Effects of wearable low-intensity continuous ultrasound on muscle biomechanical properties during delayed onset muscle soreness.

BACKGROUND: Delayed onset muscle soreness (DOMS) is one of the most prevalent musculoskeletal symptoms in individuals engaged in strenuous exercise programs. OBJECTIVE: This study investigated the effects of wearable low-intensity continuous ultrasound on muscle biomechanical properties during DOMS. METHODS: Twenty volunteers were distributed into a wearable ultrasound stimulation group (WUG) (n= 10) and medical ultrasound stimulation group (MUG) (n= 10). All subjects performed wrist extensor muscle strength exercises to induce DOMS. At the site of pain, ultrasound of frequency 3 MHz was applied for 1 h or 5 min in each subject of the WUG or MUG, respectively. Before and after ultrasound stimulation, muscle biomechanical properties (tone, stiffness, elasticity, stress relaxation time, and creep) and body temperature were measured, and pain was evaluated. RESULTS: A significant decrease was found in the tone, stiffness, stress relaxation time, and creep in both groups after ultrasound stimulation (all p< 0.05). A significant decrease in the pain and increases in temperature were observed in both groups (all p< 0.05). No significant differences were observed between the groups in most evaluations. CONCLUSION: The stiffness and pain caused by DOMS were alleviated using a wearable ultrasound stimulator. Furthermore, the effects of the wearable ultrasound stimulator were like those of a medical ultrasound stimulator.

Asymmetry of peak plantar pressure in transfemoral amputees during indoor and outdoor walking.

This study investigates the differences in peak plantar pressure between the amputated and intact limbs of transfemoral amputees when walking outdoors. Ten non-amputees (aged 24.4 ± 2.0 years, 176.9 ± 2.5 cm, 72.3 ± 7.9 kg) and six transfemoral amputees (48.5 ± 6.3 years, 173.8 ± 4.2 cm, 82.0 ± 11.9 kg) participated in the study. Over approximately 1.6 km, the participants encountered various obstacles, including stairs, uneven surfaces, hills, and level ground, both indoors and outdoors. Throughout the walking session, the peak plantar pressure in both feet was monitored using wearable insole sensors. For all terrains, the percentage asymmetry was determined. Significant changes in peak plantar pressure asymmetry were found between the intact and amputated limbs, particularly when walking on level ground indoors, uneven terrains, descending stairs, and on steep slopes outdoors (all p < 0.05). These findings highlight the greater peak plantar pressure asymmetry in transfemoral amputees when walking outside. In addition, this study revealed that not all terrains contribute uniformly to this asymmetry.

Development and validation of bioimpedance prediction equations for fat-free mass in unilateral male amputees.

BACKGROUND: Metabolic disease due to increased fat mass is observed in amputees (APTs), thereby restricting their activity. Systemic health management with periodic body composition (BC) testing is essential for healthy living. Bioelectrical impedance analysis (BIA) is a non-invasive and low-cost method to test BC; however, the APTs are classified as being exempted in the BIA. OBJECTIVE: To develop segmental estimated regression equations (sEREs) for determining the fat-free mass (FFM, kg) suitable for APTs and improve the accuracy and validity of the sERE. METHODS: Seventy-five male APTs participated in this cross-sectional study. Multiple regression analysis was performed to develop highly accurate sEREs of BIA based on independent variables derived from anthropometric measurements, dual-energy X-ray absorptiometry (DXA), and BIA parameters. The difference in validity between the predicted DXA and sum of the segmentally-predicted FFM values by sEREs (Sum_sEREs) values was evaluated using bivariate linear regression analysis and the Bland-Altman plot. RESULTS: The coefficient of determination (R2 ) and total error (TE) between DXA and Sum_sEREs were 71% and 5.4 (kg) in the cross-validation analysis. CONCLUSIONS: We confirmed the possibility of evaluating the FFM of APTs through the sEREs developed in this study. We also identified several independent variables that should be considered while developing such sEREs. Further studies are required to determine the validity of our sEREs and the most appropriate BIA frequencies for measuring FFM in APTs.

Effect of Gait Training Program with Mechanical Exoskeleton on Body Composition of Paraplegics.

PURPOSE: To identify the effect of a 52-weeks gait training program with an exoskeletal body-powered gait orthosis on the body composition of paraplegics. PATIENTS AND METHODS: Ten subjects with spinal cord injury at the thoracolumbar spine level for more than 2 years participated and were divided into exercise (n=5) and nonexercise (n=5) groups. A gait training program comprising stages 1-6 with customized exoskeletal body-powered gait orthosis was conducted for 52-weeks. A six-stage gait training program was conducted to manage the body composition and prevent obesity, and the changes in the body composition before and after the program were determined through bioelectrical impedance analysis. RESULTS: No significant changes in weight, fat-free mass (kg), lean body mass (kg), and percent fat mass (%) are seen in the exercise group before and after the 52-weeks program. However, fat-free mass (pre = 47.3± 6.5, post = 44.3 ± 5.4, kg), lean body mass (pre = 45.2 ± 6.3, post = 42.3±5.2, kg), and percent fat mass (pre = 30.1 ± 12.1, post = 40.9 ± 9.1, kg) show significant changes (p < 0.05) in the nonexercise group. In the nonexercise group, among lean body mass changes over 52-weeks in the upper limbs (-31%), trunks (-9.7%), and lower limbs (-8.6%), upper limbs exhibit the most significant decrease (p < 0.05). CONCLUSION: The gait training program with exoskeletal body-powered gait orthosis has a positive effect on fat management in the whole body and lean body mass loss in paraplegics. Furthermore, it is effective in preventing continuous muscle loss and in maintaining health by reducing body fat. Body composition measurements with bioelectrical impedance analysis for paraplegics can be applied in various clinical areas and can be combined with various arbitration methods such as rehabilitation program.

Intensive morphometric analysis of enormous alterations in skeletal bone system with micro-CT for AHNAK-/- mice.

AHNAK has been reported to be involved in actin cytoskeleton rearrangement of some cell types, calcium homeostasis, and activation of T cells. Although the functional role of AHNAK in muscle cells, epidermis, and brain has been determined, its association with apparent clinical impairment has not been found yet. During phenotypic analysis of AHNAK knock out (KO) mice for many years, we observed that AHNAK KO mice showed very slow growth. Snouts of these animals were very short, and their bones were easily broken compared to normal mice. It is known that AHNAK is closely related to calcium. However, intensive morphological studies on phenotypes of bone have yet been reported for AHNAK. Thus, the objective of the present study was to analyze the morphology of skull, mandibular, limbs, and caudal bones of AHNAK KO mice intensively using micro-CT with many factors for various ages of these mice (6 weeks, 18 weeks, and 40 weeks). As a result, it was found that the facial region of AHNAK KO mouse showed a large difference in mandible than skull. Their both femur and tibia were shortened, and bone strength was also significantly decreased compared to normal mice. Particularly, the tail bone of AHNAK KO mice exhibited morphological abnormality by age. Taken together, these results suggest that AHNAK plays an important role in bone shape, development, and metabolism. Although our results demonstrated that AHNAK has a distinct role in bone, further investigations are needed to determine various features of bone metabolism related to AHNAK in the future.

Comparison of segmental analysis and sacral marker methods for determining the center of mass during level and slope walking.

BACKGROUND: A human's center of mass (COM) is a widely used parameter in both clinical and practical applications. The segmental analysis method for determining the COM is considered the gold standard but is difficult to apply in a real environment. RESEARCH QUESTION: The purpose of this study was to confirm the efficacy of an alternative COM determination method-the sacral marker method-by comparing segmental analysis and sacral marker method results in three dimensions during level or slope walking. METHODS: Ten healthy young subjects (age = 24.0 ±â€¯4.5 yr, height = 174.5 ±â€¯5.9 cm, and weight = 66.9 ±â€¯9.4 kg) participated in the study. Each participant was monitored using a Helen Hayes full-body marker set and asked to walk on level and sloped (7°) terrain. The markers' trajectories were subsequently recorded. Each participant's COM was determined using segmental analysis and sacral marker methods via calculation and direct measurement, respectively. RESULTS: Comparative results indicated no significant differences (p > 0.05) between the segmental analysis and sacral marker method results for the COM displacement, velocity, or acceleration in the fore-aft and vertical directions. Conversely, significant differences (p < 0.05) between the two methods were observed for the COM displacement and acceleration in the medial-lateral direction, suggesting kinematic differences. SIGNIFICANCE: Based on this latter finding, caution should be exercised when determining COM kinematics using the sacral marker method.

Between-day reliability of MyotonPRO for the non-invasive measurement of muscle material properties in the lower extremities of patients with a chronic spinal cord injury.

Measuring the muscle properties of patients with spinal cord injuries (SCIs) is important to better understand their biomechanical features. In this study, we sought to evaluate the between-day reliability of MyotonPRO, a handheld device that can measure muscle mechanical properties, and assess whether it is reliable to measure muscle properties over time in patients with SCI. Thirteen men with complete SCIs (age 53.9 ±â€¯6.3 years, height 171.0 ±â€¯5.2 cm, weight 66.1 ±â€¯5.8 kg), and injury levels ranging from L1 to T12, were enrolled. Oscillation frequency; logarithmic decrement; dynamic stiffness; mechanical stress relaxation time; and creep of the biceps femoris, medial and lateral gastrocnemius, rectus femoris, tibialis anterior, and Achilles tendon were measured on consecutive days using MyotonPRO. The intraclass coefficient for most muscles and the Achilles tendon ranged from 0.53 to 0.99 for all parameters. The percentage standard error of the measurement for many parameters in most muscles and the Achilles tendon was less than 10%. Bland-Altman analysis showed a high agreement for all mechanical properties. No significant differences were observed in any muscle or Achilles tendon properties between days (all p > 0.05). These results indicate that the MyotonPRO is reliable for between-day measurements of the mechanical properties of lower limb muscles and Achilles tendon in patients with SCI.

Development of a shear force measurement dummy for seat comfort.

Seat comfort is one of the main factors that consumers consider when purchasing a car. In this study, we develop a dummy with a shear-force sensor to evaluate seat comfort. The sensor has dimensions of 25 mm × 25 mm × 26 mm and is made of S45C. Electroless nickel plating is employed to coat its surface in order to prevent corrosion and oxidation. The proposed sensor is validated using a qualified load cell and shows high accuracy and precision (measurement range: -30-30 N; sensitivity: 0.1 N; linear relationship: R = 0.999; transverse sensitivity: <1%). The dummy is manufactured in compliance with the SAE standards (SAE J826) and incorporates shear sensors into its design. We measure the shear force under four driving conditions and at five different speeds using a sedan; results showed that the shear force increases with speed under all driving conditions. In the case of acceleration and deceleration, shear force significantly changes in the lower body of the dummy. During right and left turns, it significantly changes in the upper body of the dummy.

Effects of knee sleeves on coordination of lower-limb segments in healthy adults during level walking and one-leg hopping.

The evaluation of multisegment coordination is important in gaining a better understanding of the gait and physical activities in humans. Therefore, this study aims to verify whether the use of knee sleeves affects the coordination of lower-limb segments during level walking and one-leg hopping. Eleven healthy male adults participated in this study. They were asked to walk 10 m on a level ground and perform one-leg hops with and without a knee sleeve. The segment angles and the response velocities of the thigh, shank, and foot were measured and calculated by using a motion analysis system. The phases between the segment angle and the velocity were then calculated. Moreover, the continuous relative phase (CRP) was calculated as the phase of the distal segment subtracted from the phase of the proximal segment and denoted as CRPTS (thigh-shank), CRPSF (shank-foot), and CRPTF (thigh-foot). The root mean square (RMS) values were used to evaluate the in-phase or out-of-phase states, while the standard deviation (SD) values were utilized to evaluate the variability in the stance and swing phases during level walking and in the preflight, flight, and landing phases during one-leg hopping. The walking velocity and the flight time improved when the knee sleeve was worn (p < 0.05). The segment angles of the thigh and shank also changed when the knee sleeve was worn during level walking and one-leg hopping. The RMS values of CRPTS and CRPSF in the stance phase and the RMS values of CRPSF in the preflight and landing phases changed (p < 0.05 in all cases). Moreover, the SD values of CRPTS in the landing phase and the SD values of CRPSF in the preflight and landing phases increased (p < 0.05 in all cases). These results indicated that wearing a knee sleeve caused changes in segment kinematics and coordination.

Relief of knee flexion contracture and gait improvement following adaptive training for an assist device in a transtibial amputee: A case study.

BACKGROUND: Management of a knee contracture is important for regaining gait ability in transtibial amputees. However, there has been little study of prosthesis training for enhancing mobility and improving range of motion in cases of restricted knee extension. OBJECTIVE: This study aimed to evaluate the effects of adaptive training for an assist device (ATAD) for a transtibial amputee with a knee flexion contracture (KFC). A male transtibial amputee with KFC performed 4 months of ATAD with a multidisciplinary team. During the ATAD, the passive range of motion (PROM) in the knee, amputee mobility predictor (AMP) assessment, center of pressure (COP) on a force plate-equipped treadmill, gait features determined by three-dimensional motion analysis, and Short-Form 36 Item Health Survey (SF-36) scores were evaluated. RESULTS: Following ATAD, PROM showed immediate improvement (135.6 ± 2.4° at baseline, 142.5 ± 1.7° at Step 1, 152.1 ± 1.8° at Step 2, 165.8 ± 1.9° at Step 3, and 166.0 ± 1.4° at Step 4); this was followed by an enhanced COP. Gradually, gait features also improved. Additionally, the AMP score (5 at baseline to 29 at Step 4) and K-level (K0 at baseline to K3 at Step 4) increased after ATAD. Along with these improvements, the SF-36 score also improved. CONCLUSIONS: ATAD could be beneficial for transtibial amputees by relieving knee contractures and improving gait.

Variations in gait features in elderly adults during walking considering their balance.

The aim of this study was to evaluate the influence of balance on the spatiotemporal features, lower-limb kinematics, and center of mass (COM) of the non-faller elderly during walking. In this study, 20 healthy elderly women (age, 76.2 ± 5.6 years; height, 150.1 ± 3.2 cm; weight, 55.8 ± 9.0 kg) were enrolled. Based on the Berg balance scale (BBS), the elderly were classified into two groups: poor balance (PB; BBS scores <46; n = 10; 43.8 ± 1.8) and good balance (GB; BBS scores ≥46; n = 10; 50.4 ± 2.5). The two groups had no differences in terms of the spatiotemporal features and range of motion (ROM) of the vertical COM (all p > 0.05). The ROM of the mediolateral COM was greater in PB than in GB. Hip transversal movements in the two groups were different. The impairment of the lateral balance function might contribute to an increase in the incidence of fall events in the elderly with poor balance.

Obesity Resistance and Enhanced Insulin Sensitivity in Ahnak-/- Mice Fed a High Fat Diet Are Related to Impaired Adipogenesis and Increased Energy Expenditure.

OBJECTIVE: Recent evidence has suggested that AHNAK expression is altered in obesity, although its role in adipose tissue development remains unclear. The objective of this study was to determine the molecular mechanism by which Ahnak influences adipogenesis and glucose homeostasis. DESIGN: We investigated the in vitro role of AHNAK in adipogenesis using adipose-derived mesenchymal stem cells (ADSCs) and C3H10T1/2 cells. AHNAK-KO male mice were fed a high-fat diet (HFD; 60% calories from fat) and examined for glucose and insulin tolerances, for body fat compositions, and by hyperinsulinemic-euglycemic clamping. Energy expenditures were assessed using metabolic cages and by measuring the expression levels of genes involved in thermogenesis in white or brown adipose tissues. RESULTS: Adipogenesis in ADSCs was impaired in AHNAK-KO mice. The loss of AHNAK led to decreased BMP4/SMAD1 signaling, resulting in the downregulation of key regulators of adipocyte differentiation (P<0.05). AHNAK directly interacted with SMAD1 on the Pparγ2 promoter. Concomitantly, HFD-fed AHNAK-KO mice displayed reduced hepatosteatosis and improved metabolic profiles, including improved glucose tolerance (P<0.001), enhanced insulin sensitivity (P<0.001), and increased energy expenditure (P<0.05), without undergoing alterations in food intake and physical activity. CONCLUSION: AHNAK plays a crucial role in body fat accumulation by regulating adipose tissue development via interaction with the SMAD1 protein and can be involved in metabolic homeostasis.

Evaluation of physical and emotional responses to vibrotactile stimulation of the forearm in young adults, the elderly, and transradial amputees.

Vibrotactile stimulation (VS) is widely used in the biomedical and biomechanics fields. Most studies have attempted to verify the effects and/or function of VS, but few studies have evaluated emotional response (ER) to VS, although emotions play a critical role in human behavior. This study aimed to evaluate the subjective response (SR) to VS in young, elderly, and amputee adults and to verify whether VS on the forearm evokes displeasure. Twenty-four young adults (YM: male 13, YF: female 11), 31 elderly subjects (EM: male 15, EF: female 16), and 19 transradial amputees (AM: male 11, AF: female 8) participated. Eight equally spaced vibration motors were attached around the circumference of the forearm (channels 1-4 on the lateral site and channels 5-8 on the medial site) and were located 25% of the proximal forearm. Vibration stimuli with frequencies ranging from 37Hz to 258Hz were applied. An SR 10-level test and ER (displeasure or not) test were performed. In all 3 groups, SRs to the lateral site were higher than those to the medial site (YM group, p<0.001; YF group, p=0.002; EM group, p<0.001; EF group, p=0.031; AM group, p<0.001; AF group, p=0.021). Additionally, SRs were saturated at certain frequencies (YM group, 149Hz; YF and EM groups, 198Hz; EF and AM groups, 120Hz; AF group, 176Hz). Several subjects (YM group, 7; YF group, 4; EM group, 2; EF group, 6; AM group, 3; AF group, 1) expressed displeasure, and ERs were different according to sex, age, or amputation. As a result, the lateral site was more sensitive to VS than the medial site, regardless of sex, age, or amputation. Furthermore, VS may evoke displeasure.

Effects of balance ability and handgrip height on kinematics of the gait, torso, and pelvis in elderly women using a four-wheeled walker.

AIM: Numerous elderly individuals use the four-wheeled walker (FWW) as a gait-assistive device. The walker's handgrip height is important for correct use. However, few clinical studies have investigated the biomechanical effects of the FWW's handgrip height on balance. Therefore, the present study assessed kinematic features of the gait, torso and pelvis during use of the FWW at two levels of handgrip height (48% vs 55% of the subject's height) while assessing balance in older adults. METHODS: A total of 20 older adults were allocated into two groups according to the Berg Balance Scale (BBS): good balance (GB; BBS≥46) versus poor balance (PB; BBS<45). Participants walked with the FWW at 48% or 55% handgrip height for 10 m. RESULTS: Our study showed that the double-support period and stance phase significantly increased at 55% handgrip height, but the swing phase significantly decreased in the GB group. In the PB group, velocity and stride length significantly increased at 55% handgrip height. Tilt angle of the torso in the GB group was significantly lower at 55% than at 48% handgrip height, but no differences were observed in the PB group. In the pelvis, initial contact and toe-off angles of tilt were lower in the GB group at 55% handgrip height, but no differences were observed in the PB group. CONCLUSIONS: These results showed that kinematic features of the gait, torso, and pelvis in older adults using the FWW might be dependent on the handgrip height of the FWW and the patient's balance. Additionally, greater than 48% of the body height might be appropriate for older adults with poor balance.

Development of a shear measurement sensor for measuring forces at human-machine interfaces.

Measuring shear force is crucial for investigating the pathology and treatment of pressure ulcers. In this study, we introduced a bi-axial shear transducer based on strain gauges as a new shear sensor. The sensor consisted of aluminum and polyvinyl chloride plates placed between quadrangular aluminum plates. On the middle plate, two strain gauges were placed orthogonal to one another. The shear sensor (54 mm × 54 mm × 4.1 mm), which was validated by using standard weights, displayed high accuracy and precision (measurement range, -50 to 50 N; sensitivity, 0.3N; linear relationship, R(2)=0.9625; crosstalk error, 0.635% ± 0.031%; equipment variation, 4.183). The shear force on the interface between the human body and a stand-up wheelchair was measured during sitting or standing movements, using two mats (44.8 cm × 44.8 cm per mat) that consisted of 24 shear sensors. Shear forces on the sacrum and ischium were almost five times higher (15.5 N at last posture) than those on other sites (3.5 N on average) during experiments periods. In conclusion, the proposed shear sensor may be reliable and useful for measuring the shear force on human-machine interfaces.

Assessment of forearm and plantar foot load in the elderly using a four-wheeled walker with armrest and the effect of armrest height.

BACKGROUND: Patients with hand and/or wrist pathology are recommended to have a four-wheeled walker with an arm rest (FWW-AR) rather than a standard walker or a standard four-wheeled walker (FWW). However, only a few quantitative studies have been performed to compare upper and lower extremity weight bearing. The aim of this study was to evaluate forearm and foot weight bearing using a FWW-AR and the effect of the armrest height. METHODS: Eleven elderly women (mean age 80.1±5.3 years; mean height 148.5±4.0 cm; mean weight 51.2±9.0 kg) were enrolled. The subjects walked with an FWW-AR, with the elbow in either 90 degree (D90) or 130 degree (D130) flexion, for a distance of 10 m. Surface electromyographic signals were recorded for the upper, middle, and lower trapezius, anterior deltoid, and erector spinae muscles; walking velocity was measured with the subjects weight bearing on their feet and forearms while walking. Simultaneously, the maximum plantar and forearm loads during walking with an FWW-AR were measured. RESULTS: The normalized foot plantar loads were lower at D90 than at D130, while the normalized forearm load was higher at D90 than at D130 (all P<0.05; left foot, 7.9±0.1 N/kg versus 8.8±0.1 N/kg; right foot, 8.6±0.2 N/kg versus. 9.6±0.1 N/kg; left forearm, 1.8±0.5 N/kg versus 0.8±0.2 N/kg; and right forearm, 2.0±0.5 N/kg versus 1.0±0.2 N/kg, respectively). The surface electromyographic activity of the muscles involved in shoulder elevation and the walking velocity were both lower with the elbow at D90 than at D130 (all P<0.05; left upper trapezius, 98.7%±19.5% versus 132.6%±16.9%; right upper trapezius, 83.4%±10.6% versus 108.1%±10.5%; left anterior deltoid, 94.1%±12.8% versus 158.6%±40.4%; right anterior deltoid, 99.1%±15.0% versus 151.9%±19.4%; and velocity, 0.6±0.1 m/sec versus 0.7±0.1 m/sec, respectively). CONCLUSION: Weight bearing on the lower extremities is significantly reduced when the upper extremities are supported during walking with an FWW-AR. Furthermore, the weight bearing profile is dependent on the armrest height.

Linear- and nonlinear-electromyographic analysis of supracutaneous vibration stimuli of the forearm using diverse frequencies and considering skin physiological properties.

Numerous studies have reported the efficacy of vibration in sensory feedback or substitution devices for users of myoelectric hand prostheses. Although most myoelectric hand prostheses are presently manipulated by a surface electromyogram (sEMG), only a few studies have been conducted on the effect of vibration on an sEMG. This study aimed to determine whether vibration stimulation affects the linear and nonlinear properties of surface electromyography (sEMG) considering the skin properties. The vibration stimuli, with frequencies ranging from 37 to 258 Hz, were applied to the proximal part of the arms of the eight female and seven male subjects. The skinfold thickness, hardness, and vibration threshold at the stimuli loci were measured. The root mean square (rms) and fractal dimension (DF) of the sEMG were measured at a distance of 1 cm in the upward direction from the stimuli loci. Above 223 Hz there were no differences between the rms of the genders in between the vibration stimuli (p > 0.05). Moreover, no differences were observed between the DF of the genders for any frequency (p > 0.05). Above 149 Hz, there were correlations between the rms and the skin hardness in the females. Otherwise, no correlations were observed between the rms and DF and the skin properties in both genders for most of the frequencies (all p > 0.05). These results suggest that vibration stimuli affect the linear properties of the sEMG, but not the nonlinear properties.

Bilateral asymmetry in microarchitecture of trabecular bone in male C57BL/6 mouse tibia: implication for experimental sample size estimations.

This study aimed to determine whether there is bilateral asymmetry between the left and right tibiae in the microarchitectural characteristics of the trabecular bone and estimate a moderate sample size for detections of such bilateral differences. The left and right tibiae of 20 C57BL/6 mice (12 weeks old) were scanned by micro-computed tomography, and the structural parameters of the trabecular bone were measured. There were significant differences in the structural parameters between the left and right tibiae (p<0.05); specifically, the microarchitecture was greater in quantity and quality in the left tibia than in the right tibia. Moreover, the percent of bilateral differences between the left and right tibiae ranged from 2.26% to 22.52%. For most of the structural parameters except for trabecular bone thickness (Tb.Th) and trabecular bone separation (Tb.Sp), the 20 mice involved in this study were enough to detect differences. These results show that the directional left-right asymmetry in the microarchitecture of the trabecular bone may exist despite the samples being from an inbred strain. Furthermore, we estimated a sample size for detections of such differences between the left and right tibiae.

The effects of minimally invasive laser needle system on suppression of trabecular bone loss induced by skeletal unloading.

This study was aimed to evaluate the effects of low-level laser therapy (LLLT) in the treatment of trabecular bone loss induced by skeletal unloading. Twelve mice have taken denervation operation. At 2 weeks after denervation, LLLT (wavelength, 660 nm; energy, 3 J) was applied to the right tibiae of 6 mice (LASER) for 5 days/week over 2 weeks by using a minimally invasive laser needle system (MILNS) which consists of a 100 µm optical fiber in a fine needle (diameter, 130 µm) [corrected]. Structural parameters and histograms of bone mineralization density distribution (BMDD) were obtained before LLLT and at 2 weeks after LLLT. In addition, osteocyte, osteoblast, and osteoclast populations were counted. Two weeks after LLLT, bone volume fraction, trabeculae number, and trabeculae thickness were significantly increased and trabecular separations, trabecular bone pattern factor, and structure model index were significantly decreased in LASER than SHAM (p < 0.05). BMDD in LASER was maintained while that in SHAM was shifted to lower mineralization. Osteocyte and osteoblast populations were significantly increased but osteoclast population was significantly decreased in LASER when compared with those in SHAM (p < 0.05). The results indicate that LLLT with the MILNS may enhance bone quality and bone homeostasis associated with enhancement of bone formation and suppression of bone resorption.