Haruhiko Sato

Gender Differences in Rotation of the Shank During Single-Legged Drop Landing and Its Relation to Rotational Muscle Strength of the Knee

Background Increased shank rotation during landing has been considered to be one of the factors for noncontact anterior cruciate ligament injuries in female athletes. There have been no known gender differences in rotational knee muscle strength, which is expected to inhibit exaggerated shank rotation. Hypothesis Women have less knee external rotator strength than do men. Lower external rotator strength is associated with increased internal shank rotation at the time of landing. Study Design Controlled laboratory study. Methods One hundred sixty-nine healthy young subjects (81 female and 88 male; age, 17.0 ± 1.0 years) volunteered to participate in this study. The subjects performed single-legged drop landings from a 20-cm height. Femoral and shank kinematics were measured using a 3D optoelectronic tracking system during the drop landings, and then the joint angles around the knee (flexion/extension, valgus/varus, and internal/external rotation) were calculated. The maximal isometric rotational muscle strength of the knee was measured at 30° of knee flexion in a supine position using a dynamometer. Results The female subjects had significantly less external shank rotation strength than did the male subjects (P < .001). Female subjects also exhibited significantly greater peak shank internal rotation angles than did males during landing (P < .05). Moderate but significant association was found between the maximum shank external rotation strength and the peak shank internal rotation angle during landing (r = —0.322, P < .01). Conclusion Female subjects tended to have poor shank external rotator strength. This may lead to large shank internal rotation movement during the single-legged drop landing. Clinical Relevance Improving strength training of the external rotator muscle may help decrease the rates of anterior cruciate ligament injury in female athletes.

RELIABILITY AND VALIDITY OF A DEVICE TO MEASURE MUSCLE HARDNESS

Although clinicians judge muscle tenseness by palpation, methods to quantify this have not become established. We examined the reliability and validity of a commercially available myotonometer to assess the biceps brachii and brachioradialis. Torques ranging from 0–72% of maximum effort were isometrically resisted in five men and five women, all healthy and 21–23 years of age. Root-mean-square of surface electromyographic response was also measured. Intraclass correlations were 0.80 or higher within sessions but decreased to 0.57 between sessions except for myotonometry of the biceps brachii. Correlation with isometric load was 0.79 or higher for both myotonometry and electromyography, but these relations were consistently curvilinear. The myotonometer is more useful for fleshy muscles like the biceps brachii than for thin muscles like the brachioradialis. Because hardness has a curvilinear relation with tension in the muscle, hardness cannot be considered strictly equivalent to tension.

Monitoring of body position and motion in children with severe cerebral palsy for 24 hours

Abstract Purpose: To investigate differences in position and body movements between children with severe cerebral palsy (CP) and children with typical development (TD) during the daytime and while asleep at night. Method: Fifteen children with severe quadriplegic CP living at home (GMFCS level V, 7 males, 8 females; mean age 8 years 3 months; range 3–20 years) and 15 children with TD (6 males, 9 females; mean age 8 years 7 months; range 1–16 years) participated. Body position and movements were recorded for 24 h by a body position monitor and a physical activity monitor, respectively. The amount of time spent in one position and the durations of inactive periods during the daytime and during night-time sleep were computed and analyzed for group differences. Results: In children with CP, the mean longest time spent in one position was longer than that in children with TD during night-time sleep (5.6 ± 3.5 h versus 1.6 ± 1.2 h). In contrast, no significant differences were found between the groups during the daytime (1.9 ± 1.1 h versus 1.6 ± 0.7 h). The mean longest time the body remained inactive was longer in the children with CP during both daytime and nighttime sleep (0.6 ± 0.3 h versus 0.3 ± 0.3 h for daytime, 1.4 ± 0.8 h versus 0.7 ± 0.3 h for nighttime). Conclusion: Children with severe CP living at home showed prolonged immobilized posture during night-time sleep when their caregivers would be likely to also be asleep. This may suggest that these children should receive postural care assistance at night. Implications for Rehabilitation A large number of daytime position changes are seen in children with severe cerebral palsy (CP), even if they are unable to change positions by themselves. One position is held with no movement during night-time sleep in children with severe CP. Prolonged immobility posture during night-time sleep might suggest the need for postural care assistance at night for these children.

RELATIONSHIP BETWEEN FORWARD TRUNK LEAN DURING WALKING AND MUSCULOSKELETAL FUNCTIONS FOR FEMALES

A forward trunk lean sometimes occurs to compensate for quadriceps muscle weakness. Since muscle weakness in the lower extremities is commonly observed in the elderly, quadriceps weakness may trigger age-related postural change. The objective of this study was to ascertain the association between forward trunk lean during walking and musculoskeletal strength in females aged between 46 and 79 years. Musculoskeletal functions (range of joint motion, degree of kyphosis, muscle strength) and joint moments during walking were measured for 13 females. Subjects who showed greater joint moments during walking tended to lean more. Moderate association was seen between mean trunk angle during walking and knee extension moment (r = 0.535, p = 0.060). There was no statistically significant correlation between the strength of the quadriceps muscle and the mean trunk angle in walking subjects (r = 0.095, p = 0.758). These observations suggested that muscle weakness in the quadriceps is largely independent of leaning of the trunk for this sample of subjects. Other factors may change the posture to a stoop, such as severe thoracic kyphosis, poor balance control, or fear of falling.

Assessment of grip strength in older people needs standardization by age and sex: Methodology for assessment of grip strength

This research was presented at the 5th International Society of Advance Care Planning and End of Life Care Conference Sep 9–12, 2015, Munich, Germany, and received the 3rd poster prize. This research was supported by Grants-in-Aid for Health, Labor, Scientific Research (H25-special-designation-036), and by Research Funding for Longevity Sciences from the National Center for Geriatrics & Gerontology (25-9). We greatly appreciate the assistance of the healthcare professionals in the Chita area of Aichi who contributed to the present study.

A preliminary study describing body position in daily life in children with severe cerebral palsy using a wearable device

Purpose. The effects of gravity and immobilisation are regarded as factors in the development of spinal deformity in cerebral palsy (CP). This study was to assess the body positions in daily life of children with CP using a wearable device. Method. Four institutionalised children with severe quadriplegic CP participated in this study. Four age-matched children without disability also participated as healthy controls. The participants wore a body position recorder throughout their normal daily activities for a period of 24 h. After the body position data were recorded, the amount of time spent by each subject in upright, supine, prone, and left and right lateral lying positions and the frequency of positional change were computed. Results. The pattern of body position change in daily life was clearly different among children with CP and between children with CP and healthy controls. Children with CP spent less time in the upright position and remained in one position for longer periods of time than the control children. Conclusions. Twenty-four-hour monitoring could provide quantitative information about body position, the frequency of body position changes and the period of time spent in a preferred body position, with possible implications for preventing spinal deformity.

FEASIBILITY OF ESTIMATING JOINT MOMENTS DURING GAIT WITH ONLY KINEMATIC DATA

A preliminary model is presented for estimating floor reaction forces during human walking based only on kinematic data. Such a model would be useful for supplementing purely qualitative gait analysis performed in clinics where force plates would be an unaffordable luxury, but not for situations in which quantitative data would be used in making such decisions as how to perform an orthopedic surgery. In this model, the vertical components of floor reaction forces are determined by conventional double differentiation of kinematic data, but the horizontal (fore-aft) components are based instead on constraints in which the floor reaction forces are characterized as acting through the center of mass of the upper body. To assess the accuracy of our calculations, we gathered data of gait by a healthy 22-year-old woman using a motion analysis system with force plates. Pathological gait data were also examined. Joint moments were computed from both force plate data and from our estimates of floor reaction forces. Prediction of vertical force showed higher reliability than prediction of fore-aft force. Joint moments from kinematics were successfully calculated in normal gait, but not in pathological gait, especially at the hip joint. The proposed approach may have some merit for performing a gait analysis even when no force plate is present, but the inaccuracy increases in the case of a subject whose upper body sways during gait.

Trunk deformity evaluation based on 3D measurements of front body surface landmarks in people with severe physical disabilities

ABSTRACT Purpose: To assess reliability and validity of a trunk deformity evaluation method expressed as rotational and lateral lean angles between the upper and the lower trunk and between the lower trunk and the pelvis using 3D positions of six front body surface landmarks. Methods: Inter- and intra-rater reliabilities of the proposed method in adults with typical development (n = 22) were assessed, and its validity was also assessed through correlations between the Cobb angle and the analyzed trunk deformity parameters in adults with severe physical disabilities (n = 22). Results: The mean differences between two raters and between the initial and second measures were within 2°. Moderate correlations were found between the Cobb angle and both the upper and the lower trunk lateral lean angle and the upper trunk rotation angle. Conclusions: The proposed trunk deformity evaluation appears to be a reliable and valid approach for bedridden people with physical disabilities.

Knee extensor strength assessed using a vertical squat and a simple geometric model to calculate joint torque: An evaluation of validity and clinical utility: Squat model for measuring knee strength

We propose a simple method to measure knee extensor muscle strength using a single‐legged vertical squat. The purpose of the present study was to assess the validity of this method in comparison with standard methods of measurement.

Assessing head and trunk symmetry during sleep using tri-axial accelerometers

Abstract Using two types of small, lightweight tri-axial accelerometers, we obtained evidence for the effectiveness of an approach for assessing head–trunk symmetrical or asymmetrical positions during sleep. First, we assessed the accuracy of our monitoring system in five healthy young adults (age range, 22–24 years). The participants wore acceleration monitors on the sternum and forehead; then spent 5 min in six different positions. Once accuracy was confirmed, we assessed head–trunk symmetry during night-time sleep in 10 healthy children (age range, 3–13 years) and 10 young adults (age range, 21–26 years) in their home environments. All participants wore the monitors during one night’s sleep in their homes. After computing head–trunk positions using the orientation data obtained by the accelerometers, head and trunk symmetry were evaluated. The head and trunk positions were correctly detected: the positional data from the trunk had 99% agreement, and the data from the head had 96% agreement. Both the young adults and children were observed to spend time with the head–trunk in asymmetric positions; however, the subjects changed position frequently so the asymmetrical postures were mobile. We concluded that the proposed monitoring system is a reliable and valid approach for assessing head–trunk symmetry during sleep at home. Implications for Rehabilitation We propose a head and trunk symmetry monitoring system using accelerometers. The proposed system could accurately identify head and trunk position. Asymmetrical positioning was seen in healthy participants but it was not immobile.