Advancing our understanding of skeletal muscle across the lifecourse: Protocol for the MASS_Lifecourse study and characteristics of the first 80 participants.

INTRODUCTION: Sarcopenia, the age-related loss of skeletal muscle strength and mass, carries a significant burden for affected individuals. There has been little investigation of sarcopenia using experimental medicine techniques to study human muscle tissue in detail. The aim of the Muscle Ageing Sarcopenia Studies Lifecourse (MASS_Lifecourse) study is to recruit up to 160 participants, equally divided between females and males between ages 45 and 85 years for detailed phenotyping of skeletal muscle health. Here we describe the protocol for the study and the characteristics of the first 80 participants. METHODS: We are recruiting participants from three sources in the north-east of England. Study fieldwork comprises a home visit (or videocall) for consent and assessment of health, cognition, lifestyle, and wellbeing. This is followed by a visit to a clinical research facility for assessment of sarcopenia status and collection of samples including a vastus lateralis muscle biopsy. We produced descriptive statistics for the first 80 participants, including expressing their grip strength relative to normative data in the form of Z-scores. RESULTS: The first 80 participants (53.8 % female) covered the target ages, ranging from 48 to 84 years. They were regularly physically active, reported good physical function and had a prevalence of sarcopenia (including probable sarcopenia) of 11.3 % based on the revised European consensus. Their grip strength was similar to that in the general population, with a mean Z-score of 0.09 standard deviations (95 % CI: -1.64, 1.83) above that expected. CONCLUSIONS: The MASS_Lifecourse study combines comprehensive health and lifestyle data with a range of biological samples including skeletal muscle. The findings from planned analyses should contribute to improvements in the diagnosis, treatment, and prevention of sarcopenia.

Reliability and validity of the Edinburgh Visual Gait Score for cerebral palsy when used by inexperienced observers.

The Edinburgh Visual Gait Score (EVGS) for cerebral palsy has been validated for observer reliability and validity for observers experienced in gait analysis. This study investigated the reliability and validity of the EVGS for observers inexperienced in gait analysis. Six medical students used the score to analyse videotapes from the original study by Read et al. [Read HS, Hazlewood ME, Hillman SJ, Prescott RJ, Robb JE. Edinburgh visual gait score for use in cerebral palsy. J Pediatr Orthop 2003;23:296-301]. These were viewed on two separate occasions to provide inter- and intra-observer reliability, and the results of the numerical items were compared to those from three-dimensional (3D) gait analyses for validity. Observer agreement was tested using Coefficient of Repeatability (CoR), percentage of complete agreement and the kappa statistic. The CoR for inter-observer agreement for inexperienced observers was 5.99/5.07 (Session 1/Session 2) compared to 4.60/3.95 (Session 1/Session 2) for experienced observers. The CoR for intra-observer agreement for inexperienced observers was 5.15 compared to 4.21 for experienced observers. There was complete agreement for 52% of the 10 numerical items with 3D-gait analysis data for inexperienced observers compared to 64% for experienced observers. Ranking of reliability of individual items was similar between the two groups and was generally best for events occurring at the foot and ankle. Observations of gait events by the inexperienced observers using the EVGS were reasonably reliable but not very accurate when compared to experienced observers and 3D-gait analysis.

Reliability and validity of the Visual Gait Assessment Scale for children with hemiplegic cerebral palsy when used by experienced and inexperienced observers.

This study investigated the reliability and validity of the Visual Gait Assessment Scale when used by experienced and inexperienced observers. Four experienced and six inexperienced observers viewed videotaped footage of four children with hemiplegic cerebral palsy on two separate occasions. Validity of the Scale was obtained by comparison with three-dimensional gait analysis (3DGA). The experienced observers generally had higher inter-observer and intra-observer reliability than the inexperienced observers. Both groups showed higher agreement for assessments made at the ankle and foot than at the knee and hip. The experienced observers had slightly higher agreement with 3DGA than the inexperienced observers. The inexperienced observers showed a learning effect and had higher inter-observer agreement and higher agreement with 3DGA in the second assessment of the videotapes. This scale can be used by inexperienced observers but is limited to observations in the sagittal plane and by poor reliability at the knee and hip for experienced and inexperienced observers.

The conjoint junction of the triceps surae: implications for gastrocnemius tendon lengthening.

Forty embalmed cadaver lower limbs were dissected to identify the morphology of the conjoint junction of the tendons of gastrocnemius and soleus and the location of the gastrocnemius tendon relative to bony landmarks. Five patterns of conjoint junction morphology were found: transverse (25%), oblique passing distally and medially (45%), oblique passing distally and laterally (5%) and arcuate as an inverted U (17.5%) and a U-shape (7.5%). Left-right asymmetry of the junction was observed in 31.6% of 19 paired cadaver legs. On the medial side of the calf the gastrocnemius tendon could be located between 38 and 46% of the proportion of the distance between the upper border of the calcaneus and the fibular head. Corresponding values for the midline and lateral side of the calf were 45-58% and 48-51%. The location of the gastrocnemius tendon relative to bony landmarks may help to guide incision planning for open or endoscopic division of the tendon.

The Footprint method to assess transmalleolar axis.

Torsional deformities of the lower extremities are a common reason for an orthopaedic consultation and are also part of the evaluation of a patient in gait analysis. This study assessed the level of agreement between, and the repeatability of, the Footprint method and two other methods (Prone and Jig) of measuring the transmalleolar axis (TMA) clinically. The Footprint method measures the TMA as the patient sits by projecting the position of the malleoli downwards onto lined paper while the lines of the paper are aligned with the knee axis. The Prone method projects the position of the malleoli upwards onto the sole of the foot and this is related to the visually estimated knee axis. The Jig method uses a tropometer to relate the angle between the tibial tubercle and the two malleoli. Two assessors measured twelve subjects using the three methods and six subjects were re-measured approximately 1 week later for repeatability. There was poor agreement between the three methods but the Footprint method was the most repeatable (coefficient of repeatability: 5.4). One observer then assessed the repeatability of the effect of simulated equinus on the Footprint method in 10 normal subjects on 2 separate occasions 1 week apart. Equinus was obtained by having the subjects sit and firstly extend their knee and place the foot on the floor and secondly by placing the foot under consideration on a wedge. Both conditions introduced an offset into the measurement of the TMA when compared to the measurements with the ankle at neutral in the same subjects. The reliability of the Footprint method was then assessed using 10 inexperienced observers who measured nine normal subjects each on 2 separate occasions and their results compared with those from an experienced observer. The inexperienced observers were less repeatable than an experienced observer (coefficients of repeatability 9.2 and 6.9, respectively). We recommend that different methods of measuring TMA should not be used interchangeably in clinical practice. The Footprint method was the most repeatable of the three methods tested and can be used for patients who have fixed equinus but the measurement was less repeatable when used by inexperienced observers.

The effect of simulated hamstring shortening on gait in normal subjects.

The purpose of this study was to determine the effect of simulated hamstring shortening on gait in normal subjects. Six normal subjects wore an adjustable brace to simulate three different hamstring lengths. Evaluation of the physiological cost index (PCI) and gait analysis revealed that simulated hamstring shortening produced adverse affects in the gait of normal subjects. Significant effects were only observed when the popliteal angle exceeded 85 degrees (p<0.001) and included increased effort of walking (PCI), decreased speed, stride and step length; decreased hip flexion and increased knee flexion in stance, increased posterior pelvic tilt, decreased pelvic obliquity and rotation and premature ankle dorsi- and plantar-flexion in stance. These results emphasise the need to consider the effects of changing the length of the hamstrings on joints other than the hip and knee when assessing patients for hamstring lengthening.

Regression analysis of gait parameters with speed in normal children walking at self-selected speeds.

Dimensionless analysis ensures that differences in sizes (e.g. height and weight) of children have a minimal influence on gait parameters. The results of changes in speed on gait parameters were examined using dimensionless analysis on data from a prospective 5-year study of 16 children. Linear regression analysis of peak and trough values of temporal distance parameters, ground reaction forces, joint angles, moments and powers provide a quantitative description of gait development with normalised speed. These linear relationships can be used to estimate gait parameters from speed measurements for normal subjects. However, caution is advised in using the data to attempt to predict an individual's gait parameters due to the wide spread of data about the regression lines and we do not recommend that the data be used to extrapolate the regression data to wider speed ranges.

Electrical stimulation of gluteus maximus in children with cerebral palsy: effects on gait characteristics and muscle strength.

The purpose of this study was to determine whether electrical stimulation of the gluteus maximus would improve hip extensor strength, decrease excessive passive and dynamic internal hip rotation, and improve gross motor function in children with cerebral palsy (CP). Twenty-two ambulant children (15 females, 7 males, mean age 8 years 6 months, SD 2 years 9 months, aged 5 to 14 years) with diplegic (n = 14), hemiplegic (n = 7), and quadriplegic (n = 1) CP participated in this study. All were randomly assigned to either the stimulation or control group. The stimulation group (n = 11) received electrical stimulation of the gluteus maximus of the most affected legs for 1 hour a day, 6 days a week for a period of 8 weeks. Electrodes were applied proximally and distally over the gluteus maximus, with the active electrode initially positioned over the motor points. The control group (n = 11) did not receive any extra treatment. Measurements of hip extensor strength, gait analysis, passive limits of hip rotation, and section E of the Gross Motor Function Measure were made before and after treatment for both groups. Subjectively, 7 of the 11 parents thought that the treatment made a difference to their child. However, no statistically or clinically significant improvement was found in the stimulation group when compared with the control group.

Normalisation of gait data in children.

The comparative effect of semi-dimensional (SD) and non-dimensional (ND) normalisation on the results of a longitudinal study of gait in 5-12-year old children was investigated. The use of both height and leg length in the normalisation was examined. Only ND analysis could be used to identify subjects with the same accelerations. ND analysis of the children's gait indicated that there was little change in the combination of step length and cadence used to achieve a particular velocity between 5 and 12. The first peak and mid-stance trough values of the vertical component of ground reaction force did not change with age. We recommend the use of ND normalisation rather that SD to allow comparisons between individuals of differing size and mass.

Sagittal joint kinematics, moments, and powers are predominantly characterized by speed of progression, not age, in normal children.

Twenty-six healthy 7-year-old children were enrolled in a 5-year longitudinal study to examine the importance of age and speed in the characterization of sagittal joint angles, moments, and powers. In 740 gait trials, children walking at self-selected speeds were examined on the basis of age and normalized speed [speed/(height x g)1/2]. The kinematics and kinetics in these children were characterized predominantly by normalized speed of progression and not age. The clinical relevance of these findings is that normalized speed of walking, rather than age, should be considered when comparing normal with pathologic gait.

Normalized speed, not age, characterizes ground reaction force patterns in 5-to 12-year-old children walking at self-selected speeds.

Twenty-six healthy 5-year-old children were enrolled in a 7-year longitudinal study to examine the importance of age and speed in the characterization of ground reaction forces. One thousand forty gait trials of children walking at self-selected speeds were examined on the basis of age and normalized speed [speed/(height x g)(1/2)]. Results, presented as discrete peak and trough values and as continuous trace plots over the stance phase, indicated that there was little change in ground reaction forces with age, but there were significant changes in vertical force and anterior-posterior force values with normalized speed. The ground reaction force patterns in these children were characterized predominantly by normalized speed of progression and not age. The clinical relevance of these findings is that normalized speed of walking, rather than age, should be considered when comparing normal with pathological gait.