OBJECTIVE: The aim of the present study was to investigate how canal area size changed from before surgery and up to 2 years after decompressive lumbar surgery lumbar spinal stenosis. Further, to investigate if an area change postoperatively (between 3 months to 2 years) was associated with any preoperative demographic, clinical or MRI variables or surgical method used.
METHODS: The present study is analysis of data from the NORDSTEN- SST trial where 437 patients were randomized to one of three mini-invasive surgical methods for lumbar spinal stenosis. The patients underwent MRI examination of the lumbar spine before surgery, and 3 and 24 months after surgery. For all operated segments the dural sac cross-sectional area (DSCA) was measured in mm2. Baseline factors collected included age, gender, BMI and smoking habits. Furthermore, surgical method, index level, number of levels operated, all levels operated on and baseline Schizas grade were also included in the analysis.
RESULTS: 437 patients were enrolled in the NORDSTEN-SST trial, whereof 310 (71%) had MRI at 3 months and 2 years. Mean DSCA at index level was 52.0 mm2 (SD 21.2) at baseline, at 3 months it increased to 117.2 mm2 (SD 43.0) and after 2 years the area was 127.7 mm2 (SD 52.5). Surgical method, level operated on or Schizas did not influence change in DSCA from 3 to 24 months follow-up.
CONCLUSIONS: The spinal canal area after lumbar decompressive surgery for lumbar spinal stenosis increased from baseline to 3 months after surgery and remained thereafter unchanged 2 years postoperatively.

BACKGROUND: The optimal treatment for osteoporotic vertebral burst fracture (OVBF) without neurological symptoms is still a matter of debate.
OBJECTIVE: To evaluate the safety and efficacy of percutaneous kyphoplasty (PKP) for OVBF.
METHODS: The study is a prospective study and is registered in the China Clinical Trials Registry with the registration number ChiCTR-OOC-17013227.
METHODS: The study involved 119 patients with 137 fractured vertebrae who underwent unilateral PKP for OVBF.
METHODS: The measurements were carried out independently by two physicians and measured with picture archiving and communication system (PACS) and ImageJ software (National Institutes of Health, Bethesda, MD, USA).
METHODS: The change in the spinal canal area and posterior wall protrusions (PWP) were measured before and after surgery via three-dimensional computed tomographic imaging (CT). Preoperative, postoperative, and final follow-up standing X-rays were used to measure the height of the anterior wall (HAW), height of the posterior wall (HPW), and local kyphotic angle (LKA). Additionally, visual analogue scale (VAS) and the Oswestry Disability Index (ODI) were also determined.
RESULTS: Among the 137 vertebrae assessed, 79 exhibited an increased postoperative canal area, while 57 showed a decrease, with mean values of 8.28±6.871 mm² and -9.04±5.991 mm², respectively. Notably, no significant change in postoperative canal area was identified on the entire dataset (p>.01). There was a significant decrease between median preoperative (3.9 [IQ1-IQ3=3.3-4.8] mm) and postoperative (3.7 [IQ1-IQ3=3.0-4.4] mm) PWP (p<.01). Preoperative and postoperative HAW measurements were 19.4±6.1 mm and 23.2±5.2 mm, respectively (p<.01). However, at the final follow-up, the HAW was lower than the postoperative value. The HPW was also significantly improved after surgery (p<.01), but at the final follow-up, it was significantly decreased compared with the postoperative measurement. Following surgery, KA was significantly corrected (p<.01); however, at the final follow-up, relapse was detected (average KA: 18.4±10.3°). At the final follow-up, both VAS and ODI were significantly improved compared with the preoperative period (p<.01). As for complications, 50 patients experienced cement leakage, and 16 patients experienced vertebral refracture. All patients did not develop neurological symptoms during the follow-up.
CONCLUSIONS: OVBF without neurological deficits showed significant improvement in symptoms during the postoperative period after PKP. There was no notable alteration in the spinal canal area, but a significant decrease in PWP was observed. Consequently, we posit that PKP stands as a secure and efficacious surgical intervention for treating OVBF cases devoid of neurological symptoms.

BACKGROUND: It is commonly accepted that surgical treatment is an essential component of the comprehensive management of metastatic spinal malignancies. However, up until now, the clinical classification of metastatic spinal malignancies has not been well-structured.
METHODS: After IRB approval, 86 patients with metastatic spinal malignancies were adopted. According to the vascular distribution, stability of vertebrae, and degree of nerve compression, metastatic spinal malignancies can be classified into five types. Tumors classified as type I typically appear in the vertebral body. Type II tumors are those that develop in the transverse processes, superior and inferior articular processes, and spinal pedicles. Type III denotes malignancies that are present in the spinous process and vertebral plate. Types IVa and IVb are included in type IV. Type IVa combines type I and type II, whereas type IVb combines type II and type III. Type V tumors are those of types I, II, and III that co-occur and spread in different directions into the spinal canal. 20 of included 86 patients who did not receive segmental arterial embolization were set as the non-embolization group. The embolization group included 24 patients who received segmental arterial embolization on both sides of the diseased vertebrae. 42 patients were included in the offending embolization group after receiving responsible arterial embolization. A surgical intervention was performed within 24 h following an embolization. Surgical intervention with the purpose of removing as much of the tumor as possible and providing an effective reconstruction of the spinal column.
RESULTS: In comparison with the non-embolization group and embolization group, the offending embolization group presented unique advantages in terms of bleeding volume (p<0.001), operation time (p<0.001), and local recurrence rate within 12 months (p=0.006).
CONCLUSIONS: By significantly reducing surgical trauma and local recurrence rate (12 months), responsible arterial vascular embolization procedures together with associated surgical protocols developed on the basis of the clinical classification of metastatic spinal malignancies, are worthy of clinical dissemination.

Accurate and detailed spinal canal diameter transverse foraminal morphometry measurements are essential for understanding spinal column-related diseases and surgical planning, especially for transpedicular screw fixation. This is especially because lateral cervical radiographs do not provide accurate measurements. This retrospective study was conducted to measure the dimensions of the transverse foramen sagittal and transverse diameter (TFD), spinal canal diameter, the distance of the spinal canal from the transverse foramina at the C1 to C7 cervical level, and the anteroposterior and TFDs in the Turkish population. A total of 150 patients who underwent cervical spine computed tomographic imaging with a 1:1 gender ratio were enrolled in the study. The sagittal and TFDs of the spinal canal, the distance of the spinal canal from the transverse foramen, and anteroposterior and TFDs in both right and left sides for all cervical levels C1 to C7. Foramina transversal diameters were measured using imaging tools of the imaging software in the radiology unit. The mean age of the study group was 47.99 ± 18.65 (range, 18-80) years. The majority of the distances of the spinal canal from the transverse foramen and antero-posterior (AP) & transverse (T) diameters for cervical vertebrae were significantly higher in male patients (P < .05). However, between age groups, a few measurements were found significantly different. Some of the distances of the spinal canal from the transverse foramen were significantly higher on the right side whereas all AP & T diameters were significantly higher on the left side in both male and female patients (P < .05). Almost all measurements were significantly higher on the left side for younger patients (<65 years) whereas only AP & T diameters were significantly higher on the left side for older patients (>65 years) (P < .05). Computed tomographic imaging is better than conventional radiographs for the preoperative evaluation of the cervical spine and for a better understanding of cervical spine morphometry. Care must be taken during transpedicular screw fixation, especially in female subjects, more so at the C2, C4, and C6 levels due to decreased distance of the spinal canal from the transverse foramina.

OBJECTIVE: The objective of this study was to investigate the optimal entry point and pedicle camber angle for L5 pedicle screws of different canal types.
METHODS: CT imaging data were processed by Mimics for simulated pedicle screw placement, and PD (Pedicle diameter), PCA (Pedicle camber angle), LD (Longitudinal distance), TD (Transverse distance), and PBG (Pedicle screw breach grade) were measured. Then they were divided into the Round group and Trefoil group according to the type of spinal canal. When comparing PD, PCA, LD, TD, and PBG, the two sides of the pedicle were compared separately, so they were first divided into the round-type pedicle group and the trefoil-type pedicle group.
RESULTS: In the round-type pedicle group (n = 134) and the trefoil-type pedicle group (n = 264), there was no significant difference in PD and LD, but there was a significant difference in PCA between the two groups (t = - 4.072, P < 0.05). A statistically significant difference in the distance of the Magerl point relative to the optimal entry point (t = - 3.792, P < 0.05), and the distance of the Magerl point relative to the optimal entry point was greater in the trefoil-type pedicle group than in the round-type pedicle group.
CONCLUSIONS: The optimal entry point for L5 is more outward than the Magerl point, and the Trefoil spinal canal L5 is more outwardly oriented than the Round spinal canal L5, with a greater angle of abduction during pedicle screw placement.

Previous studies have shown that the Valsalva maneuver (VM) causes spinal canal object movements. We hypothesized that this occurs because of cerebrospinal fluid (CSF) flow generated from intradural space reduction. Previous studies using myelograms reported lumbar CSF space changes during inspiration. However, no similar studies have been conducted using modern MRI. Therefore, this study analyzed intradural space reduction during the VM using cine magnetic resonance imaging (MRI).
The participant was a 39-year-old, healthy, male volunteer. Cine MRI involved fast imaging employing steady-state acquisition cine sequence during three resting and VM sets for 60 s each. The axial plane was at the intervertebral disc and vertebral body levels between Th12 and S1 during cine MRI. This examination was performed on 3 separate days; hence, data from nine resting and VM sets were available. Additionally, two-dimensional myelography was performed during rest and the VM.
Intradural space reduction was observed during the VM using cine MRI and myelography. The intradural space cross-sectional area during the VM (mean: 129.3 mm2; standard deviation [SD]: 27.4 mm2) was significantly lower than that during the resting period (mean: 169.8; SD: 24.8; Wilcoxon signed-rank test, P < 0.001). The reduction rate of the vertebral body level (mean: 26.7%; SD: 9.4%) was larger than that of the disc level (mean: 21.4%; SD: 9.5%; Wilcoxon rank sum test, P = 0.0014). Furthermore, the reduction was mainly observed on the ventral and bilateral intervertebral foramina sides at the vertebral body and intervertebral disc levels, respectively.
The intradural space was reduced during the VM, possibly because of venous dilatation. This phenomenon may be associated with CSF flow, intradural object movement, and nerve compression, potentially leading to back pain.

The purpose of this study is to investigate long-term changes in spinal sagittal balance after microsurgical decompression in lumbar canal stenosis (LCS).
Fifty-two patients who underwent microsurgical decompression for symptomatic single level L4/5 spinal canal stenosis at our hospital were included in the study. All patients had standing full spine radiographs taken preoperatively, 1 year postoperatively, and 5 years postoperatively. Spinal parameters including sagittal balance were measured from the obtained images. First, preoperative parameters were compared with 50 age-matched asymptomatic volunteers. Next, the parameters before and after surgery were compared to examine long-term changes.
Sagittal vertical axis (SVA) was significantly increased in the LCS cases compared to the volunteers (P = 0.03). Postoperative lumbar lordosis (LL) was significantly increased (P = 0.03). Postoperative mean SVA decreased but the difference was not significant (P = 0.12). Although there was no correlation between preoperative parameters and the Japanese Orthopedic Association score, postoperative pelvic incidence (PI)-LL and pelvic tilt changes correlated with changes in Japanese Orthopedic Association score (PI-LL; P = 0.0001, pelvic tilt; P = 0.04). However, after 5 years of surgery, LL decreased and PI-LL increased (LL; P = 0.08, PI-LL; P = 0.03). Sagittal balance began to deteriorate but was not significant (P = 0.31). At 5 years postoperatively, 18 of 52 patients (34.6%) were found to have L3/4 adjacent segment disease. Cases with adjacent segment disease showed significantly worse SVA and PI-LL (SVA; P = 0.01, PI-LL; P < 0.01).
In LCS, lumbar kyphosis improves and sagittal balance tends to improve after microsurgical decompression. However, after 5 years, adjacent intervertebral degeneration occurs more frequently and sagittal balance begins to deteriorate in about one third of cases.

METHODS: A prospective longitudinal magnetic resonance imaging (MRI) study.
OBJECTIVE: The objective of this study was to describe the progression of intervertebral disk (IVD) degeneration in patients who underwent posterior decompression surgery for lumbar spinal canal stenosis (LSS).
BACKGROUND: IVD degeneration contributes to the pathogenesis of LSS; however, the long-term consequences of degenerative changes after decompression surgery remain unknown.
METHODS: Of 258 consecutive patients who underwent posterior lumbar decompression surgery for LSS, 62 who underwent MRI at their 10-year follow-up were included; 17 age-matched asymptomatic volunteers were analyzed as controls. Three MRI findings representing IVD degeneration were graded on their severity: decrease in signal intensity, posterior disk protrusion (PDP), and disk space narrowing (DSN). Clinical outcome was assessed using the low back pain (LBP) score from the Japanese Orthopaedic Association scoring system. We examined the association between the progression of degenerative changes on MRI and LBP/associated factors using logistic regression adjusting for age at baseline and sex.
RESULTS: The severity of IVD degeneration tended to be higher in patients with LSS than asymptomatic volunteers at both baseline and follow-up. IVD degeneration progressed in all patients during the 10-year follow-up period. Progression of decrease in signal intensity and PDP was observed at L1/2 in 73% and at L2/3 in 34%, respectively (the highest frequencies in the lumbar spine). Progression of DSN was highest at L4/5 in 42%. The rates of PDP and DSN progression during the 10-year follow-up period tended to be greater in patients with LSS than in asymptomatic volunteers. No significant difference in the proportion of LBP deterioration was evident for individuals with and without MRI findings of progression.
CONCLUSIONS: Our study reveals a natural history of the long-term postoperative course of IVD degeneration after posterior decompression surgery for LSS. Compared with healthy controls, patients with LSS seemed to be predisposed to IVD degeneration. Lumbar decompression surgery may promote the progression of DSN; however, progression of IVD degeneration after lumbar decompression surgery was not associated with worsening LBP scores.

Spinal canal dimensions may vary according to ethnicity as reported values differ among studies in European and Chinese populations. Here, we studied the change in the cross-sectional area (CSA) of the osseous lumbar spinal canal measured in subjects from three ethnic groups born 70 years apart and established reference values for our local population. This retrospective study included a total of 1050 subjects born between 1930 and 1999 stratified by birth decade. All subjects underwent lumbar spine computed tomography (CT) as a standardized imaging procedure following trauma. Three independent observers measured the CSA of the osseous lumbar spinal canal at the L2 and L4 pedicle levels. Lumbar spine CSA was smaller at both L2 and L4 in subjects born in later generations (p < 0.001; p = 0.001). This difference reached significance for patients born three to five decades apart. This was also true within two of the three ethnic subgroups. Patient height was very weakly correlated with the CSA at both L2 and L4 (r = 0.109, p = 0.005; r = 0.116, p = 0.002). The interobserver reliability of the measurements was good. This study confirms the decrease of osseous lumbar spinal canal dimensions across decades in our local population.

In patients with combined lumbar spinal canal stenosis (LSCS), a herniated intervertebral disc (IVD) that compresses the dura mater and nerve roots is surgically treated with discectomy after laminoplasty. However, defects in the IVD after discectomy may lead to inadequate tissue healing and predispose patients to the development of IVD degeneration. Ultrapurified stem cells (rapidly expanding clones (RECs)), combined with an in situ-forming bioresorbable gel (dMD-001), have been developed to fill IVD defects and prevent IVD degeneration after discectomy. We aim to investigate the safety and efficacy of a new treatment method in which a combination of REC and dMD-001 is implanted into the IVD of patients with combined LSCS.
This is a multicentre, prospective, double-blind randomised controlled trial. Forty-five participants aged 20-75 years diagnosed with combined LSCS will be assessed for eligibility. After performing laminoplasty and discectomy, participants will be randomised 1:1:1 into the combination of REC and dMD-001 (REC-dMD-001) group, the dMD-001 group or the laminoplasty and discectomy alone (control) group. The primary outcomes of the trial will be the safety and effectiveness of the procedure. The effectiveness will be assessed using visual analogue scale scores of back pain and leg pain as well as MRI-based estimations of morphological and compositional quality of the IVD tissue. Secondary outcomes will include self-assessed clinical scores and other MRI-based estimations of compositional quality of the IVD tissue. All evaluations will be performed at baseline and at 1, 4, 12, 24 and 48 weeks after surgery.
This study was approved by the ethics committees of the institutions involved. We plan to conduct dissemination of the outcome data by presenting our data at national and international conferences, as well as through formal publication in a peer-reviewed journal.
jRCT2013210076.