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The aim of this study was to determine that low-intensity pulsed ultrasound (LIPUS) at an intensity of 140 mW/cm2 promotes functional and histologic improvements in sciatic nerve crush injury in a rat model and to investigate changes over time in relevant growth factors and receptors, exploring the mechanism of LIPUS in the recovery process after injury. Toe angle in the toe-off phase, regenerative axonal length, myelinated nerve fiber density, diameter of myelinated nerve fiber, axon diameter and myelin sheath thickness were significantly higher in the LIPUS group than in the sham group. Gene and protein expression of brain-derived neurotrophic factor (BDNF) was upregulated in the LIPUS group. In conclusion, LIPUS contributed to rapid functional and histologic improvement and upregulated BDNF expression after sciatic nerve crush injury in rats. [ABSTRACT FROM AUTHOR]

This study aimed to examine the effects of an episode of in vivo cyclic loading on rat knee articular cartilage (AC) under medium‐term observation, while also investigating relevant factors associated with the progression of post‐traumatic osteoarthritis (PTOA). Twelve‐week‐old Wistar rats underwent one episode comprising 60 cycles of 20 N or 50 N dynamic compression on the right knee joint. Spatiotemporal changes in the AC after loading were evaluated using histology and immunohistochemistry at 3 days and 1, 2, 4, and 8 weeks after loading (n = 6 for each condition). Chondrocyte vitality was assessed at 1, 3, 6, and 12 hours after loading (n = 2 for each condition). A localized AC lesion on the lateral femoral condyle was confirmed in all subjects. The surface and intermediate cartilage in the affected area degenerated after loading, but the calcified cartilage remained intact. Expression of type II collagen in the lesion cartilage was upregulated after loading, whereas the superficial lubricin layer was eroded in response to cyclic compression. However, the distribution of superficial lubricin gradually recovered to the normal level 4 weeks after loading‐induced injury. We confirmed that 60 repetitions of cyclic loading exceeding 20 N could result in cartilage damage in the rat knee. Endogenous repairs in well‐structured joints work well to rebuild protective layers on the lesion cartilage surface, which may be the latent factor delaying the progression of PTOA. [ABSTRACT FROM AUTHOR]

This study was aimed at investigating the use of ultrasound parameters obtained non-invasively through soft tissue (ST) to evaluate degeneration in cartilage and subchondral bone (SB) in the human knee. We developed a 3-D ultrasound system and introduced the ratio parameters Rcb and RcbT to suppress the attenuation effect in the ST or in both the ST and cartilage. As reference measurements, the grade for cartilage by visual judgment (Gsum) and ultrasound parameters for the cartilage and the SB were directly evaluated under arthroscopy. Rcb correlated significantly with Gsum (rs = -0.63) and with the corresponding parameter obtained directly under arthroscopy (r = 0.55). RcbT also correlated significantly with Gsum (rs = -0.46) but was not superior to Rcb. Rcb is considered to be an efficient parameter that reflects the total degeneration in both the cartilage and SB, including the information on cartilage thickness. [ABSTRACT FROM AUTHOR]

Background: Therapeutic ultrasound (US) is a promising physical therapy modality for peripheral nerve regeneration. However, it is necessary to identify the most effective US parameters and clarify the underlying mechanisms before its clinical application. The intensity of US is one of the most important parameters. However, the optimum intensity for the promotion of peripheral nerve regeneration has yet to be determined. Objectives: To identify the optimum intensity of US necessary for the promotion of peripheral nerve regeneration after crush injuries in rats and to clarify the underlying mechanisms of US by mRNA expression analysis. Methods: We inflicted sciatic nerve crush injuries on adult Lewis rats and performed ultrasound irradiation using 4 different US intensities: 0 (sham stimulation), 30, 140, and 250 mW/cm2 with frequency (5 days/week) and duration (5 min/day). We evaluated peripheral nerve regeneration by quantitative real-time PCR one week after injury. Histomorphometric analyses and motor function analysis were evaluated 3 weeks after injury. Results: US stimulation enhanced re-myelination as well as sprouting of axons, especially at an intensity of 140 mW/cm2. mRNA expression revealed that US suppressed the expression of the inflammatory cytokines TNF and IL-6 and the axonal growth inhibitors SEMA3A and GSK3β. Conclusions: An intensity of 140 mW/cm2 was optimal to support regeneration of the sciatic nerve after a crush injury in rats by, in part, the suppression of pro-inflammatory and nerve growth inhibitor gene expression. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study was to determine the effects of the lower-body positive pressure on surface blood flow during standing still and treadmill walking to explore cardiovascular safety for application to rehabilitation treatment. Thirteen healthy volunteers participated in the experiment and surface blood flows were measured in the forehead, thigh, calf, and the top of the foot during standing still and walking under various pressure conditions (0 kPa, 5 kPa, and 6.7 kPa). Results: Lower-body positive pressure decreased the blood flow in the forehead and the thigh during walking (p <.05 for each), whereas an increasing trend in blood flow was observed during standing still (p <.05). Furthermore, in the forehead and thigh, the extent of blood flow increase at the onset of walking was found to decrease in accordance with the applied pressure (p <.01 for each). These findings suggest that during walking, lower-body positive pressure modulates the blood flow, which implies safeness of this novel apparatus for use during orthopedic rehabilitation treatment. [ABSTRACT FROM AUTHOR]

Osteoporosis-related fractures are a major public health problem. Mechanobiological stimulation utilizing low-intensity pulsed ultrasound (LIPUS) is the most widely accepted modality for accelerating fracture healing. However, recent evidence has demonstrated the ineffectiveness of LIPUS, and the biophysical mechanisms of ultrasound-induced bone formation also remain elusive. Here, we demonstrate that ultrasound at a higher intensity than LIPUS effectively accelerates fracture healing in a mouse osteoporotic fracture model. Higher-intensity ultrasound promoted chondrogenesis and hypertrophic differentiation of chondrocytes in the fracture callus. Higher-intensity ultrasound also increased osteoblasts and newly formed bone in the callus, resulting in accelerated endochondral ossification during fracture healing. In addition, we found that accelerated fracture healing by ultrasound exposure was attenuated when the mechanosensitive ion channel Piezo1 was inhibited by GsMTx4. Ultrasound-induced new bone formation in the callus was attenuated in fractured mice treated with GsMTx4. Similar results were also confirmed in a 3D osteocyte-osteoblast co-culture system, where osteocytic Piezo1 knockdown attenuated the expression of osteoblastic genes after ultrasound exposure. Together these results demonstrate that higher-intensity ultrasound than clinically used LIPUS can accelerate endochondral ossification after fractures. Furthermore, our results suggest that mechanotransduction via Piezo1 mediates ultrasound-stimulated fracture healing and bone formation. • Higher-intensity ultrasound than low-intensity pulsed ultrasound accelerates fracture healing. • Higher-intensity ultrasound promotes chondrogenesis and osteogenesis in fracture callus. • Mechanosensitive ion channel Piezo1 in osteocytes senses ultrasound acoustic waves. • Piezo1 mediates ultrasound-stimulated fracture healing and bone formation. [ABSTRACT FROM AUTHOR]

Background: Although cardiopulmonary resuscitation (CPR) training is recommended in schools, there are few attempts to train all students at universities and no reports showing actual resuscitation actions at emergency settings after the training. We surveyed how many students encountered a collapsed person, whether they performed any resuscitation actions, and any reasons why they could not do any resuscitation actions.Methods: We have provided chest compression-only CPR and automated external defibrillator (AED) use training for 3000 new university students every April since 2015 and followed up on their subsequent emergency actions to collapsed persons in the real world. We carried out a questionnaire survey for 2nd through 4th-year students during the annual student health checkup period in 2018.Results: A total of 7595 students underwent the annual health checkup and 5549 of them (73.1%) responded to the survey. The rates of encountering collapsed persons and out-of-hospital cardiac arrest (OHCA) patients were 2.5 and 1.1 per 100 person-years, respectively. Of the 264 students who encountered a collapsed person, 82 (53.6%) who encountered non-OHCA collapsed persons and 54 (48.6%) who encountered OHCA persons performed at least one resuscitation action including either chest compression, AED use, or any other various resuscitation actions.Conclusions: The incidence rate of encountering OHCA patients was 1.1 per 100 person-years and half of them who encountered a collapsed person performed at least one resuscitation action. Hands-on mass training would encourage university students to perform any resuscitation actions on the emergency scene. [ABSTRACT FROM AUTHOR]

Elucidating whether there is a correlation between biomechanical functions and histomorphometric data in the rat sciatic nerve crush injury model would contribute to an accurate evaluation of the regeneration state without sacrificing animals. The gold standard for functional evaluation is the sciatic functional index (SFI) despite there being intrinsic shortcomings. Kinematic analysis is considered a reliable and sensitive approach for functional evaluation, most commonly assessed as ankle angle at various phases of a gait cycle. Studies utilizing the toe angle for functional evaluation are scarce, and changes in the toe angle following surgery remain unknown. The present study assessed correlations of ankle angle, toe angle and SFI with histomorphometric data, aiming to determine which parameters most accurately reflect changes in histomorphometric data over time. Six Lewis rats were designated as the control group. 30 animals received surgery, six of them were randomly selected on the first, second, third, fourth, and sixth week after surgery for measurements of ankle and toe angles in the “toe-off” phase, and for evaluation of SFI. Histomorphometric analysis were also performed, to determine the number of myelinated nerve fibers, diameters of myelinated nerve fibers, axon diameters, and myelin sheath thicknesses. Furthermore, we investigated changes in ankle angle, toe angle, SFI, and histomorphometric data over time, as well as correlations between ankle angle, toe angle, and SFI with histomorphometric data. The results revealed that changes in SFI, ankle angle, and toe angle highly correlate with histomorphometric data in the rat sciatic nerve crush injury model. Toe angle reflected changes in histomorphometric data with time more precisely than ankle angle or SFI did, and ankle angle was a better prognostic parameter than SFI. [ABSTRACT FROM AUTHOR]

The aim of this study was to identify ultrasound parameters reflecting subchondral porosity (Po), subchondral plate thickness (Tpl) and bone volume fraction at the trabecular bone region (BV/TVTb). Sixteen osteoarthritic human lateral femoral condyles were evaluated ex vivo using a 15-MHz pulsed-echo ultrasound 3-D scanning system. The cartilage-subchondral bone (C-B) surface region (layer 1) and inner subchondral bone region (layer 2) were analyzed; we newly introduced entropy (ENT) and correlation (COR) of ultrasound texture parameters of the parallel (x) or perpendicular (z) direction to the C-B interface for this analysis. Po, Tpl and BV/TVTb were evaluated as reference measurements using micro-computed tomography. ENTL1x (ENT of layer 1, x-direction) and ENTL1z were significantly correlated with Po (both r values = 0.58), CORL2x with Tpl (r = -0.73) and CORL2z with BV/TVTb (r = -0.66). These are efficient indicators of the characteristics of osteoarthritis-related subchondral bone; the other texture parameters were not significant. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

ABSTRACT This cross-sectional study examined the relationship of flat feet with knee pain, disability, and physical performance in patients with knee osteoarthritis (OA). Orthopedic clinic participants ( n = 95; age 61-91 years; 68.4% women) with Kellgren-Lawrence (K/L) grade ≥1 in the medial compartment underwent evaluation of navicular height and foot length for flat feet. Knee pain intensity, disability, and physical performance were evaluated using the Japanese Knee Osteoarthritis Measure, 10-m walk, timed up and go, and five-repetition chair stand tests. Of the 95 enrolled patients, 24 (25.3%) had bilateral flat feet, and significantly higher knee pain compared to patients with no flat feet (11.3 ± 8.23 points vs. 6.58 ± 6.37 points; p = 0.043). A ordinal logistic regression analysis showed that bilateral flat feet were significantly associated with increased knee pain (proportional odds ratio: 5.48, 95% confidence interval: 1.96, 15.3; p = 0.001) compared with no flat feet, adjusted for age, sex, body mass index, and tibiofemoral joint K/L grade, which is consistent across various different cutoffs of the definition of flat feet. Physical performance was similar between patients with and without bilateral flat feet. The presence of unilateral flat feet was not significantly associated with any outcome measures. These findings indicate that bilateral, but not unilateral, flat feet are associated with worse knee pain. A prospective study investigating a causal relationship between bilateral flat feet posture and knee pain as well as disability would be of particular interest to verify the potential adverse effect of altered foot posture. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2490-2498, 2017. [ABSTRACT FROM AUTHOR]

Accelerated fracture healing in patients with spinal cord injuries (SCI) is often encountered in clinical practice. However, there is no distinct evidence in the accelerated fracture healing, and the mechanisms of accelerated fracture healing in SCI are poorly understood. We aimed to determine whether SCI accelerated fracture healing in morphology and strength, to characterize the healing process with SCI, and to clarify the factors responsible for accelerated fracture healing. In total, 39 male Wistar rats were randomly divided into healthy control without intervention, SCI only, fracture with SCI, botulinum toxin (BTX) A-treated fracture with SCI, and propranolol-treated fracture with SCI groups. These rats were assessed with computed microtomography, histological, histomorphological, immunohistological, and biomechanical analyses. Both computed microtomography and histological analyses revealed the acceleration of a bony union in animals with SCI. The strength of the healed fractures after SCI recovered to the same level as that of intact bones after SCI, while the healed bones were weaker than the intact bones. Immunohistology revealed that SCI fracture healing was characterized by formation of callus with predominant intramembranous ossification and promoting endochondral ossification. The accelerated fracture healing after SCI was attenuated by BTX injection, but did not change by propranolol. We demonstrated that SCI accelerate fracture healing in both morphology and strength. The accelerated fracture healing with SCI may be due to predominant intramembranous ossification and promoting endochondral ossification. In addition, our results also suggest that muscle contraction by spasticity accelerates fracture healing after SCI. [ABSTRACT FROM AUTHOR]

We aimed to quantitatively investigate the relationship between amplitude-based pulse-echo ultrasound parameters and early degeneration of the knee articular cartilage. Twenty samples from six human femoral condyles judged as grade 0 or 1 according to International Cartilage Repair Society grading were assessed using a 15-MHz pulsed-ultrasound 3-D scanning system ex vivo. Surface roughness (Rq), average collagen content (A1) and collagen orientation (A12) in the superficial zone of the cartilage were measured via laser microscopy and Fourier transform infrared imaging spectroscopy. Multiple regression analysis with a linear mixed-effects model (LMM) revealed that a time-domain reflection coefficient at the cartilage surface (Rc) had a significant coefficient of determination with Rq and A12 (RLMMm2=0.79); however, Rc did not correlate with A1. Concerning the collagen characteristic in the superficial zone, Rc was found to be a sensitive indicator reflecting collagen disorganization, not collagen content, for the early degeneration samples. [ABSTRACT FROM AUTHOR]

We investigated the effect of low-intensity pulsed ultrasound (LIPUS) treatment combined with mesenchymal stromal cell (MSC) injection for cartilage repair and subchondral bone reconstitution for treatment of osteochondral defects. An osteochondral defect was created on both femur grooves of Wistar rats. Four weeks later, bone marrow MSCs were injected into the right knee joint. The rats were divided into two intervention groups: without or with LIPUS irradiation. Cartilage repair was evaluated histologically based on the Wakitani cartilage repair score. Subchondral bone reconstitution was evaluated as bone volume (BV)/tissue volume (TV) by micro-computed tomography analysis. MSC injection improved the cartilage repair score, and LIPUS irradiation improved BV/TV. Combination treatment promoted both cartilage repair and BV/TV improvement. Thus, MSC injection combined with LIPUS irradiation is more effective than either treatment alone in promoting concurrent cartilage repair and subchondral reconstitution. [ABSTRACT FROM AUTHOR]

An understanding of the articular cartilage degenerative process is necessary for the prevention and treatment of joint disease. The present study aimed to examine how long-term immobilization-induced cartilage degeneration is aggravated by remobilization. Sixty 8-week-old male Wistar rats were used in this study. The unilateral knee joint was immobilized using an external fixator for 8 weeks. The rats were killed at 0 and 3 days, and at 1, 2, 4 and 8 weeks after removing the fixator. After the rats were killed, the maximum knee extension angles were measured. Histological sections at the medial mid-condylar region (non-contact, transitional and contact regions of the femur and tibia) were prepared and scored. The cartilage thickness and number of chondrocytes were measured, and CD44 and Col2-3/4c expression levels were assessed immunohistochemically. The histological assessment revealed progressive aggravation of cartilage degeneration in the transitional region, with a decreased number of chondrocytes and CD44-positive chondrocytes as well as poor scoring over time, particularly in the tibia. Cyst formation was confirmed in the transitional region of the tibia at 8 weeks post-remobilization. The cartilage thickness in the transitional region was thicker than that in the contact region, particularly in the tibia. Col2-3/4c expression was observed in the non-contact and transitional regions, and the knee extension angle was recovered. In conclusion, immobilization-induced cartilage degeneration was aggravated by remobilization over time in the transitional region, followed by observations of a decreased number of chondrocytes and morphological disparity between different cartilage regions. [ABSTRACT FROM AUTHOR]

Objective. To investigate the association between knee pain during gait and 4 clinical phenotypes based on static varus alignment and varus thrust in patients with medial knee osteoarthritis (OA). Methods. Patients in an orthopedic clinic (n5266) diagnosed as having knee OA (Kellgren/Lawrence [K/L] grade ≥1) were divided into 4 phenotype groups according to the presence or absence of static varus alignment and varus thrust (dynamic varus): no varus (n5173), dynamic varus (n517), static varus (n550), and static varus1dynamic varus (n526).The knee range of motion, spatiotemporal gait parameters, visual analog scale scores for knee pain, and scores on the Japanese Knee Osteoarthritis Measure were used to assess clinical outcomes. Multiple logistic regression analyses identified the relationship between knee pain during gait and the 4 phenotypes, adjusted for possible risk factors, including age, sex, body mass index, K/L grade, and gait velocity. Results. Multiple logistic regression analysis showed that varus thrust without varus alignment was associated with knee pain during gait (odds ratio [OR] 3.30, 95% confidence interval [95% CI] 1.08-12.4), and that varus thrust combined with varus alignment was strongly associated with knee pain during gait (OR 17.1, 95% CI 3.19- 320.0). Sensitivity analyses applying alternative cutoff values for defining static varus alignment showed comparable results. Conclusion. Varus thrust with or without static varus alignment was associated with the occurrence of knee pain during gait. Tailored interventions based on individual malalignment phenotypes may improve clinical outcomes in patients with knee OA. [ABSTRACT FROM AUTHOR]

The effects of intermittent hypergravity on gait alterations and hindlimb muscle atrophy in rats induced by 2 weeks of simulated microgravity were investigated. Rats were submitted to hindlimb unloading for 2 weeks (unloading period), followed by 2 weeks of reloading (recovery period). During the unloading period, animals were subjected to the following treatments: (1) free in cages (Control); (2) continuous unloading (UL); (3) released from unloading for 1 hour per day (UL + 1G); (4) hypergravity for 1 h per day using a centrifuge for small animals (UL + 2G). The relative weights of muscles to the whole body weight and kinematics properties of hindlimbs during gait were evaluated. UL rats walked with their hindlimbs overextended, and the oscillation of their limb motion had become narrowed and forward-shifted after the unloading period, and this persisted for at least 2 weeks after the termination of unloading. However, these locomotor alterations were attenuated in rats subjected to UL + 2G centrifugation despite minor systematic changes in muscle recovery. These findings indicate hypergravity application could counteract the adverse effects of simulated or actual microgravity environments. [ABSTRACT FROM AUTHOR]

ABSTRACT To date, there have been few studies on how temperature affects the phenotype and metabolism of human chondrocytes. Thus, the purpose of this study was to elucidate the effects of culture temperature on chondrocyte redifferentiation and extracellular matrix (ECM) formation using dedifferentiated mature human chondrocytes in vitro. Dedifferentiated chondrocytes were cultured in a pellet culture system for up to 21 days. The pellets were randomly divided into three groups with different culture temperature (32, 37, and 41°C). Chondrocyte redifferentiation and ECM formation were evaluated by wet weight, messenger ribonucleic acid (mRNA), histological, and biochemical analyses. The results showed that the wet weight and the mRNA expressions of collagen type II A1 and cartilage oligomeric matrix protein at 37°C were higher than the corresponding values at 32°C. The histological and biochemical analyses revealed that the syntheses of type II collagen and proteoglycan were promoted at 37°C compared to those at 32°C, whereas they were considerably inhibited at 41°C. In conclusion, the results obtained herein indicated that temperature affects chondrocyte redifferentiation and ECM formation, and modulation of temperature might thus represent an advantageous means to regulate the phenotype and biosynthetic activity of chondrocytes. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:633-639, 2015. [ABSTRACT FROM AUTHOR]

ABSTRACT The purpose of this study was to analyze histologic, biochemical, and biomechanical differences between zonal, regional, and anatomic locations of porcine menisci. We evaluated six menisci removed from pigs. Medial and lateral menisci were divided into three regions: anterior, middle, and posterior. In each portion, the central zone (CZ) and peripheral zone (PZ) were examined histologically (hematoxylin & eosin, safranin O/Fast green, and picrosiriusred staining), using scanning electron microscopy, biochemically (hydroxyproline assay for collagen content and dimethylmethylene blue assay for glycosaminoglycan [GAG] content), and biomechanically (compression testing). Collagen content in the CZ was lower than that in the PZ. GAG content in the CZ was higher than that in the PZ. GAG content in the PZ of the posterior portion was significantly higher than that in the anterior and middle portions. Compression strength in the CZ was higher than that in the PZ. The differences in cellular phenotype, vascular penetration, and ECM not only between CZ and PZ but also among the anterior, middle, and posterior portions were clarified in the immature porcine meniscus. This result helps further our understanding of the biological characteristic of the meniscus. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1602-1611, 2014. [ABSTRACT FROM AUTHOR]

Abstract: The effect of low-intensity pulsed ultrasound (LIPUS) on articular cartilage metabolism has been characterized. However, the effect of LIPUS intensity on articular cartilage degradation factors remains unknown. This study aimed to investigate the immediate effect of LIPUS at several intensities on cultured chondrocytes treated with interleukin-1β (IL-1β) to induce an inflammatory response and on articular cartilage explants. Cultured chondrocytes and articular cartilage explants were treated by LIPUS at intensities of 0, 7.5, 30 and 120 mW/cm2 or 0, 27 and 67 mW/cm2, respectively. mRNA analysis revealed that LIPUS inhibited induction of MMP13 mRNA expression by 100 pg/mL IL-1β in cultured chondrocytes in an intensity-dependent manner. LIPUS also inhibited MMP13 and MMP1 mRNA expression in articular cartilage explants. Our results indicate that LIPUS may potentially protect articular cartilage by inhibiting MMP mRNA expression in an intensity-dependent manner and should thus be considered a useful candidate for daily treatment of OA. [Copyright &y& Elsevier]

Peripheral nerve injury (PNI) often leads to retrograde cell death in the spinal cord and dorsal root ganglia (DRG), hindering nerve regeneration and functional recovery. Repetitive magnetic stimulation (rMS) promotes nerve regeneration following PNI. Therefore, this study aimed to investigate the effects of rMS on post-injury neuronal death and nerve regeneration. Seventy-two rats underwent autologous sciatic nerve grafting and were divided into two groups: the rMS group, which received rMS and the control (CON) group, which received no treatment. Motor neuron, DRG neuron, and caspase-3 positive DRG neuron counts, as well as DRG mRNA expression analyses, were conducted at 1-, 4-, and 8-weeks post-injury. Functional and axon regeneration analyses were performed at 8-weeks post-injury. The CON group demonstrated a decreased DRG neuron count starting from 1 week post-injury, whereas the rMS group exhibited significantly higher DRG neuron counts at 1- and 4-weeks post-injury. At 8-weeks post-injury, the rMS group demonstrated a significantly greater myelinated nerve fiber density in autografted nerves. Furthermore, functional analysis showed significant improvements in latency and toe angle in the rMS group. Overall, these results suggest that rMS can prevent DRG neuron death and enhance nerve regeneration and motor function recovery after PNI., (© 2024. The Author(s).)

Early diagnosis and treatment of pre- and early-stage osteoarthritis (OA) is important. However, the cellular and cartilaginous changes occurring during these stages remain unclear. We investigated the histological and immunohistochemical changes over time between pre- and early-stage OA in a rat model of traumatic injury. Thirty-six male rats were divided into two groups, control and OA groups, based on destabilization of the medial meniscus. Histological and immunohistochemical analyses of articular cartilage were performed on days 1, 3, 7, 10, and 14 postoperatively. Cell density of proteins associated with cartilage degradation increased from postoperative day one. On postoperative day three, histological changes, including chondrocyte death, reduced matrix staining, and superficial fibrillation, were observed. Simultaneously, a compensatory increase in matrix staining was observed. The Osteoarthritis Research Society International score increased from postoperative day seven, indicating thinner cartilage. On postoperative day 10, the positive cell density decreased, whereas histological changes progressed with fissuring and matrix loss. The proteoglycan 4-positive cell density increased on postoperative day seven. These findings will help establish an experimental model and clarify the mechanism of the onset and progression of pre- and early-stage traumatic OA., (© 2024. The Author(s).)

Objective: The purpose of this study was to determine the preventive effects of treadmill exercise or physiological loading on disuse atrophy in the rat knee joint cartilage and bone during hindlimb suspension., Design: Twenty male rats were divided into 4 experimental groups, including the control, hindlimb suspension, physiological loading, and treadmill walking groups. Histological changes in the articular cartilage and bone of the tibia were histomorphometrically and immunohistochemically evaluated 4 weeks after the intervention., Results: Compared with the control group, the hindlimb suspension group showed thinning of cartilage thickness, decreased matrix staining, and decreased proportion of noncalcified layers. Cartilage thinning, decreased matrix staining, and decreased noncalcified layers were suppressed in the treadmill walking group. The physiological loading group exhibited no significant suppression of cartilage thinning or decreased noncalcified layers, but the decreased matrix staining was significantly suppressed. No significant prevention of bone mass loss or changes in subchondral bone thickness were detected after physiological loading or treadmill walking., Conclusion: Disuse atrophy of the articular cartilage caused by unloading conditions could be prevented by treadmill walking in rat knee joints., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: Although knee osteoarthritis (KOA) is a common disease, there is a lack of specific prevention and early treatment methods. Hence, this study aimed to examine the molecular changes occurring at different stages of KOA to elucidate the dynamic nature of the disease., Design: Using a low-force compression model and analyzing RNA sequencing data, we identified molecular changes in the transcriptome of knee joint cartilage, including gene expression and molecular pathways, between the cellular changes and structural damage stages of KOA progression. In addition, we validated hub genes using an external dataset., Results: Gene set enrichment analysis (GSEA) identified the following pathways to be associated with KOA: "B-cell receptor signaling pathway," "cytokine-cytokine receptor interaction," and "hematopoietic cell lineage." Expression analysis revealed 585 differentially expressed genes, with 579 downregulated and 6 upregulated genes. Enrichment and clustering analyses revealed that the main molecular clusters were involved in cell cycle regulation and immune responses. Furthermore, the hub genes Csf1r, Cxcr4, Cxcl12 , and Ptprc were related to immune responses., Conclusions: Our study provides insights into the dynamic nature of early-stage KOA and offers valuable information to support the development of effective intervention strategies to prevent the irreversible damage associated with KOA, thereby addressing a major clinical challenge., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: A nerve root anomaly, typified by a conjoined nerve root, is a rare finding. Conjoined nerve root anomalies are easily missed even in preoperative advanced imaging modalities, which can be potentially troublesome during and after surgery. In this report, we present a case of conjoined right L5-S1 nerve root in a patient with lumbar disc herniation, accompanied by spina bifida occulta, which was undiagnosed on preoperative imaging studies., Case Report: A 55-year-old Asian (Japanese) woman presented with low back pain and right leg radiating pain due to lumbar disc herniation at the right L5/S1. Physical examination revealed a positive Lasègue sign and the range of the straight leg raising test was 20° on the right side. The right patellar tendon reflex was normal; however, the right ankle jerk reflex disappeared. Although no obvious hypoesthesia was noted, mild muscle weakness (4/5) was observed in the right leg on the manual muscle test. We planned the lumbar discectomy under a microscope. During surgery, the conjoined right L5-S1 nerve root, which was compressed by herniated nucleus pulposus, was encountered. Although it was very thick and less mobile, some pieces of herniated nucleus pulposus could be removed piece by piece from the axillary part. After sequential decompressive procedures, the tightness of the conjoined right L5-S1 nerve root decreased but its mobility did not improve much. The laterality of the thickness and exit angle of the conjoined right L5-S1 nerve root was retrospectively confirmed on T2 coronal magnetic resonance images and magnetic resonance neurography. Postoperatively, right leg pain was immediately alleviated and complete improvement of muscle weakness was achieved 1 week later (5/5)., Conclusions: Magnetic resonance neurography is extremely useful for the accurate diagnosis of anomalous nerve roots because of clear visualization of the neural tissue. Discectomy under a microscope, which enables magnified three-dimensional observation of the surgical field, must provide a valid and safe procedure to achieve not only secure resection of herniated discs but also adequate exposure of anomalous nerve roots., (© 2023. The Author(s).)

Objective: Mechanical stimulation is a risk factor for knee osteoarthritis. Non-surgical compression has been used to study the effects of mechanical stimulation in vivo . However, the long-term effects of low-force compression on knee joint had not been studied. Therefore, we sought to identify the long-term effects of low-force cyclic compression on the rat knee joint., Design: In this study, we applied one session cyclic compression with a peak load of 20 ​N for 60 cycles to the rat knee joint in an approximately 140-degree flexion position (Wistar, male, 12 weeks old), followed by 1 year of observation (including data from 1 week, 2 weeks, 4 weeks, 8 weeks, 6 months, and 1 year after compression), and then performed a sub-regional analysis with hematoxylin-eosin, Safranin O and Fast Green, and MMP13 immunohistochemical staining., Results: We observed osteoarthritis-like cartilage damage, synovial inflammation, and high expression of MMP13 within 1 year after compression. However, these changes progressed slowly, with obvious matrix cracks that did not appear until 1 year after compression. In the regional analysis, we found that low-force compression caused a much slower development of injury at the compression contact site, and no significant structural cartilage damage was observed after 1 year of compression. In contrast, the non-contact site during compression at tibial cartilage in the same joint was the first to show significant structural damage., Conclusion: This study demonstrates that one session of 20 ​N cyclic compression induces a chronic osteoarthritis-like phenotype in the rat knee in the long term., (© 2022 The Authors.)

In our previous study, we developed an automatic sample injection system for pillar array columns for quantitative analysis. An autosampler was used to maintain a constant sample injection volume. However, the sample was diluted during injection using the autosampler, thus deteriorating the analytical reproducibility. In this study, we have substituted the autosampler with a syringe pump to overcome the abovementioned problem and improve the system. Sample dilution was avoided by filling the entire capillary with the sample at a constant rate. This improved system also increased the analytical reproducibility. In the previous system, the relative standard deviation (RSD) exceeded 17% of the peak height for coumarin dyes. In contrast, the improved system decreased the RSD to the range 1.2-1.8%. The analytical reproducibility was evaluated by using five types of amino acids. The RSD of each peak height was within 3.0%, confirming good reproducibility. These results indicate that the sample injection method developed in this study can be applied to biological sample analyses as a simple quantitative analysis method for pillar array columns.

It is well known that disuse affects neural systems and that joint motions become altered; however, which outcomes properly exhibit these characteristics is still unclear. The present study describes a motion analysis approach that utilizes three-dimensional (3D) reconstruction from video captures. Using this technology, disuse-evoked alterations of walking performances were observed in rodents exposed to a simulated microgravity environment by unloading their hindlimb by their tail. After 2 weeks of unloading, the rats walked on a treadmill, and their gait motions were captured with four charge-coupled device (CCD) cameras. 3D motion profiles were reconstructed and compared to those of control subjects using the image processing software. The reconstructed outcome measures successfully portrayed distinct aspects of distorted gait motion: hyperextension of the knee and ankle joints and higher position of the hip joints during the stance phase. Motion analysis is useful for several reasons. First, it enables quantitative behavioral evaluations instead of subjective observations (e.g., pass/fail in certain tasks). Second, multiple parameters can be extracted to fit specific needs once the fundamental datasets are obtained. Despite hurdles for broader application, the disadvantages of this method, including labor intensity and cost, may be alleviated by determining comprehensive measurements and experimental procedures.

Background: Before corrective surgery for idiopathic scoliosis, the stress X-rays are indispensable to collect information regarding the reducibility of deformity, deciding fusion levels, and categorizing curve types and so on. The hanging radiograph has not been conducted preoperatively so far as known. The objective of this study was to investigate retrospectively the significance of the hanging radiograph for prediction of the curve correction with surgical procedure by comparing with the side-bending and the traction radiographs., Methods: The subjects enrolled in current study were 22 cases of idiopathic scoliosis who performed posterior instrumentation and fusion by ISOLA method between 2008 and 2014. They included 2 males and 20 females, with a mean age of 16 years and 8 months. The type of curves by Lenke classification were type 1 in 20 cases, type 2 in 1 case, and type 3 in 1 case. We investigated the correction rates of main thoracic curves in side-bending, traction, and hanging positions and compared them with that after surgery. In addition, correction indices were also calculated and compared among these stress X-rays., Results: The correction rate after surgery was 65.9% that was statistically higher than those in side-bending (44.2%), traction (46.6%), and hanging (22.1%) positions. There were statistical correlations between the correction rates after surgery and in side-bending position (R=0.73) and those after surgery and in traction position (R=0.57). However, there was no statistical correlation between the correction rates after surgery and in hanging position (R=-0.01). With regard to the correction indices, that in hanging position (3.67) was statistically higher than those in side-bending (1.51) and traction (1.45) positions., Conclusions: The correction rates in side-bending and traction positions seem to be useful to estimate the amount of curve correction before surgery. Whereas, that in hanging position did not have any significance as preoperative evaluation., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://dx.doi.org/10.21037/jss-21-74). The authors have no conflicts of interest to declare., (2021 Journal of Spine Surgery. All rights reserved.)

Tendon self-renewal is a rare occurrence because of the poor vascularization of this tissue; therefore, reconstructive surgery using autologous tendon is often performed in severe injury cases. However, the post-surgery re-injury rate is relatively high, and the collection of autologous tendons leads to muscle weakness, resulting in prolonged rehabilitation. Here, we introduce an induced pluripotent stem cell (iPSC)-based technology to develop a therapeutic option for tendon injury. First, we derived tenocytes from human iPSCs by recapitulating the normal progression of step-wise narrowing fate decisions in vertebrate embryos. We used single-cell RNA sequencing to analyze the developmental trajectory of iPSC-derived tenocytes. We demonstrated that iPSC-tenocyte grafting contributed to motor function recovery after Achilles tendon injury in rats via engraftment and paracrine effects. The biomechanical strength of regenerated tendons was comparable to that of healthy tendons. We suggest that iPSC-tenocytes will provide a therapeutic option for tendon injury., (© 2021. The Author(s).)

The pathophysiology of primary osteoarthritis (OA) remains unclear. However, a specific subclassification of OA in relatively younger age groups is likely correlated with a history of articular cartilage damage and ligament avulsion. Surgical animal models of OA of the knee play an important role in understanding the onset and progression of post-traumatic OA and aid in the development of novel therapies for this disease. However, non-surgical models have been recently considered to avoid traumatic inflammation that could affect the evaluation of the intervention. In this study, an intra-articular cartilage lesion rat model induced by in vivo cyclic compressive loading was developed, which allowed researchers to (1) determine the optimal magnitude, speed, and duration of load that could cause focal cartilage damage; (2) assess post-traumatic spatiotemporal pathological changes in chondrocyte vitality; and (3) evaluate the histological expression of destructive or protective molecules that are involved in the adaptation and repair mechanisms against joint compressive loads. This report describes the experimental protocol for this novel cartilage lesion in a rat model.

Background: A vertebral fracture in a patient with diffuse idiopathic skeletal hyperostosis (DISH) is unstable due to larger moment via the long lever arm of an ankylosed spine. Therefore, surgical treatment is commonly recommended to avoid complications of nonunion and paralysis. In this report, we present 3 cases of vertebral fractures related to DISH which were primarily forced to undertake conservative treatment because of medical comorbidities and advanced age. CASE 1: A 93-year-old woman suffered from T10 vertebral fracture by a ground-level fall on her back. A trunk cast for 6 weeks was followed by brace wear for 3 months with administration of daily teriparatide. Then complete bone union was confirmed at 2 years after injury without back pain. CASE 2: An 84-year-old man suffered from T12 vertebral fracture by a fall on his back from a chair. A trunk cast for 12 weeks was followed by brace wear for 6 months with administration of daily teriparatide. Then acceptable bone union was confirmed at 1 year after the injury, and activities of daily living became independent. CASE 3: An 87-year-old woman suffered from T10 vertebral fracture due to a ground-level fall on her back when doing pruning work. Conservative treatment by trunk cast was first initiated with administration of daily teriparatide. However, delayed paralysis developed at 2 weeks after casting, so minimally invasive spinal stabilization (MISt) was performed. Bone union was obtained at 1 year after the injury without any neurological impairment., Conclusions: Favorable clinical courses have been obtained in 2 cases, whereas MISt was required for delayed paralysis in 1 case. Although surgical stabilization is the first-line treatment for vertebral fracture with DISH, conservative treatment can also be one of the options in cases with high operative risk due to serious medical comorbidities. However, during conservative treatment, cautious observation is necessary not to overlook the occurrence of paralysis., Level of Evidence: 4., Clinical Relevance: Conservative treatment for vertebral fracture with DISH can be one of the options in cases with high operative risk due to serious medical comorbidities., (This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2021 ISASS.)

The growing field of regenerative rehabilitation has great potential to improve clinical outcomes for individuals with disabilities. However, the science to elucidate the specific biological underpinnings of regenerative rehabilitation-based approaches is still in its infancy and critical questions regarding clinical translation and implementation still exist. In a recent roundtable discussion from International Consortium for Regenerative Rehabilitation stakeholders, key challenges to progress in the field were identified. The goal of this article is to summarize those discussions and to initiate a broader discussion among clinicians and scientists across the fields of regenerative medicine and rehabilitation science to ultimately progress regenerative rehabilitation from an emerging field to an established interdisciplinary one. Strategies and case studies from consortium institutions-including interdisciplinary research centers, formalized courses, degree programs, international symposia, and collaborative grants-are presented. We propose that these strategic directions have the potential to engage and train clinical practitioners and basic scientists, transform clinical practice, and, ultimately, optimize patient outcomes., (Published by Elsevier Inc.)

Compared to the Sciatic Functional Index (SFI), kinematic analysis is a more reliable and sensitive method for performing functional evaluations of sciatic nerve injury rodent models. In this protocol, we describe a novel kinematic analysis method that uses a three-dimensional (3D) motion capture apparatus for functional evaluations using a rat sciatic nerve crush injury model. First, the rat is familiarized with treadmill walking. Markers are then attached to the designated bone landmarks and the rat is made to walk on the treadmill at the desired speed. Meanwhile, the posterior limb movements of the rat are recorded using four cameras. Depending on the software used, marker tracings are created using both automatic and manual modes and the desired data are produced after subtle adjustments. This method of kinematic analysis, which uses a 3D motion capture apparatus, offers numerous advantages, including superior precision and accuracy. Many more parameters can be investigated during the comprehensive functional evaluations. This method has several shortcomings that require consideration: The system is expensive, can be complicated to operate, and may produce data deviations due to skin shifting. Nevertheless, kinematic analysis using a 3D motion capture apparatus is useful for performing functional anterior and posterior limb evaluations. In the future, this method may become increasingly useful for generating accurate assessments of various traumas and diseases.

Rodent models of sciatic nerve lesion are regularly used to assess functional deficits in nerves. Impaired locomotor functions induced by sciatic nerve lesion are currently evaluated with scoring systems despite their limitations. To overcome these shortcomings, which includes low sensitivity, little significance, and the representation of only marginal components of motion profiles, some additional metrics have been introduced. However, a quantitative determination of motion deficits is yet to be established. We used a three-dimensional motion analysis to investigate gait deficits after sciatic nerve lesion in rats. This enabled us to depict the distorted gait motion using both traditional parameters and novel readouts that are specific for the three-dimensional analysis. Our results suggest that three-dimensional motion analysis facilitates a comprehensive understanding of the gait impairment specifically, but not limited to, a sciatic lesion rat model. A broad application of these methods will improve understanding and standardized motor assessment.

Recent studies have shown that pillar array columns enable fast and quantitative analysis of amino acids. However, hydrophilic amino acids still cannot be retained on pillar array columns since they have limited retention ability. Ion-pairing liquid chromatography is a promising means of increasing analyte retention. In this study, the effects of ion-pairing reagents on the retention of eight hydrophilic amino acids (histidine, asparagine, glutamine, serine, arginine, aspartic acid, glycine, and glutamic acid) derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) under reversed-phase conditions on a conventional ODS column were studied. Among the ion-pairing reagents investigated, tetraheptylammonium bromide proved to be the most effective for increasing analyte retention. With a mobile phase consisting of 20 mM citrate buffer (pH 6.3)-acetonitrile (100:40, v/v) and 2 mM tetraheptylammonium bromide, the retention times of the eight NBD-amino acids-except NBD-arginine-were longer than 19.4 min, which was the retention time of NBD-valine when eluted without an ion-pairing reagent. As NBD-valine was well retained on pillar array columns, the chromatographic conditions may thus be applied in the analysis of hydrophilic amino acids using pillar array columns.

The surface of a material that is in contact with cells is known to affect cell morphology and function. To develop an appropriate surface for tendon engineering, we used zigzag microgroove surfaces, which are similar to the tenocyte microenvironment. The purpose of this study was to investigate the effect of microgroove surfaces with different ridge angles (RAs), ridge lengths (RLs), ridge widths (RWs), and groove widths (GWs) on human bone marrow-derived mesenchymal stem cell (MSC) shape. Dishes with microgroove surfaces were fabricated using cyclic olefin polymer by injection-compression molding. The other parameters were fixed, and effects of different RAs (180 - 30 °), RLs (5 - 500 μm), RWs (5 - 500 μm), and GWs (5 - 500 μm) were examined. Changes in the zigzag shape of the cell due to different RAs, RLs, RWs, and GWs were observed by optical microscopy and scanning electron microscopy. Cytoskeletal changes were investigated using Phalloidin immunofluorescence staining. As observed by optical microscopy, MSCs changed to a zigzag shape in response to microgroove surfaces with different ridge and groove properties. . As observed by scanning electron microscopy, the cell shape changed at turns in the microgroove surface. Phalloidin immunofluorescence staining indicated that F-actin, not only in cell filopodia but also inside the cell body, changed orientation to conform to the microgrooves. In conclusion, the use of zigzag microgroove surfaces microfabricated by injection-compression molding demonstrated the property of MSCs to alter their shapes to fit the surface.

A hypoxic environment is thought to be important for the maintenance of stemness and suppressing cell senescence, in stem cells. Therefore, a hypoxic condition is induced during cell expansion and/or induction of intended differentiation. However, the induction of these conditions requires a specially equipped hypoxia chamber and expensive gas mixtures, which are expensive and space-consuming. Owing to these restrictions, appropriate hypoxic conditions cannot be provided during cell transportation, which is increasingly required for regenerative medicine. Hence, a simple and economical culture system is required. The purpose of this study was to investigate the effects of short-term hypoxic conditions on human mesenchymal stem cell (MSC) proliferation, viability, and senescence, utilizing the CulturePal system (CulturePal-Zero and CulturePal-Five), a novel and simple hypoxic culture system with a built-in deoxidizing agent. The O2 concentration in the CulturePal-Zero was observed to reduce to <0.1% within 1 h, and to 5% within 24h in the CulturePal-Five system. Cell proliferation under these hypoxic conditions showed a sharp increase at 5% O2 concentration, and no noticeable cell death was observed even at severe hypoxic conditions (<0.1% O2) up to 72h. The p16(INK4A) (cell senescence marker) mRNA expression was retained under hypoxic conditions up to 72h, but it was up-regulated under normoxic conditions. Interestingly, the p16(INK4A) expression altered proportionately to the O2 concentration. These results indicated that the short-term hypoxic condition, at an approximate O2 concentration of 5%, would be suitable for promoting cell proliferation and repressing cell senescence, without aggravating the MSC viability. Therefore, the CulturePal systems may be suitable for providing an appropriate hypoxic condition in stem cell research and transportation.

Purpose: For successful autologous osteochondral transplantation, it is important that the cartilage in an implanted plug provide histologic replacement of damaged cartilage with cartilage that is structurally and mechanically normal. The purpose of this study was to investigate whether the press-fit technique reconstructs the normal hyaline cartilage and provides acoustic stiffness equal to that of normal intact cartilage., Methods: In 36 rabbits an osteochondral plug, 6 mm in diameter, was removed from the right patellar groove and grafted into a recipient hole, 5 mm in diameter, in the left patellar groove. Specimens at 2, 4, 8, 12, 24, and 52 weeks postoperatively were assessed by macroscopic and histologic observation and by use of an ultrasonic system. The ultrasonic acoustic stiffness, acoustic surface irregularity, and acoustic thickness of the implanted cartilage were examined and compared with normal intact cartilage., Results: The gross appearance of the implanted cartilage was glossy, maintained good surface smoothness, and survived well throughout the observation period. The cartilage recovered histologic features of hyaline cartilage. The acoustic stiffness decreased up to 12 weeks and then increased at 24 and 52 weeks after surgery. The acoustic stiffness at 8 or 12 weeks was significantly lower (acoustically softer) than that of control cartilage (P < .001). The acoustic stiffness at 52 weeks was equal to that of the control. The difference in acoustic surface irregularity was not significant. The acoustic thickness at 8 weeks was higher (acoustically thicker) than that of the control (P < .01)., Conclusions: Although the reason acoustically soft cartilage in plugs becomes acoustically stiff and whether the histology of the implanted cartilage had recovered completely remain unclear, the acoustic stiffness recovered to normal control values by 52 weeks postoperatively., Clinical Relevance: Postoperative care for up to 12 weeks should be taken after autologous osteochondral transplantation.

Objective: To compare the biomechanical stability imparted to the C1 and C2 vertebrae by either transarticular screw fixation (TSF) or screw and rod fixation (SRF) techniques in a cadaver model., Methods: Ten fresh ligamentous human cervical spine specimens were harvested from cadavers. The specimens were tested sequentially in the intact state, after injury and stabilization (unilateral left side and bilateral), and after fatiguing to 5000 cycles (0.5 Hz) at +/-1.0 N.m of flexion and extension. The specimens were stabilized by use of TSF in 5 spines or SRF in the other 5 spines. The data were converted to angular displacements, and the stabilized cases were compared with intact states for evaluating the efficacies of the two techniques in stabilizing the C1-C2 segments., Results: In the TSF group, the unilateral fixation using one screw imparted a significant stability in only the axial rotation mode. The unilateral procedure in the SRF group was effective in stabilization in all modes except in extension. The bilateral procedure in both of the groups was effective across the C1-C2 segment. However, the SRF group afforded higher stability than the corresponding TSF group in the flexion and extension modes. The degree of stability did not change after fatigue compared with the prefatigue data., Conclusion: In general, a surgeon should undertake a bilateral fixation to achieve sufficient stability across the atlantoaxial complex, and either technique will provide satisfactory results, although the SRF technique may be better in the flexion and extension modes. One should use the SRF procedure while trying to achieve stability with a unilateral system.

Purpose: To analyze the mechanical effects of autogenous osteochondral grafting procedures on articular cartilage., Methods: The intensity, duration, and interval (indexes of stiffness, surface irregularity, and thickness) of the cartilage were assessed in a porcine model using an ultrasonic measurement system. In 7 of 12 knees, 6-mm-diameter plugs were harvested from the donor knees and grafted into 5-mm recipient holes at 3 different points per knee (21 plugs). In the remaining 5 knees, 5-mm plugs were harvested and returned to their original position (28 plugs)., Results: No significant differences in the intensity, duration, and interval of the cartilage were observed with the plugs before harvesting and after grafting by the paired t test. The 3 indexes of the 6- and 5-mm plugs that were grafted correlated significantly with those before they were., Conclusions: These results suggest that osteochondral graft surgery does not affect the stiffness, surface irregularity, and thickness of the cartilage of the plugs at time zero.