Risk factors for early reoperation in patients after posterior lumbar interbody fusion surgery. A propensity-matched cohort analysis.

BACKGROUND: Reoperation is usually associated with poor results and increased morbidity and hospital costs. However, the rates, causes, and risk factors for reoperation in patients undergoing lumbar spinal fusion surgery remain controversial. This study aimed to identify the risk factors for early reoperation after posterior lumbar interbody fusion surgery and to compare the clinical outcomes between patients who underwent reoperation and those who did not. METHODS: We investigated a multicenter medical record database of 1263 patients who underwent posterior lumbar interbody fusion surgery between 2012 and 2015. A total of 72 (5.7%) reoperations within two years after surgery were identified and were propensity-matched for age, sex, number of fusion segments, and surgeon's experience. RESULTS: We analyzed a total of 114 patients (57 who underwent reoperation (R group) and 57 who did not (C group)). The mean age was 62.6 ± 13.4 years, with 78 men and 36 women. The mean number of fused segments was 1.2 ± 0.5. Surgical site infection was the most common cause of reoperation. There were significant differences in the incidence of diabetes mellitus (p = 0.024), preoperative ambulation status (p = 0.046), and ASA grade (p < 0.001) between the C and R groups. The recovery rate of the Japanese Orthopaedic Association score was significantly lower in the R group compared to the C group (R: 50.5 ± 28.8%, C: 63.9 ± 33.7%, p = 0.024). There were significant differences in the bone fusion rate (R: 63.2%, C: 96.5%, p < 0.001) and incidence of screw loosening (R: 31.6%; C: 10.5%; p = 0.006). CONCLUSION: Diabetes mellitus, preoperative ambulation status, and ASA grade were significant risk factors for early reoperation following posterior lumbar interbody fusion surgery. The patients who underwent early reoperation had worse clinical outcomes than those who did not.

Spontaneous correction of sagittal spinopelvic malalignment after decompression surgery without corrective fusion procedure for lumbar spinal stenosis and its impact on clinical outcomes: A systematic review.

BACKGROUND: The impact of a positive sagittal vertical axis (SVA) on the surgical outcome for lumbar spinal stenosis (LSS) remains unclear, because sagittal imbalance in LSS may partly result from the tendency of patients to lean forward to reduce symptoms. Such an abnormality could be normalized by decompression surgery alone without corrective fusion. As this spontaneous correction is not well known, some surgeons perform only neural decompression in patients with positive SVA and decreased lumbar lordosis (LL), unless flatback-related symptoms are present, whereas other surgeons add corrective fusion to restore spinopelvic alignment. We systematically reviewed previous studies on this issue. METHODS: PubMed, Cochrane Library, and Embase were searched for English articles on the relationship between SVA and decompression surgery for LSS. The rates of spontaneous correction in spinopelvic parameters and the impact of SVA on clinical outcomes were analyzed. RESULTS: The rate of spontaneous SVA correction from >40-50 mm to normal values following decompression surgery alone varied from 25% to 73%. Overall, the spinopelvic parameters tended to improve postoperatively, with statistically significant changes in some series. Postoperative residual sagittal imbalance, rather than preoperative imbalance, more consistently showed a negative impact on clinical outcomes, but not on leg symptoms. For predicting postoperative sagittal imbalance, 2 studies identified the cutoff of >20° for preoperative PI-LL mismatch. Another study suggested SVA >80 mm as a useful value for this purpose. CONCLUSION: In LSS treated with decompression surgery alone, postoperative rather than preoperative sagittal imbalance more consistently affects clinical outcomes, particularly low back pain. This is probably because decompression usually partly improves preoperative spinopelvic sagittal malalignment. Thus, LSS, if associated with preoperative PI-LL mismatch <20° and SVA <80 mm, may not require additional corrective fusion procedures.

Risk factors for early-onset radiographical adjacent segment disease in patients with spondylolytic spondylolisthesis after single-level posterior lumbar interbody fusion.

BACKGROUND CONTEXT: The risk factors for radiographical adjacent segment disease (ASD) in patients with degenerative spondylolisthesis have been previously reported. However, there are only few reports on patients with spondylolytic spondylolisthesis who underwent single-level posterior lumbar interbody fusion (PLIF). PURPOSE: The study aimed to investigate the risk factors for radiographical ASD in patients with L5-S1 spondylolytic spondylolisthesis who underwent single-level PLIF. STUDY DESIGN/SETTING: A retrospective study PATIENT SAMPLE: This study retrospectively reviewed 135 consecutive patients (91 men and 44 women) with symptomatic L5-S1 spondylolytic spondylolisthesis who underwent single-level PLIF. OUTCOME MEASURES: The pre- and postoperative (at the final follow-up) spinopelvic parameters, % slip, sacral slope, lumbar lordosis (LL), pelvic tilt, pelvic incidence (PI), PI minus LL (PI - LL), lumbosacral angle, C7 sagittal vertical axis, and thoracic kyphosis were measured using standing radiographs. METHODS: Radiographical ASD was defined as disc height loss (>3 mm), increase of posterior angulation (>5°), or progression of spondylolisthesis (>3 mm) between the pre- and postoperative radiographs. Pfirrmann's classification was used to evaluate disc degeneration. The radiographical parameters and changes between the pre- and postoperative values were evaluated and compared for the non-ASD and ASD groups. Binary logistic regression analysis was performed to evaluate the adjusted associations between each potential explanatory variable and ASD development. RESULTS: The radiographical ASD incidence was 11%. Additionally, 60% of the patients with ASD had radiographical ASD at 1 year and all cases of radiographical ASD in this follow-up period occurred within 3 years after the initial surgery. The mean period of ASD occurrence after initial surgery was 21.7 ± 12.6 months. No patients required reoperation for radiographical ASD. Multivariate analysis revealed that a preoperative (odds ratio [OR], 5.9; 95% confidence interval [CI], 1.2-28.9; p=.03) and a postoperative (OR, 6.5; 95% CI, 1.2-34.5; p=.03) PI - LL of ≥15° were risk factors for radiographical ASD. CONCLUSIONS: Pre- and postoperative PI - LL value mismatch was identified as significant independent risk factors for radiographical ASD in patients with L5-S1 spondylolytic spondylolisthesis. Obtaining larger lordosis at L5-S1 may be the key to preventing radiographical ASD.

Improvement of Lower Back Pain in Lumbar Spinal Stenosis After Decompression Surgery and Factors That Predict Residual Lower Back Pain.

STUDY DESIGN: Retrospective observational study. OBJECTIVES: There is no consensus to predict improvement of lower back pain (LBP) in lumbar spinal stenosis after decompression surgery. The aim of this study was to evaluate the improvement of LBP and analyze the preoperative predicting factors for residual LBP. METHODS: We retrospectively reviewed 119 patients who underwent lumbar decompression surgery without fusion and had a minimum follow-up of 1 year. LBP was evaluated using the numerical rating scale (NRS), Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) LBP score, and Roland-Morris Disability Questionnaire (RMDQ). All patients were divided into LBP improved group (group I) and LBP residual group (group R) according to the NRS score. Radiographic images were examined preoperatively and at the final follow-up. We evaluated spinopelvic radiological parameters and analyzed the differences between group I and group R. RESULTS: LBP was significantly improved after decompression surgery (LBP NRS, 5.7 vs 2.6, P < .001; JOABPEQ LBP score, 41.3 vs 79.6, P < .001; RMDQ, 10.3 vs 3.6, P < .001). Of 119 patients, 94 patients were allocated to group I and 25 was allocated to group R. There was significant difference in preoperative thoracolumbar kyphosis between group I and group R. CONCLUSIONS: Most cases of LBP in lumbar spinal stenosis were improved after decompression surgery without fusion. Preoperative thoracolumbar kyphosis predicted residual LBP after decompression surgery.

Impact of leg numbness on patient satisfaction following decompression surgery for lumbar spinal stenosis.

Decompression surgery is the most common surgical treatment for lumbar spinal stenosis (LSS). Relatively low satisfaction rate was reported. Patients often complaint of residual numbness despite significant pain relief. We hypothesized that numbness had a significant impact on patient satisfaction, but had not been evaluated, which is associated with low satisfaction rate. This study aimed to examine how much numbness is associated with patient satisfaction. We retrospectively reviewed prospectively collected data from consecutive patients who underwent decompression without fusion for LSS. We evaluated the Numeric Rating Scale (NRS) scores of low back pain (LBP), leg pain, and leg numbness preoperatively and at the final follow-up visit. Improvement was evaluated using minimum clinically important differences (MCIDs). Patient satisfaction was evaluated using the question, "How satisfied are you with the overall result of your back operation?". There are four possible answers consisting of "very satisfied (4-point)", "somewhat satisfied (3-point)", "somewhat dissatisfied (2-point)", or "very dissatisfied (1-point)". Spearman correlation was used to evaluate the association between patient satisfaction and reaching MCIDs. A total of 116 patients were included. All three components had correlation with patient satisfaction with the correlation efficient of 0.30 in LBP, 0.22 in leg pain, and 0.33 in numbness. Numbness had greatest correlation efficient value. We showed that numbness has a greater impact than leg/back pain on patient satisfaction in patients undergoing decompression for LSS. We suggest not only LBP and leg pain but also numbness should be evaluated pre- and postoperatively.

Vesicular glutamate transporter 2-immunoreactive synapses onto phrenic motoneurons in the neonatal rat.

The synaptic organization between vesicular glutamate transporter 2 (VGLUT2)-immunoreactive (ir) axon terminals and phrenic motoneurons in the neonatal rat was examined using a combined retrograde tracing and immunohistochemistry for VGLUT2. The phrenic nucleus (PhN) contained large numbers of VGLUT2-ir axon terminals, some of which made axosomatic and axodendritic synapses with PhN motoneurons. These terminals were of asymmetrical type and contained spherical clear synaptic vesicles. The results suggest that in the neonatal rat glutamatergic synapses onto PhN motoneurons exist and mediate excitatory transmission to drive PhN motoneurons.

Anatomical changes of phrenic motoneurons during development.

Although the phrenic motoneurons are relatively well-developed at the time of birth as compared to non-respiratory motoneurons, they show distinct anatomical changes during postnatal development. In the present review we summarize anatomical changes of phrenic motoneurons during pre- and postnatal development. Cell bodies of phrenic motoneurons migrate into the ventromedial region of the ventral horn of C3-C6 by E13-E14 in the rat. During development the sizes and surface areas of phrenic motoneurons are increased with changes in dendritic morphology.

Factors Influencing Patient Satisfaction After Decompression Surgery Without Fusion for Lumbar Spinal Stenosis.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: Decompression without fusion is a standard surgical treatment for lumbar spinal stenosis (LSS) with reasonable surgical outcomes. Nevertheless, some studies have reported low patient satisfaction (PS) following decompression surgery. The cause of the discrepancy between reasonable clinical outcomes and PS is unknown; moreover, the factors associated with PS are expected to be complex, and little is known about them. This study aimed to identify satisfaction rate and to clarify the factors related to PS following decompression surgery in LSS patients. METHODS: We retrospectively reviewed 126 patients who underwent lumbar decompression with a minimum follow-up of 1 year. Patients were divided into 2 groups based on the PS question. The Japanese Orthopaedic Association (JOA) scores, and the Numeric Rating Scale (NRS) scores of low back pain (LBP), leg pain, and leg numbness were compared between the 2 groups preoperatively and at the latest visit. To identify the prognostic factors for dissatisfaction, multiple logistic regression analysis was performed. RESULTS: Overall satisfaction rate was 75%. The JOA recovery rate, NRS improvement, and Short Form-8 (SF-8) were significantly higher in the satisfied group. Postoperative NRS scores of LBP, leg pain, and leg numbness were significantly lower in the satisfied group. Multivariate logistic regression analysis showed that smoking and scoliosis were significant risk factors for dissatisfaction. CONCLUSIONS: Overall satisfaction rate was 75% in patients with LSS undergoing decompression surgery. This study found that smoking status and scoliosis were associated with patient dissatisfaction following decompression in LSS patients.

Minimum clinically important difference of major patient-reported outcome measures in patients undergoing decompression surgery for lumbar spinal stenosis.

OBJECTIVE: A minimum clinically important difference (MCID) has been increasingly well known in the current era of patient-centered care because it reflects a smallest change that is meaningful for patients following a clinical intervention. Previous studies suggested MCID values are disease and/or procedure dependent. No MCID values have been reported on the lumbar spinal stenosis (LSS) following decompression surgery despite LSS is the most common spinal disease and the main treatment is decompression surgery. Therefore, this study aimed to determine the MCID values as major outcome measures including the Numeric Rating Scale (NRS) of back pain, leg pain and numbness, Roland-Morris Disability Questionnaire (RMDQ), and Physical Component Summary (PCS) and Mental Component Summary (MCS) of Short Form 8 (SF-8) for patients with LSS undergoing decompression surgery. PATIENTS AND METHODS: This is a retrospective cohort study using prospectively collected data from consecutive patients who underwent lumbar decompression without fusion for LSS at a single institution between May 2014 and March 2016. Inclusion criteria were 1) minimum 1-year follow-up 2) a complete set of preoperative and final follow-up questionnaires available, including the NRS, RMDQ, and SF-8. Revision surgery or non-degenerative etiology such as infection or tumor was excluded. MCIDs of each outcome measure were determined using two major approaches, distribution- and anchor-based methods. The distribution-based method uses the distributional characteristics of the sample. This method expresses the observed degree of variation to obtain a standardized metric such as the standard deviation or standard error of measurement. The anchor-based method uses an external criterion known as anchor to determine the factors that should be considered by patients for an important improvement. Anchor-based methods assess how much changes in the measurement instrument correspond with a minimal important change defined on the anchor. We used symptom severity, physical function, and satisfaction scores from Zurich Claudication Questionnaire as anchors for NRS and RMDQ, PCS, and MCS, respectively. RESULTS: A total of 126 patients were included. From the anchor-based method, MCIDs were determined to be 2 points for back pain, 4 points for leg pain and numbness, 5 points for RMDQ, 5 points for PCS, and 2 points for MCS. From the distribution-based method, MCIDs were determined to be 2 points for back pain, leg pain and numbness, 3-4 points for RMDQ, 6 points for PCS, and 5 points for MCS. CONCLUSION: We first identified the MCIDs of the NRS, RMDQ, and SF-8 specific to patients undergoing decompression surgery for LSS.

Risk factors for persistent numbness following decompression surgery for lumbar spinal stenosis.

OBJECTIVE: Decompression surgery is a mainstay of surgical treatment for lumbar spinal stenosis (LSS). However, up to 30% of patients have low satisfaction due to residual symptoms. In the clinical setting, improvements in leg pain are more significant than those in leg numbness. Residual numbness could be related to the relatively low satisfaction rate. However, few studies have focused on numbness; thus, elucidating the risk factors and rate of residual numbness would benefit surgeons and patients. This study aimed to clarify the risk factors for and rate of residual numbness after decompression surgery. PATIENTS AND METHODS: We retrospectively reviewed prospectively collected data from consecutive patients who underwent lumbar decompression without fusion for LSS at a single institution between January 2014 and March 2016. Patients were included if preoperative and final follow-up questionnaires and radiographs were available. A minimum one-year follow-up was required. We evaluated the Numeric Rating Scale (NRS) scores of low back pain, leg pain, and leg numbness preoperatively and at the final follow-up visit. Residual numbness was defined as a postoperative NRS ≥ 1, whereas persistent numbness was defined as a postoperative NRS ≥ 5. We compared the clinical data of patients with or without residual numbness to those of patients with or without persistent numbness. Multivariate logistic regression analysis was performed to identify risk factors for residual and persistent numbness. RESULTS: A total of 116 patients (73 men, 43 women) were included. Of them, 60% had residual numbness with a mean follow-up period of 25 months. Only durotomy differed significantly between patients with and those without residual numbness. However, the significance did not persist after logistic regression analysis. A total of 16% had persistent numbness. Diabetes mellitus, intraoperative durotomy, and preoperative NRS of numbness were identified as risk factors. There were no differences in smoking status, presence of spondylolisthesis or scoliosis, or severity of stenosis. CONCLUSIONS: We found three risk factors for persistent numbness following decompression surgery for LSS; diabetes mellitus and durotomy were modifiable, whereas preoperative numbness was not. Our findings would help surgeons minimize the incidence of persistent numbness by adequately controlling diabetes and avoiding durotomy during surgery. Providing information about the potential for residual numbness during the informed consent process is important to ensuring realistic patient expectations.

Gender Differences in Pre- and Postoperative Health-Related Quality of Life Measures in Patients Who Have Had Decompression Surgery for Lumbar Spinal Stenosis.

STUDY DESIGN: Retrospective chart audit. PURPOSE: This study aimed to investigate the gender difference in pre- and postoperative health-related quality of life (HRQOL) in patients who have had decompression surgery for lumbar spinal stenosis (LSS). OVERVIEW OF LITERATURE: Gender differences may contribute to variations in disease presentations and health outcomes. The influence of gender on pre- and postoperative HRQOL in spinal disorders remains unclear. METHODS: We reviewed 125 patients (79 men and 46 women) who had lumbar spinous process splitting laminectomy (LSPSL) for LSS. We assessed the following clinical information: Japanese Orthopedic Association (JOA) score; numerical rating scale (NRS) for low back pain (LBP), leg pain, and leg numbness; Zurich Claudication Questionnaire; JOA Back Pain Evaluation Questionnaire; Roland- Morris Disability Questionnaire (RMDQ); and Short Form 8 (SF-8) as HRQOL. We compared the HRQOLs of men and women pre- and postoperatively. RESULTS: Although the preoperative NRS results for LBP were significantly higher in women (p <0.05), there were no significant differences in clinical outcomes between men and women postoperatively. For HRQOL, the RMDQ scores were significantly worse in women preoperatively (p <0.05), but no significant differences were found postoperatively between men and women. Similarly, the SF-8 mental health score was also significantly lower in women preoperatively (p <0.05), but no significant differences were noted between the two groups postoperatively. CONCLUSIONS: LSPSL greatly reduced LBP, leg pain, and leg numbness in both genders. There were limited differences in pain and several HRQOL questionnaire responses between men and women after surgery. We found that women had greater sensitivity to and/or lower tolerance for pain than men, which led to lower HRQOL mental health scores preoperatively.

Outcome measures reflecting patient satisfaction following decompression surgery for lumbar spinal stenosis: Comparison of major outcome measures.

OBJECTIVE: Decompression surgery is the standard treatment for lumbar spinal stenosis (LSS); however, despite the good clinical outcomes reported for this procedure, a relatively high dissatisfaction rate has been reported. We hypothesized that the previously used outcome measures do not accurately reflect patient satisfaction (PS). This study aimed to examine which outcome measures reflect PS accurately in patients undergoing decompression for LSS. PATIENTS AND METHODS: Patients with LSS treated with lumbar decompression surgery between January 2014 and March 2016 were enrolled if they had the preoperative and final follow-up questionnaires including the Numeric Rating Scale (NRS), Roland-Morris Disability Questionnaire (RMDQ), Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), and Short Form-8 (SF-8). PS was evaluated using the question, "How satisfied are you with the overall result of your back operation?". There are four possible answers consisting of "very satisfied (4-point)", "somewhat satisfied (3-point)", "somewhat dissatisfied (2-point)", or "very dissatisfied (1-point)". The Spearman correlation coefficient between PS and each questionnaire was calculated. RESULTS: Postoperative JOABPEQ had strong correlation with PS (r > 0.6) whereas NRS, RMDQ and SF-8 had moderate correlation (0.4

The influence of preoperative mental health on clinical outcomes after laminectomy in patients with lumbar spinal stenosis.

OBJECTIVE: The influence of preoperative mental health on health-related quality of life (HRQOL) in patients with lumbar spinal stenosis (LSS) remains unclear. This study aims to investigate the influence of preoperative mental health HRQOL after laminectomy in patients with LSS. PATIENTS AND METHODS: We retrospectively reviewed 122 patients who had lumbar spinous process splitting laminectomy (LSPSL) for LSS. We assessed clinical information; Japanese Orthopedic Association (JOA) score; numerical rating scale (NRS) for low back pain, for leg pain, and for leg numbness; Zurich Claudication Questionnaire (ZCQ); JOA Back Pain Evaluation Questionnaire (JOABPEQ); Roland-Morris Disability Questionnaire (RMDQ); and Short Form 8 (SF-8) as patient reported outcomes. Patients were divided into two groups (Group L ≤ 36.2 points and Group NL > 36.2 points) based on the results of the preoperative mental health (MH) score in SF-8 to examine the influence of MH in LSS. We compared the HRQOL between the two groups postoperatively. RESULTS: The JOA score, NRS, and ZCQ score significantly improved after surgery. HRQOL outcomes including JOABPEQ, RMDQ, and SF-8 showed that the LSPSL improved not only the physical but also the mental function in patients with LSS. All HRQOL outcomes in Group L exhibited significantly worse scores preoperatively; however, no significant differences between two groups were found postoperatively. CONCLUSIONS: LSPSL greatly reduced low back pain, leg pain, and leg numbness. LSPSL resulted in a significant improvement based on HRQOL questionnaires even in patients with preoperative depressive mood. Not only the physical status but also the mental health may improve after LSPSL even in patients with LSS with a depressive mood preoperatively.

Minimally clinically important differences for the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) following decompression surgery for lumbar spinal stenosis.

Decompression surgery is the standard treatment in lumbar spinal stenosis (LSS). Recent studies have shown that patient satisfaction following decompression surgery does not correspond well with outcomes measured by conventional patient-reported outcome measurements. Recent study reported that the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) is the most accurate outcome measurement to reflect patient satisfaction. Nevertheless, the JOABPEQ was not studied enough, especially along with the minimally clinically important differences (MCIDs), as JOABPEQ is relatively new questionnaire. The MCID is the minimum score change which patients perceive as beneficial. Thus, knowing the MCID is critical evaluating the efficacy of intervention. The aim of this study was to determine the MCIDs of the JOABPEQ for patients with LSS undergoing decompression surgery. Patients who underwent decompression surgery for LSS were consecutively enrolled if they had a complete set of questionnaires. We determined the MCIDs of each domain in the JOABPEQ using distribution-based and anchor-based methods. The MCIDs were determined to be 20.4 in low back pain, 15.6 in lumbar function, 16.8 in walking ability, 13.4 in social life function, and 9.4 in mental health by the distribution-based method. Using the anchor-based method, the MCIDs were determined to be 28.5, 16.5, 25.0, 21.5, and 14.5, respectively. The MCIDs of the JOABPEQ in LSS were slightly different from 20-point, which was proposed in the JOABPEQ user's manual. Our findings should be considered when evaluating LSS patients undergoing decompression surgery as JOABPEQ is not LSS specific.

Structural and functional identification of two distinct inspiratory neuronal populations at the level of the phrenic nucleus in the rat cervical spinal cord.

The diaphragm is driven by phrenic motoneurons that are located in the cervical spinal cord. Although the anatomical location of the phrenic nucleus and the function of phrenic motoneurons at a single cellular level have been extensively analyzed, the spatiotemporal dynamics of phrenic motoneuron group activity have not been fully elucidated. In the present study, we analyzed the functional and structural characteristics of respiratory neuron population in the cervical spinal cord at the level of the phrenic nucleus by voltage imaging, together with histological analysis of neuronal and astrocytic distribution in the cervical spinal cord. We found spatially distinct two cellular populations that exhibited synchronized inspiratory activity on the transversely cut plane at C4-C5 levels and on the ventral surface of the mid cervical spinal cord in the isolated brainstem-spinal cord preparation of the neonatal rat. Inspiratory activity of one group emerged in the central portion of the ventral horn that corresponded to the central motor column, and the other appeared in the medial portion of the ventral horn that corresponded to the medial motor column. We identified by retrogradely labeling study that the anatomical distributions of phrenic and scalene motoneurons coincided with optically detected central and medial motor regions, respectively. Furthermore, we anatomically demonstrated closely located features of putative motoneurons, interneurons and astrocytes in these regions. Collectively, we report that phrenic and scalene motoneuron populations show synchronized inspiratory activities with distinct anatomical locations in the mid cervical spinal cord.

Impact of decompression surgery without fusion for lumbar spinal stenosis on sagittal spinopelvic alignment: minimum 2-year follow-up.

OBJECTIVEThe importance of global sagittal alignment is well known. Patients with lumbar spinal stenosis (LSS) generally tend to bend forward to relieve their neurological symptoms, i.e., they have a positive sagittal vertical axis (SVA). We hypothesized that the positive SVA associated with LSS is symptom related and should improve after surgery. However, little is known about the changes in sagittal alignment in LSS patients after decompression surgery. In this study the authors aimed to evaluate midterm radiographical changes in sagittal spinopelvic alignment after decompression surgery for LSS and to determine the factors influencing the improvement in sagittal spinopelvic alignment.METHODSThe authors retrospectively reviewed 89 patients who underwent lumbar decompression without fusion between January 2014 and September 2015 with a minimum follow-up of 2 years. Standing whole-spine radiographs at the preoperative stage and at the final follow-up were examined. We analyzed SVA, lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), thoracolumbar kyphosis (TLK), and thoracic kyphosis (TK).RESULTSLL and TK were significantly increased postoperatively. SVA and PI minus LL (PI-LL) were significantly decreased. There were no significant differences between the preoperative and postoperative PT, PI, SS, or TLK. Twenty-nine patients had preoperative sagittal malalignment with SVA > 50 mm. Thirteen of the 29 patients improved to SVA < 50 mm after decompression surgery. Lower ASA grade, preoperative higher LL, and lower PI-LL were related to patient improvement. A receiver operating characteristic curve for the preoperative PI-LL had an area under the curve value of 0.821, indicating moderate accuracy (p = 0.003). A cutoff value for preoperative PI-LL of 19.2° showed a sensitivity of 93.5% and a specificity of 71.4%.CONCLUSIONSLumbar decompression can lead to a reactive improvement in the lumbar and global sagittal alignment. However, some of the sagittal malalignment in LSS was irreversible. Preoperative PI-LL was a useful predictor to distinguish reversible from irreversible sagittal malalignment.

Impact of sagittal spinopelvic alignment on clinical outcomes and health-related quality of life after decompression surgery without fusion for lumbar spinal stenosis.

OBJECTIVEPatients with lumbar spinal stenosis (LSS) tend to bend forward to relieve neurological symptoms. They therefore have a positive sagittal vertical axis (SVA). The importance of the SVA value is well known in the field of adult spinal deformity; however, little is known about its impact on LSS. The authors sought to investigate the impact of sagittal spinopelvic alignment on clinical outcome and health-related quality of life (HRQOL) after decompression surgery for LSS.METHODSThe authors retrospectively reviewed 83 patients who underwent lumbar decompression without fusion between January 2014 and September 2015 with a minimum follow-up of 2 years. Standing whole-spine radiographs were examined preoperatively and at final follow-up. Based on the SVA, patients were allocated to a sagittal balance group (group B; SVA < 50 mm) or a sagittal imbalance group (group I; SVA ≥ 50 mm). The authors compared the groups using Japanese Orthopaedic Association (JOA), Zurich Claudication Questionnaire (ZCQ), Roland-Morris Disability Questionnaire (RMDQ), and the 8-item Short Form Health Survey (SF-8) scores.RESULTSPreoperative groups B (group pre-B) and I (group pre-I) included 58 and 25 patients, respectively. Preoperative sagittal malalignment had negative effects on the JOA score recovery rate, postoperative ZCQ physical function domain score, and numeric rating scale (NRS) score of postoperative low-back pain (LBP), but no significant effects were observed for RMDQ and SF-8 domain scores. Postoperatively, groups B (group post-B) and I (group post-I) included 60 and 23 patients, respectively. Group post-I had a significantly worse JOA score recovery rate, postoperative symptom severity domain score in the ZCQ, and NRS score for postoperative LBP. Similarly, the postoperative RMDQ score and the Physical Component Summary score of the SF-8 were significantly worse in group post-I.CONCLUSIONSPositive SVA had significantly negative effects on clinical outcome and HRQOL in LSS patients after lumbar decompression surgery.

Delayed leg paraplegia associated with hyperextension injury in patients with diffuse idiopathic skeletal hyperostosis (DISH): case report and review of the literature.

Diffuse idiopathic skeletal hyperostosis (DISH) is characterized by calcifications and ossification of ligaments and tendon insertions. The patients with DISH are susceptible to spinal column injury with trivial trauma due to immobilization of vertebrae and this easily leads to spinal cord injury. However, only few reports on hyperextension injuries of the thoracolumbar spine with DISH exist. Here we report three cases of those who developed delayed leg paraplegia after hyperextension injuries of the thoracolumbar spine with DISH. All cases complained only lower back pain without neurological deficits and plain radiographs showed no fractures at an initial assessment. The spinal fracture caused by hyperextension injury was diagnosed with computed tomography (CT) and magnetic resonance image (MRI) after delayed leg paraplegia occurred. Many of the fractures caused by hyperextension injuries are not detected only with plain radiographs in patients with DISH. Further investigations using CT and/or MRI should be recommended.

Risk factors for intervertebral instability assessed by temporal evaluation of the radiographs and reconstructed computed tomography images after L5-S1 single-level transforaminal interbody fusion: A retrospective study.

Intervertebral instability risks following L5-S1 transforaminal lumbar interbody fusion (TLIF) and causes of bony bridge formation on computed tomography (CT) remain largely unknown. We evaluated the temporal changes on plain radiographs and reconstructed CT images from 178 patients who had undergone single-level L5-S1 TLIF between February 2011 and February 2015. We statistically analyzed temporal changes the L5-S1 angle on radiographs and intervertebral stability (IVS) at the last observation. Bony bridge formation between the L5-S1 vertebral bodies and the titanium cage subsidence were analyzed by using reconstructed CT. Preoperative L5-S1 angle in the non-IVS group was significantly greater than that in the IVS group. The cage subsidence was classified as follows: type A, both upper and lower endplates; type B, either endplate; or type C, no subsidence. Types B and C decreased over time, whereas type A increased after surgery. The bony bridges between vertebral bodies were found in 87.2% of patients, and 94.5% of all bony bridges were found only in the cage, not on the contralateral side. Our findings suggested that high preoperative L5-S1 angle increased the risk of intervertebral instability after TLIF. The L5-S1 angle decreased over time with increasing type A subsidence, and almost all bony bridges were found only in the cage. These results suggest that the vertebral bodies were stabilized because of cage subsidence, and final bony bridges were created. Methods to improve bony bridge creation are needed to obtain reliable L5-S1 intervertebral bone union.

Spatiotemporal and anatomical analyses of P2X receptor-mediated neuronal and glial processing of sensory signals in the rat dorsal horn.

Extracellularly released adenosine triphosphate (ATP) modulates sensory signaling in the spinal cord. We analyzed the spatiotemporal profiles of P2X receptor-mediated neuronal and glial processing of sensory signals and the distribution of P2X receptor subunits in the rat dorsal horn. Voltage imaging of spinal cord slices revealed that extracellularly applied ATP (5-500 µM), which was degraded to adenosine and acting on P1 receptors, inhibited depolarizing signals and that it also enhanced long-lasting slow depolarization, which was potentiated after ATP was washed out. This post-ATP rebound potentiation was mediated by P2X receptors and was more prominent in the deep than in the superficial layer. Patch clamp recording of neurons in the superficial layer revealed long-lasting enhancement of depolarization by ATP through P2X receptors during the slow repolarization phase at a single neuron level. This depolarization pattern was different from that in voltage imaging, which reflects both neuronal and glial activities. By immunohistochemistry, P2X(1) and P2X(3) subunits were detected in neuropils in the superficial layer. The P2X(5) subunit was found in neuronal somata. The P2X(6) subunit was widely expressed in neuropils in the whole gray matter except for the dorsal superficial layer. Astrocytes expressed the P2X(7) subunit. These findings indicate that extracellular ATP is degraded into adenosine and prevents overexcitation of the sensory system, and that ATP acts on pre- and partly on postsynaptic neuronal P2X receptors and enhances synaptic transmission, predominantly in the deep layer. Astrocytes are involved in sensitization of sensory network activity more importantly in the superficial than in the deep layer.