Trunk orthosis with joints providing resistive force improves dynamic sagittal alignment in postoperative patients with lumbar spinal stenosis.

This study aimed to determine whether a trunk orthosis with joints providing resistive force (TORF) modifies sagittal malalignment during level walking in patients with lumbar spinal stenosis (LSS). Fifteen patients, 6 months after undergoing surgery for LSS, performed level walking at a self-selected speed while wearing a TORF. Dynamic sagittal alignment, including sagittal vertical axis, lumbar lordosis, and pelvic tilt, and spatiotemporal data as well as lower limb kinematic and kinetic data were recorded using a three-dimensional motion analysis system and six force plates. Statistical analysis was performed to compare these data with and without the TORF, respectively. Compared to the condition without the TORF, the use of the TORF significantly decreased positive sagittal vertical axis (p < 0.05) and increased the lumbar lordosis and pelvic tilt (p < 0.05). Peak hip flexion angle and extension moment during loading response (LR) significantly increased (p < 0.05), and peak hip extension angle and flexion moment during PS statistically decreased (p < 0.05). There was no difference in spatiotemporal data between the two conditions. Our findings suggest that TORF may modify the dynamic sagittal global alignment and lower limb kinematic and kinetics in postoperative LSS patients during level walking.

Comparative Study of S2-Alar-Iliac Screw Trajectories between Males and Females Using Three-Dimensional Computed Tomography Analysis: The True Lateral Angulation of the S2-Alar-Iliac Screw in the Axial Plane.

The S2 alar-iliac screw (S2AIS) is commonly used for long spinal fusion as a rigid distal foundation in spinal deformity surgeries, and it is also used in percutaneous sacropelvic fixation for providing an in-line connection to the proximal spinal constructs without using offset connectors. Although the pelvic shape is different between males and females, reports on S2AIS trajectories according to gender have been scarce in the literature. In this paper, S2AIS trajectories are compared between males and females using pelvic three-dimensional computed tomography (3D-CT) in a normal Japanese population. After resetting the caudal angulation in CT-imaging plane manipulation, the angulation of S2AIS was more lateral in the axial plane and more horizontal in the coronal plane in females. Mean distances from the midline to starting points of S2AIS tended to be shorter in females, whereas mean distances from the midline to the posterior superior iliac spine was significantly longer in females. We also found that there were positive correlations between the patients' height and the maximal lengths of S2AISs, and the patients' height and minimal areas of S2AIS pathways. Our results are useful not only for conventional open spinal surgery, but also for minimally invasive spine surgery.

Respective Correction Rates of Lateral Lumbar Interbody Fusion and Percutaneous Pedicle Screw Fixation for Lumbar Degenerative Spondylolisthesis.

Background and Objectives: There are few reports describing the radiographic correction of vertebral slippage in lateral interbody fusion and percutaneous pedicle screw fixation for lumbar degenerative spondylolisthesis. [Objectives] We evaluated the intraoperative surgical correction obtained by lateral interbody fusion and percutaneous pedicle screw procedures. Materials and Methods: Fifty patients were included in this study. According to the Meyerding classification, 35 cases were Grade 1 and 15 cases were Grade 2. Mean age was 64.7 ± 6.4 years old. Seventeen cases were male, and 33 cases were female. The mean preoperative % slip was 21.1 ± 7.0%. After lateral interbody fusion, vertebral slippage was corrected using reduction technique by percutaneous pedicle screw. Results: The slippage of vertebra was reduced to 11.5 ± 6.5% after lateral interbody fusion procedure and 4.0 ± 6.0% after percutaneous pedicle screw procedure. One year after surgery, the slippage of vertebra was 4.1 ± 6.6%. The correction rate of lateral interbody fusion was 47.7 ± 25.1%, and that of percutaneous pedicle screw was 33.8 ± 2.6%. The total correction rate was 81.5 ± 27.7%. There was no significant loss of correction one year after surgery. The Japanese Orthopaedic Association Score significantly improved from 14.7 ± 4.2 to 27.7 ± 1.7 points at final follow up. No vascular or organ injury was observed during surgery, and there were no postoperative surgical site infections or systemic complications. Conclusion: Compared with previous reports, the final correction rate and the correction rate of the percutaneous pedicle screw procedure were particularly high in this study. Lateral interbody fusion and percutaneous pedicle screw using reduction technique provide excellent clinical and radiographic outcomes for patients with lumbar degenerative spondylolisthesis.

Preliminary Clinical Outcome of One-level Mobi-C Total Disc Replacement in Japanese Population.

INTRODUCTION: In 2018, the first Mobi-CⓇ total disk replacement (TDR) case was performed in Japan. In this study, we examined the preliminary clinical outcome of Mobi-CⓇ for degenerative cervical spine disease. METHODS: We examined 24 consecutive patients who underwent 1-level TDR after 2018 and followed up for more than 6 months after surgery. The evaluation criteria included age, gender, diagnosis, follow-up period, surgical level, implant size, surgery time, intraoperative bleeding volume, complications, revision surgery, imaging findings, JOA score, and various questionnaires. RESULTS: The mean age was 52.7 years, 13 males and 11 females. There were 15 cases of cervical disk herniation and 9 cases of cervical spondylosis. The mean follow-up period was 17.4 months. Surgical levels were C3/4 in 4 cases, C4/5 in 2 cases, C5/6 in 16 cases, and C6/7 in 2 cases. The mean operation time was 138.5 minutes, the amount of intraoperative bleeding was 32.1 ml, and there were no serious intraoperative complications. The range of motion of the affected level increased significantly, from 6.6 degrees preoperatively to 12.2 degrees at final follow-up. No patients required revision surgery at final follow-up, and there were no cases of heterotopic ossification or adjacent segment disease. One patient exhibited radiculopathy due to mild subsidence 1 year after surgery, and 1 had asymptomatic contact of device plates. Preoperative and final JOA scores improved from 11.7 to 15.8 points, and NRS improved from 4.3 to 1.3 points for neck pain and 4.3 to 1.7 points for arm pain. Preoperative and final NDI improved from 39.7% to 14.0%, and EQ-5D improved from 0.602 to 0.801. CONCLUSIONS: The short-term treatment outcomes of Mobi-CⓇ TDR were generally favorable. Spine surgeons should comply with guidelines when introducing this procedure and strive to adopt this new technology in Japan.

Sequential MRI Changes After Lateral Lumbar Interbody Fusion in Spondylolisthesis with Mild and Severe Lumbar Spinal Stenosis.

OBJECTIVE: We assessed the sequential magnetic resonance imaging changes of indirect neural decompression after minimally invasive lumbar lateral interbody fusion (LIF) combined with posterior percutaneous pedicle screw (PPS) fixation for degenerative spondylolisthesis (DS) according to the severity of preoperative lumbar spinal stenosis. METHODS: A total of 43 patients (mean age, 68.7 years; 16 men and 27 women) with DS who had undergone LIF and closed reduction with PPS fixation were enrolled. The intervertebral levels were divided into the moderate stenosis (MS) group (preoperative cross-sectional area [CSA] of the thecal sac >50 mm2) and severe stenosis (SS) group (CSA ≤50 mm2). The CSA, ligamentum flavum thickness, and diameter of the thecal sac at the affected level were measured on cross-sectional magnetic resonance images at baseline, immediately postoperatively, and 2 years postoperatively. RESULTS: For the 31 and 29 intervertebral levels in the MS and SS groups, the mean CSA at baseline, immediately postoperatively, and 2 years postoperatively was 76.9 mm2 and 35.8 mm2, 104.3 mm2 and 81.4 mm2, and 130.9 mm2 and 105.7 mm2, respectively. The mean ligamentum flavum thicknesses at 2 years postoperatively became thinner than that immediately after surgery in both groups (P < 0.01). The mean diameter of the thecal sac at 2 years was longer than that immediately after surgery in both groups (MS group, P < 0.05; SS group, P < 0.01) The expansion ratio of the CSA at 2 years postoperatively was significantly greater in the SS group than that in the MS group (P < 0.01). CONCLUSIONS: Sequential enlargement of the spinal canal was obtained by the thinning of the ligamentum flavum after LIF and PPS fixation in patients with DS with both mild and severe stenosis. The effect of indirect neural decompression was equivalent even in those with severe lumbar spinal stenosis.

Vertebroplasty with posterior spinal fusion for osteoporotic vertebral fracture using computer-assisted rod contouring system: A new minimally invasive technique.

INTRODUCTION: Surgical treatment of osteoporotic vertebral fracture (OVF) has been challenging for spine surgeons, because there are potential risks of instrumentation failure; such as screw loosening, loss of correction, or pseudarthrosis, due to bone fragility in elderly patients with several comorbidities. PRESENTATION OF CASE: A 68-year-old female presented with a severe low back pain and bilateral thigh pain. She had a history of systemic scleroderma, which was complicated by interstitial lung disease. Although she initially underwent non-surgical treatment with bracing for 7 months, her symptoms had progressively deteriorated, and her radiographs showed non-union at L1 and progressive kyphotic deformity at the thoracolumbar spine. Because an anterior approach was inadvisable due to interstitial lung disease, vertebroplasty with posterior spinal fusion was performed using percutaneous pedicle screws (PPS) at the upper most and lowest instrumented vertebra combined with sublaminar taping and computer-assisted rod contouring system. Good bony union was achieved with no screw loosening at 1-year follow-up. DISCUSSION: Various surgical procedures have been applied according to the fracture type or medical condition of the patient. Minimally invasive posterior spinal fusion would be a less invasive approach in patients with poor medical condition. PPS can prevent the excessive dissection of paravertebral muscles, and this is especially advantageous at the proximal and distal end of long constructs. A recent computer-assisted rod contouring system accurately matches each screw head resulting in reduced strength of the screw-bone interface. CONCLUSION: This technique would be beneficial in the elderly or immunocompromised patients with OVF.

The Prevalence of the Use of MIS Techniques in the Treatment of Adult Spinal Deformity (ASD) Amongst Members of the Scoliosis Research Society (SRS) in 2016.

STUDY DESIGN: Electronic survey administered to Scoliosis Research Society members. OBJECTIVE: To determine the prevalence of minimally invasive surgery (MIS) techniques for the treatment of adult spinal deformity. SUMMARY OF BACKGROUND DATA: There is a paucity of data available on the practice pattern, prevalence of minimally invasive spine surgery, and the preferred minimally invasive techniques in the treatment of adult spine deformity. METHODS: An electronic nine-question survey regarding individual usage pattern of minimally invasive spine surgery techniques was administered in 2016 to the members of the Scoliosis Research Society. Determinants included complexity in condition of patient population, prevalence of use of minimally invasive techniques in the surgeon's practice, prevalence of use of a particular MIS technique, strategy elected during surgery, adoption of staging of procedures and timing between staging of procedures. RESULTS: A total of 357 surgeons responded (61.3% response rate), and 154 (43.1%) of the respondents said that they use MIS as a part of their surgical treatment of adult spinal deformity. However, of these 154 respondents, 67 (43.5%) said that their MIS usage in deformity practice was between 1% and 20%. Only 11 (7.2%) said that they used MIS 81% to 100% of the time. The top MIS approaches that surgeons chose were MIS lateral lumbar interbody fusion 109 (70.59%) and MIS percutaneous screws 91 (58.8%). CONCLUSIONS: The low rate of adoption of these techniques among the SRS members may be due to the false perception that there is not enough data to support that MIS techniques are better. This and the fact that a practitioner needs to be facile at different MIS techniques may be the true impediment to the adoption of MIS techniques in the treatment of ASD. LEVEL OF EVIDENCE: Level IV.

Safety and Efficacy of Percutaneous Pedicle Screw Placement Using a Power Tool.

INTRODUCTION: This study compared traditional manual methods and power tool use with regard to the speed and accuracy of percutaneous pedicle screw (PPS) placement and determined the advantages associated with the use of power tools. Although the indication of PPS placement in minimally invasive spine stabilization (MISt) procedures has been recently expanded, there are no reports on PPS insertion using a power tool. METHODS: We evaluated 35 patients who underwent PPS insertion using a power tool during MISt procedures. On one side, PPS insertion was performed using the manual (M) method, whereas on the contralateral side, insertion was performed using the power tool (P) method. We assessed the number of implanted PPSs, time taken to implant PPSs after guidewire insertion, and accuracy of PPS placement as ranked postoperatively using computed tomography images. RESULTS: A total of 294 PPSs were inserted (147 using the M method and 147 using the P method). The mean PPS insertion time was 10.5 s using the P method and 27.4 s using the M method. The time required for inserting a screw using the P method remained consistent in the range of 10-15 s, whereas the time using the M method tended to increase from the second screw onward, with a range of 25-30 s. With regard to PPS insertion accuracy, a 2 mm or more pedicle breach was noted in 2 (1.4%) case after the P method and in 2 (1.4%) case after the M method. CONCLUSIONS: PPS placement using power tools has the potential to save the surgical time during MISt procedures.

Quantification of L5 radiculopathy due to foraminal stenosis using three-dimensional magnetic resonance myelography.

INTRODUCTION: This study aimed to evaluate morphological changes in the L5 nerve roots in control and symptomatic patients using magnetic resonance myelography [MRM]. Moreover, the utility of MRM for the diagnosis of intraforaminal or extraforaminal lesions in patients with L5 radiculopathy was evaluated using healthy subjects as controls. METHODS: Of 270 subjects who underwent MRM of the lumbar spine at our institution between April 2007 and December 2010, 135 patients (78 men and 57 women; average age: 61.3 years) with no history of spinal surgeries and nerve roots without infections, tumors, or malformations were selected for this study. The end-point measurements included the bifurcation angle of inclination (proximal tilting angle [PTA]) of the L5 nerve root as observed via MRM, lateral angle of inclination (lateral tilting angle [LTA]), bifurcation diameter (proximal nerve root width [PW]), and dorsal root ganglion (DRG) diameter (DRG width [DW]). DW ratio was then calculated for healthy controls and symptomatic subjects. We measured each parameter using the image information unification system ShadeQuest (Yokogawa, Tokyo, Japan). Two spinal surgeons conducted the magnetic resonance imaging evaluation. RESULTS: Swelling of the L5 DRG was detected in cases with intraforaminal or extraforaminal stenosis. With regard to the cutoff value of 6.5 mm for L5 DW, foraminal stenosis can be confirmed if DW is ≥6.5 mm or more via MRM. In cases where L5 DRG was swollen to ≥1.2 times the size in healthy subjects, L5 radiculopathy with foraminal lesions can be diagnosed. CONCLUSIONS: Our findings indicated that 3D MRM is a noninvasive technique and a useful tool for the diagnosis of intraforaminal or extraforaminal lesions in the lumbar spine. Therefore, it can be combined with other diagnostic methods used for the identification of intraforaminal or extraforaminal L5 nerve root lesion.

Sagittal Alignment of Spine and Spinal Cord for Upper Cervical Irreducible Atlantoaxial Kyphosis in Elderly Patients.

STUDY DESIGN: Retrospective study. OBJECTIVE: To evaluate clinical and radiographic outcome of posterior decompression and occipito-cervical/thoracic (OCT) fusion in patients with irreducible atlantoaxial kyphosis (IAK). SUMMARY OF BACKGROUND DATA: Posterior OCT fusion is an effective surgical procedure for treating IAK in the elderly. However, it is unclear whether correction can be obtained by the strong corrective force provided by implants, even in patients in whom reduction cannot be obtained preoperatively. There are no reports of improvement in patients in whom correction could not be achieved by a rigid system. METHODS: Twenty-five patients with IAK with mild vertical subluxation due to rheumatoid arthritis and 3 patients with IAK due to os odontoideum were treated with fossa magnum decompression, C1 laminectomy and OCT fusion. RESULTS: Mean follow-up period was 4.2 years. Preoperative and postoperative neurological findings revealed improvement by 1 or more grades in 18 of 28 (64.2%) patients. The parameters of spinal alignment, sagittal spinal cord alignment, and basilar invagination were evaluated on radiographs. No significant difference between preoperative and postoperative status was seen for the clivo-axial angle, occipito-upper cervical angle, atlantodental interval, or occipito-cervical 2 angle, whereas significant improvement was seen in the cervico-medullary and dorsal CM angles (both P<0.05). No significant postoperative change in the vertical direction was seen for any of the parameters. Width of the spinal cord at the C1 level was significantly increased postoperatively, with a significant expansion of the cerebral spinal fluid space at the same level (P<0.05). CONCLUSIONS: Posterior decompression with fusion for the treatment of IAK in the elderly did not produce significant change in spinal alignment, but did significantly improve spinal cord alignment and local spinal cord compression at the C1 level, achieving satisfactory clinical outcomes.

Acute cervical spinal cord injury complicated by preexisting ossification of the posterior longitudinal ligament: a multicenter study.

STUDY DESIGN: Retrospective multicenter study. OBJECTIVE: To review the clinical characteristics of traumatic cervical spinal cord injury (SCI) associated with ossification of the posterior longitudinal ligament (OPLL). SUMMARY OF BACKGROUND DATA: Despite its potentially devastating consequences, there is a lack of information about acute cervical SCI complicated by OPLL. METHODS: This study included consecutive patients with acute traumatic cervical SCI (Frankel A, B, and C) who were admitted within 48 hours of injury to 34 spine institutions across Japan. For analysis of neurologic outcome, patients who had completed at least a 6-month follow-up were included. Neurologic improvement was defined as at least one grade conversion in Frankel grade. RESULTS: A total of 453 patients were identified (367 men, 86 women; mean age, 59 years). OPLL was found in 106 (23%) patients (87 men, 19 women; mean age, 66 years). Most of the patients with OPLL (94 of 106) were without bone injury, presenting with incomplete SCI. The prevalence of OPLL reached 34% in SCI without bone injury. The cause of SCI was predominantly falls (74%). Only 25% of the patients were aware of OPLL. Half of the OPLL patients reported gait disturbance before injury. Forty-eight (52%) OPLL patients without bone injury underwent surgery (median, 13.5 days after injury), mostly laminoplasty. Overall, no significant difference was noted in neurologic improvement between surgery group and conservative group. However, further stratification showed that surgery was associated with greater neurologic recovery in patients who had gait disturbance before injury (P = 0.04). CONCLUSION: Prevalence of OPLL among cervical SCI was alarmingly high, especially in those without bone injury. Most of cervical SCI associated with OPLL were incomplete, without bone injury, and caused predominantly by low-energy trauma. The majority of the patients were unaware of OPLL. Surgery produced better neurologic recovery in patients who had gait disturbance before injury.

Surgical results and related factors for ossification of posterior longitudinal ligament of the thoracic spine: a multi-institutional retrospective study.

STUDY DESIGN: Retrospective multi-institutional study OBJECTIVE: To describe the surgical outcomes in patients with ossification of the posterior longitudinal ligament in the thoracic spine (T-OPLL) and to clarify factors related to the surgical outcomes. SUMMARY OF BACKGROUND DATA: Detailed analyses of surgical outcomes of T-OPLL have been difficult because of the rarity of this disease. METHODS: The subjects were 154 patients with T-OPLL who were surgically treated at 34 institutions between 1998 and 2002. The surgical procedures were laminectomy in 36, laminoplasty in 51, anterior decompression via anterior approach in 25 and via posterior approach in 29, combined anterior and posterior fusion in 8, and sternum splitting approach in 5 patients. Instrumentation was conducted in 52 patients. Assessments were made on (1) The Japanese Orthopedic Association (JOA) scores (full score, 11 points), its recovery rates, (2) factors related to surgical results, and (3) complications and their consequences. RESULTS: (1) The mean JOA score before surgery was 4.6 +/- 2.0 and, 7.1 +/- 2.5 after surgery. The mean recovery rate was 36.8% +/- 47.4%. (2) The recovery rate was 50% or higher in 72 patients (46.8%). Factors significantly related to this were location of the maximum ossification (T1-T4) (odds ratio, 2.43-4.17) and the use of instrumentation (odds ratio, 3.37). (3) The frequent complications were deterioration of myelopathy immediately after surgery in 18 (11.7%) and dural injury in 34 (22.1%) patients. CONCLUSION: The factors significantly associated with favorable surgical results were maximum ossification located at the upper thoracic spine and use of instrumentation. T-OPLL at the nonkyphotic upper thoracic spine can be treated by laminoplasty that is relatively a safe surgical procedure for neural elements. The use of instrumentation allows correction of kyphosis or prevention of progression of kyphosis, thereby, enhancing and maintaining decompression effect, and its use should be considered with posterior decompression.

Initial experience of percutaneous vertebroplasty using single-plane C-arm fluoroscopy for guidance.

PURPOSE: The purpose of this study was to evaluate the feasibility and safety of percutaneous vertebroplasty (PVP) using single-plane C-arm fluoroscopy. MATERIALS AND METHODS: Lesions in the present study all comprised compression fractures with intact pedicles. A polymethylmethacrylate (PMMA) mixture was injected by the transpedicular approach under C-arm fluoroscopy using a lateral projection. Before and after PVP, the pain score was determined using visual analog scale methods. RESULTS: Between June 2002 and May 2004, we performed 31 PVPs in 17 patients during 22 treatment sessions. Underlying pathology comprised neoplasm-related compression fracture (n=9) and fractures attributed to osteoporosis (n=8). Mean pain score was 8.0 (range, 4.5-10) immediately before PVP, and 1.9 (range, 0-7) at 24 h after PVP. Mean time needed to perform PVP was 59 min. Mean time to approach a pedicle was 36 min (range, 20 min for 1 pedicle to 110 min for 3 pedicles). No complications requiring surgical intervention or exacerbating conditions beyond pre-treatment levels were noted. CONCLUSION: PVP using single-plane C-arm fluoroscopy for guidance is feasible, safe, and quick.