Modification to the placement of the navigation reference frame in posterior corrective fusion of spinal deformity with myelomeningocele: a series of 6 cases.

To show a modified placement of the navigation reference frame in posterior corrective fusion of spinal deformity with myelomeningocele. This was a retrospective, single-surgeon case series, and IRB-approved study. Six consecutive patients (one male and five females) who were diagnosed with spinal deformity with myelomeningocele underwent posterior corrective fusion surgery from the upper thoracic spine to the pelvis with preoperative computed tomography navigation (pCTN). At the level of the spina bifida, where posterior elements such as the spinous process were missing, the reference frame of the pCTN was placed on the flipped lamina or pedicles, and a pedicle screw (PS) or iliac screw (IS) was inserted. Screw deviation was investigated by using postoperative CT. A total of 55 screws were placed at the spina bifida level and pelvis. Of these, 12 ISs were placed on each side in each case. The screws placed using the pCTN were not reinserted or removed intraoperatively or postoperatively. However, only one PS was found to have perforated the spinal canal on postoperative CT but was left in place because it caused no neurological problem. By modifying the placement of the reference frame, such as placing it on the flipped lamina or pedicles, pCTN could be used even at the levels of the spina bifida, where the posterior elements are missing, to accurately place PSs and various types of ISs.

No short-term clinical improvement and mean 6° of thoracic kyphosis correction using limited-level Ponte osteotomy near T7 for Lenke type 1 and 2 adolescent idiopathic scoliosis: a preliminary study.

This study was a retrospective single surgeon case series approved by institutional review board and showed the efficacy of limited Ponte osteotomy at T6/7, 7/8 and 8/9 (limited-PO) in the sagittal plane for patients with Lenke type 1 and 2 adolescent idiopathic scoliosis (AIS). A total of 37 consecutive patients [7 males and 30 females; average age 16.0 ±â€…2.5 (range: 12-21)] over a 4-year period with posterior corrective fusion surgery were included. Initially, 18 patients were operated on without limited-PO [P(-)-group]. Midway in the series, the senior author switched to the limited-PO [P(+)-group]. The limited-PO has been performed to form the apex of thoracic kyphosis at the T7 level, together with the restoration of thoracic kyphosis. The mean amount of the correction angle of thoracic kyphosis was more in the P(+)-than in P(-)-group (13.8 ±â€…9.6° vs. 7.8 ±â€…8.0°, P  = 0.046) at 1-year after surgery. Cervical lordosis was spontaneously corrected more in P(+)-than in P(-)-group. The apex of thoracic kyphosis was controlled around the T7 level postoperatively in most cases (18/19 cases). There was no significant difference between the two groups in terms of blood loss and operative time per level, or Scoliosis Research Society-22 domain scores. Limited-PO contributed to the restoration of the whole spinal sagittal alignment for Lenke type 1 and 2 AIS; however, in this preliminary study, the clinical improvement was unclear at least in the short term, because the kyphosis angle obtained by limited-PO was only approximately 6°.

Synergistic effect of sulfonation followed by precipitation of amorphous calcium phosphate on the bone-bonding strength of carbon fiber reinforced polyetheretherketone.

Sulfonation and applications of amorphous calcium phosphate are known to make polyetheretherketone (PEEK) bioactive. Sulfonation followed by precipitation of amorphous calcium phosphate (AN-treatment) may provide PEEK with further bone-bonding strength. Herein, we prepared a carbon-fiber-reinforced PEEK (CPEEK) with similar tensile strength to cortical bone and a CPEEK subjected to AN-treatment (CPEEK-AN). The effect of AN-treatment on the bone-bonding strength generated at the interface between the rabbit's tibia and a base material was investigated using a detaching test at two time-points (4 and 8 weeks). At 4 weeks, the strength of CPEEK-AN was significantly higher than that of CPEEK due to the direct bonding between the interfaces. Between 4 and 8 weeks, the different bone forming processes showed that, with CPEEK-AN, bone consolidation was achieved, thus improving bone-bonding strength. In contrast, with CPEEK, a new bone was absorbed mainly on the interface, leading to poor strength. These observations were supported by an in vitro study, which showed that pre-osteoblast on CPEEK-AN caused earlier maturation and mineralization of the extracellular matrix than on CPEEK. Consequently, AN-treatment, comprising a combination of two efficient treatments, generated a synergetic effect on the bonding strength of CPEEK.

Bioactivity and antibacterial activity of iodine-containing calcium titanate against implant-associated infection.

Developing antimicrobial biomaterials is a major challenge in the fields of orthopaedic and dental implants. In this study, we evaluated the bone-bonding ability and antibacterial activity of a novel biomaterial for preventing implant-associated infections. We have previously reported that NaOH heat treatment improved the bone-bonding ability of titanium, which was later modified to release target ions from the calcium titanate surface. Iodine, an essential nutrient, exhibits broad-spectrum antimicrobial activity; hence, we designed a calcium titanate that releases iodine ions (Ca-I-Ti). The material was prepared from a simple solution using heat treatments as well as inexpensive devices and chemical agents. MC3T3-E1 cells seeded on Ca-I-Ti displayed high degrees of bioactivity and viability, and Ca-I-Ti exhibited antibacterial activity against methicillin-susceptible Staphylococcus aureus. In vivo biomechanical and histological experiments showed that Ca-I-Ti had excellent bone-bonding ability at 8 weeks after implantation. In a subcutaneous infection model in rats, methicillin-susceptible Staphylococcus aureus on the implant was reduced by approximately 95% compared to that on commercially pure titanium, indicating that Ca-I-Ti has antibacterial effects in vivo. In addition, no local or systemic complications were observed, and active infection in the surrounding tissues was histologically inhibited. Thus, iodine-containing calcium titanate is a safe biomaterial with excellent bioactivity and antibacterial properties, indicating its potential in preventing implant-associated infections.

An Observational Survey of Nail and Skin of Spine Surgeons-Possible Damage by Occupational Ionizing Radiation Exposure.

INTRODUCTION: Orthopedic surgeons are exposed to ionizing radiation daily. With the increase in the number of minimally invasive surgery performed under X-ray fluoroscopy, radiation exposure to unprotected fingers will increase. Although the effect of high dose radiation exposure is known, the long-term effect of exposure to low doses is unclear. This study aims to investigate damage to the nail and skin on the thumbs of spine surgeons via occupational ionizing radiation exposure. METHODS: Forty male spine surgeons (group S) and 40 males of the same age group who were not exposed to radiation (controls; group C) were included. Using a scoring system, we evaluated the damage to the fingernail and skin of the bilateral thumb. Scoring was based on fingernail pigmentation (melanonychia), fingernail crack, and periungual dermatitis status. We investigated the number of examinations and operations under radiation exposure in the last 3 months. RESULTS: Group S had 17.83 (3-28) years of surgeon experience. In group S, the dominant side scored significantly higher than the non-dominant side; however, there was no dominant vs. non-dominant difference in group C. Only the dominant side had a significantly higher score in group S than in group C. In group S, surgeon experience and the score of the dominant side were significantly correlated; however, for the non-dominant side of group S and both thumbs of group C, no correlation was observed. The kappa coefficients for fingernail pigmentation, fingernail crack, and periungual dermatitis status were 0.458, 0.248, and 0.612, respectively. The average number of examinations and operations under radiation exposure was 11.89 ± 9.04 (0-30) and 26.34 ± 14.67 (1-63), respectively. CONCLUSIONS: The dominant side in group S had a significantly higher score than the non-dominant side in group S and the dominant side in group C, suggesting the possibility of radiation damage to the dominant side in group S.

The degenerative changes of the sacroiliac joint after S2 alar-iliac screw placement.

OBJECTIVE: The goal of this study was to investigate clinical outcomes and risk factors for the progression of sacroiliac joint (SIJ) degeneration and bone formation after S2 alar-iliac screw (S2AIS) insertion. METHODS: Using preoperative and follow-up CT scan findings (median follow-up 26 months, range 16-43 months), the authors retrospectively studied 100 SIJs in 50 patients who underwent S2AIS placement. The authors measured the progression of SIJ degeneration and bone formation after S2AIS insertion, postoperative new-onset SIJ pain, S2AIS-related reoperation, and instrumentation failures. Stepwise multivariate logistic regression modeling was performed to clarify the risk factors associated with the progression of SIJ degeneration. RESULTS: Significant progression of SIJ degeneration was observed in 10% of the group with preoperative SIJ degeneration (p = 0.01). Bone formation was observed in 6.9% of joints. None of the patients with these radiographic changes had new-onset SIJ pain or underwent reoperation related to instrumentation failures. Multivariate logistic regression analysis revealed that preoperative SIJ degeneration (p < 0.01) and a young age at surgery (p = 0.03) significantly affected the progression of SIJ degeneration. CONCLUSIONS: The progression of SIJ degeneration and bone formation neither led to major screw-related complications nor affected the postoperative clinical course during the median follow-up period of 26 months. Although S2AIS insertion is a safe procedure for most patients, the results of this study suggested that preoperative degeneration and younger age at surgery affected SIJ degeneration after S2AIS insertion. Further long-term observation may reveal other effects of S2AIS insertion on SIJ degeneration.

Bioactivity and antibacterial activity of strontium and silver ion releasing titanium.

To overcome problems associated with loosening of orthopedic implants and surgical site infections, we developed a novel, titanium (Ti)-based material that releases both strontium and silver ions (CaSrAg-Ti) based on alkali-and-heat treatment. The results of commercially pure Ti (cp-Ti), Ti that releases Sr ions only (CaSr-Ti), and the novel CaSrAg-Ti material were compared. Mechanical tests were performed to evaluate the in vivo bonding properties of CaSrAg-Ti and the bone-implant contact (BIC) ratio in histological specimens was determined at 4 and 8 weeks after implantation in a rat femur. Also, the in vitro antibacterial activities of this material against methicillin-susceptible Staphylococcus aureus (MSSA) were evaluated after a 24 h incubation period by assaying colony-forming units. In addition, antibacterial activities were evaluated in vivo at 7 days after implantation in a rat subcutaneous pocket model. There was direct contact between the bone and CaSrAg-Ti in histological specimens and no apparent signs of argyrosis in any rat. The bone-bonding strength and the BIC ratio were increased by 2.7- and 2.3-fold for CaSrAg-Ti vs. cp-Ti at 4 weeks and 2.2- and 2.0-fold at 8 weeks, respectively. As compared with cp-Ti, the number of viable MSSA remaining on CaSrAg-Ti was reduced by 100 ± 0% in vitro and 94.2 ± 6.9% in vivo. Ti that releases Sr and Ag ions is a promising material that exhibits both bone-bonding properties and anti-MSSA activities.

Usefulness of model-based iterative reconstruction in low-dose lumbar spine CT after spine surgery with metal implant: a phantom study.

BACKGROUND: The major problems of computed tomography (CT) imaging include radiation exposure and severe artifacts caused by operative implants. PURPOSE: To evaluate the usefulness of the metal artifact reduction algorithm and model-based iterative reconstruction (MBIR) in postoperative low-dose (LD) spine CT. MATERIAL AND METHODS: A CT torso phantom was scanned at standard-dose (SD) and LD settings. The CT images were reconstructed by three methods: hybrid iterative reconstruction (HIR); metal artifact reduction; and MBIR. The radiation dose of the phantom imaging was evaluated by volume CT dose index (mGy), dose length product (DLP, mGy × cm), and effective dose (mSv). The image quality of the six images was visually evaluated and analyzed using Scheffe's paired comparison method. The average preference of each method was calculated based on the comparative scores. The task transfer function (TTF) and noise power spectrum for HIR and MBIR were also measured. RESULTS: The respective radiation-dose-related parameters of the SD and LD conditions were: volume CT dose index = 10.2 and 1.2 mGy; DLP = 277.9 and 33.9 mGy × cm; and effective dose = 4.2 and 0.5 mSv. The average preference for diagnostic acceptability of MBIR at LD was not significantly different from the other reconstructions of SD data. MBIR successfully reduced metal artifacts in the LD condition. The 10% TTF was higher for HIR at SD and higher for MBIR at LD. CONCLUSION: MBIR is useful for LD spine CT after spine surgery with metal implant.

In vitro study of antibacterial and osteogenic activity of titanium metal releasing strontium and silver ions.

Peri-prosthetic infection and loosening of implants are major problems in orthopaedic and dental surgery. To address these issues, surface treatment methods for titanium implants have been improved by modifying the alkali and heat treatment. We have previously fabricated calcium-treated Ti metal that releases Sr ions (CaSr-Ti), which resulted in a higher in vitro osteogenic response and early in vivo bone bonding.Further, we developed a Ti metal that released both Sr and Ag ions (CaSrAg-Ti). In this study, we evaluated the antibacterial ability and osteogenic cellular response of CaSrAg-Ti and CaSr-Ti in vitro using rat bone marrow stromal cells (BMSCs) cultured on implant samples and extract mediums (EMs) made by immersing the implant samples in the medium. CaSrAg-Ti did not show cytotoxicity and was associated with a slightly higher osteogenic response when compared to CaSr-Ti, without inhibiting the effect of Sr. The osteogenic response was also observed in the cells cultured with the CaSrAg-Ti EM; however, the response was not as high as that of the cells on the CaSrAg-Ti implant sample. Significantly higher antibacterial activity was observed along with an antibacterial efficacy of more than 95% against methicillin-susceptible Staphylococcus aureus and Escherichia coli. The main advantages of our surface treatment are its simplicity and low cost. Therefore, our treatment is promising for clinical applications in orthopaedic or dental Ti-based implants with antibacterial and early bone-bonding abilities.

Accuracy of fluoroscopic guidance with the coaxial view of the pedicle for percutaneous insertion of lumbar pedicle screws and risk factors for pedicle breach.

OBJECTIVE: In this study the authors aimed to evaluate the rate of malposition, including pedicle breach and superior facet violation, after percutaneous insertion of pedicle screws using the coaxial fluoroscopic view of the pedicle, and to assess the risk factors for pedicle breach. METHODS: In total, 394 percutaneous screws placed in 85 patients using the coaxial fluoroscopic view of the pedicle between January 2014 and September 2017 were assessed, and 445 pedicle screws inserted in 116 patients using conventional open procedures were used for reference. Pedicle breach and superior facet violation were evaluated by postoperative 0.4-mm slice CT. RESULTS: Superior facet violation was observed in 0.5% of the percutaneous screws and 1.8% of the conventionally inserted screws. Pedicle breach occurred more frequently with percutaneous screws (28.9%) than with conventionally inserted screws (11.9%). The breaches in percutaneous screws were minor and did not reduce the interbody fusion rate. The angle difference between the percutaneous and conventionally inserted screws was comparable. Insertion at the L3 or L4 level, right-sided insertion, placement around a trefoil canal, smaller pedicle angle, and a small difference between the screw and pedicle diameters were found to be risk factors for pedicle breach by percutaneous pedicle screws. CONCLUSIONS: Percutaneous pedicle screw placement using the coaxial fluoroscopic view of the pedicle carries a low risk of superior facet violation. The screws should be placed carefully considering the level and side of insertion, canal shape, and pedicle angle.

Cervical spinal computed tomography utilizing model-based iterative reconstruction reduces radiation to an equivalent of three cervical X-rays.

PURPOSE: To evaluate radiation dose and image quality of cervical spinal computed tomography scanned with low-radiation dose (LD-CT) utilizing model-based iterative reconstruction (MBIR). METHODS: We retrospectively examined 14 patients (65.5 ± 13.9 years) who underwent both standard-radiation-dose CT (SD-CT) reconstructed with hybrid iterative reconstruction and LD-CT of cervical spine. The radiation dose, objective image quality indicator, which includes signal-to-noise and contrast-to-noise, and subjective image quality score of the anatomical landmarks in the SD-CT and LD-CT were statistically compared. In addition, the measurement errors of the length of C3 vertebrae (height, anteroposterior length, inner and outer pedicle diameters) between SD-CT and LD-CT were analyzed. RESULTS: Radiation dose of LD-CT was reduced to one-sixth of the dose of SD-CT. The objective image quality indicator of LD-CT was significantly better than that of SD-CT. The subjective image quality of LD-CT was relatively worse than that of SD-CT but generally graded as clinically accepted or higher. There was no remarkable difference between SD-CT and LD-CT in the measurement value of height and anteroposterior length. Inner pedicle diameter was significantly (0.21 ± 0.13 mm) smaller, and outer pedicle diameter was (0.24 ± 0.14 mm) larger on LD-CT than on SD-CT. CONCLUSION: Cervical spinal LD-CT that utilized MBIR enabled radical decrease in radiation dose and provided sufficient image quality for clinical use. This scanning protocol can be a good alternative for protecting patients from exposure to unnecessary radiation, especially when a patient requires multiple CT scans.

Bioactive effects of strontium loading on micro/nano surface Ti6Al4V components fabricated by selective laser melting.

Selective laser melting (SLM) titanium alloys require surface modification to achieve early bone-bonding. This study investigated the effects of solution and heat treatment to induce the sustained release of strontium (Sr) ions from SLM Ti6Al4V implants (Sr-S64). The results were compared with a control group comprising an untreated surface [SLM pure titanium (STi) and SLM Ti6Al4V (S64)] and a treated surface to induce the release of calcium (Ca) ions from SLM Ti6Al4V (Ca-S64). The surface-treated materials showed homogenous nanoscale network formation on the original micro-topographical surface and formed bone-like apatite on the surface in a simulated body fluid within 3 days. In vitro evaluation using MC3T3-E1 cells showed that the cells were viable on Sr-S64 surface, and Sr-S64 enhanced cell adhesion-related and osteogenic differentiation-related genes expression. In vivo rabbit tibia model, Sr-S64 provided significantly greater bone-bonding strength and bone-implant contact area than those in controls (STi and S64) in the early phase (2-4 weeks) after implantation; however, there was no statistical difference between Ca-S64 and controls. In conclusion, Sr solution and heat treatment was a safe and effective method to enhance early bone-bonding ability of S-64 by improving the surface characteristics and sustained delivery for Sr.

Utility of Thoracolumbar Low-Dose CT With Model-Based Iterative Reconstruction for Measuring Pedicle Diameter Using a Radiation Dose Less Than a One-Time Lumbar X-Ray.

STUDY DESIGN: Retrospective. OBJECTIVE: To evaluate the image quality of low-radiation-dose computed tomography (LD-CT) of the thoracolumbar spine, using model-based iterative reconstruction (MBIR) for measuring pedicle diameter. SUMMARY OF BACKGROUND DATA: MBIR can drastically reduce radiation dose but its utility in spine surgery planning is unknown. METHODS: We identified patients (mean age, 70.5 ±â€Š13.3 yrs) who incidentally underwent both standard-radiation-dose CT (SD-CT) with hybrid iterative reconstruction and LD-CT with MBIR of the thoracolumbar spine within 2 years. We compared radiation dose, subjective image sharpness, signal-to-noise ratio, and contrast-to-noise ratio for the two tests. Additionally, inner pedicle diameters were measured on SD-CT (DSD) and LD-CT (DLD), and statistically compared. RESULTS: We included 24 CT and 84 pedicles for each CT group. The radiation dose of LD-CT estimated by volume CT dose index was 1.21 ±â€Š0.42 mGy, one-sixth the dose of SD-CT. The effective dose of LD-CT was 0.58 ±â€Š0.31 mSv, equivalent to or less than that of a one-time lumbar X-ray in a previous report. LD-CT was significantly inferior in subjective image sharpness for the contour of vertebrae and trabecular structure, but superior for signal-to-noise ratio and contrast-to-noise ratio. The intra-rater reliability (intra-RR) and inter-RR for DLD were 0.985 and 0.892, respectively, comparable to those of DSD. DLD was consistently 0.30 mm smaller than DSD when compared within the same pedicle, regardless of pedicle diameter. CONCLUSION: LD-CT with MBIR produced a radiation dose equivalent to a one-time lumbar X-ray and provided excellent images for measuring pedicle diameter. LD-CT can be a substitute for SD-CT when planning spine surgery if the relationship between DSD and DLD is sufficiently understood. LEVEL OF EVIDENCE: 3.

In vivo and in vitro bioactivity of a "precursor of apatite" treatment on polyetheretherketone.

We recently developed a surface treatment, "precursor of apatite" (PrA), for polyetheretherketone (PrA-PEEK) via a simple, low-temperature process aiming to achieve stronger and faster adhesion to bone. The treatment involves three steps: H2SO4 immersion, exposure to O2 plasma discharge, and alkaline simulated body fluid (alkaline SBF) treatment. This method produces homogeneous fine particles of amorphous calcium phosphate on the PEEK, and we confirmed that PrA-PEEK had excellent apatite formation ability in an SBF immersion test. In the present study using PEEK implants in rabbit tibia, mechanical tests, and histological and radiological analyses revealed that PrA provided the PEEK substrate with excellent bone-bonding properties and osteo-conductivity at early stages (4 and 8 weeks), extending to 16 weeks. In vitro study using MC3T3-E1 cells revealed via XTT assay that PrA on the PEEK substrate resulted in no cytotoxicity, though PrA treatment seemed to suppress gene expression of integrin ß-1 and Alp after 7-day incubation as shown by real-time PCR. On the whole, PrA treatment succeeded in giving in vivo bone-bonding properties to the PEEK substrate, and the treatment is a safe and promising method that can be applied in clinical settings. There was an inconsistency between in vivo and in vitro bioactivity, and this discrepancy indicated that apatite formation does not always need activation of osteoblasts at very early stage and that optimal conditions at cell and organism level may be different. STATEMENT OF SIGNIFICANCE: Polyetheretherketone (PEEK) is an attractive engineering polymer used for spine and dental surgery. To further improve clinical outcome of PEEK-based materials, we developed "Precursor of apatite" (PrA) treatment on the PEEK surface to confer bone-bonding properties. The advantages of this treatment are that it does not require high-temperature processing or special chemicals, and it is inexpensive. The present study clarified excellent in vivo bone-bonding property of PrA treatment. In addition, the results revealed important insights indicating that optimal conditions, especially wettability and crystallinity in calcium phosphate, differ at cell and organism levels. Moreover, our results indicated that prediction of in vivo bioactivity should be done in combination with multiple in vitro tests.

Sagittal imbalance treated with L5 pedicle subtraction osteotomy with short lumbar fusion from L4 to sacrum using four screws into L4 for enhanced fixation two additional vertebral screws: a technical note.

PURPOSE: To report on suggested technique with four screws in a single vertebra (two pedicle screws and two direct vertebral body screws) for enhanced fixation with just one level cranially to a pedicle subtraction osteotomy (PSO). METHODS: A 60-year-old woman underwent L4/5 fusion surgery for degenerative spondylolisthesis. Two years later, she was unable to stand upright even for a short time because of lumbar kyphosis caused by subsidence of the fusion cage and of Baastrup syndrome in the upper lumbar spine [sagittal vertical axis (SVA) of 114 mm, pelvic incidence of 75°, and lumbar lordosis (LL) of 41°]. She underwent short-segment fusion from L4 to the sacrum with L5 pedicle subtraction osteotomy. We reinforced the construct with two vertebral screws at L4 in addition to the conventional L4 pedicle screws. RESULTS: After the surgery, her sagittal parameters were improved (SVA, 36 mm; LL, 54°). Two years after the corrective surgery, she maintained a low sagittal vertical axis though high residual pelvic tilt indicated that the patient was still compensating for residual sagittal misalignment. CONCLUSION: PSO surgery for sagittal imbalance usually requires a long fusion at least two levels above and below the osteotomy site to achieve adequate stability and better global alignment. However, longer fixation may decrease the patients' quality of life and cause a proximal junctional failure. Our novel technique may shorten the fixation area after osteotomy surgery. These slides can be retrieved under Electronic Supplementary Material.

Decreased rate of surgical site infection after spinal surgery with instrumentation using bundled approach including surveillance and intrawound vancomycin application.

Surgical site infections (SSIs) increase the risk of mortality, postsurgery, extend hospital stay, and increase the costs of healthcare. Our aim in this study was to evaluate the effectiveness of a multidisciplinary, evidence-based, surveillance program combined with intrawound application of vancomycin in lowering the incidence rate of SSI after spinal surgery with instrumentation.We conducted a retrospective analysis of 637 patients who underwent spinal fusion with instrumentation in our institution at 3 different time periods: prior to our surveillance program (control group), surveillance only (surveillance group 1), and surveillance combined with intrawound vancomycin application (surveillance group 2). The following covariates were considered in the evaluation of between-group differences in SSI rate: sex, age, surgical site, National Nosocomial Infection Surveillance (NNIS) risk index, American Society of Anesthesiologists (ASA) physical status classification, and other health comorbidities. The causative organism in cases of SSI was confirmed in all cases.The rate of SSI was significantly lower in the surveillance group 2 (1.4%) than in the control group (4.6%; P = .04). On multivariate logistic regression analysis, steroid use (adjusted odd's ratio (OR), 6.06; 95% confidence interval (CI), 1.45-23.6) and operative time (adjusted OR.1.01; 95% CI, 1.00-1.01) were identified as independent risk factors of SSI. Staphylococcus species and Propionibacterium acnes were the principal causative organisms.A bundled approach that includes surveillance and intrawound application of vancomycin is an effective strategy to lower the risk of SSI after spinal fusion with instrumentation. The use of steroid and longer operative time are risk factors of SSI.Our findings support the implementation of a program of surveillance, combined with intrawound vancomycin application, to reduce the incidence rate of SSIs in spinal surgery.

Factors influencing spinal sagittal balance, bone mineral density, and Oswestry Disability Index outcome measures in patients with rheumatoid arthritis.

PURPOSE: To identify the factors influencing spinal sagittal alignment, bone mineral density (BMD), and Oswestry Disability Index (ODI) outcome measures in patients with rheumatoid arthritis (RA). METHODS: We enrolled 272 RA patients to identify the factors influencing sagittal vertical axis (SVA). Out of this, 220 had evaluation of bone mineral density (BMD) and vertebral deformity (VD) on the sagittal plane; 183 completed the ODI questionnaire. We collected data regarding RA-associated clinical parameters and standing lateral X-ray images via an ODI questionnaire from April to December 2012 at a single center. Patients with a history of spinal surgery or any missing clinical data were excluded. Clinical parameters included age, sex, body mass index, RA disease duration, disease activity score 28 erythrocyte sedimentation rate (DAS28-ESR), serum anti-cyclic citrullinated peptide antibody, serum rheumatoid factor, serum matrix metalloproteinase-3, BMD and treatment type at survey, such as methotrexate (MTX), biological disease-modifying anti-rheumatic drugs, and glucocorticoids. We measured radiological parameters including pelvic incidence (PI), lumbar lordosis (LL), and SVA. We statistically identified the factors influencing SVA, BMD, VD, and ODI using multivariate regression analysis. RESULTS: Multivariate regression analysis showed that larger SVA correlated with older age, higher DAS28-ESR, MTX nonuse, and glucocorticoid use. Lower BMD was associated with female, older age, higher DAS28-ESR, and MTX nonuse. VD was associated with older age, longer disease duration, lower BMD, and glucocorticoid use. Worse ODI correlated with older age, larger PI-LL mismatch or larger SVA, higher DAS28-ESR, and glucocorticoid use. CONCLUSIONS: In managing low back pain and spinal sagittal alignment in RA patients, RA-related clinical factors and the treatment type should be taken into consideration.

Influence of spinopelvic alignment and morphology on deviation in the course of the psoas major muscle.

BACKGROUND: In some people, the psoas major rises laterally or anteriorly at the L4/5 disc level and detaches from the most posterior aspect of the disc despite the absence of transitional vertebrae; this is called the "rising psoas sign." There are no reports of the relationship between spinopelvic parameters and rising psoas sign. The objective of this study was to investigate the relationship between spinopelvic parameters and deviations in the location and shape of psoas major muscle at the L4/5 disc level. METHODS: We investigated the preoperative location and shape of both psoas major muscles in 64 patients treated with lateral lumbar interbody fusion. Spinopelvic parameters were measured on X-ray films. The morphology of psoas major at the L4/5 disc level was investigated with magnetic resonance images. The morphological measurements were normalized by the anteroposterior diameter of the center of the L4 vertebral body, which was measured by computed tomography. The rising psoas sign was classified into 2 types: bilateral or unilateral. RESULTS: The pelvic incidence (PI) was significantly larger for the bilateral type than the others (normal and unilateral types) (60.2 ± 11.0 vs. 46.7 ± 8.7, p < 0.001). The PI correlated significantly with the normalized anteroposterior diameter of the pelvis (R = 0.66, p < 0.001). The receiver-operator characteristic curve showed an optimal cutoff value of PI = 54, with 75% sensitivity and 78.5% specificity. The coronal L1-4 Cobb angle was significantly larger in the unilateral type than the others (normal and bilateral types) (p < 0.0001). In the unilateral type, the Cobb angle in the recumbent position correlated significantly with the normalized distance of the lateral deviation of psoas major (R = 0.60, p = 0.0085). CONCLUSION: The rising psoas sign was related to a higher PI and lumbar scoliosis. It was firstly elucidated that the spinopelvic alignment and morphology influence the deviation of the course of the psoas major muscle. STUDY DESIGN: A retrospective morphological study.

Preoperative assessment of the ureter with dual-phase contrast-enhanced computed tomography for lateral lumbar interbody fusion procedures.

BACKGROUND: Performing the minimally invasive lateral lumbar interbody fusion (LIF), such as the extreme lateral interbody fusion (XLIF) and oblique lateral interbody fusion (OLIF), through a retroperitoneal approach has become increasingly popular. Although urological injury is a major complication of LIF, the anatomical location of the ureter and its risk of injury have not been assessed. The purpose of this study was to evaluate the efficacy of dual-phase contrast-enhanced computed tomography for assessing the location of the ureter and risk of its injury in consecutive LIF cases. METHODS: 27 cases (12 men and 15 women) were enrolled in the study. Dual-phase contrast-enhanced CT was performed preoperatively, and the risk of ureteral injury was assessed. The location of the ureter was classified using the psoas muscle and vertebral body as reference structures for OLIF and XLIF procedures, respectively. During the OLIF procedures, the location of the ureter was additionally assessed with direct vision and manual palpation in all cases. Simultaneously, potential vascular anomalies were assessed with both 3D and axial images of CT. RESULTS: A total of 125 among 162 ureters, excluding 13 with insufficient enhancement and 24 (44.4%) within the kidney at the L2-L3 level, were assessed preoperatively; 113 ureters (90.4%) were classified as anatomically close to the surgical corridor for OLIF, and 20 ureters (16.0%) as having a potential risk of injury during XLIF. In one case, OLIF was converted to a conventional posterior procedure because of a vascular anomaly. Intraoperative findings showed that ureters moved anteriorly with the peritoneum in all cases, as assessed by manual palpation under direct vision. CONCLUSIONS: Dual-phase contrast-enhanced CT is useful in assessing the location of the ureter, kidney, and vascular structures simultaneously. Both OLIF and XLIF have a potential risk of urological injury.

Vertebral Endplate Cyst as a Predictor of Nonunion After Lumbar Interbody Fusion: Comparison of Titanium and Polyetheretherketone Cages.

STUDY DESIGN: The bone union rate after lumbar interbody fusion (LIF) using titanium (Ti) or polyetheretherketone (PEEK) cages was investigated retrospectively. OBJECTIVE: To assess whether the PEEK cage is superior to the Ti cage in terms of bone union after LIF. SUMMARY OF BACKGROUND DATA: We previously reported that the formation of vertebral endplate cysts is useful for predicting nonunion after LIF using Ti cages. METHODS: We examined 144 levels in 117 patients treated from March 2005 to July 2012 with transforaminal LIF using Ti (93 levels in 77 patients) or PEEK cages (51 levels in 40 patients) with pedicle screw fixation. Using computed tomography, vertebral endplate cyst (cyst sign) was evaluated at 3 months, and bone union status was evaluated at 1 and 2 years postoperatively. The relationship between cyst sign and union status was analyzed statistically. The bone union rate and the accuracy of the cyst sign were compared between the two groups. RESULTS: The postoperative bone union rate was 75.2% and 74.5% at 1 year, and 82.8% and 80.4% at 2 years for Ti and PEEK groups, respectively. The rate of positive cyst sign was 17.2% and 13.7%, respectively. The nonunion rate with positive cyst sign was 100% and 100% at 1 year, and 56.2% and 71.4% at 2 years, respectively. Calculated for the cyst sign and union status, the sensitivity was 69.6% and 53.8%, and the specificity was 100% and 100%, respectively. There were no significant differences in bone union rate, rate of positive cyst sign, nonunion rate with positive cyst sign, sensitivity, and specificity between the two groups. CONCLUSION: The cyst sign was useful for predicting nonunion after LIF using PEEK or Ti cages. The bone union rate after LIF did not differ significantly between the two groups. LEVEL OF EVIDENCE: 3.