Suguru Torii

Inconsistent knee varus moment reduction caused by a lateral wedge in knee osteoarthritis

Kakihana W, Akai M, Nakazawa K, Naito K, Torii S: Inconsistent knee varus moment reduction caused by a lateral wedge in knee osteoarthritis. Am J Phys Med Rehabil 2007;86:446–454. Objective:To determine—with the assistance of a larger sample size—whether the inconsistency of reducing the knee-joint varus moment with a lateral wedge in patients with medial compartment knee osteoarthritis (OA) persists and if so, what underlying mechanisms may explain it. Design:Crossover design whereby 51 patients with bilateral isolated medial compartment knee OA and 19 age-matched healthy controls walked with two different wedge conditions: a 0-degree control wedge and a 6-degree lateral wedge. We conducted three-dimensional motion analysis, hip–knee–ankle (HKA) angle measurement, and radiologic assessment with Kellgren–Lawrence grade. We investigated frontal plane angles and moments at the knee and subtalar joints, ground reaction forces, and center of pressure (CoP). Moments were derived using a three-dimensional inverse dynamics model of the lower extremity. Results:Nine patients (17.6%) had an increased knee-joint varus moment with the 6-degree lateral wedge via the medially shifted location of the CoP. These patients did not differ from the remaining patients in HKA angle and radiologic assessment. Conclusion:In approximately 18% of patients with bilateral medial compartment knee OA, the 6-degree lateral wedge seems to fail to reduce the knee-joint varus moment. The indication and limitations of lateral wedge should be confirmed by a randomized controlled study.

Non-uniform changes in magnetic resonance measurements of the semitendinosus muscle following intensive eccentric exercise

This study was designed to determine the regional differences of magnetic resonance (MR) measurements in the hamstrings [biceps femoris muscle long head (BFl) and short head (BFs), semimembranosus muscle (SM), and semitendinosus muscle (ST)] following eccentric knee-flexion exercise. Twelve male volunteers performed eccentric knee-flexion exercise. Maximum isometric torque, plasma creatine kinase (CK) activity, muscle soreness, and MR images of the hamstrings were measured before and immediately following exercise, and on the first, second, third and seventh days following the exercise. Cross-sectional areas (CSAs) and transverse relaxation times (T2s) of the hamstrings were measured from the T2-weightened MR imaging sequences of 30% (proximal), 50% (middle), and 70% (distal) areas of the thigh length. The CSA of the ST at proximal and middle regions had significantly increased on the third day, but no significant changes were found for the BFl or SM. Immediately following exercise, T2 values had increased significantly in the BFs, BFl, and ST. On the third day, T2 values of only ST increased significantly at proximal, middle and distal regions. Significant differences of T2 values between proximal and distal regions in the ST were found for the second, third and seventh days following the exercise. These results suggest that because of the anatomical characteristics of the muscles, the degrees of response following the exercise differed among the muscles and the regions of ST muscle.

Association between in vivo knee kinematics during gait and the severity of knee osteoarthritis

BACKGROUND Osteoarthritis patients may exhibit different kinematics according to the disease stage. However, changes in the frontal and horizontal planes in each stage remain unclear. The purpose of this study was to investigate changes in the knee kinematic gait variables of osteoarthritis patients, including the frontal and horizontal planes, with respect to the severity of the disease. METHODS Forty-five patients with knee osteoarthritis and 13 healthy young subjects were recruited for the experiment. All subjects were examined while walking on a 10-m walkway at a self-selected speed. In each trial, we calculated the angular displacements of flexion/extension, abduction/adduction, and external/internal tibial rotation. We also measured muscle strength, range of motion (ROM), and alignment. We compared the differences in osteoarthritis severity and knee kinematic variables between osteoarthritis patients and normal subjects. RESULTS The flexion angle at the time of foot contact was significantly less in patients with severe and moderate osteoarthritis than in normal subjects (both p<0.01). The abduction angle at the 50% stance phase was significantly less in patients with severe osteoarthritis than in normal subjects (p<0.05). The excursion of axial tibial rotation was significantly less in patients with early osteoarthritis than in normal subjects (p<0.05). CONCLUSION Osteoarthritis patients had different knee kinematics during gait, depending on the progress of osteoarthritis. Early-stage patients exhibit decreased axial tibial rotation excursion, while severe-stage patient exhibit increased knee adduction.

Effect of a lateral wedge on joint moments during gait in subjects with recurrent ankle sprain.

Kakihana W, Torii S, Akai M, Nakazawa K, Fukano M; Naito K: Effect of a lateral wedge on joint moments during gait in subjects with recurrent ankle sprain. Am J Phys Med Rehabil 2005;84:858-864. This study assessed the biomechanic effects of wearing a lateral wedge on the subtalar joint moment during gait in athletes with and without an unstable lateral ankle. A crossover design was applied whereby 50 collegiate males walked with two different wedges: a 0° control wedge and a 6° lateral wedge. We investigated frontal plane angles and moments at the subtalar joint and the knee joint, as well as ground reaction forces and center of pressure excursion. Moments were derived using a three-dimensional inverse dynamics model of the lower extremity. The 6° lateral wedge significantly increased the subtalar joint valgus moment (P < 0.001) and reduced the knee joint varus moment (P < 0.001) when compared with no wedge. The differences between wedge conditions were associated with a laterally shifted location of the center of pressure during stance phase. However, there were diverse, sometimes reversed effects with the wedge among the athletes with an unstable lateral ankle. These results indicate that biomechanical indications and limitations of lateral wedges in unstable lateral ankles should be analyzed in more detail, possibly leading to new guidelines for the use of such foot orthoses.

Differential gene expression of muscle-specific ubiquitin ligase MAFbx/Atrogin-1 and MuRF1 in response to immobilization-induced atrophy of slow-twitch and fast-twitch muscles.

We examined muscle-specific ubiquitin ligases MAFbx/Atrogin-1 and MuRF1 gene expression resulting from immobilization-induced skeletal muscle atrophy of slow-twitch soleus and fast-twitch plantaris muscles. Male C57BL/6 mice were subjected to hindlimb immobilization, which induced similar percentage decreases in muscle mass in the soleus and plantaris muscles. Expression of MAFbx/Atrogin-1 and MuRF1 was significantly greater in the plantaris muscle than in the soleus muscle during the early stage of atrophy. After a 3-day period of atrophy, total FOXO3a protein level had increased in both muscles, while phosphorylated FOXO3a protein had decreased in the plantaris muscle, but not in the soleus muscle. PGC-1α protein expression did not change following immobilization in both muscles, but basal PGC-1α protein in the soleus was markedly higher than that in plantaris muscles. These data suggest that although soleus and plantaris muscles atrophied to a similar extent and that muscle-specific ubiquitin protein ligases (E3) may contribute more to the atrophy of fast-twitch muscle than to that of slow-twitch muscle during immobilization.

Anticipatory modulation of neck muscle reflex responses induced by mechanical perturbations of the human forehead.

The aim of this study was to test whether anticipation of upcoming head blow stimuli, which elicit reflex responses in the neck muscle, makes the reflex responses greater or not. In nine healthy subjects the reflex responses were elicited in the sternocleidomastoid (SCM) muscle in the eyes-open (EO) and eyes-closed (EC) conditions, which corresponded to the predictable and unpredictable conditions, respectively. The subjects were instructed not to resist the perturbations after the impact. The results demonstrated that the reflex response of the SCM muscle was significantly smaller in the predictable EO condition than in the unpredictable EC condition (P < 0.05), although no significant differences were observed in either the background EMG activities or the head accelerations. Further, this effect of anticipation was observed only in the later reflex EMG component, which most probably mediated the stretch reflex pathway. In contrast, no significant difference was observed in the early component, which was presumed to be the vestibular-collic reflex. The reduced stretch reflex response was suggested to be functionally relevant to the task requirement, i.e., to let the neck extension movement occur, and not to resist after the impact of the head blow. It was concluded that the anticipation has an effect on reducing the stretch reflex responses in the neck muscle, but does not have any effect on the presumed vestibular-collic reflex under the present experimental paradigm. It is suggested that the gain of the stretch reflex pathway is modulated by anticipatory information of upcoming mechanical event.

Prediction and validation of total and regional skeletal muscle volume using B-mode ultrasonography in Japanese prepubertal children

Very few effective field methods are available for accurate, non-invasive estimation of skeletal muscle volume (SMV) and mass in children. We aimed to develop regression-based prediction equations for SMV, using ultrasonography, in Japanese prepubertal children, and to assess the validity of these equations. In total, 145 healthy Japanese prepubertal children aged 6-12 years were randomly divided into two groups: the model development group (sixty boys, thirty-seven girls) and the validation group (twenty-nine boys, nineteen girls). Reference data in the form of contiguous MRI with 1-cm slice thickness were obtained from the first cervical vertebra to the ankle joints. The SMV was calculated by the summation of digitised cross-sectional areas. Muscle thickness was measured using B-mode ultrasonography at nine sites in different regions. In the model development group, strong, statistically significant correlations were observed between the site-matched SMV (total, arms, trunk, thigh and lower legs) measured by MRI and the muscle thickness×height measures obtained by ultrasonography, for both boys and girls. When these SMV prediction equations were applied to the validation groups, the measured total and regional SMV were also very similar to the values predicted for boys and girls, respectively. With the exception of the trunk region in girls, the Bland-Altman analysis for the validation group did not indicate any bias for either boys or girls. These results suggest that ultrasonography-derived prediction equations for boys and girls are useful for the estimation of total and regional SMV.

Comparison of the morphology of the rotator cuff muscles across age groups

We aimed at investigating the morphological difference of the rotator cuff (RC) muscles among age groups from elementary school students to college students. The subjects included 10 college (22.6 ± 1.8 years), 10 high school (16.8 ± 0.6 years), 10 junior high school (13.9 ± 0.6 years), and 10 elementary school (10.4 ± 0.5 years) students. Consecutive oblique sagittal magnetic resonance T1‐weighted images of the dominant shoulder were acquired for each participant. Muscle length, maximal anatomical cross‐sectional area (ACSA), the position of the maximal ACSA at full muscle length, muscle volume, and the individual‐to‐total RC muscle volume ratio for the supraspinatus, external rotators (infraspinatus and teres minor), and subscapularis were evaluated. The muscle length, maximal ACSA, and muscle volume in the RC muscles significantly increased with increasing age (P < 0.01), but there was no significant difference between college and high school students except in regard to the volume of the external rotators. There was no difference in the position of the maximal ACSA or the individual‐to‐total RC muscle volume ratio among the groups. The findings of this study show that the size of each RC muscle increases with increasing age, but the position of maximal ACSA and the proportion of each muscle to the total RC muscle volume are similar among age groups from elementary school students to college students. Clin. Anat. 27:365–369, 2014.

Prediction and validation of total and regional fat mass by B-mode ultrasound in Japanese pre-pubertal children.

The present study was performed to develop regression-based prediction equations for fat mass by ultrasound in Japanese children and to investigate the validity of these equations. A total of 127 healthy Japanese pre-pubertal children aged 6-12 years were randomly separated into two groups: the model development group (fifty-four boys and forty-four girls) and the validation group (eighteen boys and eleven girls). Total body, trunk, arm and leg fat masses were initially determined by dual-energy X-ray absorptiometry (DXA, Delphi A-QDR whole-body scanner; Hologic, Inc., Bedford, MA, USA). Then, fat thickness was measured by B-mode ultrasound (5 MHz scanning head) at nine sites (arm: lateral forearm, anterior and posterior upper arm; trunk: abdomen and subscapular; leg: anterior and posterior thigh, anterior and posterior lower leg). Regression analyses were used to describe the relationships between the site-matched fat masses (total body, arm, trunk and leg) obtained by DXA and ultrasound in the development group. When these fat mass prediction equations were applied to the validation group, the measured total and regional fat mass was very similar to the predicted fat mass (mean difference calculated as predicted - measured fat mass ± 2 SD; total body 0·1 (SD 0·5) kg, arm 0·1 (SD 0·3) kg, trunk - 0·1 (SD 0·3) kg, leg 0·1 (SD 0·5) kg for boys; total body 0·5 (SD 1·3) kg, arm 0·0 (SD 0·3) kg, trunk 0·1 (SD 0·8) kg, leg 0·3 (SD 0·6) kg for girls), and the Bland-Altman analysis did not indicate a bias. These results suggest that ultrasound-derived prediction equations for boys and girls are useful for estimating total and regional fat mass.

Is There a Chronic Elevation in Organ-Tissue Sleeping Metabolic Rate in Very Fit Runners?

It is unclear whether the resting metabolic rate of individual organ-tissue in adults with high aerobic fitness is higher than that in untrained adults; in fact, this topic has been debated for years using a two-component model. To address this issue, in the present study, we examined the relationship between the measured sleeping energy expenditure (EE) by using an indirect human calorimeter (IHC) and the calculated resting EE (REE) from organ-tissue mass using magnetic resonance imaging, along with the assumed metabolic rate constants in healthy adults. Seventeen healthy male long-distance runners were recruited and grouped according to the median V·O2peak: very fit group (>60 mL/min/kg; n = 8) and fit group (<60 mL/min/kg; n = 9). Participants performed a graded exercise test for determining V·O2peak; X-ray absorptiometry and magnetic resonance imaging were used to determine organ-tissue mass, and IHC was used to determine sleeping EE. The calculated REE was estimated as the sum of individual organ-tissue masses multiplied by their metabolic rate constants. No significant difference was observed in the measured sleeping EE, calculated REE, and their difference, as well as in the slopes and intercepts of the two regression lines between the groups. Moreover, no significant correlation between V·O2peak and the difference in measured sleeping EE and calculated REE was observed for all subjects. Thus, aerobic endurance training does not result in a chronic elevation in the organ-tissue metabolic rate in cases with V·O2peak of approximately 60 mL/min/kg.