Yukitaka Nagamoto

Three-dimensional measurement of growth of ossification of the posterior longitudinal ligament

OBJECT Ossification of the posterior longitudinal ligament (OPLL) is a progressive disease that causes cervical myelopathy. Because 2D evaluation of ossification growth with plain lateral radiographs has limitations, the authors developed a unique technique to measure ossification progression and volume increase by using multidetector CT scanning. METHODS The authors used serial thin-slice volume data obtained by multidetector CT scanning in 5 patients. The mean patient age was 63 years, and the mean follow-up duration was 3.1 years. First, a 3D model of OPLL was semiautomatically segmented at a specific threshold. Then, a preoperative model of OPLL was superimposed on a postoperative model using voxel-based registration of the vertebral bodies. Progression and volume increase were measured using a digital viewer that was developed by the authors. Progression was visualized using a color-coded contour on the surface of the OPLL model. RESULTS All patients had progression of 0.5 mm or greater. The mean values concerning OPLL growth were as follows: maximum progression length, 4.7 mm; progression rate, 1.5 mm/year; volume increase, 1622 mm(3); volume expansion rate, 37%; and volume increase rate, 484 mm(3)/year. The accuracy of superimposition by voxel-based registration, defined as closeness to the true value, was less than 0.31 mm. For intraobserver reproducibility of the volume measurement, the mean intraclass correlation coefficient, root mean square error, and coefficient of variation were 0.987, 16.0 mm(3), and 1.7%, respectively. CONCLUSIONS Ossification of the posterior longitudinal ligament progresses even after surgery. Three-dimensional evaluation with the aid of CT scans is a useful and reliable method for assessing that growth.

Kinematics of the thoracic spine in trunk rotation: in vivo 3-dimensional analysis.

Study Design. In vivo 3-dimensional (3D) study of the thoracic spine. Objective. To demonstrate axial rotations (ARs) and coupled motions of the thoracic spine. Summary of Background Data. In vivo 3D kinematics of the thoracic spine in trunk rotation with intact thorax and soft tissues has not been well-known. There were no quantitative data of AR in the consecutive thoracic spinal segments. Patterns of coupled motion with AR have been controversial. Methods. Thirteen healthy volunteers underwent 3D computed tomography of the thoracic spine in 3 positions; neutral, right, and left maximum trunk rotation. Relative motions of vertebrae were calculated by automatically superimposing the vertebrae in a neutral position over images in rotational positions, using voxel-based registration. Motions were represented with 6 degrees of freedom by Euler angles and translations on the local coordinate system. Results. Mean (±SD) relative rotational angles of T1 with respect to L1 to 1 side were 24.9° ± 4.9° in maximum trunk rotation. AR of each thoracic segment with respect to the inferior adjacent vertebra to 1 side was 1.2° ± 0.8° at T1–T2, 1.6° ± 0.7° at T2–T3, 1.4° ± 0.9° at T3–T4, 1.6° ± 0.8° at T4–T5, 1.8° ± 0.7° at T5–T6, 1.9° ± 0.6° at T6–T7, 2.3° ± 0.7° at T7–T8, 2.5° ± 0.8° at T8–T9, 2.7° ± 0.6° at T9–T10, 2.6° ± 0.8° at T10–T11, 1.3° ± 0.7° at T11–T12, and 0.5° ± 0.4° at T12–L1. Significantly larger segmental AR was observed at the middle thoracic segments (T6–T11) than at the upper (T1–T6) and lower (T11–L1) segments. At the upper thoracic segments, coupled lateral bending with AR was observed in the same direction as AR. However, at the middle and lower thoracic segments, coupled lateral bending occurred both in the same and opposite directions. Conclusion. In vivo 3D ARs and coupled motions of the consecutive thoracic spinal segments in trunk rotation were investigated accurately for the first time.

In vivo three-dimensional segmental analysis of adolescent idiopathic scoliosis

IntroductionAn accurate assessment of three-dimensional (3D) intervertebral deviation is crucial to the better surgical correction of adolescent idiopathic scoliosis (AIS). However, a precise 3D study of intervertebral deviation has not been previously reported.ObjectiveThe purpose of the present study is to evaluate the intervertebral coronal inclination, axial rotation and sagittal angulation of AIS using 3D bone models and a local coordinate system.Materials and methods3D bone models of the thoracic and lumbar spine of ten AIS patients were constructed using computed tomography. The local coordinate axis was determined semi-automatically for each vertebra. By using these local coordinates, the intervertebral deviation angles were calculated in the coronal, axial and sagittal planes and projected to subjacent local coordinates.ResultThe intervertebral deformity in the coronal plane was larger near the apical region and smaller near the junctional region. Conversely, the intervertebral rotation in the axial plane was smaller near the apical region, and larger near the junctional region. Concerning the sagittal plane deformity, the constant tendency was not recognized.ConclusionUsing a local coordinate system for the vertebra of AIS, we measured the 3D intervertebral coronal, axial and sagittal deviation of the thoracolumbar spine and found that the change in the intervertebral inclination angle in the coronal plane increased toward the apical region and decreased toward the junctional region, and that the converse tendency was noted for the axial intervertebral rotational angle. This analysis provides an improved 3D guide for the surgical correction of AIS.

In vivo three-dimensional kinematics of the cervical spine during head rotation in patients with cervical spondylosis.

Study Design. Kinematics of the cervical spine during head rotation was investigated using 3-dimensional (3D) magnetic resonance imaging (MRI) in patients with cervical spondylosis (CS). Objective. To demonstrate in vivo 3D kinematics of the spondylotic cervical spine during head rotation. Summary of Background Data. Several in vivo studies have identified kinematic differences between normal and spondylotic subjects, but only two-dimensional flexion/extension motion has been investigated. Differences of in vivo 3D cervical motion during head rotation between normal and spondylotic subjects have yet to be clarified. Methods. Ten healthy volunteers (control group) and 15 patients with CS (CS group) underwent 3D MRI of the cervical spine with the head rotated to 5 positions (neutral, ±45° and ±maximal head rotation). Relative motions of the cervical spine were calculated by automatically superimposing a segmented 3D MRI of the vertebra in the neutral position over images for each position using volume registration. The 3D motions of adjacent vertebra were represented with 6 degrees of freedom by Euler angles and translations on the coordinate system. Results. Compared with the control group, the CS group showed significantly decreased mean axial rotation and mean coupled lateral bending at C5–C6 and C6–C7 and significantly increased mean coupled lateral bending at C2–C3 and C3–C4, although both the groups showed the same pattern of coupled motions. Conclusion. The in vivo 3D kinematics of the spondylotic cervical spine during head rotation was accurately depicted and compared with those of healthy cervical spines for the first time.

Patient satisfaction with surgery for cervical myelopathy due to ossification of the posterior longitudinal ligament

OBJECT Surgical results in cervical myelopathy caused by ossification of the posterior longitudinal ligament (OPLL) evaluated with a patient-based method have not yet been reported. The purpose of this study was to examine patient satisfaction with surgery for cervical myelopathy due to OPLL and to clarify factors related to satisfaction. METHODS Clinical data in 103 patients (74 male and 29 female) who underwent surgery for cervical OPLL were retrospectively reviewed. The average age at surgery was 57 years, and the average follow-up period was 9.3 years. Outcomes were assessed using an original satisfaction questionnaire, the conventional Japanese Orthopaedic Association (JOA) scoring system, the JOA Cervical Myelopathy Evaluation Questionnaire, the 36-Item Short Form Health Survey, and the hospital anxiety and depression scale. Spearman rank correlation coefficients for 5-scale patient satisfaction against outcome measures were calculated to test relationships between variables. All variables were compared between the satisfied (responses of very satisfied or satisfied) and dissatisfied (responses of dissatisfied or very dissatisfied) groups. Parameters exhibiting a significant Spearman rank correlation or difference between the groups were entered in a stepwise logistic regression analysis model, with satisfaction as the dependent variable. RESULTS Sixty-nine patients were included in the analysis. There was not a significant difference in clinical data between these 69 study patients and the other 34 patients. Fifty-five patients (80%) were satisfied with the results of the surgery, and 58 patients (84%) reported that their condition was improved by the surgery. All patients who reported being very improved were either very satisfied or satisfied with the results of surgery. Quality of life (QOL), physical function (PF), and role physical (RP) were significantly correlated with patient satisfaction. The dissatisfied group had significantly more severe pain; lower maximum conventional JOA scores; lower maximum recovery rates; worse lower-extremity function (LEF); reduced QOL; and lower PF, RP, and vitality scores. Stepwise logistic regression analysis showed that PF, QOL, LEF, and maximum recovery rate based on JOA score were correlated with satisfaction. CONCLUSIONS Eighty percent of patients were satisfied with the surgical results after treatment of cervical myelopathy due to OPLL. Surgery for cervical OPLL was effective, as evaluated by both doctor- and patient-based methods. Patient satisfaction was related to QOL, PF (especially LEF), and improvement.

Kinematics of the thoracic spine in trunk lateral bending: in vivo three-dimensional analysis

BACKGROUND CONTEXT In vivo three-dimensional kinematics of the thoracic spine in trunk lateral bending with an intact rib cage and soft tissues has not been well documented. There is no quantitative data in the literature for lateral bending in consecutive thoracic spinal segments, and there has not been consensus on the patterns of coupled motion with lateral bending. PURPOSE To demonstrate segmental ranges of motion (ROMs) in lateral bending and coupled motions of the thoracic spine. STUDY DESIGN In vivo three-dimensional biomechanics study of the thoracic spine. PATIENT SAMPLE Fifteen healthy male volunteers. OUTCOME MEASURES Computed analysis by using voxel-based registration. METHODS Participants underwent computed tomography of the thoracic spine in three supine positions: neutral, right maximum lateral bending, and left maximum lateral bending. The relative motions of vertebrae were calculated by automatically superimposing an image of vertebrae in a neutral position over images in bending positions, using voxel-based registration. Mean values of lateral bending were compared among the upper (T1-T2 to T3-T4), the middle-upper (T4-T5 to T6-T7), the middle-lower (T7-T8 to T9-T10), and the lower (T10-T11 to T12-L1) parts of the spine. RESULTS At lateral bending, the mean ROM (±standard deviation) of T1 with respect to L1 was 15.6°±6.3° for lateral bending and 6.2°±4.8° for coupled axial rotation in the same direction as lateral bending. The mean lateral bending of each spinal segment with respect to the inferior adjacent vertebra was 1.4°±1.3° at T1-T2, 1.3°±1.2° at T2-T3, 1.4°±1.3° at T3-T4, 0.9°±0.9° at T4-T5, 0.8°±1.0° at T5-T6, 1.1°±1.1° at T6-T7, 1.7°±1.2° at T7-T8, 1.3°±1.2° at T8-T9, 1.6°±0.7° at T9-T10, 1.8°±0.8° at T10-T11, 2.3°±1.0° at T11-T12, and 2.2°±0.8° at T12-L1. The smallest and the largest amounts of lateral bending were observed in the middle-upper and the lower parts, respectively. There was no significant difference in lateral bending between the upper and the middle-lower parts. Coupled axial rotation of each segment was generally observed in the same direction as lateral bending. However, high variability was found at the T2-T3 to T5-T6 segments. Coupled flexion was observed at the upper and middle parts, and coupled extension was observed at the lower part. CONCLUSIONS This study revealed in vivo three-dimensional motions of consecutive thoracic spinal segments in trunk lateral bending. The thoracolumbar segments significantly contributed to lateral bending. Coupled axial rotation generally occurred in the same direction with lateral bending. However, more variability was observed in the direction of coupled axial rotation at T2-T3 to T5-T6 segments in the supine position. These results are useful for understanding normal kinematics of the thoracic spine.

The utility of superficial abdominal reflex in the initial diagnosis of scoliosis: a retrospective review of clinical characteristics of scoliosis with syringomyelia

BackgroundWith increasing use of magnetic resonance imaging (MRI), underlying syringomyelia is increasingly found in patients with presumed idiopathic scoliosis. To determine the indications for MRI in the differential diagnosis of scoliosis, several clinical characteristics of syringomyelia have been reported. Neurological signs, particularly abnormal superficial abdominal reflex (SAR), are important in establishing the initial diagnosis of scoliosis. However, the prevalence of abnormal SAR in patients with scoliosis and the sensitivity of this sign in predicting syringomyelia are not well known. We aimed to determine the diagnostic utility of SAR and other characteristics of syringomyelia in patients with scoliosis.MethodsWe reviewed the medical records of 93 patients with scoliosis, 90 of whom underwent corrective surgery. All patients underwent MRI to determine the presence of syringomyelia. Mean age at surgery was 12.5 years. Abnormal SAR was defined as unilateral or bilateral absence or hyporeflexia of SAR. We calculated indices of diagnostic utility of abnormal SAR for non-idiopathic scoliosis and for syringomyelia. Abnormal SAR, left thoracic curve pattern, gender, and curve flexibility were compared between scoliosis with syringomyelia and idiopathic scoliosis. Logistic regression analysis was performed with the existence of syringomyelia as the dependent variable and curve flexibility as the independent variable.ResultsAbnormal SAR was observed in 20 patients (prevalence 22%). All 6 patients with myopathic scoliosis displayed bilateral absence of SAR. The sensitivity of abnormal SAR for non-idiopathic scoliosis was 38%, with 96% specificity, 90% PPV (positive predictive value), and 60% NPV (negative predictive value). Syringomyelia was identified in 9 of the 93 patients (9.7%); 8 of these had abnormal SAR. The sensitivity of abnormal SAR for syringomyelia in presumed idiopathic scoliosis was 89%, with 95% specificity, 80% PPV, and 98% NPV. Gender, abnormal neurological findings, and curve flexibility differed significantly between patients with syringomyelia and those with idiopathic scoliosis (P < 0.05). In the logistic regression model, the area under the receiver operating characteristic (ROC) curve was 0.79 and the cut-off value of curve flexibility for syringomyelia was 50% (P = 0.08).ConclusionAbnormal SAR was a useful indicator not only for syringomyelia, but also for myogenic scoliosis.

Surgical outcomes of temporary short-segment instrumentation without augmentation for thoracolumbar burst fractures

BACKGROUND Short-segment posterior spinal instrumentation for thoracolumbar burst fracture provides superior correction of kyphosis by an indirect reduction technique, but it has a high failure rate. We investigated the clinical and radiological results of temporary short-segment pedicle screw fixation without augmentation performed for thoracolumbar burst fractures with the goal of avoiding treatment failure by waiting to see if anterior reconstruction was necessary. METHODS We studied 27 consecutive patients with thoracolumbar burst fracture who underwent short-segment posterior instrumentation using ligamentotaxis with Schanz screws and without augmentation. Implants were removed approximately 1 year after surgery. Neurological function, kyphotic deformity, canal compromise, fracture severity, and back pain were evaluated prospectively. RESULTS After surgery, all patients with neurological deficit had improvement equivalent to at least 1 grade on the American Spinal Injury Association impairment scale and had fracture union. Kyphotic deformity was reduced significantly, and maintenance of the reduced vertebra was successful even without vertebroplasty, regardless of load-sharing classification. Therefore, no patients required additional anterior reconstruction. Postoperative correction loss occurred because of disc degeneration, especially after implant removal. Ten patients had increasing back pain, and there are some correlations between the progression of kyphosis and back pain aggravation. CONCLUSION Temporary short-segment fixation without augmentation yielded satisfactory results in reduction and maintenance of fractured vertebrae, and maintenance was independent of load-sharing classification. Kyphotic change was caused by loss of disc height mostly after implant removal. Such change might have been inevitable because adjacent endplates can be injured during the original spinal trauma. Kyphotic change after implant removal may thus be a limitation of this surgical procedure.

Surgical outcomes for painless drop foot due to degenerative lumbar disorders.

Study Design: Twenty patients presenting with painless drop foot who had undergone lumbar spine surgery for degenerative lumbar diseases were included in this retrospective study. Objective: This study aims to investigate which causative factors and patient symptoms significantly affected surgical outcome. Summary of Background Data: Drop foot is a neuromuscular condition that results in dorsiflexion palsy of the ankle. Patients with drop foot often complain of leg pain. Rarely, patients experience painless drop foot due to lumbar degenerative disease. For these patients, the only purpose of surgery is to improve the palsy; this makes it difficult to determine whether surgical intervention is indicated. No studies have focused on the results of surgical treatment for painless drop foot caused by degenerative lumbar diseases. Methods: Preoperative strength of the tibialis anterior and duration of palsy were recorded and considered with surgical outcome. Results: Sixty-five percent of patients recovered from drop foot after surgery. Drop foot was caused mainly by impairment of the L5 nerve root. Patients with a longer duration of palsy had poorer results. Conclusions: Duration of palsy had the greatest effect on recovery. As the only goal of this surgery is improvement in the strength of the tibialis anterior, caution must be exercised when considering surgery for patients with longstanding palsy.

In vivo 3D kinematic changes in the cervical spine after laminoplasty for cervical spondylotic myelopathy.

OBJECT Cervical laminoplasty is an effective procedure for decompressing the spinal cord at multiple levels, but restriction of neck motion is one of the well-known complications of the procedure. Although many authors have reported on cervical range of motion (ROM) after laminoplasty, they have focused mainly on 2D flexion and extension on lateral radiographs, not on 3D motion (including coupled motion) nor on precise intervertebral motion. The purpose of this study was to clarify the 3D kinematic changes in the cervical spine after laminoplasty performed to treat cervical spondylotic myelopathy. METHODS Eleven consecutive patients (6 men and 5 women, mean age 68.1 years, age range 57-79 years) with cervical spondylotic myelopathy who had undergone laminoplasty were included in the study. All patients underwent 3D CT of the cervical spine in 5 positions (neutral, 45° head rotation left and right, maximum head flexion, and maximum head extension) using supporting devices. The scans were performed preoperatively and at 6 months after laminoplasty. Segmental ROM from Oc-C1 to C7-T1 was calculated both in flexion-extension and in rotation, using a voxel-based registration method. RESULTS Mean C2-7 flexion-extension ROM, equivalent to cervical ROM in all previous studies, was 45.5° ± 7.1° preoperatively and 35.5° ± 8.2° postoperatively, which was a statistically significant 33% decrease. However, mean Oc-T1 flexion-extension ROM, which represented total cervical ROM, was 71.5° ± 8.3° preoperatively and 66.5° ± 8.3° postoperatively, an insignificant 7.0% decrease. In focusing on each motion segment, the authors observed a statistically significant 22.6% decrease in mean segmental ROM at the operated levels during flexion-extension and a statistically insignificant 10.2% decrease during rotation. The most significant decrease was observed at C2-3. Segmental ROM at C2-3 decreased 24.2% during flexion-extension and 21.8% during rotation. However, a statistically insignificant 37.2% increase was observed at the upper cervical spine (Oc-C2) during flexion-extension. The coupling pattern during rotation did not change significantly after laminoplasty. CONCLUSIONS In this first accurate documentation of 3D segmental kinematic changes after laminoplasty, Oc-T1 ROM, which represented total cervical ROM, did not change significantly during either flexion-extension or rotation by 6 months after laminoplasty despite a significant decrease in C2-7 flexion-extension ROM. This is thought to be partially because of a compensatory increase in segmental ROM at the upper cervical spine (Oc-C2).