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Shinsuke Katoh

Publications and source records attributed to Shinsuke Katoh.

11 recordsLinked to original sources
PubMed2006

High-grade slippage of the lumbar spine in a rat model of spondylolisthesis: effects of cyclooxygenase-2 inhibitor on its deformity.

STUDY DESIGN: Radiographic and histologic evaluation of spondylolisthesis in a rat model. OBJECTIVES: To investigate the effects of etodolac, a cox-2 inhibitor, on the severity of spondylolisthesis in a 4-week-old rat model. SUMMARY OF BACKGROUND DATA: Spondylolisthesis occurs associated with spondylolysis in some pediatric patients. In such patients, the percent of forward slippage varies individually ranging between 0% and 100%. The factors determining the severity of forward slippage have not been clarified as yet. In earlier studies, we found that growth plate stress fracture was the basic lesion and that slippage was a consequence of the stress fracture. Hence, we hypothesized that the capacity of bone healing might be an important determinant of the degree of forward slippage. METHODS: A lumbar spine slippage model was prepared in 4-week-old rats with vertebral physis fracture. To disrupt the fracture healing, the cyclooxygenase-2 (cox-2) inhibitor etodolac was used, and its effects on slippage and deformity were evaluated radiologically and histologically. RESULTS: In the etodolac group, forward slip significantly increased (P < 0.05) to the Meyerding Grade III while in the control rats it was Grade I or II. Bone remodeling of the vertebral body was suppressed by etodolac. Histologically, epiphyseal separation with slippage was observed in all the control and etodolac-treated rats. However, in the etodolac-treated group, the epiphyseal plate was greatly separated and did not present periosteal thickening at the physis fracture site. CONCLUSION: Vertebral forward slippage occurred in young rats after epiphyseal separation. In the etodolac group, slippage increased as deterioration of the bone healing capacity increased. Poor bony healing is suggested as one of the determinants of high-grade spondylolisthesis in children and adolescents.

Animals↗
PubMed2006

MRI signal changes of the pedicle as an indicator for early diagnosis of spondylolysis in children and adolescents: a clinical and biomechanical study.

STUDY DESIGN: Clinical review of pediatric patients with lumbar spondylolysis and biomechanical analysis using finite-element lumbar spine model. OBJECTIVES: To evaluate the usefulness of the signal changes observed on MR images of the pedicle for the early diagnosis of spondylolysis, and to investigate the pathomechanism of the signal changes based on the stresses in pedicles, as predicted using finite-element analyses. Furthermore, to evaluate the usefulness of the signal change to predict the bony healing following conservative treatment. SUMMARY OF BACKGROUND DATA: Since early-stage spondylolysis can achieve osseous healing conservatively, it is important to diagnose this disorder as early as possible. Presently, there is no well-established, noninvasive, and reliable diagnostic tool for the early diagnosis. METHODS: Thirty-seven pediatric patients with spondylolysis were included. Sixty-eight defects were examined and their stages as revealed on CT scans were recorded. High signal changes (HSC) of the pedicles on axial T2-weighted MRI were compared with the CT-based stages of the defect. Among them, 16 patients, including 15 boys and 1 girl, were treated conservatively for at least a 3-month period. Bony healing of the fracture site was evaluated on CT, and the results were compared between two groups with or without HSC at the initial consultation. Using a three-dimensional nonlinear finite-element model of the L3-L5 segment, stress distributions in the pars and pedicle regions were analyzed in response to 400 N compression and 10.6 Nm moment. RESULTS: Based on CTs, 68 pars defects were classified as follows: 8 very early, 24 late-early, 16 progressive, and 20 terminal stages. All defects in very early and late-early stages (100%) showed HSC on T2-weighted MRI at the ipsilateral pedicle. Among 16 progressive stages, eight (50%) showed HSC, while no defects of the terminal stage (0%) were found to have HSC. In total, 29 pars defects were treated conservatively out of 16 patients. In 19 of the HSC positive defects, 15 (79%) showed bony healing after the conservative treatment, whereas none of the 10 HSC negative defects (0%) showed any healing. The results were statistically significant at P < 0.05 (chi). Stress results from the finite-element model indicated that pars interarticularis showed the highest value in all loading modes, and the pedicle showed the second highest. CONCLUSIONS: The correlation between the high stresses in the pedicle and the corresponding HSC suggest that signal changes in MRI could be used as an indicator for early diagnosis of spondylolysis. The HSC of the pedicle provided useful information to diagnose early stage spondylolysis. Furthermore, the HSC may be a good indicator as to whether a bony union will result from conservative treatment.

Adolescent↗
PubMed2006

Effects of monofilament nylon coated with basic fibroblast growth factor on endogenous intrasynovial flexor tendon healing.

PURPOSE: We developed a monofilament nylon thread that can release various growth factors to enhance intrinsic reparative processes after flexor tendon injury. We evaluated the properties of this thread in vitro and in vivo. METHODS: Nylon threads were coated with gelatin that subsequently was cross-linked in glutaraldehyde. The thread was soaked in basic fibroblast growth factor (bFGF) solution (400 microg/mL). Exogenous bFGF in the thread was released constantly over the course of 1 week. The biologic activity of bFGF and the biomechanical strength of the thread were examined in vitro and its efficacy was investigated in an in vivo rabbit tendon repair model after early flexion exercises. The sutured sites were examined histologically (hematoxylin-eosin, immunohistochemistry, in situ hybridization), biochemically (Western blot test), and biomechanically (ultimate load) after surgery. RESULTS: This gelatin-coated thread absorbed iodine 125-labeled bFGF in a time-dependent manner. The total amount of bFGF absorbed by the thread within the tendon tissue was between 3 and 15 mug depending on the concentration of bFGF solution. Basic fibroblast growth factor protein was delivered selectively-not in the surrounding scar but in the repaired tendon-for 3 weeks. Histologic analysis showed that the cellular density at the repaired site increased in accordance with the expression of bFGF messenger RNA and protein in the tendon. Endogenous bFGF expression seemed to be enhanced transiently by exogenous bFGF during the first few weeks. The epitenon showed a vigorous fibroblastic response to the coated thread and the ultimate load also was increased significantly at 3 weeks after surgery. CONCLUSIONS: This bFGF-coated nylon suture gave excellent results in delivering a drug selectively to tendon; it also induced an increase of biomechanical strength and a thickening of the epitenon layer in vivo during a 3-week period, thereby accelerating cellular proliferation, initially peripherally and later centrally. This system may become a therapeutic tool to be used in hand surgery.

Animals↗
PubMed2005

Athletes with unilateral spondylolysis are at risk of stress fracture at the contralateral pedicle and pars interarticularis: a clinical and biomechanical study.

BACKGROUND: Unilateral spondylolysis is common in youths; its clinical and biomechanical features, especially effects on the contralateral side, are not fully understood. HYPOTHESIS: Unilateral spondylolysis predisposes the contralateral side to stress fracture, especially in athletes actively engaged in sporting activities involving torsion of the trunk. STUDY DESIGN: Case series and descriptive laboratory study. METHODS: Thirteen athletes younger than age 20 with unilateral spondylolysis were included. The contralateral pedicle and pars of spondylolytic vertebrae were examined using computed tomography and magnetic resonance imaging. Using a finite element model of the intact ligamentous L3-S1 segment, stress distributions were analyzed in response to 400-N axial compression and 10.6-N.m moment in flexion, extension, lateral bending, and axial rotation. Unilateral spondylolysis was created in the model at L5. The stress results from the unilateral defect model were compared to the intact model predictions and correlated to the contralateral defects seen in patients. RESULTS: Among 13 patients, there were 6 early-, 2 progressive-, and 5 terminal-stage defects. Three (23.1%) showed contralateral stress fracture. Among them, 2 belonged to the progressive-stage and 1 to the terminal-stage spondylolysis group. The remaining 4 patients in the terminal defect group showed stress reactions, such as sclerosis at the contralateral pedicle. In the finite element analysis model with an L5 left spondylolysis, the stresses at the contralateral and pars interarticularis were found to increase in all loading modes, with increases as high as 12.6-fold compared to the intact spine. CONCLUSIONS: Unilateral spondylolysis could lead to stress fracture or sclerosis at the contralateral side due to an increase in stresses in the region. CLINICAL RELEVANCE: Surgeons should be aware of possibility of contralateral stress fractures in cases in which patients, especially athletes engaged in active sports, show unilateral spondylolysis and persistent low back pain complaints.

Adolescent↗
PubMed2005

Asynchronous progressive diaphyseal dysplasia.

We report the case of a 42-year-old Japanese woman with unusual diaphyseal dysplasia of bilateral femora. Radiographs showed thickening and sclerosis of the cortex with resultant enlargement of the diaphysis, unclear demarcation of the surface of the cortex, and no periosteal reaction. These changes were found on the left femur at the first presentation, and those on the right femur developed within several years. Although this patient partly presented characteristics of Ribbing disease and Camurati-Engelmann disease, the focal involvement of bilateral femora suggested an unknown pathogenesis.

Journal Article↗
PubMed2004

Vertebral forward slippage in immature lumbar spine occurs following epiphyseal separation and its occurrence is unrelated to disc degeneration: is the pediatric spondylolisthesis a physis stress fracture of vertebral body?

STUDY DESIGN: Radiographic and histologic evaluation of a rat model of lumbar spine slippage. OBJECTIVES: To clarify the pathomechanism of slippage in the immature spine. SUMMARY OF BACKGROUND DATA: There are controversial hypotheses regarding the pathogenesis of slippage of the pediatric spine with pars defects. Some studies supported that disc degeneration was its cause, while others indicated the growth plate injury was the cause. METHODS: An immature lumbar spine slippage model in 4-week-old rats was used. Following posterior destabilizing surgery, the lumbar spine was radiographically and histologically examined at 1, 3, 5, and 7 days after surgery. RESULTS: Radiographically, slippage occurred about 7% in the % slip on day 7, and no slippage was observed before day 5. Histologically, epiphyseal separation also appeared on day 7; before day 5, the growth plate showed no abnormalities. Within 7 days after the operation, the anulus fibrosus did not show any sign indicating degeneration. The nucleus pulposus was also normal up to day 7. CONCLUSION: The findings of this study support the hypothesis that vertebral forward slippage of the immature spine occurs following epiphyseal separation and its occurrence is unrelated to disc degeneration.

Animals↗
PubMed2003

The pathogenesis of slippage and deformity in the pediatric lumbar spine: a radiographic and histologic study using a new rat in vivo model.

STUDY DESIGN: Rat lumbar spines with posterior destabilizing surgery were evaluated radiographically and histologically. OBJECTIVES: To create an appropriate rat model showing the vertebral slippage and deformities frequently observed in pediatric patients with spondylolysis, and to clarify their pathogenesis. SUMMARY OF BACKGROUND DATA: There are controversial hypotheses regarding the pathogenesis of slippage and deformities of the pediatric spine with pars defects. Furthermore, there is no appropriate animal model mimicking those conditions. METHODS: After posterior destabilizing surgery, the lumbar spines of young (4-week-old) and adult (26-week-old) rats were radiographically examined at weekly intervals during 3 weeks, and histologically 3 weeks after the surgery. RESULTS: Slippage occurred in the young rats, but not in the adult rats. In the young rats, 7.2% slippage was observed 1 week after the surgery, whereas the slippage in the adult rats was 0%. The difference in percentage of slippage between the two groups was significant (P < 0.05). Lumbar deformity also was seen in the young rats, but not in the adult rats. The lumbar index of L6, as an indicator of L6 rounding, was 91.7% immediately after surgery. It had decreased to 87.7, 84.6, and 74%, respectively, 1, 2, and 3 weeks after surgery. Histologic examination showed growth plate injury in the young group and pronounced disc degeneration in the adult group. CONCLUSIONS: The young rat with posterior destabilizing surgery was an appropriate animal model, mimicking the slippage and deformities radiographically seen in pediatric patients with spondylolysis. The histologic examination indicated that vertebral growth plate impairment was the basic lesion causing such slippage and deformities in pediatric spines.

Aging↗
PubMed2003

A new endoscopic technique to decompress lumbar nerve roots affected by spondylolysis. Technical note.

The authors describe a new endoscopic technique to decompress lumbar nerve roots affected by spondylolysis. Short-term clinical outcome was evaluated. Surgery-related indications were: 1) radiculopathy without low-back pain; 2) no spinal instability demonstrated on dynamic radiographs; and 3) age older than 40 years. Seven patients, four men and three women, fulfilled these criteria and underwent endoscopic decompressive surgery. Their mean age was 60.9 years (range 42-70 years). No subluxation was present in four patients, whereas Meyerding Grade I slippage was demonstrated in three. For endoscopic decompression, a skin incision of 16 to 18 mm in length was made, and fenestration was performed to identify the affected nerve root. The proximal stump of the ragged edge of the spondylotic lesion, and the fibrocartilaginous mass compressing the nerve root were removed. The follow-up period ranged from 6 to 22 months (mean 11.7 months). Clinical outcome was evaluated using Gill criteria; in three patients the outcome was excellent, and in four it was good. This new endoscopic technique was useful in the decompression of nerve roots affected by spondylolysis, the technique was minimally invasive, and the clinical results were acceptable.

Adult↗
PubMed2002

Normal and spondylolytic pediatric spine movements with reference to instantaneous axis of rotation.

STUDY DESIGN: A radiologic study of lumbar kinematics in the pediatric spine was conducted. OBJECTIVES: To clarify the kinematic alteration in the pediatric spine with pars defects by measuring the location of the instantaneous axis of rotation. SUMMARY OF BACKGROUND DATA: Vertebral slippage and deformities such as wedging of L5 are observed frequently in pediatric patients with spondylolysis. However, the kinematics of pediatric lumbar spine with pars defects has not yet been well documented. METHODS: Radiographs of 70 pediatric patients (57 boys and 13 girls) with low back pain were examined. The control group (without spondylolysis) consisted of 22 patients (15 boys and 7 girls; mean age, 14.6 years; range, 10-18 years), and the lysis group (with spondylolysis at L5) consisted of 48 patients (42 boys and 6 girls; mean age, 14.5 years; range, 11-18 years). The lysis group was further divided into four subgroups according to the stage of defects and existence of slippage: Group 1 (early stage defect), Group 2 (progressive stage defect), Group 3 (terminal stage defect without slippage), and Group 4 (terminal stage defect with slippage of more than 5%; olisthesis). The instantaneous axis of rotation at L4-L5 and L5-S1 from the extended to the flexed position was measured on lateral dynamic radiograms taken in with the subject in the recumbent position. The relation between lumbar index and the site of instantaneous axis of rotation at L5-S1 also was analyzed. RESULTS: The site of instantaneous axis of rotation at L5-S1 and L4-L5 in the control group was not located in the rotating cranial vertebra. In 1 of the 11 patients in the early-stage subgroup, the instantaneous axis of rotation at L5-S1 was found in the cranial vertebra. In 4 of the 11 patients in the progressive stage, 11 of the 16 patients in the terminal stage, and in 7 of the 10 patients in the olisthesis subgroup, the instantaneous axis of rotation was located in the cranial vertebra. Cranial deviation in the instantaneous axis of rotation was observed more frequently in the vertebra with severe deformity less than 80% of the lumbar index than in the vertebra with milder deformity. CONCLUSIONS: The instantaneous axis of rotation deviated cranially as the stage of pars defects advanced, and as the wedge deformity increased. Kinematic alteration of the lumbar spine in pediatric patients with spondylolysis may affect chondrocytes of the endplate, perhaps contributing to the consequent spine deformities occurring secondarily to spondylolysis.

Adolescent↗
PubMed2002

Natural history of extruded lumbar intervertebral disc herniation.

We studied the natural history of extruded lumbar intervertebral discs using MRI. Forty-nine patients with lumbar disc herniation were included in this study. Ages ranged from 19 to 57. On the T2-weighted sagittal MR image, the signal intensity in the herniated mass was measured and the ratio to that in the original nucleus (i.e., nucleus pulposus from which they extruded) was calculated (signal intensity ratio; SIR). The relationship with SIR and duration of illness was evaluated. In ten patients who were re-examined by MRI after conservative treatment, the size of the herniation measured by T1-weighted axial MR image was compared before and after treatment. The signal intensity of HNP became higher than that of the original nucleus immediately following herniation and thereafter decreased with time, suggesting that initial hydration of the HNP occurred shortly after herniation followed by dehydration of the HNP. The size of the HNP with a SIR value of 1.2 and higher on T2-weighted MR images decrease with time, however, the HNP with a SIR below 1.2 did not show any size reduction. The SIR of 1.2 and higher is a good indicator predicting spontaneous reduction of the HNP. Dehydration in the HNP may play an important role in the reduction of the lumbar disc herniation.

Adult↗