Chest computed tomography is a valid measure of body composition in individuals with advanced lung disease

There is growing interest in evaluating body composition using routine clinical computed tomography (CT) scans; however, the validity of this technique in lung transplant patients has not been described. The study objectives were to determine the reliability of measuring fat compartments from thoracic CT and evaluate the validity of muscle and fat cross‐sectional area (CSA) from thoracic CT by comparing to bioelectrical impedance analysis (BIA). Thoracic CT scans from lung transplant assessments were obtained for analysis. Total thoracic muscle CSA, pectoral muscle CSA, subcutaneous adipose tissue (SAT), and mediastinal adipose tissue (MAT) were manually segmented by two independent raters. Reliability was analysed using intra‐class correlation coefficient (ICC). Correlations were determined between CT measures with fat‐free mass index (FFMI), body fat mass index (BFMI) and per cent body fat (%BF) from BIA; and anthropometrics [body mass index (BMI) and waist circumference (WC)]. High inter‐ and intra‐rater reliability were found for SAT and MAT (ICCs = 0.99). Pectoral and total muscle CSA were correlated with FFMI (r = .41, p = .003 and r = .57, p < .001, respectively). SAT was associated with whole‐body fat from BIA and with BMI and WC (r = .61 to .80, p < .001). MAT was associated with BMI (r = .58, p < .001) and WC (r = .61, p < .001). This study supports the reliability and validity of using thoracic CT to measure muscle and fat. Future studies are needed to investigate whether these CT‐based measures are predictive of clinical and post‐transplant outcomes in advanced lung disease.     

Impact of blood flow‐restricted bodyweight exercise on skeletal muscle adaptations

This study ascertains the ability of bodyweight blood flow‐restricted (BFR) exercise training to promote skeletal muscle adaptations of significance for muscle accretion and metabolism. Six healthy young individuals (three males and three females) performed six weeks of bodyweight BFR training. Each session consisted of five sets of sit‐to‐stand BFR exercise to volitional failure with 30‐second inter‐set recovery. Prior to, and at least 72 h after training, muscle biopsies were taken from m. vastus lateralis to assess changes in fibre type‐specific cross‐sectional area (CSA), satellite cell (SC) and myonuclei content and capillarization, as well as mitochondrial protein expression. Furthermore, magnetic resonance imaging was used to assess changes in whole thigh muscle CSA. Finally, isometric knee extensor muscle strength was evaluated. An increase in knee extensor whole muscle CSA was observed at middle and distal localizations after training (3·2% and 3·5%, respectively) (P<0·05), and a trend was observed towards an increase in type I fibre CSA, whereas muscle strength did not increase. Additionally, the number of SCs and myonuclei associated with type I fibres increased by 65·7% and 20%, respectively (P<0·05). No significant changes were observed in measures of muscle capillarization and mitochondrial proteins. In conclusion, six weeks of bodyweight‐based BFR exercise promoted myocellular adaptations related to muscle accretion, but not metabolic properties. Moreover, the study revealed that an appropriate total training volume needs further investigation before recommending bodyweight BFR to patient populations.     

Ultrasound assessment of hamstring muscle size using posterior thigh muscle thickness

Several studies have investigated the relationship between ultrasound‐measured muscle thickness (MT) and individual muscle cross‐sectional area (CSA) and muscle volume (MV) in extremity and trunk muscles; however, the hamstring muscle has not been studied. The purpose of this study was to examine the relationship between posterior thigh MT by ultrasound and the muscle CSA and MV of the hamstring obtained by magnetic resonance imaging (MRI). Ten young women aged 20–31 had MT measured by ultrasound at three sites on the medial anterior (50% of thigh length; TL) and posterior (50% and 70% of TL) aspects of the thigh. On the same day, a series of continuous muscle CSA along the thigh was measured by MRI. In each slice, the anatomical CSA of the hamstring (biceps femoris, semitendinosus and semimembranosus) and quadriceps muscle was analysed, and the CSAs at 50% and 70% of TL and maximal CSA of the hamstring (CSA_max) were determined. MV was calculated by multiplying CSA by slice thickness. A significant correlation was observed between posterior 50% MT and 50% hamstring CSA (r = 0·848, P = 0·002) and between posterior 70% MT and 70% hamstring CSA (r = 0·679, P = 0·031). Posterior 50% MT (r = 0·732, P = 0·016) and 50% MTxTL (r = 0·873, P = 0·001) were also correlated to hamstring MV. Anterior:posterior 50% thigh MT ratio was correlated to MV ratio of quadriceps and hamstring muscles (r = 0·803, P = 0·005). Our results suggest that posterior thigh MT reflects hamstring muscle CSA and MV. The anterior:posterior MT ratio may serve as a surrogate for MV ratio of quadriceps and hamstring.     

Relationship between ultrasound muscle thickness and MRI‐measured muscle cross‐sectional area in the forearm: a pilot study

Previous studies have investigated the relationship between ultrasound‐measured muscle thickness (MT) and individual muscle cross‐sectional area (CSA); however, the forearm muscle had not yet been studied. The purpose of this study was to examine the relationship between forearm MT by ultrasound and the muscle CSA of the forearm obtained by magnetic resonance imaging (MRI). Ten young and middle‐aged adults had both ultrasound and MRI measurements at 30% the distance from the styloid process of the ulna to the head of the radius. Handgrip strength (HGS) was also measured. Strong correlations (P<0·001) were observed between MRI‐measured muscle CSA (total and flexor and extensor components) and MT‐ulna (ranged r = 0·937–0·946) and MT‐radius (ranged r = 0·884–0·891). HGS was also correlated (P<0·001) with forearm MT (MT‐ulna, r = 0·877; MT‐radius, r = 0·852) and MRI‐measured muscle CSA (flexor CSA, r = 0·910; extensor CSA, r = 0·923). Our results suggest that forearm MT is closely associated with MRI‐measured forearm muscle CSA in young and middle‐aged adults and suggest that ultrasound‐measured forearm muscle thickness may be a useful variable for evaluating muscle CSA and function in the forearm.     

Effects of detraining on muscle strength and mass after high or moderate intensity of resistance training in older adults

This study examined the effects of a 12 weeks detraining period on muscle strength and mass in older adults who had previously participated in a 12 weeks resistance training programme of high [80% of one repetition maximum (1‐RM)] or moderate (60% of 1‐RM) intensity. Twenty older adults (60–74 years), separated into a high (HI; n = 10; age: 65 ± 5 years) and a moderate (MI; n = 10; age: 66 ± 4 years) intensity resistance training group, were measured in the 1‐RM knee extension and flexion strength, and the midthigh cross sectional areas (CSAs) of quadriceps, hamstrings and total thigh before and after a 12 weeks training period as well as after a 12 weeks detraining period. Maximum knee extension and flexion strength and the CSAs of all muscles decreased significantly (P<0·05) with detraining but remained higher (P<0·05) than pretraining levels for both groups. The HI group had a greater decrement (P<0·05) in maximum strength and the CSA of total thigh compared to the MI group but strength levels and the CSA following detraining were higher (P<0·05) for the HI group. The above data suggest that after a short detraining period of 12 weeks, muscle strength and hypertrophy levels of older adults decrease but remain greater than pretraining irrespective of training intensity. Greater declines in muscle strength are observed following HI training but still muscular strength and muscle mass are retained at a higher level than with MI probably due to the higher gains achieved during the training period.     

Effects of rest intervals and training loads on metabolic stress and muscle hypertrophy

We investigated the effects of volume‐matched resistance training (RT) with different training loads and rest intervals on acute responses and long‐term muscle and strength gains. Ten subjects trained with short rest (30 s) combined with low load (20 RM) (SL) and ten subjects performed the same protocol with long rest (3 min) and high load (8 RM) (LH). Cross‐sectional area (CSA) of the upper arm was measured by magnetic resonance imaging before and after 8 weeks of training. Acute stress markers such as growth hormone (GH) and muscle thickness (MT) changes have been assessed pre and post a single RT session. Only the SL group demonstrated significant increases in GH (7704·20 ± 11833·49%, P<0·05) and MT (35·2 ± 16·9%, P<0·05) immediately after training. After 8 weeks, the arm CSA s in both groups significantly increased [SL: 9·93 ± 4·86% (P<0·001), LH: 4·73 ± 3·01% (P<0·05)]. No significant correlation between acute GH elevations and CSA increases could be observed. We conclude that short rest combined with low‐load training might induce a high amount of metabolic stress ultimately leading to improved muscle hypertrophy while long rest with high‐load training might lead to superior strength increases. Acute GH increases seem not to be directly correlated with muscle hypertrophy.     

Effect of very low‐intensity resistance training with slow movement on muscle size and strength in healthy older adults

We previously reported that low‐intensity [50% of one repetition maximum (1RM)] resistance training with slow movement and tonic force generation (LST) causes muscle hypertrophy and strength gain in older participants. The aim of this study was to determine whether resistance training with slow movement and much more reduced intensity (30%1RM) increases muscle size and strength in older adults. Eighteen participants (60–77 years) were randomly assigned to two groups. One group performed very low‐intensity (30% 1RM) knee extension exercise with continuous muscle contraction (LST: 3‐s eccentric, 3‐s concentric, and 1‐s isometric actions with no rest between each repetition) twice a week for 12 weeks. The other group underwent intermitted muscle contraction (CON: 1‐s concentric and 1‐s eccentric actions with 1‐s rest between each repetition) for the same time period. The 1RM, isometric and isokinetic strengths, and cross‐sectional image of the mid‐thigh obtained by magnetic resonance imaging were examined before and after the intervention. LST significantly increased the cross‐sectional area of the quadriceps muscle (5·0%, P<0·001) and isometric and isokinetic knee extension strengths (P<0·05). CON failed to increase muscle size (1·1%, P = 0·12), but significantly improved its strength (P<0·05). These results indicate that even if the intensity is as low as 30% 1RM, LST can increase muscle size and strength in healthy older adults. The large total contraction time may be related to muscle hypertrophy and strength gain. LST would be useful for preventing sarcopenia in older individuals.     

MR IDEAL-IQ脂肪定量技术评价进行性假肥大性肌营养不良患儿骨骼肌脂肪浸润程度

目的 采用MR基于最小二乘估算法和不对称回波迭代分解的水脂分离(IDEAL-IQ)脂肪定量技术评估进行性假肥大性肌营养不良(DMD)患儿臀部及大腿骨骼肌脂肪浸润程度,观察脂肪分数(FF)与临床资料的相关性.方法 纳入89例经病理学和/或基因检测确诊的DMD患儿,记录其臀部及双侧大腿MR T1WI及IDEAL-IQ数据....     

Estimation of muscle atrophy based on muscle thickness in knee surgery patients

The purpose of this study was to establish an accurate estimation of muscle atrophy in the quadriceps femoris (QF) muscle group. Eighteen individuals who underwent meniscectomy participated in the study (nine men and nine women, mean age 44·4 years). Both operated and non‐operated thighs were scanned by magnetic resonance imaging to determine the volume and thickness of the QF muscle group. Muscle volume was estimated using eleven axial images, and muscle thickness was measured at the anterior, lateral and medial regions of the proximal, mid‐ and distal thigh, respectively. A stepwise linear regression analysis was performed to obtain the relationship between the difference in muscle volume and the difference in muscle thickness between operated and non‐operated limbs. There was no significant difference in muscle volume of the QF between operated (806·6 ± 220·0 cm³) and non‐operated (913·7 ± 241·5 cm³) limbs. Based on the stepwise linear regression analysis, the difference in muscle volume was significantly correlated with the difference in muscle thickness at the anterior proximal thigh and lateral mid‐thigh and anterior mid‐thigh (R = 0·93, P<0·01). In conclusion, the difference in muscle volume between operated and non‐operated limbs can be estimated accurately by measuring muscle thickness of the QF at three sites: the anterior proximal thigh, the lateral mid‐thigh and anterior mid‐thigh. Muscle thickness can be measured easily using imaging techniques such as ultrasonography. We propose that this method provides an easy and accurate estimate of knee surgery‐induced muscle atrophy in clinical medicine.     

Atrophy of individual thigh muscles measured by MRI in older adults with knee osteoarthritis: A cross-sectional study

BackgroundThe characteristics of thigh-muscle cross-sectional area (CSA) in older adults with knee osteoarthritis (KOA) remain controversial.ObjectivesThis study aimed to evaluate atrophy of individual thigh muscles in older adults with KOA and to determine which muscle CSA should be measured to detect KOA-related muscle atrophy of the thigh.MethodsIn older adults, individual thigh-muscle CSA measured by 1.5 Tesla MRI was analyzed at 5% intervals of the femoral length (FL) around the mid-thigh between the proximal 25% of the FL and the distal 25%. Participants with KOA grade ≤ 1 and grade ≥ 2 were compared for ratios of quadriceps muscle (QM) CSA to total thigh, individual QM CSA to QM, and individual hamstring (HAM) CSA to HAM at 5% intervals.ResultsWe included 40 older adults [20 males; mean (SD) age 73.3 (4.7) years; 20 with KOA grade ≤ 1 and 20 with KOA grade ≥ 2]. The ratio of vastus medialis (VM) CSA to QM from the proximal 25% to distal 15% and the ratio of semi-membranosus (SM) CSA to HAM at the distal 10% to 25% were significantly lower with KOA grade ≥ 2 than grade ≤ 1; the effect sizes were 0.34 to 0.67 for VM and 0.40 to 0.60 for SM. The effect sizes were greatest for the ratios of VM CSA to QM at the mid-thigh with 5% intervals and the ratio of SM CSA to HAM at the distal 25%.ConclusionsThe ratio of VM CSA to QM and/or that of SM CSA to HAM were low and were the best indicators to detect KOA-related muscle atrophy of the thigh. However, to detect KOA-related muscle atrophy, the VM CSA ratio should be analyzed in the thigh region around the mid-thigh, whereas the SM CSA ratio should be analyzed in the thigh region at the muscle belly.     

Inflammation marker,damage marker and anabolic hormone responses to resistance training with vascular restriction in older males

The goal of this study was to examine anabolic hormone, muscle damage marker and inflammation marker responses to two types of resistance training protocols in older men. Thirty‐six healthy older males (mean age = 56·6 ± 0·6 years) completed 6 weeks of high‐intensity resistance training (HI‐RT), low‐intensity resistance training with vascular restriction (LI‐BFR) or no exercise control group (CON) three times per week. Three upper body exercises were performed by both exercise groups at the same intensity (at 80% 1‐RM), but lower body exercises were performed by the HI‐RT group at 80% 1‐RM and by the LI‐BFR group at 20% 1‐RM with vascular restriction. Resting serum creatine kinase (CK), interleukin 6 (IL‐6), insulin‐like growth factor‐I (IGF‐I), IGF binding protein 3 (IGFBP‐3) and testosterone (T) were measured before and after training. No significant group differences in resting CK, IL‐6, IGF‐I, IGFBP‐3 and T were detected following training (P>0·05). In addition, there were no significant changes in muscle cross‐sectional area (CSA), but a trend for significant decreases in the percent changes in thigh subcutaneous fat (P = 0·051). Although training‐induced anabolic hormone response did not reach statistical significance, our findings on CK and IL‐6 indicated that the LI‐BFR training protocol was safe and well tolerated for older men to perform to improve muscular strength.     

Effect of self‐administered stretching on NIRS‐measured oxygenation dynamics

This study determined human skeletal muscle oxygenation dynamics during and after a single bout of self‐administered stretching (SAS) of the plantar flexors. Nine healthy recreationally fit men (n = 7; age = 25·7 years) and women (n = 2; age = 23·5 years) performed two protocols: (i) one bout of SAS for 4 min and (ii) one bout of moderate intensity cycling for 4 min. We used near infrared spectroscopy to measure changes in muscle deoxygenated haemoglobin–myoglobin ([HHb]) and blood volume ([Hb_tot]) of gastrocnemius medialis muscle before, during and after stretching. The SAS caused an increase (P<0·05) in [HHb] during stretching between 60 and 240 s relative to baseline, but not at 30 s. No significant difference was found for [Hb_tot] at any time interval during SAS. Furthermore, the increase in local blood flow (suggested by [Hb_tot] changes) was found to be significantly increased relative to baseline at 1, 5 and 10 min after SAS, thus providing novel evidence for a poststretch hyperaemia. No significant interaction for [HHb] was found between stretching and cycling conditions, suggesting that the metabolic disturbance during stretching closely resembles moderate intensity exercise. These findings suggest that a single self‐administered stretch for 60 s can produce a substantial microcirculatory event and that blood flow may be enhanced for up to 10 min after stretching.     

Local architecture of the vastus intermedius is a better predictor of knee extension force than that of the other quadriceps femoris muscle heads

The purpose of this study was to determine whether the muscle architecture of each head of the quadriceps femoris (QF) at multiple regions can be used to predict knee extension force. Muscle thickness and pennation angle were measured using sonographic images from multiple regions on each muscle of the QF with the knee flexed to 90°. The fascicle lengths of the rectus femoris (RF), vastus lateralis (VL) and vastus intermedius (VI) muscles were estimated based on sonographic images taken along the length of the thigh. The muscle architecture of the vastus intermedius was determined in two separate locations using sonographic images of the anterior (ant‐VI) and lateral portions (lat‐VI). The maximal voluntary contraction (MVC) was measured during isometric knee extension at a knee joint angle of 90°. The relationship between MVC force and muscle architecture was examined using a stepwise linear regression analysis with MVC force as the dependent variable. The muscle thickness of the ant‐VI was selected as an independent variable in the first step of the linear regression analysis (R² = 0·66, P<0·01). In the second step, pennation angle of the lat‐VI was added to the model (R² = 0·91, P<0·01). These results suggest that among the four muscles that make up the QF, the muscle architecture of the VI is the best predictor of knee extension force.     

Reproducibility of contractile properties of the human paralysed and non‐paralysed quadriceps muscle

This study assessed the reproducibility of electrically evoked, isometric quadriceps contractile properties in eight people with spinal cord injury (SCI) and eight able‐bodied (AB) individuals. Over all, the pooled coefficients of variation (CV_ps) in the SCI group were significantly lower (ranging from 0·03 to 0·15) than in the AB group (ranging from 0·08 to 0·21) (P<0·05). Furthermore, in all subjects, the variability of force production increased as stimulation frequency decreased (P<0·01). In subjects with SCI, variables of contractile speed are clearly less reproducible than tetanic tension or resistance to fatigue. Contractile properties of quadriceps muscles of SCI subjects were significantly different from that of AB subjects. Muscles of people with SCI were less fatigue resistant (P<0·05) and produced force–frequency relationships that were shifted to the left, compared with AB controls (P<·01). In addition, fusion of force responses resulting from 10 Hz stimulation was reduced (P<·05) and speed of contraction (but not relaxation) was increased (P<0·05), indicating an increased contractile speed in paralysed muscles compared with non‐paralysed muscles. These results correspond with an expected predominance of fast glycolytic muscle fibres in paralysed muscles. It is concluded that quadriceps dynamometry is a useful technique to study muscle function in non‐paralysed as well as in paralysed muscles. Furthermore, these techniques can be reliably used, for example, to assess therapeutic interventions on paralysed muscles provided that expected differences in relative tetanic tension and fatigue resistance are larger than ～5% and differences in contractile speed are larger than ～15%.     

A new vessel segmentation algorithm for robust blood flow quantification from two‐dimensional phase‐contrast magnetic resonance images

Blood flow measurements in the ascending aorta and pulmonary artery from phase‐contrast magnetic resonance images require accurate time‐resolved vessel segmentation over the cardiac cycle. Current semi‐automatic segmentation methods often involve time‐consuming manual correction, relying on user experience for accurate results. The purpose of this study was to develop a semi‐automatic vessel segmentation algorithm with shape constraints based on manual vessel delineations for robust segmentation of the ascending aorta and pulmonary artery, to evaluate the proposed method in healthy volunteers and patients with heart failure and congenital heart disease, to validate the method in a pulsatile flow phantom experiment, and to make the method freely available for research purposes. Algorithm shape constraints were extracted from manual reference delineations of the ascending aorta (n = 20) and pulmonary artery (n = 20) and were included in a semi‐automatic segmentation method only requiring manual delineation in one image. Bias and variability (bias ± SD) for flow volume of the proposed algorithm versus manual reference delineations were 0·0 ± 1·9 ml in the ascending aorta (n = 151; seven healthy volunteers; 144 heart failure patients) and ?1·7 ± 2·9 ml in the pulmonary artery (n = 40; 25 healthy volunteers; 15 patients with atrial septal defect). Interobserver bias and variability were lower (P = 0·008) for the proposed semi‐automatic method (?0·1 ± 0·9 ml) compared to manual reference delineations (1·5 ± 5·1 ml). Phantom validation showed good agreement between the proposed method and timer‐and‐beaker flow volumes (0·4 ± 2·7 ml). In conclusion, the proposed semi‐automatic vessel segmentation algorithm can be used for efficient analysis of flow and shunt volumes in the aorta and pulmonary artery.     

Ultrasound measurements of carotid intima–media thickness by two semi‐automated analysis systems

Increased carotid intima–media thickness (cIMT) is associated with an increased risk of cardiac events and stroke. Several semi‐automated edge‐detection techniques for measuring cIMT are used for research and in clinical practice. Our aim was to compare two currently available semi‐automated techniques for the measurement of cIMT. Carotid ultrasound recordings were obtained from 99 subjects (mean age 54·4 ± 8·9 years, range 33–69) without known cardiovascular diseases using a General Electric (GE) Vivid 7 ultrasound scanner, 8‐MHz transducer. The far‐wall cIMT was evaluated 1–2 cm proximal to the carotid bulb. Three diastolic images (ECG R‐wave) from the left and three images from the right common carotid arteries were analysed using GE and Artery Measurement System (AMS) semi‐automated softwares. Mean systolic and diastolic blood pressures were 120 ± 13 and 76 ± 8 mmHg, respectively. The cIMT_mean (left + right)/2 by GE and cIMT_mean (left + right)/2 AMS were highly correlated (r = 0·92, P<0·001). Higher values were measured by GE (0·72 ± 0·12 mm) compared with AMS (0·69 ± 0·12 mm), and this was significant (P<0·001). The coefficients of variation for the intra‐observer variability of cIMT_mean (left + right)/2 were 1·0% (GE) and 2·2% (AMS). cIMT_mean measured by GE's semi‐automated edge‐detection method correlated well with that measured by AMS. However, there were small but significant systematic differences between the cIMT_mean values measured by the two techniques. Thus, the use of only one type of measurement program seems favourable in follow‐up studies and when evaluating treatment effects.     

Thigh composition in young and elderly men determined by computed tomography

Summary. Computed tomography (CT) was used to quantify components of the thigh in young (n= 13) and elderly (n= 11) men. Cross-sectional areas (CSA) of the total limb, total muscle plus bone, quadriceps compartment, hamstring compartment and bone were measured at each of five scan sites along the length of the thigh. Non-muscle tissue (NMT) areas within the muscle compartments were measured using changes in density based on Hounsfield units. Skin plus subcutaneous fat areas and quadriceps and hamstring lean muscle areas were calculated by subtraction. Geometric formulae were used to calculate related volumes for each thigh component. Volumes were also predicted from regression equations employing thigh length and component CSA from single mid-limb CT scans. The results showed that while total thigh CSA was not different in elderly men, they had significantly smaller total muscle plus bone (13-0%), and quadriceps (26.4%), and hamstring (17.9%) muscle areas. The elderly men also had significantly greater CSA for skin plus subcutaneous fat (37-6%), and for NMT in the quadriceps (59.4%) and hamstring (127.3%) muscle compartments. These results suggest that comparisons of relative leg muscle strength between young and elderly men may be misleading due to the decrease in actual muscle tissue associated with ageing. Appropriate quantification of muscle size and CSA must be carried out before such comparisons can be meaningful.     

Texture analysis of ultrasound images is a sensitive method to follow‐up muscle damage induced by eccentric exercise

The grey level of co‐occurrence matrix (GLCM) is a texture analysis approach accounting for spatial distribution of the pixels from an image and can be a promising method for exercise‐induced muscle damage (EIMD) studies. We followed up the time changes of two GLCM texture parameters and echo intensity (EI) on ultrasound images after eccentric contractions. Thirteen untrained women performed two sets of ten elbow flexions eccentric contractions. Ultrasound images were acquired at baseline and 24 h, 48 h, 72 h and 96 h after exercise. Two GLCM texture parameters were calculated for the brachialis muscle: contrast (CON) and correlation (COR). Peak torque, EI, muscle thickness (MT) and soreness were measured. The peak torque and soreness decreased immediately after the intervention in comparison with all the measures. MT increased immediately after the intervention remaining for 72 h (P<0·05). Significant increases (P<0·05) were observed for COR (48, 72 and 96 h) and EI only at 72 and 96 h. The increasing COR represents high similarity between grey levels, which could be observed on US images after few days on eccentric training for elbow flexors.     

Effects of hydrostatic pressure and deviatoric stress on human articular chondrocytes for designing neo‐cartilage construct

Autologous chondrocyte implantation is a promising therapy for the treatment of the articular cartilage defects. Recently, we have developed a three‐dimensional chondrocyte construct manufactured with a collagen gel/sponge scaffold and cyclic hydrostatic pressure. However, the roles of various mechanical stresses, specifically hydrostatic pressure and deviatoric stress, as well as poststress loading, were unclear on metabolic function in chondrocytes. We hypothesized that hydrostatic pressure and deviatoric stresses each alter individual metabolic characteristics of chondrocytes. We embedded human articular chondrocytes within an agarose hydrogel and applied hydrostatic pressure and/or deviatoric stress individually or simultaneously for 4 days. Subsequently, we kept the cell constructs without stress for an additional 3 days. With hydrostatic pressure and/or deviatoric stress, more cells proliferated significantly than no stress (p < .05) and more cells proliferated near the inner side of the construct than the outer (p < .05). Cartilage specific aggrecan core protein and collagen type II were upregulated significantly after off‐loading hydrostatic pressure alone at Day 7 (p < .05). On the other hand, these molecules were upregulated significantly immediately after deviatoric stress alone and combined with hydrostatic pressure at Day 4 (p < .05). Tissue inhibitor of metalloproteinase‐2 was upregulated significantly after off‐loading hydrostatic pressure alone and combined deviatoric stress at Day 7 (p < .05). Metalloproteinnase‐13 was upregulated significantly with deviatoric stress at Day 4 (p < .05) and combined with hydrostatic pressure at Day 4. These results suggest that metabolic functions are regulated by the combination of hydrostatic pressure and deviatoric stress and by the timing of stress loading.     

Exercise induced effects on muscle function and range of motion in patients with hip osteoarthritis

Background and purpose

Patients with hip osteoarthritis have impairments in muscle function (muscle strength and power) and hip range of motion (ROM), and it is commonly believed that effective clinical management of osteoarthritis should address these impairments to reduce pain and disability. Therefore, the purpose of this study was to compare the short‐ and long‐term effects of 4 months of physiotherapist‐supervised strength training, physiotherapist‐supervised Nordic Walking (NW), or unsupervised home‐based exercise (HBE) on muscle function and hip ROM in patients diagnosed with hip osteoarthritis.

Methods

Secondary outcome analyses from an observer‐blinded three‐armed parallel‐design randomized controlled trial in 60+‐year‐old patients with clinical hip osteoarthritis (American College of Rheumatology criteria) who were not on a waiting list for hip replacement. One hundred and fifty‐two patients were randomized to either 4 months of physiotherapist‐supervised, moderate, progressive, strength training (n = 50), physiotherapist‐supervised NW (n = 50), or unsupervised HBE (n = 52). Maximal isometric hip and thigh muscle strength and leg extensor power and active hip ROM were assessed at baseline 2, 4, and 12 months.

Results

Intention‐to‐treat‐analyses did not show any significant between‐group differences for improvements in muscle strength and power or ROM at any time points. Short‐term significant (p < .05) increases in muscle strength were present in the physiotherapist‐supervised exercise groups and in the long‐term for muscle power in the NW‐group. All exercise modes resulted in significant increases of ROM but long‐term improvements were only shown for NW and HBE.

Discussion

Four months of physiotherapist‐supervised, progressive, moderate, and strength training was less effective than hypothesized for improving muscle strength and power in patients with hip osteoarthritis who are not awaiting hip replacement. Our results may indicate that in these patients, improvements in disability are not necessarily dependent on improvements in strength and power or ROM.