山内 かづ代

BACKGROUND: Previous studies reported that the publication rate of abstracts presented at overseas meetings was around 50 %. The study objectives were to determine the rate of publication in English-language journals and the impact factor (IF) for all papers presented at the Annual Meeting of the Japanese Orthopaedic Association (JOA) and Annual Research Meeting of the Japanese Orthopaedic Association (JOAR), and to compare the publication rates and IFs from abstracts accepted for oral versus poster presentations. METHODS: Titles and first authors were identified for 1,676 abstracts of free papers accepted for presentation to the JOA in 2006 and 2007, and 1,529 abstracts to the JOAR from 2006 to 2008. We identified the associated journal publications by searching PubMed, and IFs were determined using the journal citation reports. The publication rates and IFs for papers accepted for oral versus poster presentations were compared using statistical analysis. RESULTS: The overall publication rate was 25.5 % from the JOA and 50 % from the JOAR. There were no significant differences in yearly publication rates, or between oral and poster presentations for each year. The average IFs for all publications from the JOA was 2.45 and that from the JOAR was 3.5. There were no significant differences in yearly IFs, or between oral and poster presentations for each year (P > 0.05). CONCLUSIONS: The rate from JOAR was similar to publication rates for abstracts presented at overseas orthopedic meetings, however, the rate from JOA was half that of publication rates for abstracts presented at overseas orthopedic meetings, indicating that JOA may provide a below average contribution of new medical data to the international scientific community. No significant difference in publication rates between oral and poster presentations were found, and this suggests a need for improvement of the review system for the annual meeting and that review scores at the meetings did not predict the publication fate of abstracts.

PURPOSE: Osteoarthritic pain is largely considered to be inflammatory pain. Sensory nerve fibers innervating the knee have been shown to be significantly damaged in rat models of knee osteoarthritis (OA) in which the subchondral bone junction is destroyed, and this induces neuropathic pain (NP). Pregabalin was developed as a pain killer for NP; however, there are no reports on pregabalin use in OA patients. The purpose of this study was to investigate the efficacy of pregabalin for pain in OA patients. MATERIALS AND METHODS: Eighty-nine knee OA patients were evaluated in this randomized prospective study. Patients were divided into meloxicam, pregabalin, and meloxicam+pregabalin groups. Pain scores were evaluated before and 4 weeks after drug application using a visual analogue scale (VAS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Pain scales among groups were compared using a Kruskal-Wallis test. RESULTS: Before drug application, there was no significant difference in VAS and WOMAC scores among the three groups (p>0.05). Significant pain relief was seen in the meloxicam+pregabalin group in VAS at 1, 2, and 4 weeks, and WOMAC score at 4 weeks, compared with the other groups (p<0.05). No significant pain relief was seen in the meloxicam only group in VAS during 4 weeks and WOMAC score at 4 weeks compared with the pregabalin only group (p>0.05). CONCLUSION: Meloxicam+pregabalin was effective for pain in OA patients. This finding suggests that OA pain is a combination of inflammatory and NP.

STUDY DESIGN: Assessment of pain-related behavior and immunohistology of the dorsal root ganglion in a rat model. OBJECTIVE: To investigate pain-related behavior in a rat model of nerve crush plus inflammation using the CatWalk system. SUMMARY OF BACKGROUND DATA: A definitive method for evaluating animal models of lumbar disease has not been established. Von Frey testing has often been used in this type of study, but the reliability remains in question. The CatWalk system is a computer-assisted apparatus for analyzing gait that provides an automated way to assess gait function during pain. However, there have been few reports using this system for models of lumbar disease. METHODS: Fourteen rats were divided into 2 groups: a treatment group and a sham group. For the treatment group, nucleus pulposus was applied to the sciatic nerve and the sciatic nerve was pinched. Two different methods for assessment of pain-related behavior, von Frey testing and CatWalk analysis, were used before surgery and at 4 and 7 days after surgery. Immunohistochemistry was used to examine calcitonin gene-related peptide expression in L4 to L6 dorsal root ganglia. RESULTS: No significant differences were found between the treatment and sham control groups using von Frey testing. However, significant differences in 4 parameters were found between the 2 groups using the CatWalk system (P < 0.05). The proportion of calcitonin gene-related peptide-immunoreactive neurons was higher in the treatment group than in the control group (P < 0.05). CONCLUSION: Our results demonstrate that the CatWalk system is useful for the measurement of pain-related behavioral change in our rat model in which nociception was indicated at a cellular level. Although further studies are needed, we think that this system is a valid alternative method for the evaluation of models of lumbar disease in rodents.

PURPOSE: The pathological mechanism of lumbar spinal stenosis is reduced blood flow in nerve roots and degeneration of nerve roots. Exercise and prostaglandin E1 is used for patients with peripheral arterial disease to increase capillary flow around the main artery and improve symptoms; however, the ankle-brachial index (ABI), an estimation of blood flow in the main artery in the leg, does not change after treatment. Lumbar spinal nerve roots contain somatosensory, somatomotor, and unmyelinated autonomic nerves. Improved blood flow by medication with prostaglandin E1 and decompression surgery in these spinal nerve roots may improve the function of nerve fibers innervating muscle, capillary, and main vessels in the lower leg, resulting in an increased ABI. The purpose of the study was to examine whether these treatments can improve ABI. MATERIALS AND METHODS: One hundred and seven patients who received conservative treatment such as exercise and medication (n=56) or surgical treatment (n=51) were included. Low back pain and leg pain scores, walking distance, and ABI were measured before treatment and after 3 months of conservative treatment alone or surgical treatment followed by conservative treatment. RESULTS: Low back pain, leg pain, and walking distance significantly improved after both treatments (p<0.05). ABI significantly increased in each group (p<0.05). CONCLUSION: This is the first investigation of changes in ABI after treatment in patients with lumbar spinal stenosis. Improvement of the spinal nerve roots by medication and decompression surgery may improve the supply of blood flow to the lower leg in patients with lumbar spinal stenosis.

BACKGROUND: Our purpose was to examine platelet-rich plasma (PRP) for its effect on bone formation and to follow the immunohistochemical changes in calcitonin gene-related peptide (CGRP) in dorsal root ganglion neurons innervating the discs as a possible index of nociceptive nerve transmission in a rat model. METHODS: A total of seventy rats were used. Ten constituted a non-punctured disc sham group, while another ten rats constituted a group that underwent puncture of the L4-L5 discs. Forty rats were in experimental groups in which the L4-L5 discs were punctured; posterolateral lumbar arthrodesis was performed with PRP (the PRP group) or without the use of PRP (the normal arthrodesis group), with twenty rats in each group. The remaining ten rats were used as blood donors. Four and eight weeks after surgery, microcomputed tomography examinations were done to evaluate the amount of bone and the L4-L5 spines were harvested to evaluate bone union, followed by resection of dorsal root ganglion neurons. The percentages of Fluoro-Gold-labeled and CGRP-immunoreactive neurons were calculated. RESULTS: The platelet count and the concentration of growth factors in PRP were higher than those in blood (p &lt; 0.05). The bone volumes observed in the PRP group were significantly greater than those of the normal arthrodesis group at four and eight weeks (p &lt; 0.05). Three (30%; 95% confidence interval [CI], 6% to 65%) of ten rats in the normal arthrodesis group and eight (80%; 95% CI, 44% to 98%) of ten rats in the PRP group were considered to have bone fusion four weeks after surgery (p &lt; 0.05). At eight weeks, seven (70%; 95% CI, 34% to 94%) of ten rats in the normal arthrodesis group and nine (90%; 95% CI, 55% to 99%) of ten rats in the PRP group were considered to have bone fusion (p = 0.27). The proportion of CGRP-immunoreactive neurons was significantly greater in the punctured group than in the other groups. There were no significant differences between the normal arthrodesis group and the PRP group. CONCLUSIONS: PRP appears to promote bone formation in rats and has a tendency to shorten the period of bone union in this rat model of posterolateral lumbar arthrodesis, but it did not influence the proportion of CGRP-immunoreactive neurons, a likely indicator of inflammatory pain originating from the degenerative intervertebral disc. CLINICAL RELEVANCE: The ability of PRP in this model suggests that it may be able to shorten the period of union and lead to an early return to social activities after treatment.

PURPOSE: To evaluate L5 nerve root injuries caused by outwardly misplaced S1 pedicle screws. Pedicle screws remain the criterion standard for fixation of L5-S1 to correct lumbosacral instability. When inserting S1 pedicle screws, it is possible to injure the L5 nerve root if screws are inserted outwardly and the tip of the screw perforates the anterior cortex of the sacrum. Despite this risk, to our knowledge this type of injury has never been reported as a case series. METHODS: We experienced 2 cases of L5 nerve root injury caused by outwardly-inserted S1 pedicle screws. In both cases, bilateral S1 pedicle screws were inserted outwardly using a free-hand technique, and on one side, screws induced severe pain by impinging on an L5 root. Computed tomography after the selective rootgraphy of the injured nerve showed the nerve compressed laterally by screw threads in Case 1 and crushed between the screw threads and the sacral body in Case 2. RESULTS: In both cases, leg pain disappeared immediately after the infiltration of the nerve with lidocaine, but symptoms recurred within a few days in Case 1 and within an hour in Case 2. Conservative treatment of three spinal nerve infiltrations was effective in Case 1, but reinsertion of the rogue screw was necessary in Case 2. CONCLUSIONS: Surgeons should recognize that lateral inclination of S1 pedicle screws can cause L5 nerve root injury, which may require reinsertion of the screw, especially in cases where insertion is difficult because of overlapping surrounding muscle or bony tissue.

STUDY DESIGN: Prospective study. OBJECTIVE: To examine the efficacy of teriparatide or bisphosphonate treatment to reduce pedicle screw (PS) loosening after instrumented lumbar posterolateral fusion in postmenopausal women with osteoporosis. SUMMARY OF BACKGROUND DATA: Failure of fixation caused by loosening of PSs in osteoporosis is a problem in spinal surgery. Oral administration of bisphosphonate or intermittent injection of parathyroid hormone treatment increases bone mass and reduces the risk of osteoporotic vertebral fractures. Although these treatments may be factor in improving bone quality, a clinical study of the efficacy of bisphosphonate or parathyroid hormone for reducing PS loosening that addresses the quality of the bone marrow and pedicle cortex has not yet been reported. METHODS: Sixty-two women with osteoporosis diagnosed with degenerative spondylolisthesis were divided into 3 groups: a teriparatide group (daily subcutaneous injection of 20 μg of teriparatide, n = 20), a bisphosphonate group (daily oral administration 2.5 mg of risedronate, n = 20), and a control group (without medication for osteoporosis, n = 22). All patients underwent decompression and 1- or 2-level instrumented posterolateral fusion with a local bone graft. Loosening of PSs and surgical outcome were evaluated radiographically, clinically, and by computed tomography 12 months after surgery. RESULTS: At 12-month follow-up, the incidence of PS loosening was 7% to 13% in the teriparatide group, 13% to 26% in the risedronate group, and 15% to 25% in the control group. The incidence of PS loosening in the teriparatide group was significantly lower than that in the risedronate or the control group (P < 0.05). In contrast, the extent of PS loosening in the risedronate group was not significantly different from that in the control group (P > 0.05). CONCLUSION: Our findings suggest that administration of teriparatide increased the quality of the lumbar spine bone marrow and pedicle cortex.

Trophic support and myelination of axons by Schwann cells in the PNS are essential for normal nerve function. Herein, we show that deletion of the LDL receptor-related protein-1 (LRP1) gene in Schwann cells (scLRP1(-/-)) induces abnormalities in axon myelination and in ensheathment of axons by nonmyelinating Schwann cells in Remak bundles. These anatomical changes in the PNS were associated with mechanical allodynia, even in the absence of nerve injury. In response to crush injury, sciatic nerves in scLRP1(-/-) mice showed accelerated degeneration and Schwann cell death. Remyelinated axons were evident 20 d after crush injury in control mice, yet were largely absent in scLRP1(-/-) mice. In the partial nerve ligation model, scLRP1(-/-) mice demonstrated significantly increased and sustained mechanical allodynia and loss of motor function. Evidence for central sensitization in pain processing included increased p38MAPK activation and activation of microglia in the spinal cord. These studies identify LRP1 as an essential mediator of normal Schwann cell-axonal interactions and as a pivotal regulator of the Schwann cell response to PNS injury in vivo. Mice in which LRP1 is deficient in Schwann cells represent a model for studying how abnormalities in Schwann cell physiology may facilitate and sustain chronic pain.

STUDY DESIGN: Immunohistochemistry for tumor necrosis factor (TNF)-α in nucleus pulposus of adolescent patients with lumbar disc herniation. OBJECTIVE: To examine whether an inflammatory cytokine is expressed in the nucleus pulposus of adolescent patients with lumbar disc herniation. SUMMARY OF BACKGROUND DATA: TNFα is thought to play a crucial role in the radicular pain caused by lumbar disc herniation in adult patients. However, the expression of TNFα in the nucleus pulposus of adolescent patients with lumbar disc herniation has not been explored. METHODS: Five samples of nucleus pulposus from adolescent patients with lumbar disc herniation (age, 12-16 yr; n = 5) or controls requiring surgery for other back problems (age, 12-16 yr; n = 4; nonpainful scoliosis) were harvested during surgery. Nucleus pulposus specimens were immunostained using TNFα antibodies and immunostained cells in the nucleus pulposus were counted. We compared the expression of TNFα between the 2 groups. RESULTS: In patients with lumbar disc herniation, more TNFα-immunoreactive cells were seen in the nucleus pulposus in comparison with patients with nonpainful scoliosis (P < 0.01). CONCLUSION: The results suggest that TNFα may play a role in adolescent patients with lumbar disc herniation. The TNFα expression may be related with disc degeneration and pain in adolescent patients with lumbar disc herniation.