Pressure Dynamics on Intervertebral Disc Cages in Transforaminal Lumbar Interbody Fusion: A Cadaver Study.

OBJECTIVE: This study aimed to quantify the change in pressure on the cage during compression manipulation in lumbar interbody fusion. While the procedure involves applying compression between pedicle screws to press the cage against the endplate, the exact compression force remains elusive. We hypothesize that an intact facet joint might serve as a fulcrum, potentially reducing cage pressure. METHODS: Pressure on the intervertebral disc cage was measured during compression manipulation in 4 donor cadavers undergoing lumbar interbody fusion. Unilateral facetectomy models with both normal and parallel compression and bilateral facetectomy models were included. A transforaminal lumbar interbody fusion cage with a built-in load cell measured the compression force. RESULTS: Pressure data from 14 discs indicated a consistent precompression pressure average of 68.16 N. Following compression, pressures increased to 125.99 N and 140.84 N for normal and parallel compression postunilateral facetectomy, respectively, and to 154.58 N and 150.46 N for bilateral models. A strong linear correlation (correlation coefficient: 0.967, P < 0.0001) between precompression and postcompression pressures emphasized the necessity of sufficient precompression pressure for achieving desired postcompression outcomes. None of the data showed a decrease in compression force to the cage with the compression maneuver. CONCLUSIONS: Both normal and parallel compression maneuvers effectively increased the pressure on the cage, irrespective of the facet joint resection status. Compression manipulation consistently enhanced compressive force on the cage. However, when baseline pressure is low, the manipulation might not yield significant increases in compression force. This underlines the essential role of meticulous precompression preparation in enhancing surgical outcomes.

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°.

Association of two-staged surgery with systemic perioperative complications in lateral lumbar interbody fusion for adult spinal deformity: a propensity score-weighted study.

PURPOSE: Adult spinal deformity (ASD) surgery carries a higher risk of perioperative systemic complications. However, evidence for the effect of planned two-staged surgery on the incidence of perioperative systemic complications is scarce. Here, we evaluated the effect of two-staged surgery on perioperative complications following ASD surgery using lateral lumbar interbody fusion (LLIF). METHODS: The study was conducted under a retrospective multi-center cohort design. Data on 293 consecutive ASD patients (107 in the two-staged group and 186 in the one-day group) receiving corrective surgery using LLIF between 2012 and 2021 were collected. Clinical outcomes included occurrence of perioperative systemic complications, reoperation, and intraoperative complications, operation time, intraoperative blood loss, transfusion, and length of hospital stay. The analysis was conducted using propensity score (PS)-stabilized inverse probability treatment weighting to adjust for confounding factors. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated in a PS-weighted cohort. RESULTS: In this cohort, 19 (18.4%) patients in the two-staged group and 43 (23.1%) patients in the one-day group experienced any systemic perioperative complication within 30 days following ASD surgery. In the PS-weighted cohort, compared with the patients undergoing one-day surgery, no association with the risk of systemic perioperative complications was seen in patients undergoing two-staged surgery (PS-weighted OR 0.78, 95% CI 0.37-1.63; p = 0.51). CONCLUSION: Our study suggested that two-staged surgery was not associated with risk for perioperative systemic complications following ASD surgery using LLIF.

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).

Salvage Oblique Lateral Interbody Fusion for Pseudarthrosis after Posterior/Transforaminal Lumbar Interbody Fusion: A Technical Note.

OBJECTIVE: This study aims to demonstrate the efficacy of salvage oblique lumbar interbody fusion (OLIF) surgery for pseudarthrosis after posterior/transforaminal lumbar interbody fusion (PLIF/TLIF). METHODS: The study group were patients with leg or back pain induced by pseudarthrosis after PLIF/TLIF. These patients underwent salvage OLIF surgeries in our institutions between July 2015 and Oct 2019. We retrospectively evaluated their clinical and radiographic outcomes. RESULTS: Seven consecutive patients (all male; mean age 68.4 ± 9.3 years, range 53-81 years) were included in this study. There was no intraoperative complications in all cases. Six of 7 patients achieved bone union (at average 33.4 months follow-up) and had a successful postoperative course. Only 1 patient failed to gain bony fusion and required additional revision surgery due to progression of sagittal and coronal malalignment at 18 months after salvage OLIF surgery. CONCLUSIONS: The salvage OLIF approach was useful option for pseudarthrosis after PLIF/TLIF. It enabled us to build a rigid anterior support, allowed for extensive curettage of intervertebral scar tissue, and reduced the rate of the complications associated with dealing with posterior scar tissue.

Possible Association of Pedicle Screw Diameter on Pseudoarthrosis Rate After Transforaminal Lumbar Interbody Fusion.

BACKGROUND: Although pedicle screw sizes may affect the rate of bone union after lumbar fusion surgery, there is currently no supportive clinical evidence. METHODS: Eighty-five patients older than 50 years who underwent single-level L4/5 transforaminal lumbar interbody fusion with posterior pedicle screw (PS) fixation were analyzed. Patients with factors that potentially inhibit bone fusion, such as Parkinson disease, were excluded. Bone union was assessed using computed tomography and dynamic radiographs 1 year after surgery. Explanatory factors considered included sex, age, smoking, bone density, material of the cage, PS diameter (PSD), relative PS length, theoretical maximum PSD (PSDmax), which was defined as the maximum diameter of the screw that may be inserted without breaking cortical bone around the pedicle, and the filling index, which was defined as the difference between the cross-sectional area of maximum PS and actual PS (PSDmaxˆ 2 - PSD ˆ 2). Japanese Orthopaedic Association scores before and 1 year after surgery were evaluated as a clinical outcome. RESULTS: Nineteen levels were diagnosed as pseudoarthrosis. A multivariate logistic regression analysis identified a larger filling index (P = 0.016) and older age (P = 0.047) as risk factors for pseudoarthrosis. The Japanese Orthopaedic Association score 1 year after surgery and its recovery rate were significantly worse in patients with pseudoarthrosis than in those with fusion. CONCLUSIONS: The selection of an appropriately sized screw is important for achieving rigid fusion after transforaminal lumbar interbody fusion. Preoperative planning using multiplanar reconstruction computed tomography is an important approach for ensuring good clinical results.

Remaining spine deformity after revision surgery for pelvic reconstruction and spinopelvic fixation: illustrative case.

BACKGROUND: Pelvic deformity after resection of malignant pelvic tumors causes scoliosis. Although the central sacral vertical line (CSVL) is often used to evaluate the coronal alignment and determine the treatment strategy for scoliosis, it is not clear whether the CSVL is a suitable coronal reference axis in cases with pelvic deformity. This report proposes a new coronal reference axis for use in cases with pelvic deformity and discusses the pathologies of spinal deformity remaining after revision surgery. OBSERVATIONS: A 14-year-old boy who had undergone internal hemipelvectomy and pelvic ring reconstruction 2 years prior was referred to our hospital with severe back pain. His physical and radiographic examinations revealed severe scoliosis with pelvic deformity. The authors planned a surgical strategy based on the CSVL and performed pelvic ring reconstruction using free vascularized fibula graft and spinopelvic fixation from L5 to the pelvis. After the procedure, although the patient's back pain was relieved, his scoliosis persisted. At the latest follow-up, his spinal deformity correction was acceptable with corset bracing. Therefore, the authors did not perform additional surgeries. LESSONS: The CSVL may not be appropriate for evaluating coronal alignment in cases with pelvic deformity. Accurate preoperative planning is required to correct spinal deformities with pelvic deformity.

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.

Preserving the Pelvic Ring at the Sciatic Notch During Resection of Malignant Bone Tumors at the Posterior Ilium.

Resection of malignant bone tumors in the posterior ilium may result in pelvic ring disruption. Preserving the pelvic ring and keeping an adequate surgical margin is ideal, but is challenging, especially when the tumor extends to the sacroiliac joint. The current report proposes a line from the lateral point of the second sacral dorsal foramen to the anterior surface of sacral ala (S2 -sacral ala line), and cutting from the line to the ilium over the sciatic notch and to the sacral wing using thread saws. This preserves the cortex at the sciatic notch and the distal sacroiliac joint. Two posterior iliac tumors extending to the sacroiliac joint, a metastatic melanoma in a 75-year-old male, and an osteosarcoma in a 56-year-old male were resected. The resections were performed along the S2 -sacral ala line, and consequently lumbo-sacro-pelvic fusions were performed. Both patients were able to walk with one crutch. Indications for the method using the S2 -sacral ala line for iliac tumors may be limited. However, the method can increase pelvic ring preservation in cases with posterior iliac malignant bone tumors.

The spontaneous restoration of the course of psoas muscles after corrective surgery for adult spinal deformity.

BACKGROUND: A previous study demonstrated that spinopelvic alignment and morphology influence a deviation in the course of psoas muscle (PM). However, it is unknown whether such deviations might be caused by a decrease in lumbar lordosis (LL) or the lateral deviation of the lumbar spine following scoliosis. The purpose of this study was to elucidate the close relationship between the coronal and sagittal lumbar alignment and a deviation in the course of PM. METHODS: We investigated the preoperative and postoperative spinopelvic parameters and the morphology of PM at L4/5 level in 30 patients treated with corrective surgery for adult spinal deformity who were diagnosed with "rising psoas sign" before surgery. Spinopelvic parameters were measured on X-ray films. Investigation of the morphology of PM and the morphological measurements were performed using computed tomography (CT) images. The "rising psoas sign" was classified as bilateral- or unilateral-type as defined in the previous study. RESULTS: Among 18 patients who had bilateral-type rising psoas sign before surgery, 11 patients remained bilateral-type after surgery despite an increase in LL. The pelvic incidence of these 11 patients was significantly larger than that of the other 7 patients (53.5 ± 10.2° vs 43.2 ± 5.8°) (p = 0.037). The magnitude of postoperative increase in LL positively correlated with that of the posterior shift of PM (r = 0.41, p = 0.025). The degree of restoration of the lumbar spine following scoliosis was positively correlated with that of the medial shift of PM (r = 0.66, p = 0.025). CONCLUSION: The decrease in LL and the lateral deviation of lumbar spine following scoliosis caused a deviated course of the PM, which was spontaneously corrected by the restoration of lumbar alignment. However, the bilateral-type deviation in patients with higher pelvic incidence was considered to be within the range of normal variation.

Outcomes of lumbar decompression surgery in patients with diffuse idiopathic skeletal hyperostosis (DISH).

BACKGROUND: Only a few studies have described the effect of diffuse idiopathic skeletal hyperostosis (DISH) on the clinical results after lumbar surgery. The aim of the study is to clarify the associations between DISH and the clinical results after lumbar decompression surgery. METHODS: The outcomes of 328 consecutive patients who underwent primary lumbar decompression surgery for treatment of lumbar canal stenosis with or without grade I spondylolisthesis were analysed retrospectively. The major outcome measures were surgery-free survival and the need for further surgery because of same-segment disease (SSD) and/or adjacent-segment disease (ASD). RESULTS: Of the 328 patients, 69 (60 men and nine women) were diagnosed with DISH. The Japanese Orthopaedic Association score before and at 1 year after the surgery did not differ significantly between patients with and without DISH. However, the rate of revision surgery in the follow-up period was significantly higher in patients with DISH than in those without (19% vs 6.9%, p = 0.0050). Cox proportional-hazards modelling revealed that DISH and sex (female) were independent risk factors for the need for revision surgery after decompression surgery for degenerative lumbar spine. The rate of revision surgery was higher in the sub-group of DISH with ossification extended to L2 or more than that for those with the ossification extended to L1 (26% vs 8%, p = 0.11), but the difference did not reach statistical significance. CONCLUSIONS: DISH is a risk factor for revision surgery after decompression surgery for degenerative lumbar spine because of SSD and/or ASD.

Occipital and external acoustic meatus to axis angle: a useful predictor of oropharyngeal space in rheumatoid arthritis patients with atlantoaxial subluxation.

OBJECTIVE: Dyspnea and/or dysphagia is a life-threatening complication after occipitocervical fusion. The occiput-C2 angle (O-C2a) is useful for preventing dyspnea and/or dysphagia because O-C2a affects the oropharyngeal space. However, O-C2a is unreliable in atlantoaxial subluxation (AAS) because it does not reflect the translational motion of the cranium to C2, another factor affecting oropharyngeal area in patients with rheumatoid arthritis (RA) who have reducible AAS. The authors previously proposed the occipital and external acoustic meatus to axis angle (O-EAa; i.e., the angle made by McGregor's line and a line joining the external auditory canal and the middle point of the endplate of the axis [EA line]) as a novel, useful, and powerful predictor of the anterior-posterior narrowest oropharyngeal airway space (nPAS) distance in healthy subjects. The aim of the present study was to elucidate the validity of O-EAa as an indicator of oropharyngeal airway space in RA patients with AAS. METHODS: The authors investigated 64 patients with RA. The authors collected lateral cervical radiographs at neutral position, flexion, extension, protrusion, and retraction and measured the O-C2a, C2-C6, O-EAa, anterior atlantodental interval (AADI), and nPAS. Patients were classified into 2 groups according to the presence of AAS and its mobility: group N, patients without AAS; and group R, patients with reducible AAS during dynamic cervical movement. RESULTS: Group N had a significantly lower AADI and O-EAa than group R in all but the extension position. The O-EAa was a better predictor for nPAS than O-C2a according to the mixed-effects models in both groups (marginal R2: 0.510 and 0.575 for the O-C2a and O-EAa models in group N, and 0.250 and 0.390 for the same models, respectively, in group R). CONCLUSIONS: O-EAa was superior to O-C2a in predicting nPAS, especially in the case of AAS, because it affects both O-C2a and cranial translational motion. O-EAa would be a useful parameter for surgeons performing occipitocervical fusion in patients with AAS.

Posterior Dural Shifts Following Spinous Process-Splitting Multi-Level Intervertebral Lumbar Laminectomies.

Study Design: Retrospective cohort study. Purpose: The aim of our study is to evaluate the extent of posterior spinal dural shift following spinous process splitting multi-level intervertebral lumbar laminectomies, and determine the relationship between posterior spinal dural shift and preoperative parameters. Overview of Literature: There are no existing studies on the posterior spinal dural shift after spinous process-splitting multi-leveled lumbar laminectomies. Methods: We examined 37 patients who underwent spinous process-splitting laminectomies in at least two intervertebral levels, including at the L5/S level. We defined the distance between the vertebral bodies and the anterior edge of the dural sac in the magnetic resonance images at the L5 vertebral level as the anterior dural space (ADS) and detected the difference (d-ADS) between preoperative ADS (pre-ADS) and postoperative ADS (post-ADS). We assessed the relationship between ADS or d-ADS, and preoperative parameters, including age, sex, lumbar lordosis, focal lordosis (FL), and number of decompression levels. Results: Post-ADS was significantly greater than pre-ADS (p <0.001). Pre-ADS was significantly correlated with FL (p =0.44, p <0.01) and also with post-ADS (p =0.43, p <0.01). d-ADS was negatively correlated with pre-ADS (p =-0.37, p <0.05). A single regression analysis revealed that the relationship between d-ADS and pre-ADS was described as d-ADS=3.67-0.46×pre-ADS. In one of three patients whose d-ADS was above the range of two standard errors, reoperation was performed because of impingement of the nerve root caused by the excessive posterior dural shift. Conclusions: Posterior dural shifts occur after spinous process-splitting multi-level lumbar laminectomies, including at the L5/S level. FL and pre-ADS are good predictive factors for posterior dural shift. Excessive posterior dural shift may lead to stretching and impingement of nerve roots and thus require attention.

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.