The effect of age and joint angle on the proportionality of extensor and flexor strength at the knee joint

Functional movements require concerted actions of monoarticular and biarticular agonists and antagonists. Understanding age-related changes of muscle function on performance requires insight in the contributions of different muscles to joint moments. Young and elderly participants performed isometric knee extensions and flexions at combinations of knee and hip joint angles. This approach allowed assessing changes in contribution of monoarticular and biarticular knee joint flexors and extensors. Reduced moments were found for elderly persons (flexors: -43%; extensors: -33%). In the flexor group, this reduction was mainly caused by retardation of the biarticular muscles; in the extensors, by reduced strength of the monoarticular muscles. This age-related reduction of joint moments occurred to be joint angle dependent for the extensors. In the flexor group, the reduction was almost invariant. Due to this difference in joint angle dependence, the proportionality between extensors and flexors varied over joint angles and differed with age. It has been discussed how this is related to changes in performances occurring with age

Strain of carpal ligaments during wrist-joint motion

To obtain a more accurate apprehension of the mechanics of the wrist-joint, the kinematical behaviour of the carpals and the length changes of the ligaments during hand-motions are determined. These structures are represented by radio-opaque markers. Using X-ray photogrammetric principles the 3D coordinates of those markers are calculated at some fifty positions of a movement-cycle. Clear differences are observed between these 3D, experimentally obtained data and prevailing concepts on ligament behaviour based on 2D kinematics of the carpal bones. It is suggested, based on results, that during some motions the carpal joint is not stabilized by one of the tested ligaments. [Edited author abstract; In English

The importance to including objective functional outcomes in the clinical follow up of total knee arthroplasty patients.

In clinical practice, it is increasingly important to assess patients' daily functionality routinely and objectively. Acceleration-based gait analysis (AGA) has shown to be reliable and technically suitable for routine clinical use outside the laboratory. This study investigated the suitability of AGA for measuring function in orthopaedic patients with symptomatic gonarthrosis listed for total knee arthroplasty (TKA) by investigating (a) the ability of AGA to distinguish patients from healthy subjects, (b) the sensitivity to gait changes of AGA in assessing recovery following total knee arthroplasty in a subpopulation, and (c) correlations between AGA parameters and clinical scales. Gait was assessed using AGA in 24 patients with symptomatic gonarthrosis listed for TKA, and in 24 healthy subjects. AGA parameters (e.g. speed, asymmetry) and clinical scales (e.g. KSS) were used to monitor progress in 12 patients 3months after TKA. The Mann-Whitney-U test, Receiver Operating Characteristic (ROC) curves, repeated measurement ANOVA and Pearson correlations were performed. AGA differentiated pathological from healthy gait. The area under the ROC curve, sensitivity and specificity values were high for speed, step frequency and step length. Different recovery profiles were found, with clinical scales showing faster recovery rates. None or only weak correlations were found between AGA and clinical scores. AGA was found to be of clinical relevance in identifying and monitoring patients with symptomatic gonarthrosis in orthopaedic practice, providing objective and additional information about function beyond clinical scales. This, together with the fact that AGA can be applied routinely, suggests the suitability of AGA for use in rehabilitation programs

Satellite cell content is specifically reduced in type II skeletal muscle fibers in the elderly

Satellite cells (SC) are essential for skeletal muscle growth and repair. As sarcopenia is associated with type II muscle fiber atrophy, we hypothesized that SC content is specifically reduced in the type II fibers in the elderly. A total of 8 elderly (E:76+/-1y) and 8 young (Y:20+/-1y) healthy males were selected. Muscle biopsies were collected from the vastus lateralis in both legs. ATPase staining and a pax7-antibody were used to determine fiber type specific SC content (i.e. pax7-positive SC) on serial muscle cross-sections. In contrast to the type I fibers, the proportion and mean cross-sectional area of the type II fibers were substantially reduced in the E versus the Y. The number of SC per type I fiber was similar in E and Y. However, the number of SC per type II fiber was substantially lower in the E versus the Y (0.044+/-0.003 vs 0.080+/-0.007; P<0.01). In addition, in the type II fibers the number of SC relative to the total number of nuclei and the number of SC per fiber area were also significantly lower in the E. This study is the first to show type II fiber atrophy in the elderly to be associated with a fiber type specific decline in SC content. The latter is evident when SC content is expressed per fiber or per fiber area. The decline in SC content might be an important factor in the etiology of type II muscle fiber atrophy, which accompanies the loss of skeletal muscle with aging. Key words: skeletal muscle, sarcopenia, muscle stem cells, atrophy, metabolism

Strength Training Affects Lower Extremity Gait Kinematics, Not Kinetics, in People With Diabetic Polyneuropathy

Increased forefoot loading in diabetic polyneuropathy plays an important role in the development of plantar foot ulcers and can originate from alterations in muscle strength, joint moments and gait pattern. The current study evaluated whether strength training can improve lower extremity joint moments and spatiotemporal gait characteristics in patients with diabetic polyneuropathy. An intervention group receiving strength training during 24 weeks and a control group receiving no intervention. Measurements were performed in both groups at t= 0, t= 12, t= 24 and t= 52 weeks at an individually preferred and standardized imposed gait velocity. The strength training did not affect the maximal amplitude of hip, knee and ankle joint moments, but did result in an increase in stance phase duration, stride time and stride length of approximately 5 %, during the imposed gait velocity. In addition, both groups increased their preferred gait velocity over one year. Future longitudinal studies should further explore the possible effects of strength training on spatiotemporal gait characteristics. The current study provides valuable information on changes in gait velocities and the progressive lower extremity problems in patients with polyneuropathy

Problematic Activities of Daily Life are Weakly Associated With Clinical Characteristics in COPD

BACKGROUND: Problematic activities of daily life (ADLs) can be the main reason to refer patients with chronic obstructive pulmonary disease (COPD) for pulmonary rehabilitation. To date, information on problematic ADLs and their clinical correlates in COPD remain scarce. This retrospective chart review aimed to identify the most prevalent self-reported problematic ADLs in COPD patients, determine performance and satisfaction scores of these problematic ADLs, and explore the association between 13 clinical determinants and 4 problematic ADL domains. METHODS: A total of 820 COPD patients entering pulmonary rehabilitation assessment were included in this retrospective study. Self-reported problematic ADLs were assessed using the Canadian Occupational Performance Measure, administered by occupational therapists in the form of a semistructured interview. RESULTS: COPD patients (59% male, age 63.6 +/- 9.3 years, FEV1 (%pred): 46.4 +/- 18.4) reported 2999 problematic ADLs. The most prevalent problematic ADLs were walking (68%), stair climbing (35%), and cycling (30%). Moreover, 30% of the patients reported "not able to do any of the scored problematic ADL" and 44% were "not satisfied at all with the performance of any of the scored problematic ADL." Significant but weak associations were found between clinical determinants (eg, physical and psychosocial) and problematic ADLs. CONCLUSIONS: The lack of a strong association between problematic ADLs and clinical determinants emphasizes the need for individualized assessment of these ADLs to allow tailored intervention

Wrist joint kinematics and ligament behaviour

Contains fulltext : mmubn000001_134380266.pdf (publisher's version ) (Open Access)Promotores : J. Kauer en R. Huiskes131 p