稲毛 一秀

PURPOSE: Recent studies have revealed the impact of spinopelvic factors on the risk of dislocation after total hip arthroplasty (THA). This study examined the risk factors of impingement that can lead to dislocation using pre- and postoperative spinopelvic radiographs. METHODS: We studied 143 consecutive patients with end-stage hip osteoarthritis who were eligible for THA at our institute. Pre-operative pelvic incidence (PI), sacral slope (SS), lumbar lordosis (LL), sagittal vertical axis (SVA) in the standing and sitting position, and centre-edge angle (CE) were measured. The post-operative SS, LL, SVA, femoral shaft angle, and radiographic alignment of the acetabular component were also measured. We performed a multiple linear regression analysis to determine the risk factors for anterior and posterior impingement using pre-operative demographic and radiographic parameters. The clearance of anterior and posterior implant impingement was used for the surrogate-dependent variable for dislocation. RESULTS: A total of 95 patients were included in the analysis. There were significant differences in SS, LL, and SVA between the standing and sitting positions (P < 0.001). A multiple linear regression analysis showed that the PI-LL, LL changes, and CE were associated with the posterior impingement (β = - 0.21, 0.24, and -0.27, respectively). Moreover, PI-LL was also associated with the anterior impingement in the sitting position (β = - 0.27). CONCLUSION: Our results suggest that a flatback with a rigid spine leads to posterior impingement, and a well-balanced spine leads to anterior impingement, which can be a potential risk factor for dislocation.

PURPOSE: In this multicenter retrospective observational study, we examined the early effects of romosozumab in patients with severe osteoporosis in terms of time-course changes in bone metabolism marker, improvement in bone density, and adverse effects. MATERIALS AND METHODS: Patients with severe osteoporosis were included. We investigated the progress of TRACP 5b and P1NP before and 1-2 months after the administration of romosozumab. We also investigated the bone density of lumbar spine, femoral neck, and the entire femur, measured by the DXA method, before and 5-7 months after the administration of romosozumab. RESULTS: A total of 70 patients (7 males and 63 females, age 75.0±3.6 years) participated in this study. Significant improvements in TRACP 5b and P1NP levels were observed before and 1-2 months after romosozumab administration. The average bone density of lumbar spine, femoral neck, and the entire femur were measured before and 5-7 months after romosozumab administration; and a significant increase only observed in the lumbar spine. CONCLUSION: Consistent with the findings of previous clinical studies, romosozumab has both bone formation-enhancing and bone resorption effects (dual effect). In addition, romosozumab also demonstrated improvement in bone density from the early phase after the administration, though the result was only seen in the lumbar spine.

BACKGROUND: When treating cancer patients, the progression of symptoms is accompanied by the deterioration of systemic conditions and motor function. From a risk-benefit perspective, a certain level of physical function must be maintained to continue cancer treatment. Recently, outpatient cancer treatment has become more common. Motor function is important to determine the feasibility of continuing cancer treatment. The study aimed to evaluate the motor function of patients with visceral cancer using locomo tests established by Japanese Orthopaedic Association. METHODS: Locomo tests were performed, and the results were compared with data from non-cancer individuals. Background data were matched by propensity score matching. Data from 53 cancer patients (group C) were compared with that of 75 non-cancer patients (group N). RESULTS: The average score in the two-step test of group C was lower than that of group N (1.27: 1.37, p = 0.004). The average function in the stand-up test of group C was worse than that of group N (p = 0.001). The average score in the 25-question geriatric locomotive function scale (GLFS) of group C was significantly higher than that of group N (19.92: 5.29, SE 2.21, p < 0.001). Higher 25-question GLFS scores indicate reduced mobility. The proportion of the locomo stage 2 in group C was significantly higher than in group N (51%: 13%, p < 0.001). The results of the two field tests revealed a clinically minimal difference between the two groups, but a statistically significant difference. Locomo tests may be detect potential motor dysfunction in outpatient cancer patients with apparently maintained motor function. CONCLUSIONS: Even in cancer patients who attend outpatient clinics, their motor functions could be potentially impaired. Therapeutic interventions to maintain and enhance motor function for cancer patients could be useful for continuing cancer treatment, and furthermore, improving prognosis.

This study aimed to perform a comparative analysis of postoperative results between lumbar degenerative spondylolisthesis (LDS) treated with oblique lateral interbody fusion (OLIF) and transforaminal lumbar interbody fusion (TLIF) from the Chiba spine surgery registry database. Sixty-five patients who underwent single-level OLIF (O group) for LDS with ≥ 3 years' follow-up were retrospectively reviewed. The control group comprised 78 patients who underwent single-level TLIF (T group). The analyzed variables included global alignment, radiological parameters of fused segments, asymptomatic and symptomatic ASD incidence, clinical outcomes at 3 years postoperatively using the Japanese Orthopedic Association Back Pain Evaluation Questionnaire data, visual analogue scale scores for low back pain, lower extremity pain, and lower extremity numbness. There was no significant change in global alignment between the two groups. The rate of improvement in anterior intervertebral disc height was not significantly different between the groups at 1-month postoperatively. However, at the final evaluation, the anterior intervertebral disc height and incidence of asymptomatic ASD were significantly higher in the O group. There was no significant difference in symptomatic ASD, reoperation cases, or clinical results between groups. Thus, single-level OLIF can maintain the corrected disc height, but as it has no effect on global alignment, its benefit is limited.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The aim of this study was to investigate whether a preoperative difference in lumbar lordosis (D-LL) between the standing and supine positions is associated with clinical outcomes after transforaminal lumbar interbody fusion (TLIF). SUMMARY OF BACKGROUND DATA: Several factors have been reported to be associated with surgical outcomes after TLIF. However, the association between preoperative D-LL and clinical outcomes after TLIF is unknown. METHODS: We enrolled 45 lumbar degenerative disease patients (mean age: 65.7 ± 11.3 years old; 24 males) treated with single-level TLIF. Surgical outcomes were assessed using Oswestry disability index, visual analog scale (VAS; low back pain [LBP], lower-extremity pain, numbness, LBP in motion, in standing, and in sitting), Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, Japanese Orthopaedic Association score for intermittent claudication (JOA score), and Nakai's scoring system. The preoperative D-LL between the standing radiograph and computed tomography (CT) in the supine position was defined as LL in supine CT-standing radiograph. Patients were divided into two groups according to D-LL value (D-LL >-4°, and D-LL ≤-4°). Clinical outcomes were compared between the groups, and correlations between preoperative D-LL and clinical outcomes were analyzed. RESULTS: There were no significant differences in preoperative clinical parameters between the two groups. Postoperative VASs for lower extremity pain, numbness, LBP in standing, and JOA score in D-LL >-4° group were significantly worse than in the D-LL ≤-4° group (P < 0.05). Preoperative D-LL showed a weak correlation with postoperative lower extremity pain and numbness (P < 0.05). CONCLUSION: This study revealed that lumbar degenerative disease patients, who have greater preoperative kyphotic lumbar alignment in the standing versus supine position, tend to have postoperative residual symptoms after TLIF. A preoperative comparison of lateral radiographs between the standing and supine positions is useful to predict patients' postoperative residual symptoms.Level of Evidence: 3.

STUDY DESIGN: An in vivo model to study the effect of an injectable hyaluronic acid (HA) hydrogel following puncture-induced lumbar disc injury in rabbits. OBJECTIVES: The aim of this study was to determine the efficacy of an injectable HA hydrogel to maintain disc height and tissue hydration, promote structural repair, and attenuate inflammation and innervation in the lumbar discs. SUMMARY OF BACKGROUND DATA: Previously, we have demonstrated that HA hydrogel alleviated inflammation, innervation, and pain to promote disc repair. Nevertheless, the effect of an injectable HA hydrogel in the lumbar disc in a weight-bearing animal model was not performed. METHODS: We have adopted a surgically puncture-induced disc injury at lumbar levels in a rabbit model. The discs were grouped into sham, puncture with water injection, and puncture with HA hydrogel injection. Postoperatively, we measured changes in disc height using x-ray. We used magnetic resonance imaging to assess disc degeneration on tissue hydration after euthanasia. Post-mortem, we determined histological changes, innervation (PGP9.5) and inflammation (interleukin [IL]-6, IL-1β, and tumor necrosis factor [TNF]-α) in the discs. RESULTS: We have demonstrated a significant reduction of disc height and T2/T1ρ mapping with histological evidence of degenerative discs, increase of innervation and inflammation in puncture-induced disc injury over time. In the HA hydrogel group, disc height was increased at weeks four and eight. A slight increase of T2 mapping, but significantly in T1ρ mapping, was observed in the HA hydrogel group at week 8. We observed homogenous NP distribution and organised AF lamellae at week eight and a slight reduced innervation score in the treatment group. HA hydrogel significantly downregulated IL-6 expression at day 1. This, however, was only slightly reduced for IL-1β and TNF-α. CONCLUSION: An injectable HA hydrogel had the protective effects in suppressing the loss of disc height, promoting tissue hydration for structural repair, and attenuating inflammation and innervation to prevent further disc degeneration.Level of Evidence: N/A.

腕時計型のウエアラブル端末装置を用いて、腰痛患者の日常の活動量を計測・蓄積したデータを用い、日常および腰椎手術前後における活動量を客観的に評価することで腰痛患者の実態を評価し、患者立脚型アウトカムとの関連を調査した。ウエアラブル端末を用いた腰痛患者の客観的な活動量評価は、患者の記憶や主観に基づく従来型アンケート形式の評価と比較すると、より患者の実態に即した評価が得られると考えられる。

腕時計型のウエアラブル端末装置を用いて、腰痛患者の日常の活動量を計測・蓄積したデータを用い、日常および腰椎手術前後における活動量を客観的に評価することで腰痛患者の実態を評価し、患者立脚型アウトカムとの関連を調査した。ウエアラブル端末を用いた腰痛患者の客観的な活動量評価は、患者の記憶や主観に基づく従来型アンケート形式の評価と比較すると、より患者の実態に即した評価が得られると考えられる。

Spinal sagittal malalignment due to vertebral fractures (VFs) induces low back pain (LBP) in patients with osteoporosis. This study aimed to elucidate spinal sagittal malalignment prevalence based on VF number and patient characteristics in individuals with osteoporosis and spinal sagittal malalignment. Spinal sagittal alignment, and VF number were measured in 259 patients with osteoporosis. Spinal sagittal malalignment was defined according to the SRS-Schwab classification of adult spinal deformity. Spinal sagittal malalignment prevalence was evaluated based on VF number. In patients without VFs, bone mineral density, bone turnover markers, LBP scores and health-related quality of life (HRQoL) scores of normal and sagittal malalignment groups were compared. In 205 of the 259 (79.2%) patients, spinal sagittal malalignment was detected. Sagittal malalignment prevalence in patients with 0, 1, or ≥2 VFs was 72.1%, 86.0%, and 86.3%, respectively. All LBP scores and some subscale of HRQoL scores in patients without VFs were significantly worse for the sagittal malalignment group than the normal alignment group (p < 0.05). The majority of patients with osteoporosis had spinal sagittal malalignment, including ≥70% of patients without VFs. Patients with spinal sagittal malalignment reported worse LBP and HRQoL. These findings suggest that spinal sagittal malalignment is a risk factor for LBP and poor HRQoL in patients with osteoporosis.

我々痛み診療に従事する医師にとって骨粗鬆症と腰痛は非常に密接した病態であり,それらの機序を正確に理解することが診断および治療の観点から非常に重要である.骨粗鬆症患者が腰痛を訴える原因として1.脊椎疾患の合併,2.骨折,3.骨粗鬆化(骨粗鬆状態そのものがもたらす疼痛),4.サルコペニアの合併の4つが注目されている.重要な点は,これらの原因は独立して存在するのではなく,お互いが重複して存在することが多いということである.このことを常に念頭に置き,腰痛のある骨粗鬆症患者を診察,治療していくことが重要であると考える.(著者抄録)

STUDY DESIGN: A retrospective observational study was performed. PURPOSE: We investigated the relationships between skeletal muscle mass, bone mineral density (BMD), and trabecular bone score (TBS) in patients with osteoporotic vertebral compression fractures (VCFs). OVERVIEW OF LITERATURE: The TBS has attracted attention as a measurement of trabecular bone microarchitecture. It is derived from data obtained using dual-energy X-ray absorptiometry (DXA) and is a reported indicator of VCFs, and its addition to the Fracture Risk Assessment Tool increases the accuracy of fracture prediction. METHODS: BMD, skeletal muscle mass, and TBS were measured in 142 patients who visited Shimoshizu National Hospital from April to August 2019. Patients were divided into a VCF group and a non-VCF group. Whole-body DXA scans were performed to analyze body composition, including appendicular skeletal muscle mass index (SMI; lean mass [kg]/height [m2]) and BMD. The diagnostic criteria for sarcopenia was an appendicular SMI <5.46 kg/m2. A logistic regression analysis was conducted to identify the risk factors for VCFs. RESULTS: The significant (p<0.05) findings (VCF group vs. non-VCF group, respectively) included age (79 vs. 70 years), femoral BMD (0.50 vs. 0.58 g/cm2), TBS (1.25 vs. 1.29), and lower limb muscle mass (8.6 vs. 9.9 kg). The VCF group was significantly older and had a lower femur BMD and decreased leg muscle mass than the non-VCF group. Based on the multiple logistic regression analysis, lower femoral BMD and decreased leg muscle mass were identified as risk factors for vertebral fracture independent of age, but the TBS was not. CONCLUSIONS: Patients with VCFs had low BMD, a low TBS, and low skeletal muscle mass. Lower femoral BMD and decreased leg muscle mass were identified as risk factors for VCFs independent of age, whereas the TBS was not identified as a risk factor for VCFs.

Objective: In recent years, there has been an increase in research on the therapeutic effects of exergaming, but there have been few studies on these types of interventions for chronic low back pain. In this study, we hypothesized that the Nintendo Ring Fit Adventure (RFA) exergame would be effective for patients with chronic low back pain, and we conducted a randomized prospective longitudinal study. Materials and Methods: Patients with chronic low back pain were included in this study. Twenty randomly selected patients (9 males and 11 females, mean age 49.3 years) were included in the RFA group, and RFA exergaming was performed once a week for 40 minutes for 8 weeks. Twenty patients (12 males and 8 females, mean age 55.60 years) served as the control group and received oral treatment for 8 weeks. Pain and psychological scores (pain self-efficacy, pain catastrophizing, and kinesiophobia) were measured and analyzed before and after 8 weeks of treatment in both groups. Results: In the RFA group, low back pain, buttock pain, and pain self-efficacy were significantly improved after 8 weeks of RFA exergaming, but there was no significant improvement in lower limb numbness, pain catastrophizing, or kinesiophobia. In the control group, no significant improvement was observed after 8 weeks of oral treatment. Conclusion: RFA exergaming increased pain self-efficacy and reduced pain in patients with chronic low back pain. Future treatment protocols should be developed to improve pain self-efficacy. Approval code: 2894, School of Medicine, Chiba University.

＜文献概要＞既存椎体骨折は将来の椎体骨折を4倍,またすべての骨折リスクを2倍に高めるとも報告されている。すなわち,骨粗鬆症性椎体骨折受傷直後から骨折の連鎖を止めるための薬物治療(二次骨折予防)を開始することが必須である。そこで本稿では,骨粗鬆症性椎体骨折に対する薬物療法について,(1)骨折の連鎖を止めるための薬物治療(二次骨折予防),(2)術前後の薬物治療(骨癒合促進)の2つの観点から概説する。

われわれ痛み診療に従事する医師にとって、骨粗鬆症と腰痛は非常に密接した病態であり、それらの機序を正確に理解することが診断および治療の観点から非常に重要である。骨粗鬆症患者が腰痛を訴える原因として、(1)骨折、(2)骨粗鬆化、(3)サルコペニア、(4)酸化ストレスの4つが注目されている。重要な点は、これらの原因は独立して存在するのではなく、お互いが重複して存在することが多いということである。このことを常に念頭に置き、腰痛のある骨粗鬆症患者を診察、治療していくことが重要であると考える。(著者抄録)

腰痛の予防においては、初発発生率の抑制、慢性化・悪化の防止、再発予防などが基本的な概念となる。健康的な生活を送るよう心がけることや理想体重の維持など生活習慣改善は腰痛予防に寄与し、運動療法は腰痛予防に有用である。運動療法による腰痛予防は「腰への負担をかけない姿勢や動作を取ること」や「筋力トレーニングやストレッチなどの体操を行うこと」を習慣づけ日常生活での姿勢改善と体幹筋筋力と筋持久力を回復することが重要である。また、腰痛予防や治療には日々新しいアイデアが創出され、昨今ではフィットネスゲームを腰痛改善を含む健康増進に役立てるexergamingも腰痛予防・治療の手段として報告されている。(著者抄録)

＜文献概要＞はじめに 後彎症は脊柱アライメント異常を呈する疾患であるが,加齢とともに増悪する傾向があり患者の生活の質(QOL)を著しく阻害することは周知の事実である.具体的には後彎変形による歩行能力低下に起因した日常生活動作(ADL)低下および持続的な慢性背筋疲労による難治性腰痛が臨床的な問題である.これらの症状は治療抵抗性(リハビリテーション介入や鎮痛薬を含めた薬剤介入など多くの保存的治療が無効)であることもよく知られている.一方で,近年ではこのような病態に対する手術的治療法の有効性が報告されているが,侵襲が大きすぎる点と高額の医療費がかかる点からスタンダードな治療法になるにはいたっていない.すなわち高齢社会を迎え患者数は年々増大しているが,その対策は後手に回っているといえる.そこで本稿では,高齢者後彎症の(1)病態メカニズム,(2)治療戦略に関する最新の知見について概説する.

OBJECTIVES: To examine improvement in acute low back pain (LBP) using ultrasound-guided hydrorelease of the multifidus muscle. METHODS: This prognostic cohort study was conducted in a private clinic on samples of 75 patients with acute LBP diagnosed based on physical and imaging findings. Hydrorelease of the multifidus muscle was performed at the L4/5 level. The LBP visual analog scale (VAS) scores (cm) before and 5 minutes after hydrorelease were statistically evaluated. We defined improvement rate (%) as {LBP VAS scores (cm) immediately before hydrorelease - LBP VAS scores (cm) 5 minutes after hydrorelease} × 100 / LBP VAS scores (cm) immediately before hydrorelease and examined the correlation of the Heckmatt score and average age with the improvement rate. RESULTS: LBP VAS scores (cm) before and 5 minutes after hydrorelease were 7.19 ± 1.01 (mean ± SD) and 2.85 ± 1.25, respectively (p < 0.05). No significant correlations were noted between the LBP improvement rate and the Heckmatt score or age. There were no gender variations in the improvement rate. CONCLUSIONS: Ultrasound-guided hydrorelease of the multifidus muscle led to considerable LBP VAS score improvement at the outpatient level. The improvement rate showed no correlations with the Heckmatt score or age, and there were no significant gender variations in the improvement rate. Therefore, fatty degeneration of muscles and change in muscle echogenicity due to age and gender may not be associated with muscular LBP. These findings suggest that multifidus muscle hydrorelease could be useful in the diagnosis and treatment of acute LBP.

This study examined the factors that inhibit the therapeutic effects of cognitive behavioral therapy (CBT) and clarify the adaptation judgment criteria of CBT. We included patients with chronic low back pain and allocated them to the adaptation (with visual analog scale [VAS] improvement) or non-adaptation group (without VAS improvement). The patients were analyzed using various psychological tests. CBT improved depressive symptoms and catastrophic thinking; however, they were not correlated with the VAS and did not directly affect low back pain improvement. The non-adaptation group showed an unexplainable/vague sense of anxiety; an excessive focus on searching for pain; a strong intimacy desire; a strong tendency of medical dependency; and fantasy or distortion of the actual experience, especially self-image. Moreover, the patients showed a low ability to objectively express or attribute meaning to pain due to poor language skills, attention-deficit hyperactivity disorder, and emotional value judgment. Individuals with the aforementioned characteristics of pre-CBT psychological tests should select a different treatment approach given the high poor-adaption possibility. Even patients with depressive or anxious symptoms are not necessarily adaptable for CBT. Therefore, pre-CBT tests for treatment suitability are necessary. Future studies should establish a protocol for psychotherapy suitable for the non-adaptation group.

We investigated the relationship between trunk muscle mass and spinal pathologies by gender. This multicenter cross-sectional study included patients aged ≥ 30 years who visited a spinal outpatient clinic. Trunk and appendicular muscle mass were measured using bioelectrical impedance analysis. The Oswestry Disability Index (ODI), visual analog scale (VAS) score for low back pain, sagittal vertical axis (SVA), and EuroQol 5 Dimension (EQ5D) score were investigated to evaluate spinal pathology. The association between trunk muscle mass and these parameters was analyzed by gender using a non-linear regression model adjusted for patients' demographics. We investigated the association between age and trunk muscle mass. We included 781 men and 957 women. Trunk muscle mass differed significantly between men and women, although it decreased with age after age 70 in both genders. Lower trunk muscle mass was significantly associated with ODI, SVA, and EQ5D score deterioration in both genders; its association with VAS was significant only in men. Most parameters deteriorated when trunk muscle mass was < 26 kg in men and < 19 kg in women. Lower trunk muscle mass was associated with lumbar disability, spinal imbalance, and poor quality of life in both genders, with significant difference in muscle mass.

【目的】超高齢社会の本邦においては,ロコモティブシンドローム(ロコモ)予防の観点からバランス能力の向上をもたらすことができる確立したトレーニング法の開発が喫緊の課題といえる。そのような状況の中,我々はバランス能力向上の新たなトレーニング法としてスリングセラピーの一種であるredcordを使用したAthlete Tuning Method(ATM)トレーニングに注目した。プレリミナリーな位置付けでまずは安全性を考慮し健常ボランティアを対象とし,その有効性についてロコモ度テストを尺度して検討した。【方法】対象は健常ボランティアとした。これらの被験者に対してバランス能力向上のためにATMトレーニングを同一プロトコール(所要時間:1時間程度,頻度:週2回以上)にて実施した。評価としては,研究開始前および3ヵ月後にロコモ度テスト(立ち上がりテスト,2ステップテスト)と生体インピーダンス法(MC-780A,Tanita社)による骨格筋量指数の変化についての検討を行った。(著者抄録)

Study Design: Retrospective observational study. Purpose: Lumbar spinal stenosis (LSS) has traditionally been evaluated morphologically, there is a paucity of literature on quantitative assessment of LSS. The purpose of this study was to investigate whether intraspinal diffusion tensor imaging (DTI) parameters such as apparent diffusion coefficient (ADC) and fractional anisotropy (FA) are useful for assessing LSS. Overview of Literature: Quantitative assessment of LSS is challenging. Methods: Study participants comprised five healthy volunteers (mean age, 27.2 years) and 27 patients with LSS (mean age, 58.4 years) who were individually assessed using 3.0 Tesla magnetic resonance imaging. Intraspinal ADC and FA values of 10 intervertebral discs from healthy volunteers and 52 intervertebral discs from LSS patients were measured. Also, intraspinal canal area, Schizas classification (A: normal, B: mild stenosis, C: severe stenosis) and correlations with symptoms were investigated. Clinical symptoms were checked for the presence of low back pain (LBP), intermittent claudication (IMC), and bladder and bowel dysfunction (BBD). Results: Compared to healthy individuals, LSS patients had significantly lower ADC (p<0.05) and significantly higher FA values (p<0.01). In Schizas classification, stenosis worsened from A to C. ADC values decreased significantly while FA values increased significantly in that order (p<0.05). A positive correlation was found between intraspinal canal area and ADC values (r=0.63, p<0.01) and a negative correlation between intraspinal canal area and FA values (p=-0.61, p<0.01). No correlations were noted between LBP and ADC or FA values. On the other hand, ADC values were significantly lower (p<0.05) and FA values were significantly higher (p<0.05) in patients with IMC or BBD. Conclusions: Intraspinal DTI parameters such as ADC and FA values were associated with the Schizas classification, intraspinal canal area, and clinical symptoms, suggesting that ADC and FA may be useful for quantitative assessment of LSS.

BACKGROUND: Chronic pain is a highly refractory and complicated condition that persists even without nociception. Several genome-wide gene expression analyses have shown that the immune response and inflammatory cytokines affect chronic pain establishment in the acute pain phase. However, compared with the acute phase, the chronic phase has a poorly elucidated gene expression profile. This study aimed to determine the gene expression profile in the spinal cord of a neuropathic pain mouse model in the chronic phase to elucidate the chronic pain characteristics. METHODS: We established a sciatic nerve cuff mouse model as a neuropathic pain model by placing a 2-mm section of a split PE-20 polyethylene tube around the sciatic nerve. The spinal cord was harvested at the L4-6 level at 28 postoperative days. Next, we examined differentially expressed genes (DEGs) through RNA sequencing (RNA-seq) compared with the sham group; moreover, we conducted enrichment analyses of the expressed genes. To reveal the chronic pain characteristics, we compared the gene expression profiles of the spinal cord between the acute and chronic phases in the neuropathic pain model. Among the chronic pain-related genes categorized in the dendrites, we focused on cyclin-dependent kinase-like 5 (CDKL5). We analyzed CDKL5 expression and function using real-time polymerase chain reaction (PCR), immunohistochemistry, and neurite extension assay in Neuro 2a (N2a) cells. We used three types of CDKL5 plasmids: wild type, nuclear localization signal-attached, and K42R kinase-dead CDKL5. RESULTS: We identified 403 DEGs, including 104 upregulated and 43 downregulated genes (false discovery rate < 0.01). Rather than inflammation or immune response, the most enriched terms in the chronic phase were "regulation of plasma membrane-bounded cell projection organization" and "dendrite." Real-time PCR assay confirmed increased CDKL5 expression in the ipsilateral dorsal horn. CDKL5 was broadly expressed in the ipsilateral dorsal horn across all layers. The neurite extension assay revealed that the cytoplasmic kinase function of CDKL5 was necessary for neurite outgrowth in N2a cells. CONCLUSION: RNA-seq of the spinal cord revealed that the most enriched genes during the chronic pain phase were involved in regulating axon and dendrite morphogenesis, including CDKL5. Our findings suggest that neural remodeling affects chronic pain establishment. Since patients with CDKL5 mutations have shown reduced pain perception, our findings suggest that CDKL5 in the spinal cord could result in neural remodeling during the chronic pain phase through cytoplasmic kinase activity.