PubMed Health⌕ Search

Biomedical subjects

Hideki Sudo

Publications and source records attributed to Hideki Sudo.

7 recordsLinked to original sources
PubMed2006

Biomechanical study on the effect of five different lumbar reconstruction techniques on adjacent-level intradiscal pressure and lamina strain.

OBJECT: The objectives of this study were to compare the biomechanical effects of five lumbar reconstruction models on the adjacent segment and to analyze the effects of three factors: construct stiffness, sagittal alignment, and the number of fused segments. METHODS: Nondestructive flexion-extension tests were performed by applying pure moments to 10 calf spinal (L3-S1) specimens. One-segment (L5-6) or two-segment (L5-S1) posterior fusion methods were simulated: 1) one-segment posterolateral fusion (PLF); 2) one-segment PLF with interbody fusion cages (one-segment PLIF/PLF); 3) two-segment PLF; 4) two-segment PLIF/PLF; and 5) two-segment PLF in kyphosis (two-segment kyphotic PLF). The range of motion (ROM) of the reconstructed segments, intradiscal pressure (IDP), and lamina strain in the upper (L4-5) adjacent segment were analyzed. The ROM was significantly decreased in the PLIF/PLF models compared with that in the PLF alone models after both the one- and two-segment fusions. If the number of fused segments was increased, the pressure and strains were also increased in specimens subjected to the PLIF/PLF procedure, more so than the PLF-alone procedure. In the one-segment PLIF/PLF model the authors observed a reduced IDP and lamina strain compared with those in the kyphotic two-segment PLF model despite the latter's higher levels of initial stiffness. CONCLUSIONS: If the number of fused levels can be reduced by using PLIF to correct local kyphosis, then this procedure may be valuable for reducing adjacent-segment degenerative changes.

Animals↗
PubMed2006

Long-term follow up of surgical outcomes in patients with cervical disorders undergoing hemodialysis.

OBJECT: As increasing numbers of patients receive long-term hemodialysis, the number of reports regarding hemodialysis-related cervical spine disorders has also increased. However, there have been few reports summarizing the surgical results in patients with these disorders. The objective of this study was to evaluate the long-term follow up and clinical results after surgical treatment of cervical disorders in patients undergoing hemodialysis. METHODS: Seventeen patients in whom surgery was performed for cervical spine disorders while they received long-term hemodialysis therapy were enrolled in this study. Of these, 15 underwent follow-up review for more than 3 years after surgery, and these represent the study population. The remaining two patients died of postoperative sepsis. The average follow-up period was 120 months. Five patients without spinal instability underwent spinal cord decompression in which bilateral open-door laminoplasty was performed. Ten patients with destructive spondyloarthropathy (DSA) underwent reconstructive surgery involving pedicle screw (PS) fixation. In eight patients in whom posterior instrumentation was placed, anterior strut bone grafting was performed with autologous iliac bone to treat anterior-column destruction. Marked neurological recovery was obtained in all patients after the initial surgery. In the mobile segments adjacent to the site of previous spinal fusion, the authors observed progressive destructive changes with significant instability in four patients (40%) who underwent circumferential spinal fusion. No patients required a second surgery after laminoplasty for spinal canal stenosis without DSA changes. CONCLUSIONS: Cervical PS-assisted reconstruction provided an excellent fusion rate and good spinal alignment. During the long-term follow-up period, however, some cases required extension of the spinal fusion due to the destructive changes in the adjacent vertebral levels. Guidelines or recommendations to overcome these problems should be produced to further increase the survival rates of patients undergoing hemodialysis.

Adult↗
PubMed2003

Types of spinal instability that require interbody support in posterior lumbar reconstruction: an in vitro biomechanical investigation.

STUDY DESIGN: Pedicle screw fixation alone for sequential spinal instabilities was biomechanically compared with pedicle screw fixation using interbody cages. OBJECTIVE: To evaluate biomechanical effects of interbody cages on construct stiffness, pedicle-screw strain, and the adjacent level in posterior lumbar reconstruction using pedicle screw fixation. SUMMARY OF BACKGROUND DATA: It remains undetermined what types of spinal instability require interbody support in posterior lumbar reconstruction. METHODS: For this study, 10 calf spines (L3-L6) were used. Sequential destabilization was performed at L4-L5 followed by posterior reconstruction using pedicle screw fixation (PS) and interbody cages as follows: intact + PS (I-PS), medial facetectomy + PS (MF-PS), total facetectomy + PS (TF-PS), partial discectomy + PS (D-PS), and D-PS + interbody cages (PLIF). Biomechanical testing was performed under flexion and extension loading modes. Construct stiffness (L4-L5), rod-screw bending strain, and range of motion (ROM) at the upper adjacent level (L3-L4) were analyzed. RESULTS: In terms of construct stiffness (L4-L5), all the reconstructions except D-PS demonstrated higher construct stiffness than the intact spine (P < 0.05). The PLIF showed the highest stiffness among all the reconstructions (P < 0.05). In terms of ROM (L3-L4), all the reconstructions increased the ROM, as compared with the intact state (P < 0.05). Importantly, PLIF showed significantly greater ROM than all the other reconstructions except I-PS (P < 0.05). In terms of rod-screw strain, the D-PS resulted in higher strain than the other groups (P < 0.05). The PLIF presented less strain than the other reconstructions (P < 0.05). CONCLUSIONS: For spinal instability with preserved anterior load sharing, pedicle screw fixation alone is biomechanically adequate, and interbody cages should not be used because they further increase segmental motion at the adjacent segment. However, PS alone provides insufficient stability and high implant strain in case of damaged anterior column. In such cases, additional interbody cages significantly increase construct stiffness and decrease hardware strain. However, they increase ROM at the adjacent segment as well.

Animals↗
PubMed2003

NF-kappa B-dependent induction of cyclin D1 by retinoblastoma protein (pRB) family proteins and tumor-derived pRB mutants.

The retinoblastoma protein (pRB) and its homologues, p107 and p130, prevent cell cycle progression from G(0)/G(1) to S phase by forming complexes with E2F transcription factors. Upon phosphorylation by G(1) cyclin-cyclin-dependent kinase (Cdk) complexes such as cyclin D1-Cdk4/6 and cyclin E-Cdk2, they lose the ability to bind E2F, and cells are thereby allowed to progress into S phase. Functional loss of one or more of the pRB family members, as a result of genetic mutation or deregulated phosphorylation, is considered to be an essential prerequisite for cellular transformation. In this study, we found that pRB family proteins have the ability to stimulate cyclin D1 transcription by activation of the NF-kappaB transcription factor. The cyclin D1-inducing activity of pRB is abolished by adenovirus E1A oncoprotein but not by the deletion of the A-box, the B-box, or the C-terminal region of the pocket, indicating that multiple pocket sequences are independently involved in cyclin D1 activation. Intriguingly, tumor-derived pRB pocket mutants retain the cyclin D1-inducing activity. Our results reveal a novel role of pRB family proteins as potential activators of NF-kappaB and inducers of G(1) cyclin. Certain pRB pocket mutants may give rise to a cellular situation in which deregulated E2F and cyclin D1 cooperatively promote abnormal cell proliferation.

Adenovirus E1A Proteins↗
PubMed2003

In vitro biomechanical effects of reconstruction on adjacent motion segment: comparison of aligned/kyphotic posterolateral fusion with aligned posterior lumbar interbody fusion/posterolateral fusion.

OBJECT: Posterior lumbar interbody fusion (PLIF) was developed to overcome the limitations of posterolateral fusion in correcting spinal deformity and maintaining lumbar lordosis. In this study the authors compare the biomechanical effects of three different posterior reconstructions on the adjacent motion segment. METHODS: Ten calf spinal (L2-S1) specimens underwent nondestructive flexion-extension testing (+/- 6 Nm). The specimens were destabilized at the L5-S1 levels after intact testing. This was followed by pedicle screw fixation with and without interbody cages as follows: 1) with straight rods ("aligned" posterolateral fusion); 2) with kyphotically prebent rods ("kyphotic" posterolateral fusion); and 3) with interbody cages combined with straight rods ("aligned" PLIF/posterolateral fusion). The range of motion (ROM) of the operative segments, the intradiscal pressure (IDP), and longitudinal lamina strain in the superior adjacent segment (L4-5) were analyzed. The ROM associated with aligned PLIF/posterolateral fusion-treated specimens was significantly less than both the aligned and kyphotic posterolateral fusion-treated procedures in both flexion and extension loading (p < 0.05). The aligned PLIF/posterolateral fusion was associated with greater IDP and the lamina strain compared with the aligned and kyphotic posterolateral fusion groups in flexion loading. Under extension loading, greater IDP and lamina strain were present in the kyphotic posterolateral fusion group than in the aligned posterolateral fusion group. The highest IDP and lamina strain were shown in the aligned PLIF/posterolateral fusion group. CONCLUSIONS: Compared with kyphotic posterolateral fusion, PLIF may lead to even higher load at the superior adjacent level because of the increased stiffness of the fixed segments even if local kyphosis is corrected by PLIF.

Animals↗
PubMed2002

Spinal cord compression by multistrand cables after solid posterior atlantoaxial fusion. Report of three cases.

The sublaminar wiring procedure has been commonly used for stabilizing the atlantoaxial complex. Multistrand braided cables were introduced in the early 1990s. In previous biomechanical studies these cables were demonstrated to be superior to monofilament wires in terms of their flexibility, mechanical strength, and fatigue-related characteristics. To the authors' knowledge, they are the first to describe clinically the occurrence of delayed spinal cord compression resulting from multistrand cables after the completion of rigid spinal arthrodesis in the upper cervical spine. Three patients underwent posterior atlantoaxial fusion in which two sublaminar multistrand cables were placed. Between 15 and 48 months postoperatively, they suffered from upper- and lower-extremity numbness as well as gait disturbance. Plain radiography and computerized tomography myelography revealed spinal cord compression caused by the sublaminar cables, although fusion was complete and physiological alignment was maintained at the fused segment. The radiographs obtained immediately after surgery demonstrated that the initial cable placement had been properly performed. The shape of the cable at the initial surgery was oval and then gradually became circular. The anterior arc of the circular shape of the cable in fact led to the spinal cord compression. Considering the mechanism of this late complication, a cable tends to spring open because of its high flexibility and becomes circular shaped even after the complete arthrodesis. When applying multistrand cables for intersegmental fixation at the atlantoaxial complex, delayed complications related to bowing of the cables is possible.

Adult↗