimicrobial agents and two dyes were investigated. MICs were measured by the agar dilution method recommended by the CLSI (formerly NCCLS). MBC measurements and time-kill assays were performed using a slightly modified quantitative suspension test based on the European Standard EN 1040. RESULTS: No evident resistance to disinfectants was seen among the 283 strains of Acinetobacter spp. isolated in 2002, but the MIC(90)s of chlorhexidine gluconate, benzalkonium chloride and alkyldiaminoethylglycine hydrochloride were 50, 50 and 400 mg/L, respectively. Interestingly, the MICs of alkyldiaminoethylglycine hydrochloride and benzethonium chloride for four and three clinical isolates, respectively, reached 800 mg/L (approximately half the in-use concentration). The MBCs for the 28 disinfectant reduced susceptibility (DRS) isolates, for which the MICs of at least one of the four disinfectants tested were higher than the MIC(90), were comparable to those for susceptible isolates, in general; however, significant differences (P < 0.01) were observed between disinfectant-susceptible and DRS isolates in the time-kill assays of chlorhexidine gluconate, benzalkonium chloride and benzethonium chloride. Furthermore, DRS isolates tended to demonstrate multiresistance profiles to ceftazidime, ciprofloxacin and amikacin (P < 0.05). CONCLUSIONS: Since several Acinetobacter clinical isolates have developed augmented resistance to multiple antimicrobials and disinfectants, it is worth checking the susceptibility to disinfectants if multidrug-resistant Acinetobacter spp. are recurrently isolated clinically.

Reduction of disinfectant bactericidal activities in clinically isolated Acinetobacter species in the presence of organic material.

OBJECTIVES: In clinical Acinetobacter species, the reduction effects of organic material on bactericidal activities of four major disinfectants were investigated: chlorhexidine gluconate (CHX), benzethonium chloride (BZT), benzalkonium chloride (BZK) and alkyl diaminoethyl glycine hydrochloride (ADH). METHODS: The bactericidal activities of the four disinfectants against 283 strains of Acinetobacter species recovered from 97 Japanese hospitals in March 2002 were investigated by four different tests: MIC measurements, MBC measurements, time-killing assays and adaptation assays. Moreover, disinfectant efficacy was examined in the presence of BSA in two tests: MBC measurements and time-killing assays. RESULTS: No clinical isolates were able to withstand the in-use concentrations of the four disinfectants, although the MIC90 of ADH reached 100 mg/L. Strains for which MICs of at least two disinfectants were higher than MIC90 measured by the broth microdilution method were defined as isolates with 'disinfectant reduced susceptibility (DRS)'. In the presence of 3.0% BSA, the MBCs of BZK, BZT and ADH for DRS isolates rose to 512 and 1024 mg/L, which were about half their in-use concentrations. Moreover, the times for bacterial complete killing were remarkably prolonged in DRS isolates even after a 10 min of exposure to 1000 mg/L of ADH, a half of its in-use concentration. The MICs of CHX for DRS isolates rose to 640 mg/L after repetitive passages in subinhibitory concentrations of CHX. CONCLUSIONS: Given that the bactericidal effects of the four major disinfectants were considerably reduced in the presence of organic material (BSA) and DRS isolates tended to adapt to CHX, continuous surveys of the profiles of susceptibility to disinfectants among clinically isolated Acinetobacter species are very necessary from the standpoint of nosocomial infection control.

Prevalence of Ile-460-Val/ParE substitution in clinical Streptococcus pneumoniae isolates that were less susceptible to fluoroquinolones.

A total of 73 clinical isolates of Streptococcus pneumoniae were measured for susceptibilities to nine fluoroquinolones, and nucleotide sequences of the quinolone resistance-determining regions (QRDRs) were determined. MIC90s of sparfloxacin, tosufloxacin, grepafloxacin, and gatifloxacin were less than 0.5 mg/L and the MIC90 of ciprofloxacin was 2 mg/L, although MIC values of some isolates to ciprofloxacin were more than 2 mg/L. We found that 60 of 73 isolates had only Ile-460-Val/ParE substitution and two isolates had an additional substitution of Ser-114-Gly/GyrA, while none of the isolates had any other substitutions in QRDRs of either ParC/E or GyrA/B. The isolates carrying Ile-460-Val/ParE substitution were more resistant to the fluoroquinolones norfloxacin and ciprofloxacin than the isolates with no amino acid substitution and the differences in MIC values were significant, suggesting that Ile-460-Val/ParE substitution in recent clinical S. pneumoniae isolates should be involved in the low-level fluoroquinolone resistance.

Quantitative analysis of cereulide, an emetic toxin of Bacillus cereus, by using rat liver mitochondria.

An emetic toxin cereulide, produced by Bacillus cereus, causes emetic food poisonings, but a method for quantitative measurement of cereulide has not been well established. A current detection method is a bioassay method using the HEp-2 cell vacuolation test, but it was unable to measure an accurate concentration. We established a quantitative assay for cereulide based on its mitochondrial respiratory uncoupling activity. The oxygen consumption in a reaction medium containing rat liver mitochondria was rapid in the presence of cereulide. Thus uncoupling effect of cereulide on mitochondrial respiration was similar to those of uncouplers 2,4-dinitrophenol (DNP), carbonylcyanide m-chlorophenylhydrazone (CCCP), and valinomycin. This method gave constant results over a wide range of cereulide concentrations, ranging from 0.05 to 100 microg/ml. The minimum cereulide concentration to detect uncoupled oxygen consumption was 50 ng/ml and increased dose-dependently to the maximum level. Semi-log relationship between the oxygen consumption rate and the cereulide concentration enables this method to quantify cereulide. The results of this method were highly reproducible as compared with the HEp-2 cell vacuolation test and were in good agreement with those of the HEp-2 cell vacuolation test. The enterotoxin of B. cereus or Staphylococcus aureus did not show any effect on the oxygen consumption, indicating this method is specific for the identification of cereulide as a causative agent of emetic food poisonings.

Nosocomial spread of ceftazidime-resistant Klebsiella pneumoniae strains producing a novel class a beta-lactamase, GES-3, in a neonatal intensive care unit in Japan.

Klebsiella pneumoniae strain KG525, which showed high-level resistance to broad-spectrum cephalosporins, was isolated from the neonatal intensive care unit (NICU) of a Japanese hospital in March 2002. The ceftazidime resistance of strain KG525 was transferable to Escherichia coli CSH-2 by conjugation. Cloning and sequence analysis revealed that production of a novel extended-spectrum class A beta-lactamase (pI 7.0), designated GES-3, which had two amino acid substitutions of M62T and E104K on the basis of the sequence of GES-1, was responsible for resistance in strain KG525 and its transconjugant. The bla(GES-3) gene was located as the first gene cassette in a class 1 integron that also contained an aacA1-orfG fused gene cassette and one unique cassette that has not been described in other class 1 integrons and ended with a truncated 3' conserved segment by insertion of IS26. Another five ceftazidime-resistant K. pneumoniae strains, strains KG914, KG1116, KG545, KG502, and KG827, which were isolated from different neonates during a 1-year period in the same NICU where strain KG525 had been isolated, were also positive for GES-type beta-lactamase genes by PCR. Pulsed-field gel electrophoresis and enterobacterial repetitive intergenic consensus-PCR analyses displayed genetic relatedness among the six K. pneumoniae strains. Southern hybridization analysis with a GES-type beta-lactamase gene-specific probe showed that the locations of bla(GES) were multiple and diverse among the six strains. These findings suggest that within the NICU setting genetically related K. pneumoniae strains carrying the bla(GES) gene were ambushed with genetic rearrangements that caused the multiplication and translocation of the bla(GES) gene.