Safety of terminally gamma-ray-sterilized screws coated with fibroblast growth factor 2-calcium phosphate composite layers in non-human primates

Screws coated with fibroblast growth factor 2 (FGF-2)-calcium phosphate (CP) composite layers exhibit enhanced soft tissue and bone formation and angiogenesis because of the biological activity of FGF-2. Furthermore, the mitogenic activity of the FGF-2 within the composite layers remains unchanged after gamma-ray sterilization, which may improve the storage stability prior to clinical use. However, the in vivo safeties of these screws as spinal implants remain unknown. Here, a randomized controlled trial, involving non-human primates, investigated the safety of using FGF-2-CP composite layer-coated screws after either gamma-ray sterilization or aseptic processing. Titanium alloy screws coated with FGF-2-CP composite layers and subjected to either gamma-ray sterilization at 25 kGy (GS group) or aseptic storage (AS group) were implanted into the vertebral bodies of two cynomolgus monkeys exceeding 12 weeks (day 99). Physiological, histological, and radiographic investigations were performed to evaluate the safeties of the screws. There were no serious adverse events, such as surgical site infection, significant loss of body weight, or abnormal blood test results. No radiolucent areas were observed around the screws from the GS or AS group throughout the study. In the intraosseous region, no significant differences were observed in bone and fibrous tissue apposition rates and rate of bone formation between the two groups (p = 0.49, 0.77, and 0.11, respectively). Neither tumor lesions nor accumulation of lymphocytes and neutrophils were observed in either group. Our data suggest that FGF-2-CP composite layer-coated screws subjected to terminal gamma-ray sterilization are as safe as those fabricated in aseptic processing.

Clinical Trial for the Safety and Feasibility of Pedicle Screws Coated with a Fibroblast Growth Factor-2-Apatite Composite Layer for Posterior Cervical Fusion Surgery

To solve the instrument loosening problem, we developed a fibroblast growth factor-2-calcium phosphate composite layer as a novel coating material to improve screw fixation strength. The primary aim of the present study was to demonstrate the safety and feasibility of screws coated with the FGF-2-calcium phosphate composite layer for posterior instrumented surgery of the cervical spine. The trial design was a single-arm, open-label, safety and feasibility study. Patients receiving fusion of the cervical spine from C2 (or C3) to C7 (or T1) were recruited. The primary endpoint to confirm safety was any screw-related adverse events. Seven patients who underwent posterior fusion surgery of the cervical spine were enrolled in the present study. The coated pedicle screws were inserted bilaterally into the lowest instrumented vertebrae. There was only one severe adverse event unrelated with the coated screw. Three out of the fourteen coated screws showed loosening. The present results prove the safety and feasibility of pedicle screws coated with the FGF-2-calcium phosphate composite layer for fusion surgery in the cervical spine. This is the first step to apply this novel surface coating in the field of spine surgery.

Can Proximal Junctional Kyphosis after Surgery for Adult Spinal Deformity Be Predicted by Preoperative Dynamic Sagittal Alignment Change with 3D Gait Analysis? A Case–Control Study

Background: Severe spinal deformity is a risk factor for proximal junctional kyphosis (PJK) in surgery for adult spinal deformity (ASD). However, standing X-ray imaging in patients with dynamic spinal imbalance can underestimate the risk of PJK because of compensation mechanisms. This study aimed to investigate whether preoperative dynamic spinal alignment can be a predictive factor for PJK. Methods: We retrospectively included 27 ASD patients undergoing three-dimensional (3D) gait analysis before surgery. Dynamic spinal parameters were obtained using a Nexus motion capture system (Vicon, Oxford, UK). The patients were instructed to walk as long as possible around an oval walkway. The averaged dynamic parameters in the final lap were compared between patients with PJK (+) and with PJK (−). Results: PJK occurred in seven patients (26%). The dynamic angle between the thoracic spine and pelvis was larger in patients with PJK (+) than in those with PJK (−) (32.3 ± 8.1 vs. 18.7 ± 13.5 °, p = 0.020). Multiple logistic regression analysis identified this angle as an independent risk factor for PJK. Conclusions: Preoperative thoracic anterior inclination exacerbated by gait can be one of preoperative independent risk factors for PJK in patients undergoing corrective surgery for ASD.

Development of a quantitative method to evaluate pedicle screw loosening after spinal instrumentation using digital tomosynthesis

Background

In general, the diagnosis of pedicle screw (PS) loosening is evaluated qualitatively based on the presence of a radiolucent area around the implant wider than 1 mm on plain radiographs and computed tomography (CT). Digital tomosynthesis is a novel imaging technology that can acquire reconstructed tomographic images of patients in different postures with relatively low radiation. In this study, PS loosening is evaluated quantitatively by measuring the PS displacement angle in the vertebrae using digital tomosynthesis.

Methods

We evaluated 41 patients who underwent posterior spinal fusion surgery using PS. The 72 pedicle screws at the cranial end of the fused segments were evaluated. The patients were divided in two groups, one with PS loosening (7 patients, 12 screws) and the other without PS loosening (34 patients, 60 screws), based on conventional CT findings. All patients underwent tomosynthesis in two different postures during a single CT session.

Results

The displacement angles of the PS in patients in a lying position and in a standing position were measured using selected slices of the same cross-sectional view from digital tomosynthesis. The displacement angle was significantly greater in the PS loosening group (5.7°) than in the group without PS loosening (0.6°) (p<0.01). Based on the ROC analysis, the optimal cut-off value of the PS displacement angle for identification of loosened screws was 1.7° with a sensitivity of 100% and specificity of 93% (AUC = 0.98).

Conclusions

This new method using digital tomosynthesis has the potential to aid diagnosis of PS loosening quantitatively and more accurately than conventional evaluations.

Paravertebral foramen screw fixation for posterior cervical spine surgery: clinical case series

OBJECTIVE

The goal of this study was to clarify the clinical utility of paravertebral foramen screws (PVFSs) and to determine intraoperative indicators for appropriate screw placement during posterior cervical fusion surgery to improve its safety.

METHODS

The authors included data from 46 patients (29 men and 17 women, mean age 61.7 years) who underwent posterior cervical spine surgery with 94 PVFSs. Of the 94 PVFSs, 77 were used in C6, 9 in C3, 5 in C4, and 3 in C5. According to the cervical lateral radiographic view, the authors divided the 94 PVFSs into 3 groups as follows: a longer group, in which the tip of PVFS was located anteriorly from the line of the posterior wall of the vertebral body (> +0 mm); an intermediate group, in which the screw tip was located up to 2 mm posteriorly to the posterior wall of the vertebral body (-2 to 0 mm); and a shorter group, in which the screw tip was located more than 2 mm posteriorly (< -2 mm). The accuracy of screw placement was assessed using CT imaging in the axial plane, and the proportion of screws penetrating a vertebral foramen or a transverse foramen was compared between the 3 groups. Screw loosening was defined as a lucent zone around the screw evaluated on cervical radiography at 1 year after surgery. Complications related to PVFS insertion and revision surgery related to PVFS were evaluated.

RESULTS

The authors classified 25 PVFSs into the longer group, 43 into the intermediate group, and 26 into the shorter group. The proportion of screws penetrating a vertebral foramen was largest in the shorter group, and the proportion penetrating a transverse foramen was largest in the longer group. Screw loosening was confirmed for 3 of 94 PVFSs. One PVFS inserted in C6 unilaterally within a long construct from C2 to C7 showed loosening, but it did not cause clinical symptoms. Revision surgery was required for 2 PVFSs inserted in C3 bilaterally as the lower instrumented vertebra in occiput-cervical fusion because they pulled out. There was no neurovascular complication related to PVFS insertion.

CONCLUSIONS

PVFSs are useful for posterior cervical fusion surgery as alternative anchor screws, and the line of the posterior wall of the cervical body on lateral fluoroscopic images is a potential intraoperative reference to indicate an appropriate trajectory for PVFSs.

Continuous local antibiotic perfusion for patients with surgical site infection after instrumented spinal surgery; a novel technique to retain the implants

OBJECTIVES

To describe the novel technique of continuous local antibiotic perfusion (CLAP) for a surgical site infection (SSI) after instrumented spinal surgery.

METHODS

CLAP was applied to 4 continuous patients at our institution who developed SSI after instrumented spinal surgery.

RESULTS

All 4 patients were successfully treated and the infection was controlled. The implant was retained in all patients. The duration of CLAP ranged from 2 to 3 weeks. The blood level of the antibiotic used (gentamicin) at 1 week after the initiation of CLAP did not increase in any patient. No other adverse events occurred in any patient. Dramatic improvements in laboratory parameters, including the white blood cell (WBC) counts and C-reactive protein (CRP) levels were seen in every patient at 1 week after the initiation of CLAP.

CONCLUSIONS

CLAP controlled the infection without severe adverse events in all 4 patients, and the implants were retained. Despite its cost and the discomfort of patients, CLAP may become an option for the treatment of SSIs after instrumented spinal surgery. A large number of case series are needed to verify the efficacy of CLAP for patients with SSIs after instrumented spinal surgery.

Imaging-Based Diagnosis of Epiconus Syndrome From the Distance of the Lesion to Where the Spinal Cord Terminates Not From the Disc Level: A Case Series

Objective This study aimed to analyze the neurological symptoms caused by thoracolumbar lesions according to their distance from where the spinal cord terminates for a better description of epiconus syndrome. Methods We retrospectively reviewed cases of patients with neurological symptoms caused by a thoracolumbar lesion in a single institute. Neurological symptoms were analyzed according to the distance from the proximal end of the lesion to where the spinal cord terminates using MRI or CT myelograms. The symptoms were classified into epiconus syndrome, thoracic myelopathy, and conus medullaris syndrome. The distance was described regarding the length of a vertebral body (VB). Results We included 19 patients in this series. The spinal cord terminates were at the lower third of the L1 vertebra most frequently (32%) in the range of T12 to L2 vertebra. The border between thoracic myelopathy and epiconus syndrome was 2VB proximal from where the spinal cord terminates, and that between epiconus syndrome and conus medullaris syndrome was 1VB. Mean disease duration until symptoms changed was 2.4 months in epiconus syndrome, while it was 25 months in thoracic myelopathy, and 10.3 months in conus medullaris syndrome. Conclusion Epiconus syndrome is caused by lesion 1-2VB proximal to where the spinal cord terminates. This study may provide further helpful information for clinical practice in the treatment of epiconus syndrome.

Novel method for selecting slices of the same cross-sectional view from digital tomosynthesis for monitoring posterior spinal instrumentation

BACKGROUND

A method to evaluate pedicle screw loosening on digital tomosynthesis images is yet to be established owing to lack of methods for selecting slices of the same cross-sectional view. We aimed to develop an objective method for selecting slices of the same cross-sectional view on digital tomosynthesis images.

METHODS

First, an objective method of pixel selection was developed by measuring the size of glass disk and titanium alloy screw on digital tomosynthesis images followed by comparison with the actual sizes. Second, a method for selecting slices of the same cross-sectional view was explored on a bone model with posterior spinal instrumentation using the screw centerline and rod curvature as indicators of the same cross section. The angle between the screw centerline and rod was calculated to verify the accuracy in obtaining the same cross-sectional view. Third, the method for selecting slices of the same cross-sectional view was applied to six patients after posterior lumbar spinal instrumentation.

RESULTS

The pixel selection method enabled objective determination of a pixel on the peripheral lines of objects with an error as low as 200 μm in distance measurements on titanium alloy and glass. The mean differences of rod-screw angles between two slices were less than 1° and were not statistically significant in the bone model and patient images.

CONCLUSION

A method for selecting slices of the same cross-sectional view on digital tomosynthesis images was successfully developed. This method can enable objective and quantitative evaluations of pedicle screw loosening.

Exercise training using hybrid assistive limb (HAL) lumbar type for locomotive syndrome: a pilot study

Background

With a rapidly aging population in Japan, locomotive syndrome is becoming an increasingly serious social problem. Exercise therapy using the lumbar type HAL, which is a wearable robot suit that can assist voluntary hip joint motion, would be expected to cause some beneficial effects for people with locomotive syndrome. The purpose of this study was to assess whether the deterioration of low back pain and any other adverse events would occur following HAL exercise therapy. Moreover, the changes of motor ability variables were evaluated.

Methods

We enrolled 33 participants (16 men, 17 women) with locomotive syndrome in this study. They received exercise training (sit-to-stand, lumbar flexion-extension, and gait training) with HAL (in total 12 sessions). We assessed the change of low back pain (lumbar VAS). More than 50% and 25 mm increase compared to baseline was defined as adverse events. One-leg standing time (OLST), 10-m walking test (10MWT), Timed Up and Go test (TUG), 1-min sit-to-stand test (1MSTS), FIM mobility scores and EQ-5D were measured.

Results

Of the 33 participants, 32 (16 men, 16 women) (97.0%) completed all 12 exercise training sessions using the lumbar type HAL. One woman aged 82 years withdrew because of right upper limb pain after the second session regardless of the use of HAL. There was no participant who had deterioration of low back pain. Any other adverse events including external injuries and/or falling, skin disorders, uncontrollable cardiovascular or respiratory disorders, and other health disorders directly related to this exercise therapy did not occur. Several outcome measures of motion ability including OLST, TUG and 1MSTS, EQ VAS and lumbar pain improved significantly after this HAL training.

Conclusions

Almost all patients with locomotive syndrome completed this exercise training protocol without any adverse events related to HAL. Furthermore, balance function variables including OLST, TUG and 1MSTS improved after this HAL exercise therapy even though mobility function variables including 10MWT and FIM mobility scores did not show any significant change. These findings suggest that the exercise therapy using the lumbar type HAL would be one of the options for the intervention in locomotive syndrome.

Correlation between osteoarthritis of the atlantoaxial facet joint and a high-riding vertebral artery

BACKGROUND

A high-riding vertebral artery (HRVA) is an intraosseous anomaly that narrows the trajectory for C2 pedicle screws. The prevalence of a HRVA is high in patients who need surgery at the craniovertebral junction, but reports about HRVAs in subaxial cervical spine disorders are limited. We sought to determine the prevalence of HRVAs among patients with subaxial cervical spine disorders to elucidate the potential risk for VA injury in subaxial cervical spine surgery.

METHODS

We included 215 patients, 94 were with a main lesion from C3 to C7 (subaxial group) and 121 were with a main lesion from T1 to L5 (thoracolumbar group). A HRVA was defined as a maximum C2 pedicle diameter of < 3.5 mm on axial CT. The sex, age of patients, body mass index (BMI), osteoarthritis of the atlantoaxial (C1-2) facet joints, and prevalence of a HRVA in the 2 groups were compared and logistic regression was used to identify the factors correlated with a HRVA.

RESULTS

The patients in the subaxial group were younger than those in the thoracolumbar group, but their sex and BMI did not differ significantly between the 2 groups. The mean osteoarthritis grade of the C1-2 facet joints of patients in the subaxial group was significantly higher than that in those in the thoracolumbar group. A HRVA was found in 26 patients of 94 (27.7 %) in the subaxial group and in 19 of 121 (15.7 %) in the thoracolumbar group. The prevalence of a HRVA in the subaxial group was significantly higher and osteoarthritis of C1-2 facet joints correlated significantly with a HRVA.

CONCLUSIONS

The prevalence of a HRVA in patients with subaxial cervical spine disorders is higher than in those without and osteoarthritis of the C1-2 facet joints is correlated with a HRVA.

Accidental anterior longitudinal ligament rupture during lateral lumbar interbody fusion disclosed after posterior corrective fusion surgery resulting in local hyper-lordosis

Objective: To report a case of anterior longitudinal ligament (ALL) injury that was not noticeable during lateral lumbar interbody fusion and was disclosed after posterior corrective fusion surgery. Case presentation: After performing lateral lumbar interbody fusion followed by posterior corrective fusion surgery, we observed an anterior longitudinal ligament rupture that required additional surgery. Postoperative pain in the left lower limb and muscle weakness due to nerve traction appeared, but this was improved by stabilization between the vertebral bodies. Conclusion: Unidentified anterior longitudinal ligament rupture can result in unexpected local lordosis during posterior surgery, possibly related to lower extremity palsy. Therefore, checking for possible rupture during and after anterior surgery is important. If the ALL damage is disclosed before posterior surgery, the proper surgical strategy for the posterior surgery must be considered.

Sudden, Transient Intraoperative Hypotension During the Use of the Cantilever Technique for Correction of Adult Spine Deformity

Intraoperative hypotension is a common but critical complication of spinal surgery. However, it is uncommon to experience sudden transient intraoperative hypotension in patients undergoing surgery for adult spine deformity (ASD) without the presence of major vascular injury, spinal cord injury, or cardiac events. We report a patient who experienced sudden transient intraoperative hypotension during the use of the cantilever technique for correction of an ASD. A 58-year-old woman underwent two-stage surgery (anterior correction followed by posterior fusion) for an ASD that caused low back pain. During the posterior fusion procedure, she experienced sudden transient intraoperative hypotension during the use of a cantilever technique. As soon as we paused the use of this technique, her hypotension resolved. Postoperative radiography revealed excessive segmental lordosis at the L4/5 level, suggesting an accidental rupture of the anterior longitudinal ligament (ALL). We believe that the mechanism of our patient’s sudden hypotension was a decrease in venous return due to compression and stretching of the inferior vena cava at the time of rod application when the use of the cantilever technique caused ALL rupture. Sudden hypotension during posterior spinal correction surgery is possible, especially in patients with a ruptured ALL.

Characteristics of relief and residual low back pain after discectomy in patients with lumbar disc herniation: analysis using a detailed visual analog scale

Background

Several authors have reported favorable results in low back pain (LBP) for patients with lumbar disc herniation (LDH) treated with discectomy. However, detailed changes over time in the characteristics and location of LBP before and after discectomy for LDH remain unclear. To clarify these points, we conducted an observational study to determine the detailed characteristics and location of LBP before and after discectomy for LDH, using a detailed visual analog scale (VAS) bilaterally.

Methods

We included 65 patients with LDH treated by discectomy in this study. A detailed VAS for LBP was administered with the patient under 3 different conditions: in motion, standing, and sitting. Bilateral VAS was also administered (affected versus opposite side) for LBP, lower extremity pain (LEP), and lower extremity numbness (LEN). The Oswestry Disability Index (ODI) was used to quantify clinical status. Changes over time in these VAS and ODI were investigated. Pfirrmann grading and Modic change as seen by magnetic resonance imaging (MRI) were reviewed before and 1 year after discectomy to determine disc and endplate condition.

Results

Before surgery, LBP on the affected side while the patients were in motion was significantly higher than LBP while they were sitting (p = 0.025). This increased LBP on the affected side in motion was improved significantly after discectomy (p < 0.001). By contrast, the residual LBP while sitting at 1 year after surgery was significantly higher than the LBP while they were in motion or standing (p = 0.015). At 1 year following discectomy, residual LBP while sitting was significantly greater in cases showing changes in Pfirrmann grade (p = 0.002) or Modic type (p = 0.025).

Conclusions

Improvement of LBP on the affected side while the patient is in motion suggests that radicular LBP is improved following discectomy by nerve root decompression. Furthermore, residual LBP may reflect increased load and pressure on the disc and endplate in the sitting position.

Spontaneous symptomatic lumbar intervertebral pseudoarthrosis associated with diffuse idiopathic skeletal hyperostosis treated with a combined posteroanterior fusion: a case report and review of literature

Although diffuse idiopathic skeletal hyperostosis (DISH) is generally asymptomatic, in rare cases it involves multiple segments and can present with intervertebral pseudoarthrosis which requires treatment. We report a case of a 47-year-old female patient with intervertebral pseudoarthrosis and severe dynamic instability in the L4-5 intervertebral disc due to DISH and provide a brief review of literature. The patient developed severe lower back pain and intermittent claudication due to the instability in the only mobile part between multiple fused vertebrae from C7 to L4 and fusion segment from L5 to the ilium. We performed long-range posterior spinal and two-stage 360° fusion with L4-5 lateral interbody fusion. After the surgery the pain and intermittent claudication were improved and bony fusion was successful. Reports of intervertebral pseudoarthrosis in DISH with no history of trauma are extremely rare. We have only been able to find 5 cases. Compared to the previous reports, the present case describes a youngest patient, first case of female, and had the longest fusion due to DISH. Therefore, the patient required long-range fusion from T10 to the iliac bone in order to achieve adequate stabilization. Moreover, the present case is the first example of choosing a lateral interbody fusion, which provides even more robust consolidation.

New methods for diagnosing lumbar foraminal stenosis using dynamic digital tomosynthesis radiculography

The symptoms of lumbar radiculopathy, in particular foraminal stenosis, often exacerbated when the patient is upright. However, it is difficult to detect the compression of nerve roots while the patient is upright using conventional MRI. In this study, we analyzed the compression of lumbar nerve roots using dynamic digital tomosynthesis radiculography (DTRG) in patients diagnosed with lumbar radiculopathy. And we determined the relationship between leg pain and nerve compression while the patients are either prone or upright. We evaluated 30 patients with unilateral leg pain diagnosed as lumbar radiculopathy by physical examination and MRI. The patients were divided in two groups, one with foraminal stenosis (17 patients) and the other with canal stenosis (13 patients), based on MRI findings. All patients underwent DTRG to determine the diameter of their nerve roots in the foramen while prone and upright. Pain while prone or upright was assessed using a 100-point visual analogue scale (VAS) questionnaire. The VAS for leg pain while upright was significantly higher in the foraminal stenosis group (58 ± 24.7) than it was in the canal stenosis group (19.6 ± 13.2; p = 0.0002)). The nerve root diameter while prone or upright was significantly smaller in the foraminal stenosis group (1.2 ± 0.2 mm) than it was in the canal stenosis group (0.2 ± 0.1 mm; p < 0.0001). DTRG has the potential to visualize nerve compression while the patient is upright to reveal the relevance of foraminal stenosis to clinical findings. DTRG is useful for diagnosis of lumbar foraminal stenosis.

Thoracic myelopathy caused by calcification of the ligamentum flavum

Calcification of the ligamentum flavum (CLF), which is a rare disorder that can potentially cause myelopathy, occurs uncommonly in the thoracic spine. Here, we report a rare case of thoracic myelopathy caused by CLF in a 78-year-old man. Magnetic resonance imaging (MRI) showed posterior spinal cord compression by a hypo-signal intense mass, and computed tomography (CT) revealed CLF and vacuum disc phenomenon at T10/11. After undergoing posterior decompression and instrumented fusion (T9–T12), the patient’s gait difficulties improved. The pathogenesis of CLF is largely unknown; however, it involves accumulation of calcium pyrophosphate dehydrate crystals (CPPD), and CLF from CPPD deposition tends to occur within a thickened and hypertrophic ligament. CLF occurs predominantly in the cervical spine and less frequently in the lumbar spine, with few cases involving the thoraco-lumbar spine. The thoracic spine is characterized by hypomobility; however, the thoraco-lumbar spine has a mobile segment which may potentiate CLF formation. Decompression with fusion surgery can be useful for treating patients with thoraco-lumbar CLF.

Successful Use of the Hybrid Assistive Limb for Care Support to Reduce Lumbar Load in a Simulated Patient Transfer

STUDY DESIGN

Prospective experimental study in humans.

PURPOSE

To determine whether the hybrid assistive limb (HAL) for Care Support can reduce lumbar load during a patient transfer.

OVERVIEW OF LITERATURE

The prevalence of work-related low back pain (LBP) among nurses is high. In particular, transferring patients poses a high risk for LBP due to the large lumbar load. Attempts to reduce the lumbar load are crucial to avoid the risk of LBP. Therefore, we investigated the effects of the HAL for Care Support.

METHODS

Nineteen volunteers (16 men, three women) lifted a 60-kg doll from a seated position to a standing position. The first transfer was performed without the HAL for Care Support, and the second was performed with the HAL for Care Support assistive robot. We evaluated transfer performance, the visual analog scale (VAS) score for lumbar fatigue, and electromyogram analyses of the trunk and hip.

RESULTS

Four participants (two men, two women) succeeded with the HAL for Care Support even though they were unable to perform the task without it. The mean lumbar fatigue VAS score for all participants without the HAL for Care Support was 62 mm, while that with it was 43 mm. With lumbar assistance from the HAL for Care Support, subjective lumbar fatigue during the transfer decreased significantly. A power analysis indicated adequate statistical power to detect a difference in the VAS score for lumbar fatigue (0.99). The activity of the left gluteus maximus alone increased significantly during transfers with the HAL for Care Support. No adverse events occurred during use of the HAL for Care Support for transfers.

CONCLUSIONS

The HAL for Care Support was able to reduce lumbar load in a simulated patient transfer.

Thoracic kyphosis and pelvic anteversion in patients with adult spinal deformity increase while walking: analyses of dynamic alignment change using a three-dimensional gait motion analysis system

PURPOSE

To determine dynamic changes of spinopelvic alignment while walking using a three-dimensional (3D) gait motion analysis in adult spinal deformity (ASD) patients.

METHODS

This study included 20 ASD patients. The 3D gait motion analysis (Vicon) was performed during continuous walking to their limit. Dynamic parameters were obtained using reflective markers on the spinous processes, which were segmented into thoracic (T-), lumbar (L-), and whole spine (S-), sagittal spinal distance (SVA) and coronal one (CVA), sagittal spinal angle to the vertical axis (SA) and coronal one (CA), sagittal pelvic angle to the horizontal axis (P-SA) and coronal (P-CA), and thoracic limited spinal angle to the pelvic angle (T-P SA) and lumbar one (L-P SA). The dynamic variables at the final lap were compared with those at the first lap of an oval walkway.

RESULTS

Spinal kyphotic deformity deteriorated significantly. As for pelvic angle, the mean P-SA parameters (first lap/final lap) were 3.2°/5.2°. Anteversion of pelvic sagittal angle increased significantly after continuous walking to their limit. In particular, regarding limited spinal angle to the pelvic angle, the mean T-P SA parameters were 30.5°/36.2° and L-P SA parameters were 6.4°/6.8°. Thoracic kyphotic angle increased significantly, but lumbar kyphotic angle did not change.

CONCLUSION

Decrease of thoracic kyphosis and pelvic retroversion has been recognized as a compensation for ASD on standing radiograph. Our 3D gait motion analysis to determine spinal balance found thoracic kyphosis and pelvic anteversion increased significantly in patients with ASD after continuous walking to the limit of their endurance until they were fatigued, indicating a failure of compensation for ASD. These slides can be retrieved under Electronic Supplementary Material.

A novel unidirectional porous β-tricalcium phosphate grafting for vertebral fracture in the elderly: preliminary case series

Objective: To treat vertebral fractures with posterior wall injury in the elderly, vertebral bone grafting is generally performed through a posterior transpedicular approach, combined with pedicle screw fixation. An autologous bone is ideal to treat this disorder. However, harvesting autologous bones from the elderly with osteoporosis is limited by the amount and quality of available autologous bone. Thus, we developed a bone-grafting substitute. The newly developed unidirectional porous β-tricalcium phosphate, with a porosity of 57% (UDPTCP; Affinos^®, Kuraray Co., Ltd., Tokyo, Japan), is used in the bone-grafting procedure. This is the first report of UDPTCP used as an artificial bone graft in patients with an acute vertebral burst fracture.

Materials and Methods: UDPTCP (mean: 4.2 g) was implanted through the pedicle, and posterior instrumentation was achieved with pedicle screws in five elderly patients. Resorption of UDPTCP and substitution with the autologous bone were evaluated on computed tomography (CT) and plain X-ray performed immediately and at 3, 6, and 12 months after the operation.

Results: In case 1, the pedicle screws did not loosen, and UDPTCP was completely resorbed and replaced with the autologous bone at 3 postoperative months. In the other four cases, although the pedicle screws or the caudal part loosened because of osteoporosis, resorption of UDPTCP was observed at 3 postoperative months. At 6 postoperative months, progressive substitution with the autologous bone was confirmed, and at 12 postoperative months, formation of the good autologous bone was confirmed.

Conclusion: This preliminary case series demonstrated that the newly developed UDPTCP shows good clinical potential as a bone-graft substitute for acute vertebral burst fractures in the elderly, including patients with osteoporosis.

Visualization of walking speed variation-induced synchronized dynamic changes in lower limb joint angles and activity of trunk and lower limb muscles with a newly developed gait analysis system

PURPOSE

To evaluate a newly developed system for dynamic analysis of gait kinematics and muscle activity.

METHODS

We recruited 10 healthy men into this study. Analyses of three-dimensional motion and wireless surface electromyogram (EMG) were integrated to achieve synchronous measurement. The participants walked continuously for 10 min under two conditions: comfortable and quick pace. Outcome measures were joint angles of the lower limbs determined from reflective markers and myoelectric activity of trunk and lower limbs determined from EMG sensors, comparing comfortable and quick gait pace.

RESULTS

Lower limb joint angle was significantly greater at the quick pace (maximum flexion of the hip joint: 4.1°, maximum extension of hip joint: 2.3°, and maximum flexion of the knee joint while standing: 7.4°). The period of maximum flexion of the ankle joint during a walking cycle was 2.5% longer at a quick pace. EMG amplitudes of all trunk muscles significantly increased during the period of support by two legs (cervical paraspinal: 55.1%, latissimus dorsi: 31.3%, and erector spinae: 32.6%). EMG amplitudes of quadriceps, femoral biceps, and tibialis anterior increased significantly by 223%, 60.9%, and 67.4%, respectively, between the periods of heel contact and loading response. EMG amplitude of the gastrocnemius significantly increased by 102% during the heel-off period.

CONCLUSION

Our gait analysis synchronizing three-dimensional motion and wireless surface EMG successfully visualized dynamic changes in lower limb joint angles and activity of trunk and lower limb muscles induced by various walking speeds.

Cauda equina schwannoma with concomitant intervertebral disc herniation: A case report and review of literature

The coexistence of lumbar intervertebral disc (IVD) herniation and cauda equina schwannoma in symptomatic patients is uncommon. We experienced a case with a surgically treated cauda equina schwannoma with concomitant lumbar IVD herniation (L2/L3); both were relatively small but presented with painful symptoms in combination. A 45-year old man complained of low back pain and right anterior thigh pain six months prior to surgery. He underwent conservative treatment; however, his pain suddenly worsened three months before surgery, with abnormal sensations and pain in his right buttock and posterior thigh. A magnetic resonance imaging (MRI) scan revealed an L2/L3 disc herniation extruding to the center of the lumbar spinal canal and compressing the thecal sac. Incidentally, an intrathecal tumor was suspected, and enhanced MRI revealed a round tumor measuring 10-mm in diameter at the L2/L3 intervertebral level, which was uniformly enhanced by gadolinium chelate, radiologically diagnosed as a schwannoma. Microscopic discectomy and tumor resection were performed and the patient's symptoms disappeared immediately. Schwannoma is generally slow-growing, and usually asymptomatic when the tumor size is small. Therefore, we suspected that the tumor occasionally impinged on the left L3 root with L2/3 IVD herniation, leading to acute worsening of the patient's symptoms. Altogether, in case of tumor in patients undergoing conservative treatment for cauda equina schwannoma, we should consider that symptoms can acutely worsen with the occurrence of lumbar IVD herniation.

C5 pure motor spinal cord injury: A case with a rare manifestation of cervical spinal cord injury

We report an extremely rare case showing a fifth cervical spine (C5) level pure motor cervical spinal cord injury (SCI). A 55-year-old-man lost consciousness and fell into a bathtub. Immediately after regaining consciousness, the patient had right arm drop alone. He was referred to our department for investigation of right arm drop 4 months later. Neurological examination revealed motor weakness of the right deltoid muscle. MRI of the cervical spine revealed a C3-4 level central disc herniation compressing the spinal cord. An electromyogram study revealed bilateral neurogenic discharges in the deltoid, supraspinatus and infraspinatus muscles. We diagnosed a C5 segmental pure motor SCI. We chose conservative therapy for the present patient. At the latest follow-up visit, the patient showed modest recovery of motor weakness. Although it is unusual, this case illustrates the possibility that C5 segmental pure motor palsy can occur as one of the manifestations of cervical SCI.

Vertebral fracture after removing pedicle screws used for posterior lumbar interbody fusion: A case report

It is uncommon to remove pedicle screws after posterolateral lumbar interbody fusion (PLIF), and there are a few case reports of vertebral fracture involving holes remaining after screw removal. We report a case of the vertebral fracture after removing pedicle screws instrumented for PLIF. A 66-year-old woman with osteopenia, who underwent PLIF at L4-S1 10 years earlier, underwent PLIF at L3-L4 to correct adjacent-segment degeneration. We removed L5 and S1 pedicle screws, and inserted L3 pedicle screws. After surgery, she presented with severe progressive low back pain. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed an L5 body fracture involving the pedicle screw holes. Revision surgery, including posterolateral fusion from L3 to S2 alar iliac and L5 vertebroplasty, was performed. One year after the revision surgery, the patient remained pain-free and returned to normal activity. Possible reasons for instrumented vertebral body fracture after pedicle screw removal are decrease of vertebral mass, increased mechanical stress caused by PLIF at the adjacent segment, stress-shielding-related osteopenia, and spinal imbalance. Vertebral body fractures associated with spinal implant removal are rare, but possible, especially in elderly patients with osteopenia and osteoporosis.

Unidirectional porous β-tricalcium phosphate induces bony fusion in lateral lumbar interbody fusion

Lateral lumbar interbody fusion (LLIF) often requires the use of allograft or artificial bone. We used β-tricalcium phosphate artificial bone with a porosity of 57% consisting of a novel unidirectional porous structure (Affinos®) in patients (5 male and 9 female) who underwent LLIF from August 2015 as a substitute for autologous bone. We evaluated 60 graft windows in the cages at 30 intervertebral levels. To evaluate interbody bony fusion, CT multi-planar reconstruction coronal and sagittal images obtained 1 year after surgery were assessed. Intra-cage bony fusion was observed in 39 of 60 graft windows and so total bony fusion rate was 65%. Intra-cage bony fusion was confirmed in 17 of 29 (58.6%) graft windows with autologous bone and 22 of 31 (70.9%) graft windows with Affinos®. There was no significant difference in the rate of bony fusion between autologous bone and Affinos® (p = 0.418). In conclusion, the rate of bony fusion using Affinos® in LLIF cages was not inferior to that using autologous bone graft. Affinos® is a candidate for graft material in LLIF surgery and further exploration is warranted.

Successful detection of postoperative improvement of dynamic sagittal balance with a newly developed three-dimensional gait motion analysis system in a patient with iatrogenic flatback syndrome: A case report

A 75-year-old Japanese woman with Parkinson's disease complained of lower back pain and gait disturbance because of iatrogenic flatback syndrome. The preoperative global spinal parameters were as follows: C7SVA, 168 mm; TK, 52°; LL, -0.8°; PI, 57°; PT, 55°; TPA, 60°. We performed 3D gait analysis using a VICON System and calculated the dynamic SVA. Preoperatively, her flexion deformity gradually progressed during walking. The dynamic parameters gradually increased as follows: thoracic SVA, 216-241 mm; lumbar SVA, 53-69 mm; spinal SVA, 270-311 mm. We performed two-stage corrective surgery. Her lower back pain and gait disturbance significantly improved. The postoperative global spinal parameters were as follows: C7SVA, 1 mm; TK, 47°; LL, 61°; PI, 52°; PT, 20°; TPA, 13°. Dynamic SVA detected by our 3D gait analysis using VICON were as follows: thoracic SVA, 128 mm; lumbar SVA, 4.9 mm; and spinal SVA, 133 mm. The postoperative dynamic SVA did not change during walking. This is the first report of a patient with iatrogenic flatback syndrome whose postoperative improvement of dynamic spinal sagittal alignment was successfully detected with a newly developed 3D gait analysis system that enabled us to analyze a dynamic change of SVA based on the patient's actual walking with a continuous long-distance gait. Our 3D gait analysis has potential usefulness for evaluating postoperative sagittal balance for iatrogenic flatback syndrome.