Biomedical subjects

Kiyoshi Kaneda

Publications and source records attributed to Kiyoshi Kaneda.

9 recordsLinked to original sources

PubMed2003

Static and dynamic analysis of five anterior instrumentation systems for thoracolumbar scoliosis.

STUDY DESIGN: A nondestructive biomechanical investigation among five anterior spinal instrumentation systems for scoliosis. OBJECTIVES: The purpose of this study is to analyze the static and dynamic biomechanical stability of five different systems. SUMMARY OF BACKGROUND DATA: Although a variety of anterior spinal instrumentation systems for scoliosis are available, very few attempts have been made at comparative biomechanical studies. METHODS: Thirty calf spines were underwent static biomechanical tests, including flexion-extension, axial rotation, and lateral bending loading modes in the multisegmental spinal model. Five anterior instrumentation systems included: 1) Texas Scottish Rite Hospital system; 2) Bad Wildungen Metz; 3) anterior ISOLA; 4) Cotrel-Dubousset Hoph; and 5) Kaneda Anterior Scoliosis System. The initial and postfatigue stability after a cyclic loading test were analyzed by measuring the range of motion at instrumented segments compared to the intact within the same specimen (% to intact). RESULTS: Two-rod systems showed a significant decrease in range of motion compared to one-rod systems in flexion-extension (P < 0.001) and axial rotation (P < 0.05). In lateral bending, all systems demonstrated a significant decrease in range of motion of less than 40% to the intact (P < 0.001). After cyclical loading test, all systems increased in range of motion. In flexion-extension, one-rod systems depicted a significant increase in range of motion, compared to two-rod systems (P < 0.05). CONCLUSIONS: In the initial stability analysis, two-rod systems are superior to one-rod systems. For one-rod systems, repeated physiologic loading may result in reduced stability in flexion-extension.

Analysis of Variance↗

PubMed2003

Local kyphosis reduces surgical outcomes of expansive open-door laminoplasty for cervical spondylotic myelopathy.

STUDY DESIGN: This retrospective study analyzed the effects of cervical alignment on surgical results of expansive laminoplasty (ELAP) for cervical spondylotic myelopathy (CSM). OBJECTIVE: To determine the limitation of posterior decompression by ELAP for CSM in the presence of local kyphosis. SUMMARY OF BACKGROUND DATA: Several studies have reported that cervical malalignment affected surgical outcomes of ELAP. However, there has been no report to demonstrate crucial determinants of surgical outcomes of ELAP for CSM in relation to cervical sagittal alignment. METHODS: The study group comprised 114 patients who underwent ELAP for CSM. All were followed up for more than 2 years. The Japanese Orthopedic Association (JOA) scoring system for cervical myelopathy (full score, 17 points) was used to evaluate surgical outcomes for each patient 2 years after surgery. Statistical analysis with multivariate logistic regression models was used to ascertain the risk factors affecting postoperative surgical outcomes. RESULTS: The average JOA scores were 9.9 points before surgery and 14 points 2 years after surgery. The recovery rate was 60.2%. Statistical analysis showed that signal intensity change on MRI and local kyphosis were the most crucial risk factors for poor surgical outcomes. Calculated with the logistic regression model, the highest risk of poor recovery was local kyphosis exceeding 13 degrees. CONCLUSIONS: The influence of cervical malalignment on neurologic recovery after ELAP for CSM was shown. When patients have local kyphosis exceeding 13 degrees, anterior decompression or posterior correction of kyphosis as well as ELAP should be considered. Expansive laminoplasty for CSM is best indicated for patients with local kyphosis less than 13 degrees.

Adult↗

PubMed2003

Bone ingrowth fixation of artificial intervertebral disc consisting of bioceramic-coated three-dimensional fabric.

STUDY DESIGN: The bone-bonding characteristic of the new artificial intervertebral disc consisting of bioceramic-coated three-dimensional fabric was evaluated mechanically and histologically in an in vivo sheep model. OBJECTIVES: To investigate the mechanical properties and the histologic appearance of the interface between the three-dimensional fabric disc and the vertebral body, and to evaluate these alterations in vivo under a spinal segmentally mobile condition. SUMMARY OF BACKGROUND DATA: Bone ingrowth to the bioceramic-coated three-dimensional fabric surface had been demonstrated already under a stable environment in preliminary animal studies. METHODS: For this study, 20 sheep underwent two-level lumbar intervertebral disc replacement with three-dimensional fabric discs (Group I) or bioceramic spacers as a comparative material (Group II). All operative segments were stabilized temporarily with spinal instrumentation for the initial ingrown phase. Four animals each were killed at 4, 6, 15, and 24 months in Group I and at 6 months in Group II, and the operative segments were subjected to either a detachment test or histologic evaluation. RESULTS: The interfacial tensile strength at 6 months was significantly higher in Group I than in Group II. No significant decrease in tensile strength was detected until 24 months after surgery in Group I. Histologically, bone ingrowth to the three-dimensional fabric surface was observed 4 months after surgery, and no aseptic loosening occurred until 24 months after surgery. CONCLUSIONS: The findings show that the three-dimensional fabric disc was firmly fixed to the vertebral body by bone ingrowth, and that this biologic fixation was preserved even under the spinal segmentally mobile condition.

Animals↗

PubMed2003

Diagnostic accuracy of magnetic resonance imaging for detecting posterior ligamentous complex injury associated with thoracic and lumbar fractures.

OBJECT: The posterior ligamentous complex (PLC) in the thoracic and lumbar spine is one of the region's important stabilizers. The precise diagnosis of PLC injury is required to evaluate the instability of the injured spine; however, the accuracy of magnetic resonance (MR) imaging for diagnosing PLC injury has remained unclear. In this study, the authors compared preoperative MR imaging findings with direct intraoperative observation of PLC injury, clarifying the former's diagnostic accuracy regarding detection of PLC injury associated with the thoracic and lumbar fractures. METHODS: Data obtained in 35 patients who sustained thoracic or lumbar injuries were reviewed. There were 17 burst fractures, six flexion-distraction injuries, and 12 fracture dislocations. Each patient underwent MR imaging examination within 3 weeks of injury. Three radiologists independently evaluated sagittal MR images in a blinded fashion. The PLC-related information was retrospectively collected from each operative record. The diagnostic accuracy of MR imaging was analyzed by comparing imaging-documented intraoperative findings. The PLC injuries were detected in 23 patients (65.7%) by direct observation during posterior spinal procedures. The diagnostic accuracy of MR imaging in detecting injury of the supraspinous ligament (SSL) and interspinous ligament (ISL) was 90.5 and 94.3%, respectively. The specificity of T1-weighted MR imaging alone for depicting the SSL was significantly greater than T2-weighted imaging alone (p < 0.05). The overall mean kappa coefficient for MR imaging findings of PLC injury was 0.803, which indicated excellent interobserver reliability; that for ISL (0.915) was significantly greater than that for SSL (0.69) (p < 0.05). CONCLUSIONS: This study clarified a high diagnostic accuracy and interobserver reliability of MR imaging for PLC injury. The precise diagnosis of PLC injury is essential to determine the mechanical instability of the injured thoracic and lumbar spine, especially in differentiating unstable (three-column) burst fractures from the relatively stable (two-column) type. The authors conclude that MR imaging is a powerful diagnostic tool to evaluate PLC injury associated with thoracic and lumbar fractures.

Humans↗

PubMed2002

Artificial intervertebral disc replacement using bioactive three-dimensional fabric: design, development, and preliminary animal study.

STUDY DESIGN: A new artificial intervertebral disc was developed, and its intrinsic biomechanical properties, bioactivity, and the effectiveness as a total disc replacement were evaluated in vitro and in vivo. OBJECTIVES: To introduce a new artificial intervertebral disc and to evaluate the in vitro mechanical properties, fusion capacity to bone, and segmental biomechanics in the total intervertebral disc replacement using a sheep lumbar spine. SUMMARY OF BACKGROUND DATA: The loss of biologic fusion at the bone-implant interface and prosthetic failures have been reported in previous artificial discs. There have been no clinically applicable discs with detailed experimental testing of in vivo mechanics and interface fusion capacity. METHODS: The artificial intervertebral disc consists of a triaxial three-dimensional fabric (3-DF) woven with an ultra-high molecular weight polyethylene fiber, and spray-coated bioactive ceramics on the disc surface. The arrangement of weave properties was designed to produce mechanical behavior nearly equivalent to the natural intervertebral disc. Total intervertebral disc replacement at L2-L3 and L4-L5 was performed using 3-DF disc with or without internal fixation in a sheep lumbar spine model. The segmental biomechanics and interface histology were evaluated after surgery at 4 and 6 months. RESULTS: The tensile-compressive and torsional properties of prototype 3-DF were nearly equivalent to those of human lumbar disc. The lumbar segments replaced with 3-DF disc alone showed a significant decrease of flexion-extension range of motion to 28% of control values as well as partial bony fusion at 6 months. However, the use of temporary fixation provided a nearly physiologic mobility of the spinal segment after implant removal as well as excellent bone-disc fusion at 6 months. CONCLUSION: An artificial intervertebral disc using a three-dimensional fabric demonstrated excellent in vitro and in vivo performance in both biomechanics and interface histology. There is a potential for future clinical application.

Animals↗

PubMed2002

Complications related to hydroxyapatite vertebral spacer in anterior cervical spine surgery.

STUDY DESIGN: This is a report of complications related to the hydroxyapatite vertebral spacer used for anterior cervical reconstructive surgery. Compression of the spinal cord by broken fragments of hydroxyapatite spacer as well as its surrounding radiolucent clear zone were observed in seven patients. OBJECTIVES: To report complications related to the use of hydroxyapatite vertebral spacer for anterior cervical reconstructive surgery and to discuss how to prevent these complications. SUMMARY OF BACKGROUND DATA: Despite previous articles reporting the clinical applications of hydroxyapatite vertebral spacer for the cervical spine, clinical reports regarding the long-term results of hydroxyapatite spacer for anterior cervical surgery and its complications have been limited. METHODS: The authors reviewed patients who underwent anterior reconstructive surgery using the hydroxyapatite spacer at other hospitals and had postoperative complications related to hydroxyapatite spacer. RESULTS: Seven patients previously treated by anterior cervical spine surgery using the hydroxyapatite vertebral spacer were referred to the authors because of unsatisfactory surgical outcomes. All the patients had a radiolucent clear zone around the spacer and experienced severe neck pain. Four had fracture of the hydroxyapatite spacer, and two had compression of the spinal cord by retropulsed fragments of broken hydroxyapatite spacers. CONCLUSIONS: Although hydroxyapatite has been used in many medical fields because of its bioactive characteristics, its mechanical properties should be improved to lessen the risks of breakage and subsequent spinal cord compression. Gentle insertion maneuvers are also important to avoid the production of cracks inside the spacer.

Aged↗

PubMed2002

An in vitro human cadaveric study investigating the biomechanical properties of the thoracic spine.

STUDY DESIGN: An in vitro human cadaveric study comparing the effects of anterior and posterior sequential destabilization conditions on thoracic functional unit mechanics was studied. OBJECTIVES: To investigate the biomechanical properties of the human thoracic spine. SUMMARY OF BACKGROUND DATA: Few studies have addressed the mechanical role of the costovertebral joints under torsion in the stability of the human thoracic spine. METHODS: Sixteen functional spinal units with intact costovertebral joints were obtained from six human cadavers and randomized into two groups based on destabilization procedures: Group 1, anterior to posterior sequential resection; and Group 2, posterior to anterior sequential destabilization. Biomechanical testing was performed after each destabilization procedure, and the range of motion under maximum load was calculated. RESULTS: Group 1: Under flexion-extension, lateral bending, and axial rotation loading, discectomy increased the range of motion by 193%, 74%, and 111%, respectively. Moreover, subsequent right rib head resection further increased the range of motion by 81%, 84%, and 72%, respectively. Group 2: Under all loading conditions laminectomy + medial facetectomy resulted in a 22-30% increase in range of motion. Subsequent total facetectomy led to an additional 15-28% increase in range of motion. CONCLUSION: The rib head joints serve as stabilizing structures to the human thoracic spine in the sagittal, coronal, and transverse planes. In anterior scoliosis surgery additional rib head resection after discectomy may achieve greater curve and rib hump correction. The lateral portion of the facet joints plays an important role in providing spinal stability and should be preserved to minimize postoperative kyphotic deformity and segmental instability when performing decompressive wide laminectomy.

Aged↗

PubMed2002

The correlation between bursoscopic and histologic findings of the acromion undersurface in patients with subacromial impingement syndrome.

PURPOSE: Ideally, decompression of the coracoacromial arch in patients with shoulder impingement syndrome should be done only at the site of impingement. However, it is very difficult to determine the exact site of impingement before acromioplasty. The objectives of this study were to investigate the relationship between findings and the histopathologic changes of the undersurface of the acromion in subacromial impingement syndrome and to evaluate the usefulness of bursoscopy in identifying the site of the impingement. TYPE OF STUDY: Case series. METHODS: We investigated the correlation between subacromial bursoscopic findings and histopathologic changes of the coracoacromial arch in 50 patients with subacromial impingement syndrome. The acromion and the coracoacromial ligaments removed during acromioplasty were fixed in 10% formalin, decalcified, embedded in paraffin, and cut into sections along the direction of the coracoacromial ligament. After staining with toluidine blue, the specimens were evaluated for pathology using an optical microscope. RESULTS: The pathologic changes were classified into 3 types according to the direction of proliferative fibrocartilaginous changes at the enthesis of the acromial insertion of the coracoacromial ligament. The bursoscopic findings were classified into 4 types. Subacromial abnormalities in the bursoscopy findings correlated with histopathologic changes at the undersurface of the acromion. On the other hand, cases with normal findings on the undersurface of the acromion on bursoscopy had hypertrophic changes of fibrocartilage at the insertion of the coracoacromial ligament to the acromion. These results suggest that, with normal findings on the undersurface of the acromion in patients with subacromial impingement syndrome, there is impingement at the coracoacromial ligament. CONCLUSIONS: Bursoscopy is a useful procedure to determine the impingement site in patients with subacromial impingement.

Acromion↗

PubMed2002

Simultaneous strain measurement with determination of a zero strain reference for the medial and lateral ligaments of the ankle.

The strain changes of the central part of the anterior talofibular ligament (ATFL), the posterior talofibular ligament (PTFL), the calcaneofibular ligament (CFL), and the tibiocalcaneal ligament (TCL) were measured simultaneously for a full range of ankle motion. Twelve fresh frozen amputated ankles were used. To measure the strain changes of the ligaments, a Galium-Indium-filled silastic strain transducer was implanted in the center of each ligament. The zero strain reference was determined immediately after the measurement of strain changes in five of the 12 ankles by tensile testing of each bone-ligament-bone preparation. The maximum strain change of the ATFL, the PTFL, the CFL and the TFL were 7.9%, 5.9%, 5.3% and 5.2%, respectively. The ATFL was elongated in plantar flexion and shortened in dorsiflexion. The PTFL and the CFL were shortened in plantar flexion and elongated in dorsiflexion. The TCL was the longest around the neutral position and became shorter in planter flexion and dorsiflexion. The results showed that the ATFL was taut in plantar flexion over 16.2 degrees, the PTFL and the CFL were taut in dorsiflexion over 18 degrees and 17.8 degrees respectively, and the TCL was taut between 9.5 degrees of dorsiflexion and 9.5 degrees of plantar flexion. The length change pattern was different among the ankle ligaments, although there was only a slight difference between that of the PTFL and the CFL. This study provides fundamental data useful in studying ankle ligament reconstruction.

Adolescent↗