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.

Recurrence rate after posterior percutaneous screw fixation without anterior debridement for pyogenic spondylitis compared with conservative treatment: a propensity score-matched analysis.

PURPOSE: Previous studies have shown that percutaneous pedicle screw (PPS) posterior fixation without anterior debridement for pyogenic spondylitis can improve patient quality of life compared with conservative treatment. However, data on the risk of recurrence after PPS posterior fixation compared with conservative treatment is lacking. The aim of this study was to compare the recurrence rate of pyogenic spondylitis after PPS posterior fixation without anterior debridement and conservative treatment. METHODS: The study was conducted under a retrospective cohort design in patients hospitalized for pyogenic spondylitis between January 2016 and December 2020 at 10 affiliated institutions. We used propensity score matching to adjust for confounding factors, including patient demographics, radiographic findings, and isolated microorganisms. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for recurrence of pyogenic spondylitis during the follow-up period in the matched cohort. RESULTS: 148 patients (41 in the PPS group and 107 in the conservative group) were included. After propensity score matching, 37 patients were retained in each group. PPS posterior fixation without anterior debridement was not associated with an increased risk of recurrence compared with conservative treatment with orthosis (HR, 0.80; 95% CI, 0.18-3.59; P = 0.77). CONCLUSIONS: In this multi-center retrospective cohort study of adults hospitalized for pyogenic spondylitis, we found no association in the incidence of recurrence between PPS posterior fixation without anterior debridement and conservative treatment.

Radiological follow-up of the degenerated facet joints after lateral lumbar interbody fusion with percutaneous pedicle screw fixation: Focus on spontaneous facet joint fusion.

BACKGROUND: Lateral lumbar interbody fusion (LLIF) is widely used in degenerative lumbar spine surgery. Previous studies of radiographic investigations after LLIF have assessed the anterior interbody fusion rate, the changes in the segmental lumbar lordosis, efficacy of indirect neural decompression, and remodeling of the ligamentum flavum hypertrophy and spinal canal dimension, and so on. The purpose of this study was to evaluate the radiological changes in the degenerated facet joints following LLIF with bilateral percutaneous pedicle screw (PPS) fixation, focusing on spontaneous fusion. METHODS: We retrospectively analyzed 31 patients (79 surgical levels) who underwent two- or three-level LLIF with PPS fixation without direct posterior decompression and bone grafting. We assessed the fusion rate and characteristics of the facet joints' fusion process on the preoperative, immediately postoperative, 12-month, and at least 2-year computed tomography (CT) images. On average, the last follow-up CT was performed after 30.2 months. Multivariate logistic regression analysis investigated factors related to spontaneous facet joint fusion postoperatively. RESULTS: The fusion rates of the interbody and facet joints were 32.9% (26/79) and 19.0% (15/79) after 12-months and 79.7% (63/79) and 58.2% (46/79) at the final CT follow-up, respectively. Of the 46 cases with spontaneous facet fusion, three cases fused posteriorly only. Concomitant anterior interbody fusion was seen in 43/46 (93.5%) cases. Facet fusion started in a ring shape from the outermost joint edges, exposing subchondral bone without cartilage covering, and progressed to the central thicker cartilage regions. Multivariate analysis established that concomitant anterior interbody fusion (adjusted odds ratio [aOR]: 12.10, P = 0.0035) and preoperative facet joint osteoarthritis of Weishaupt Grade â‰§ 1 (aOR: 4.770, P = 0.0068) were significant contributing factors to postoperative spontaneous facet fusion. CONCLUSIONS: Our study shows that spontaneous facet fusion frequently occurs after LLIF and may be an indicator of the inherent structural stability of the LLIF construct.

Risk factors for implant removal after spinal surgical site infection.

PURPOSE: Few studies have investigated the risk factors for implant removal after treatment for spinal surgical site infection (SSI). Therefore, there is no firmly established consensus for the management of implants. We aimed to investigate the incidence and risk factors for implant removal after SSI managed with instrumentation, and to examine potential strategies for avoiding implant removal. METHODS: Following a survey of seven spine centers, we retrospectively reviewed the records of 55 patients who developed SSI and were treated with reoperation, out of 3967 patients who had spinal instrumentation between 2003 and 2012. We examined implant survival rate and applied logistic regression analysis to assess the potential risk factors for implant removal. RESULTS: The overall rate of implant retention was 60% (33/55). A higher implant retention rate was observed for posterior cervical surgery than for posterior-thoracic/lumbar surgery (100 vs. 49%, P < 0.001). On univariate analysis, significant risk factors for implant removal included greater blood loss, delay of reoperation, and delay of intervention with effective antibiotics. Multivariate analysis revealed that a delay in administering effective antibiotics was an independent and significant risk factor for implant removal in posterior-thoracic/lumbar surgery (odds ratio 1.17; 95% confidence interval 1.02-1.35, P = 0.028). CONCLUSIONS: Patients with SSI who underwent posterior cervical surgery are likely to retain the implants. Immediate administration of effective antibiotics improves implant survival in SSI treatment. Our findings can be applied to identify SSI patients at higher risk for implant removal.

Analysis of detailed clinical characteristics of spinal subdural hematoma following lumbar decompression surgery.

BACKGROUND: Only a few reports have described symptomatic patients with postoperative spinal subdural hematoma (SSH) for which further surgery may have been required. No report has focused on the detailed clinical characteristics of postoperative SSH, including asymptomatic cases, in a case series. The reasons for this may be that SSH is an implicitly recognized rare entity, and there is no established consensus regarding the significance of performing postoperative magnetic resonance imaging (MRI) for all cases and the time at which to perform it. In this case-controlled retrospective analysis, we attempted to identify a detailed clinical presentation of SSH after open lumbar decompression surgery using MRI taken uniformly at 14 days before hospital discharge. METHODS: We retrospectively studied 196 patients who underwent routine MRI following open lumbar spinous process-splitting decompression surgery between 2012 and 2016. We assessed the frequency, clinical presentation, and radiological findings of SSH that developed postoperatively. Furthermore, we used a multivariate analysis to identify factors that were postulated to increase the risk of SSH postoperatively. RESULTS: None of the patients developed serious neurologic deficits, such as paresis or bladder and bowel dysfunction that required emergency evacuation. However, our results showed that postoperative SSHs, including asymptomatic SSHs, developed considerably frequently (43/182 patients, 23.6%). Furthermore, of the 43 patients with SSH, three presented with new postoperative neurologic findings that were strongly suspected to be associated with SSH. Multivariate analysis identified that preoperative hypertension (adjusted odds ratio [aOR]: 2.501, P = 0.018), anticoagulant therapy (aOR: 2.716, P = 0.021), and multilevel procedures (aOR: 2.327, P = 0.034) were significant risk factors of postoperative SSH. CONCLUSIONS: Spine surgeons should be aware that postoperative SSH is not rare and is a potential cause of recurrent pain or neurologic deterioration perioperatively.

The O-C2 angle established at occipito-cervical fusion dictates the patient's destiny in terms of postoperative dyspnea and/or dysphagia.

PURPOSE: We have revealed that the cause of postoperative dyspnea and/or dysphagia after occipito-cervical (O-C) fusion is mechanical stenosis of the oropharyngeal space and the O-C2 alignment, rather than total or subaxial alignment, is the key to the development of dyspnea and/or dysphagia. The purpose of this study was to confirm the impact of occipito-C2 angle (O-C2A) on the oropharyngeal space and to investigate the chronological impact of a fixed O-C2A on the oropharyngeal space and dyspnea and/or dysphagia after O-C fusion. MATERIALS AND METHODS: We reviewed 13 patients who had undergone O-C2 fusion, while retaining subaxial segmental motion (OC2 group) and 20 who had subaxial fusion without O-C2 fusion (SA group). The O-C2A, C2-C6 angle and the narrowest oropharyngeal airway space were measured on lateral dynamic X-rays preoperatively, when dynamic X-rays were taken for the first time postoperatively, and at the final follow-up. We also recorded the current dyspnea and/or dysphagia status at the final follow-up of patients who presented with it immediately after the O-C2 fusion. RESULTS: There was no significant difference in the mean preoperative values of the O-C2A (13.0 ± 7.5 in group OC2 and 20.1 ± 10.5 in group SA, Unpaired t test, P = 0.051) and the narrowest oropharyngeal airway space (17.8 ± 6.0 in group OC2 and 14.9 ± 3.9 in group SA, Unpaired t test, P = 0.105). In the OC2 group, the narrowest oropharyngeal airway space changed according to the cervical position preoperatively, but became constant postoperatively. In contrast, in the SA group, the narrowest oropharyngeal airway space changed according to the cervical position at any time point. Three patients who presented with dyspnea and/or dysphagia immediately after O-C2 fusion had not resolved completely at the final follow-up. The narrowest oropharyngeal airway space and postoperative dyspnea and/or dysphagia did not change with time once the O-C2A had been established at O-C fusion. CONCLUSIONS: The O-C2A established at O-C fusion dictates the patient's destiny in terms of postoperative dyspnea and/or dysphagia. Surgeons should pay maximal attention when establishing the O-C2A during surgery, because their careless decision for the O-C2A may cause persistent dysphagia or a life-threatening consequence. We recommend that the O-C2A in O-C fusion should be kept at least at more than the preoperative O-C2A in the neutral position.

Quantification of changes in gait characteristics associated with intermittent claudication in patients with lumbar spinal stenosis.

STUDY DESIGN: Cross-sectional observational study. OBJECTIVE: To quantify changes in gait characteristics associated with claudication after continuous walking, and to investigate the relationship between walking capacity and gait characteristics in patients with lumbar spinal stenosis (LSS). SUMMARY OF BACKGROUND DATA: Walking difficulty due to pain or neurological symptoms accompanied by continuous walking may have negative effects on gait characteristics in patients with LSS. However, there are few detailed reports on the association of these changes with intermittent claudication and their relationship with walking capacity. METHODS: For this study, 11 LSS patients with intermittent claudication were recruited. The subjects continued walking until they expressed a difficulty in continuing further. Postural sway, autocorrelation peak (AC), stride frequency (SF), and coefficient of variance (CV) were analyzed using accelerometers. To detect changes in gait parameters, we compared acceleration at the start and at the end of the walking task. RESULTS: Walking difficulty during the test increased from 4 (interquartile range, 1-5) to 9 (interquartile range, 7-10). The postural sway significantly increased after the onset of maximum walking difficulty. AC, SF, or CV did not show significant change. Maximum walking distance significantly correlated with postural sway at the cervical sensor (r=-0.64), and CV (ρ=-0.66), an index of gait variability, at the beginning of the walking task. CONCLUSIONS: The change in gait parameters associated with claudication during continuous walking is detectable using accelerometers. Postural sway increases after the provocation of walking difficulty due to pain or neurological symptoms. In addition, walking capacity correlated with postural sway of the upper trunk and gait variability during walking initiation. This methodology warrants further studies to confirm its usefulness as an assessment tool for patients with LSS.

The reinforcement of a C2 laminar screw by a C2 laminar hook as an anchor of occipito-C2 fusion.

Although a C1-C2 transarticular screw (TAS) or a C2 pedicle screw (PS) is the most rigid anchor for C2, each entails the risk of vertebral artery injury. Although a C2 laminar screw (LS) is often used as an alternative anchor in such cases, its anchoring strength may be inadequate. We introduce a technical tip, in which a C2 LS is reinforced by a C2 infralaminar hook without extending the fusion range. Six patients, for whom a unilateral TAS or C2 PS was risky or impossible, were treated with O-C2 fusion using this technique. The post-operative course of each patient was uneventful. Bone union was achieved in all patients, except one who died of indifferent disease before the confirmation of bone union by computed tomography. This method would be a safe and non-technical-demanding option when the placement of a TAS or PS is risky or impossible.

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.

Lumbar Spinal Surgery in Patients With Parkinson Disease: A Multicenter Retrospective Study.

STUDY DESIGN: A multicenter, retrospective study. OBJECTIVE: To identify the factors that affect surgery-related complications and to clarify the surgical strategy for treating lumbar disorders in Parkinson disease (PD). SUMMARY OF BACKGROUND DATA: Previous studies have reported a high complication rate for spinal surgery in patients with PD. Because of the limited number of studies, there are no guidelines for spinal surgery for PD patients. METHODS: We retrospectively reviewed the records for 67 PD patients who underwent lumbar spinal surgery. The patients were divided into 3 groups: 12 patients underwent laminectomy (Laminectomy), 24 underwent fusion surgery (Fusion) for lumbar canal stenosis, and 31 underwent corrective surgery for spinal deformity (Deformity). We assessed surgery-related complications in each group. The Cox proportional hazards model was used to identify the factors that predicted surgical failure. RESULTS: The percentages of patients who experienced failure of the initial surgery were 33.3% in the Laminectomy group, 45.8% in the Fusion group, and 67.7% in the Deformity group. The rates of implant failure were high in the Fusion and Deformity groups (33.3% and 38.7%, respectively). The Deformity group had a high rate of postoperative fracture (41.9%). These complications occurred at the most caudal site within a year after surgery and resulted in progression of kyphotic deformity. Multivariate analysis revealed that preoperative lumbar lordosis angle (LL) (per -1 degree) was associated with a failure of the initial surgery (hazard ratio, 1.024; 95% confidence interval, 1.008-1.04; P=0.003). CONCLUSIONS: We have demonstrated that a small preoperative LL increases the risk for failure of the initial surgery. Attaining and maintaining the proper lumbar lordosis with rigid fixation may be necessary in PD patients with a small preoperative LL.

Reduction of atlantoaxial subluxation causes airway stenosis.

STUDY DESIGN: A cross-sectional study. OBJECTIVE: The purpose of this study was to investigate the effect of reduction of anterior atlantoaxial subluxation (AAS) on the oropharyngeal airway space. SUMMARY OF BACKGROUND DATA: Our previous studies have shown that reduction of the occipito-C2 angle (O-C2A) makes the mandible shift posteriorly, resulting in oropharyngeal airway stenosis, which occasionally causes postoperative dysphagia after occipitocervical fusion. Based on this background, we hypothesized that reduction of AAS would also cause oropharyngeal airway stenosis independent of the O-C2A, because it also shifts the mandible posteriorly. To our knowledge, there are no data demonstrating an association between reduction of AAS and the oropharyngeal airway space. METHODS: The authors prospectively evaluated 64 patients with rheumatoid arthritis. We analyzed lateral cervical plain radiographs of 5 different positions (neutral, flexion, extension, retraction, and protrusion), and measured the O-C2A, C2-C6 angle, anterior atlantodental interval, anteroposterior distance of the narrowest oropharyngeal airway space (nPAS), and so on. The subjects were classified into 2 groups: group R comprised patients with a "reducible AAS" in dynamic cervical movement, and group N comprised "patients without AAS" patients. RESULTS: In the multiple regression analysis, the change in the O-C2A was the only significant independent variable related to the percentage change in the nPAS from the neutral position in group N. On the contrary, the change in the anterior atlantodental interval and change in the O-C2A were significantly related to the percentage change in the nPAS in group R. No cases in group N and 7 cases (28%) in group R showed a paradoxical decrease in the nPAS in extension, in which the O-C2A is largest and reduction of AAS is obtained. CONCLUSION: Reduction of AAS has a negative effect on the oropharyngeal airway space. Therefore, reduction of AAS during occipitocervical fusion may cause postoperative dysphagia despite maintenance of the O-C2A.

Utility of the analysis of intracranial venous sinuses using preoperative computed tomography venography for safe occipital screw insertion.

STUDY DESIGN: Prospective descriptive study. OBJECTIVE: To verify the feasibility and utility of evaluating venous sinuses (VSs) using computed tomography venography (CTV) concomitant with preoperative CT angiography (CTA) for safe occipital screw fixation. SUMMARY OF BACKGROUND DATA: Preoperative evaluation of the vertebral artery by CTA is indispensable in occipitocervical spinal instrumentation surgery. Despite accumulating evidence showing the potential of CTV, no studies have reported the usefulness of concomitant use of CTV and CTA before placement of occipital plate-screw constructs. METHODS: We analyzed 30 consecutive patients who underwent CTV simultaneously with CTA. First, we investigated VS anatomy in individual cases and classified the continuity patterns of relevant VSs. Subsequently, we evaluated the probable risk zones for VS injury, from the viewpoint of occipital screw insertion. RESULTS: VSs can be clearly visualized using CTV simultaneously with CTA examination without significant increase of radiation exposure or extra workload for radiographical technicians. VS continuity was classified into 4 categories: the confluence type (n = 9), bifurcation type (n = 8), transverse type (n = 11), and others (n = 2). The confluence of sinuses and their relevant VSs were greatly variable between individuals, and occasionally, some cases with high-risk morphology for VS injury in occipital screw placement were observed. CONCLUSION: Our findings indicate that there is no universal position for safe insertion of occipital screws that is applicable to all individuals. It is risky to determine optimal screw placement, only on the basis of traditional cadaveric information such as occipital bone thickness and several external bony landmarks. Spine surgeons must recognize that VS injury may occasionally lead to life-threatening complications. The detailed information on VSs obtained by preoperative CTV examination combined with CTA in individual cases can be useful in preoperative planning and can contribute greatly to the improvement of surgical safety. LEVEL OF EVIDENCE: 2.

Does the formation of vertebral endplate cysts predict nonunion after lumbar interbody fusion?

STUDY DESIGN: A retrospective study was conducted to investigate the impact of vertebral endplate cyst formation on union status after lumbar interbody fusion. OBJECTIVE: To assess the impact of cyst formation at the vertebral endplate in the early detection of nonunion after lumbar interbody fusion. The relationship between vertebral endplate cyst formation and subsequent union status was evaluated retrospectively using dynamic x-ray and computed tomography (CT) and multiplanar reconstruction. SUMMARY OF BACKGROUND DATA: Although many studies have reported on the assessment of bony union after lumbar interbody fusion, no study has reported on the radiological risk factors for nonunion in the early postoperative period. The meaning and importance of vertebral endplate cyst formation have not been reported and should be clarified. METHODS: Radiological vertebral endplate changes at 93 levels were assessed in 76 patients after transforaminal lumbar interbody fusion, using a titanium cage with pedicle screw fixation. Computed tomographic findings for the vertebral endplate at 3 months were compared between nonunion and union cases. The relationship between vertebral endplate cyst formation and union status was tested statistically. RESULTS: Fifty-nine union cases were compared with 17 nonunion cases. The overall union rate was 75.2% at 1 year and 82.8% at 2 years. At 1 year, the sensitivity of cyst formation for subsequent nonunion was 69.6%, specificity was 100%, positive predictive value was 100%, and negative predictive value was 90.9%. Multivariate logistic regression analysis showed that a multioperated back was a significant predictor of cyst formation (odds ratio [OR]: 3.8; 95% confidence interval [CI]: 1.1-13.1) and that cyst formation and multioperated back were significant predictors of nonunion (OR: 12.3; 95% CI: 1.8-133 and OR: 116; 95% CI: 22.4-infinity, respectively). CONCLUSION: These findings show a relationship between vertebral endplate cyst formation in the early postoperative period and nonunion after lumbar interbody fusion. Endplate cyst formation is a useful early predictor of subsequent nonunion.