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Kazuo Yonenobu

Publications and source records attributed to Kazuo Yonenobu.

33 records · Page 2Linked to original sources
PubMed2004

Effects of rotation on measurement of lower limb alignment for knee osteotomy.

The purposes of this study were to clarify the effects of rotation on two-dimensional measurement of lower limb alignment for knee osteotomy using a three-dimensional method and to determine whether this 3-D simulation method could help with planning of knee osteotomy. We developed computer software to calculate femorotibial angle (FTA) and hip-knee-ankle angle (HKA) and simulate knee osteotomy from a CT-based 3-D bone model of the lower limb. Lower limb rotation on anteroposterior long-standing radiographs was measured by superimposing the 3-D bone models. Changes in alignment with limb rotation were calculated using the software. FTA after virtual closed-wedged osteotomy was measured for a hypothetical case of a rotation error of the osteotomy plane in reattaching the proximal cutting surface to the distal cutting surface. For 31 varus knees in 20 patients with medial compartment arthritis, the mean rotation angle, relative to the epicondylar axis, with variable limb position was 7.4 +/- 3.9 degrees of internal rotation (mean +/- SD), ranging from 8 degrees of external rotation to 14 degrees of internal rotation; the mean changes in FTA and HKA were 3.5 +/- 2.2 degrees (range, 0.4-8.6) and 1.6 +/- 1.3 degrees (range, 0.2-4.9), respectively. The FTA "flexion angle" (lateral view alignment from neutral AP) and the absolute HKA "flexion angle" correlated with the change in FTA and HKA with limb rotation, respectively (FTA, R = 0.999; HKA, R = 0.993). The mean change in FTA after virtual closed-wedged osteotomy was 3.2 degrees for internal and external 10 degrees rotation errors in reattaching the osteotomy plane. Rotation may affect measurement of lower limb alignment for knee osteotomy, and 3-D methods are preferable for surgical planning.

Adult↗
PubMed2004

Outcome of total en bloc spondylectomy for solitary metastasis of the thoracolumbar spine.

BACKGROUND: Total en bloc spondylectomy (TES) was devised to minimize the incidence of local recurrence following resection of spinal tumor. Successful local control with TES has been reported for patients with primary malignant or aggressive benign spinal tumors. As for metastatic spinal tumors, however, only a few surgeons except for the inventor group have reported the outcome of TES. The purpose of this study was to investigate whether TES could provide radical resection of the tumor in patients with solitary spinal metastases. METHODS: Twelve patients underwent TES for a solitary metastatic tumor of the thoracolumbar spine. Primary malignancies included breast cancer in four patients, thyroid cancer in three, renal cell carcinoma in three, lung cancer in one, and unknown in one. All patients were regularly followed up with plain radiographs, computed tomography scans, and magnetic resonance imaging to detect local recurrence. RESULTS: In two of the four cases with paraspinal tumor extension, local recurrences developed at 25 months after surgery. Seven patients have survived for an average of 61 months, while the remaining five died of disseminated metastases with a mean survival of 23 months after surgery. Local recurrences were common in patients with paraspinal extensions. TES for lesions with paraspinal extensions failed to provide curative resection of the tumor. CONCLUSION: Given the great technical demands and potential risks of TES, the indication for TES with spinal metastases should be limited to cases with solitary lesions that do not extend to the paraspinal area.

Adult↗
PubMed2004

[The advanced technology of three-dimensional medical imaging in spine, bone and joints].

The advanced technology of three-dimensional (3-D) medical imaging allows us to understand the patient specific anatomy in detail. Especially, in orthopedic surgery, treated spinal diseases or the disorders of bone and joints, the 3-D computed tomography(CT), such as multi-slice CT and helical CT is a useful tool for clinical diagnosis and surgical treatment. Since 1995, by the use of these 3-D CT image data, computer navigation system and surgical robot were developed and applied to a spinal instrumentation surgery and an artificial joint replacement. Now surgeons can perform the precise and safe surgical procedure by the computer guidance on the base of 3-D medical imaging.

Arthrography↗
PubMed2003

Posterior approach to the degenerative cervical spine.

Laminoplasty has been gradually accepted as a treatment for choice for cervical compression myelopathy. The historical perspective of laminoplasty is described. The aims of laminoplasty are to expand the spinal canal, to secure spinal stability, to preserve the protective function of the spine, and to preserve spinal mobility. Laminoplasty is indicated in myelopathic patients with a developmentally narrow spinal canal or multiple-level involvement combined with a relatively narrow canal. Several laminoplasty techniques and supplementary techniques are described, together with expected outcomes and complications of surgery.

Adult↗
PubMed2003

Mechanical stress-induced apoptosis of endplate chondrocytes in organ-cultured mouse intervertebral discs: an ex vivo study.

STUDY DESIGN: Various amounts of static mechanical load were applied to mouse intervertebral discs in organ cultures. The apoptosis then was examined using nick end labeling. Two mitogen-activated protein kinase (MAPK) inhibitors were added to the medium. OBJECTIVES: To establish an experimental model for detecting factors regulating chondrocyte apoptosis induced by mechanical stress, and to determine the role of MAPK and p38 in the stress-induced apoptotic pathway of endplate chondrocytes. SUMMARY OF BACKGROUND DATA: The cause of degenerative change in the cartilaginous endplate (CEP) remains unclear. The authors' previous findings using a mouse model suggested that apoptosis in the cartilaginous endplate may play a role in intervertebral disc degeneration, and that mechanical stress may induce apoptosis. If apoptosis of endplate chondrocytes is involved in the cascade of intervertebral disc degeneration, then how apoptosis is induced by mechanical stress should be important in preventing disc degeneration. However, the mechanism of apoptosis induced by mechanical stress remains unclear. METHODS: Mouse coccygeal discs were harvested and organ cultured. Various static compression loads (0, 0.2, 0.4, 0.8, and 1.0 MPa) were applied on intervertebral discs placed in culture bottles for 24 hours. Paraffin-embedded sections of the harvested discs were stained using Safranin-O and the nick end labeling procedure. The apoptotic cells were counted in the cartilaginous endplate and junctional anulus fibrosus of each intervertebral disc. In addition, U0126 (MAPK inhibitor) and SB202190 (p38 inhibitor) were added to the culture medium to determine their regulatory roles in the apoptosis of endplate chondrocytes induced by mechanical load. RESULTS: Histologically, loaded discs became bulged, and the disc space became narrow. Apoptosis was absent in discs without load, but was particularly noticeable in loaded discs (load weight, 1.0 MPa). The number of apoptotic cells increased depending on the weight of the load. The two MAPK inhibitors significantly increased the number of apoptotic cells. CONCLUSIONS: Chondrocyte apoptosis was induced using a static mechanical load especially in the cartilaginous endplate in an organ culture. Apoptosis occurred similarly to previous findings using an in vivo model. This culture system thus reflected the apoptosis demonstrated in vivo. Because biologically active reagents such as MAPK inhibitors can be simply added to culture media, this system may be a useful method for detecting factors that influence apoptosis induced by mechanical stress. Both MAPK inhibitors increased the occurrence of apoptosis. This suggests that these two MAPKs can counteract the apoptotic pathway induced by mechanical stress.

Animals↗
PubMed2003

Lateral atlantoaxial joint arthrography in atlantoaxial rotatory fixation.

There has been much debate about the pathogenesis of atlantoaxial rotatory fixation. Intraarticular abnormality has not been well documented thus far. This is the first case of chronic atlantoaxial rotatory fixation in which atlantoaxial joints were examined by consecutive arthrography. A 7-year-old girl was diagnosed with atlantoaxial rotatory fixation on a three-dimensional CT scan. Arthrography of the lateral atlantoaxial joints indicated a rupture of the joint capsule on the dislocated side at first, followed by a successful repair after 5 weeks' immobilization with a halo apparatus. Because torticollis recurred after taking off the halo vest, we performed surgery in which severe adhesion of the cartilage surface of facet joint was noted on the undislocated side and release of the adhesion was needed to mobilize the atlas. Atlantoaxial arthrodesis by screw fixation facilitated a solid fusion of the segment.

Arthrography↗
PubMed2003

Automated segmentation of acetabulum and femoral head from 3-D CT images.

This paper describes several new methods and software for automatic segmentation of the pelvis and the femur, based on clinically obtained multislice computed tomography (CT) data. The hip joint is composed of the acetabulum, cavity of the pelvic bone, and the femoral head. In vivo CT data sets of 60 actual patients were used in the study. The 120 (60 x 2) hip joints in the data sets were divided into four groups according to several key features for segmentation. Conventional techniques for classification of bony tissues were first employed to distinguish the pelvis and the femur from other CT tissue images in the hip joint. Automatic techniques were developed to extract the boundary between the acetabulum and the femoral head. An automatic method was built up to manage the segmentation task according to image intensity of bone tissues, size, center, shape of the femoral heads, and other characters. The processing scheme consisted of the following five steps: 1) preprocessing, including resampling 3-D CT data by a modified Sinc interpolation to create isotropic volume and to avoid Gibbs ringing, and smoothing the resulting images by a 3-D Gaussian filter; 2) detecting bone tissues from CT images by conventional techniques including histogram-based thresholding and binary morphological operations; 3) estimating initial boundary of the femoral head and the joint space between the acetabulum and the femoral head by a new approach utilizing the constraints of the greater trochanter and the shapes of the femoral head; 4) enhancing the joint space by a Hessian filter; and 5) refining the rough boundary obtained in step 3) by a moving disk technique and the filtered images obtained in step 4). The above method was implemented in a Microsoft Windows software package and the resulting software is freely available on the Internet. The feasibility of this method was tested on the data sets of 60 clinical cases (5000 CT images).

Acetabulum↗
PubMed2003

4-dimensional computer-based motion simulation after Total Hip Arthroplasty.

This paper represents a novel 4-dimensional(4D) computer-based motion simulation system for patients having had Total Hip Arthroplasty(THA). By constructing the skeletal model of the patient's lower extremity and measuring daily motions, we simulated the movement of the inner structures including the skeleton and the artificial joint. This system visually represents not only the 3-dimensional(3D) anatomical structure but also the 4-dimensional dynamic functions that represent the time sequential transitions of the position of each component. Clinicians can get detailed information of the movement of the hip joint quantitatively and give precise guidance for the patients with regard to postoperative daily motions. The measurement error was evaluated by performing experiments using OpenMRI and the results indicated sufficient accuracy of this system. We believe that this system enables clinicians to reveal the causes of complications after THA and encourages the development of new surgical techniques, materials. and designs of prostheses.

Arthroplasty, Replacement, Hip↗
PubMed2002

Cervical kyphosis: predictive factors for progression of kyphosis and myelopathy.

STUDY DESIGN: A retrospective study of 13 patients with cervical kyphosis. The authors propose new methods of measuring spinal cord compression and predicting the progression of kyphosis. OBJECTIVES: To ascertain predictive factors for progression of cervical kyphosis and myelopathy. SUMMARY OF BACKGROUND DATA: Cervical kyphosis may be congenital, result from decompression surgery, or occur as a posttraumatic deformity. Although there is the potential for progressive deformity and the development of myelopathy in all these situations, there are few previous reports of predictive factors for progression of cervical kyphosis and myelopathy in patients with cervical kyphosis. METHODS: The authors studied radiographs and magnetic resonance imaging scans of 13 patients with cervical kyphosis, including 9 who had been operated on and had postsurgical secondary kyphosis, and 4 with idiopathic kyphosis without any of the above causes. Compression of the spinal cord at the apex of the cervical kyphosis was evaluated by magnetic resonance imaging of the ratio between the anteroposterior diameter of the medulla-pons junction and the spinal cord at the apex. RESULTS: The mean ratio between the anteroposterior diameter of the medulla-pons junction and the spinal cord at the apex in five patients in whom myelopathy did not develop was 0.37, and was 0.21 in the patients in whom myelopathy developed. Progression of cervical kyphosis was associated with osteophyte formation at the anterior aspect of the vertebral body. CONCLUSION: A ratio below 0.3 between the anteroposterior diameter of the medulla-pons junction and the spinal cord at the apex was a risk factor for cervical myelopathy. One of the most predictable risk factors of progression of the cervical kyphosis was osteophyte formation at the anterior aspect of the vertebral body.

Adolescent↗
PubMed2002

Pulsatile cerebrospinal fluid flow measurement using phase-contrast magnetic resonance imaging in patients with cervical myelopathy.

STUDY DESIGN: A technical report is presented. OBJECTIVE: To investigate the relation between the severity of myelopathy and the degree of cerebrospinal fluid flow disturbance by using magnetic resonance imaging to measure the velocity of the cerebrospinal fluid flow in patients with cervical spondylotic myelopathy. SUMMARY OF BACKGROUND DATA: Analyses of pulsatile cerebrospinal fluid flow measured by phase-contrast magnetic resonance imaging in healthy subjects and patients with Arnold-Chiari syndrome have been reported. Few studies have evaluated the change of pulsatile cerebrospinal fluid flow velocity and the waveform of the plotted velocity in patients with cervical spondylotic myelopathy. METHODS: Study 1: Pulsatile cerebrospinal fluid flow was measured at C7, positioned with cervical spine flexion and extension, to investigate the influence of cervical alignment on the pulsatile cerebrospinal fluid flow in five patients with cervical spondylotic myelopathy. Study 2: In 31 patients with cervical spondylotic myelopathy, pulsatile cerebrospinal fluid flow was measured at C3 and C7, with the neck set centrally. The relevance of cerebrospinal fluid flow disturbance and the severity of myelopathy evaluated by the Japanese Orthopedic Association scoring system also were studied. RESULTS: Study 1: The waveform of plotted pulsatile cerebrospinal fluid flow velocity showed no change resulting from the position of the cervical spine. Study 2: A high correlation between the Japanese Orthopedic Association score and the cerebrospinal fluid pulsatile flow amplitude at C7 was demonstrated (r = 0.75; P < 0.0001). The average Japanese Orthopedic Association score of 14 patients whose cerebrospinal fluid flow velocity waveforms were absent was significantly lower (P < 0.0001) than that of 17 patients whose waveforms were present. CONCLUSIONS: The disturbance of pulsatile cerebrospinal fluid flow demonstrated high correlation with the severity of myelopathy. Measurement of cerebrospinal fluid flow disturbance can quantify the degree of dural sac and spinal cord compression.

Aged↗
PubMed2002

Expression of neurotrophic factors in the dorsal root ganglion in a rat model of lumbar disc herniation.

A variety of molecules released by inflammatory reactions in the dorsal root and dorsal root ganglion (DRG) may play important roles in the pathology of neuronal abnormalities in lumbar disc herniation. In order to elucidate the pathophysiological mechanisms of painful radiculopathy, secondary to lumbar disc herniation, we evaluated pain-related behavior and the change of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) expression in the DRG and dorsal root using a rat model of lumbar disc herniation. In the nucleus pulposus (NP) group, the left L4/5 nerve roots were exposed after hemilaminectomies and autologous intervertebral discs, which were obtained from coccygeal intervertebral discs, were implanted on each of the exposed nerve roots without mechanical compression. Rats in the NP group, but not the sham-operated rats, developed mechanical allodynia on the ipsilateral hind paw for 1 day after surgery and showed a significant increase in the number of NGF-immunoreactive (IR) cells in the nerve root and DRG. NGF-IR cells in the nerve root and DRG included macrophages and Schwann cells, because these cells were labeled for NGF and ED-1 or glial fibrillary acid protein by dual immunostaining. A significant increase in the percentage of BDNF-IR neurons in the DRG was observed in the NP group at 3 days after surgery and the increase in BDNF mRNA expression was confirmed using in situ hybridization histochemistry and reverse transcription-polymerase chain reaction. We also injected NGF into the endoneurial space of the normal rat spinal nerve root and found that the NGF injection produced dose-dependent mechanical allodynia on the ipsilateral hind paw at 1 day after surgery and an increase in the percentage of BDNF-IR neurons in the DRG at 3 days after surgery compared to the group receiving saline injection. These findings suggest that in the lumbar disc herniation model, i.e. neuritis of the nerve root, increased NGF produced by the inflammatory responses in the dorsal root and DRG tissues may affect the production of BDNF in the DRG and may play important roles in the modulation of the dorsal horn neurons. These changes in neurotrophic factors in the primary afferents may be involved in the pathophysiological mechanisms of neuropathic pain produced by lumbar disc herniation.

Animals↗
PubMed2002

Distribution of genes for parathyroid hormone (PTH)-related peptide, Indian hedgehog, PTH receptor and patched in the process of experimental spondylosis in mice.

OBJECT: Little is known about the molecular mechanisms underlying the process of spondylosis. The authors determined the extent of genetic localization of major regulators of chondrogenesis such as Indian hedgehog (Ihh) and parathyroid hormone (PTH)-related peptide (PTHrP) and their receptors during the development of spondylosis in their previously established experimental mouse model. METHODS: Experimental spondylosis was induced in 5-week-old ICR mice. The cervical spines were chronologically harvested, and histological sections were prepared. Messenger (m) RNA for PTHrP, Ihh, PTH receptor (PTHR; a receptor for PTHrP), patched (Ptc; a receptor for Ihh), bone morphogenetic protein (BMP)-6, and collagen type X (COL10; a marker for mature chondrocyte) was localized in the tissue sections by performing in situ hybridization. In the early stage, mRNA for COL10, Ihh, and BMP-6 was absent; however, mRNA for PTHrP, PTHR, and Ptc was detected in the anterior margin of the cervical discs. In the late stage, evidence of COL10 mRNA began to be detected, and transcripts for Ihh, PTHrP, and BMP-6 were localized in hypertrophic chondrocytes adjacent to the bone-forming area in osteophyte. Messenger RNA for Ptc and PTHR continued to localize at this stage. In control mice, expression of these genes was absent. CONCLUSIONS: The localization of PTHrP, Ihh, BMP-6, and the receptors PTHR and Ptc demonstrated in the present experimental model indicates the possible involvement of molecular signaling by PTHrP (through the PTHR), Ihh (through the Ptc), and BMP-6 in the regulation of chondrocyte maturation leading to endochondral ossification in spondylosis.

Animals↗
PubMed2002

Long-term results of expansive laminoplasty for ossification of the posterior longitudinal ligament of the cervical spine: more than 10 years follow up.

OBJECT: The authors report the long-term (more than 10-year) results of cervical laminoplasty for ossification of the posterior longitudinal ligament (OPLL) of the cervical spine as well as the factors affecting long-term postoperative course. METHODS: The authors reviewed data obtained in 92 patients who underwent cervical laminoplasty between 1982 and 1990. Three patients were lost to follow up, 25 patients died within 10 years of surgery, and 64 patients were followed for more than 10 years. Results were assessed using the Japanese Orthopaedic Association (JOA) scoring system for cervical myelopathy. The recovery rate was calculated using the Hirabayashi method. The mean neurological recovery rate during the first 10 years after surgery was 64%, which declined to 60% at the last follow-up examination (mean follow up 12.2 years). Late neurological deterioration occurred in eight patients (14%) from 5 to 15 years after surgery. The most frequent causes of late deterioration were degenerative lumbar disease (three patients), thoracic myelopathy secondary to ossification of the ligamentum flavum (two patients), or postoperative progression of OPLL at the operated level (two patients). Postoperative progression of the ossified lesion was noted in 70% of the patients, but only two patients (3%) were found to have related neurological deterioration. Additional cervical surgery was required in one patient (2%) because of neurological deterioration secondary to progression of the ossified ligament. The authors performed a multivariate stepwise analysis, and found that factors related to better clinical results were younger age at operation and less severe preexisting myelopathy. Younger age at operation, as well as mixed and continuous types of OPLL, was highly predictive of progression of OPLL. Postoperative progression of kyphotic deformity was observed in 8% of the patients, although it did not cause neurological deterioration. CONCLUSIONS: When the incidence of surgery-related complications and the strong possibility of postoperative growth of OPLL are taken into consideration, the authors recommend expansive and extensive laminoplasty for OPLL.

Adult↗
PubMed2001

Problems of posterior lumbar interbody fusion (PLIF) for the rheumatoid spondylitis of the lumbar spine.

We performed posterior lumbar interbody fusion (PLIF) on 7 patients with rheumatoid spondylitis (RA) of the lumbar spine with severe low-back pain and/or cauda equina symptoms, and evaluated the effectiveness of PLIF for the lumbar spinal instability in RA secondary to destruction of the anterior elements, including vertebral endplates and the apophyseal joint. The subjects were 7 patients with classic RA, 2 men and 5 women, mean age 65 years old, and the mean duration of RA was 21 years. All had severe low-back pain and difficulty with walking. According to the ARA classification, the patients were at stage 3 or worse and in class 3. Diagnostic imaging including magnetic resonance imaging (MRI), tomography, myelography, and computed tomographic myelography (CTM) of the lumbar spine clearly delineated pathology, destruction of the vertebral endplate, subluxation, and cauda compression which can be well treated with PLIF. We performed L4/5PLIF (5 cases), L3/4 and L4/5 PLIF (2 cases), and posterior fixation with instruments for anterior column repair and stabilization and posterior decompression. Autografts (all cases) and Brantigan IF cage (2 cases) were used. Stable fixation of the lumbar spine was achieved after surgery, and improvement in gait and activities of daily living were achieved through the relief of low-back pain and radicular pain; the mean duration of follow-up was 22 months. Postoperative, plain radiography, CT, and MRI revealed the enlargement of the lumbar canal and fusion and incorporation of grafted bone, but in some cases, collapse of graft, migration of pedicle screw, instability of adjacent level, and collapse of adjacent vertebra were noted. PLIF with spinal instruments is a preferred treatment for rheumatoid spondylitis of the lumbar spine, but in the mutilating type of RA with severe osteoporosis, PLIF in combination with a long fixation system and/or augmentation of the vertebral bodies might be needed.

Aged↗