Kinematic variability, fractal dynamics and local dynamic stability of treadmill walking

<p>Abstract</p> <p>Background</p> <p>Motorized treadmills are widely used in research or in clinical therapy. Small kinematics, kinetics and energetics changes induced by Treadmill Walking (TW) as compared to Overground Walking (OW) have been reported in literature. The purpose of the present study was to characterize the differences between OW and TW in terms of stride-to-stride variability. Classical (Standard Deviation, SD) and non-linear (fractal dynamics, local dynamic stability) methods were used. In addition, the correlations between the different variability indexes were analyzed.</p> <p>Methods</p> <p>Twenty healthy subjects performed 10 min TW and OW in a random sequence. A triaxial accelerometer recorded trunk accelerations. Kinematic variability was computed as the average SD (MeanSD) of acceleration patterns among standardized strides. Fractal dynamics (scaling exponent α) was assessed by Detrended Fluctuation Analysis (DFA) of stride intervals. Short-term and long-term dynamic stability were estimated by computing the maximal Lyapunov exponents of acceleration signals.</p> <p>Results</p> <p>TW did not modify kinematic gait variability as compared to OW (multivariate T², p = 0.87). Conversely, TW significantly modified fractal dynamics (t-test, p = 0.01), and both short and long term local dynamic stability (T²p = 0.0002). No relationship was observed between variability indexes with the exception of significant negative correlation between MeanSD and dynamic stability in TW (3 × 6 canonical correlation, r = 0.94).</p> <p>Conclusions</p> <p>Treadmill induced a less correlated pattern in the stride intervals and increased gait stability, but did not modify kinematic variability in healthy subjects. This could be due to changes in perceptual information induced by treadmill walking that would affect locomotor control of the gait and hence specifically alter non-linear dependencies among consecutive strides. Consequently, the type of walking (i.e. treadmill or overground) is important to consider in each protocol design.</p

Artrodese do quadril: estudo retrospectivo com mais de 20 anos de seguimento Hip arthrodesis: a minimum 20 year follow-up retrospective study

OBJETIVO: Avaliar os resultados a longo prazo de setenta pacientes submetidos à artrodese do quadril pela técnica original descrita por Davis. MÉTODOS: Realizamos um estudo clínico retrospectivo com 70 pacientes, operados entre 1982 e 1995. A presença de sintomas sobre a coluna lombar, joelho ipsilateral e quadril contralateral foi aferida assim como o sucesso da consolidação da artrodese, o posicionamento da mesma e a eventual indicação para conversão à artroplastia total do quadril. RESULTADOS: O tempo médio de seguimento foi 21,6 anos. Uma consolidação satisfatória foi constatada em 48 pacientes (85,7%). A dor lombar foi presente em 11 pacientes (19,6%) e osteoartrite dolorosa do joelho em quatro pacientes (7,1%). Discussão: Dois trabalhos com seguimento superior ao nosso estudo ( 35 e 38 anos) apresentaram repercussões sobre a coluna lombar mais prevalentes (57% e 62%), assim como dor no joelho homolateral (45% e 57%) e indicação para conversão em artroplastia total do quadril (17% e 28%). CONCLUSÃO: Concluímos que a artrodese do quadril pela técnica de Davis apresenta resultados satisfatórios até o vigésimo ano, porém a presença de dor lombar é mais frequente com o passar dos anos e a dor no joelho homolateral sugere associação com a posição inicial em abdução do quadril artrodesado. Nivel de Evidência III, estudo clinico.<br>OBJECTIVE: To evaluate the long-term results of seventy patients who underwent hip arthrodesis using the original technique described by Davis. METHODS: We carried out a retrospective study involving seventy patients submitted to hip arthrodesis between 1982 and 1995. The presence of symptoms involving the lumbar spine, ipsilateral knee, and contralateral hip was noted, as well as the success of the arthrodesis fusion, its positioning, and the need for conversion surgery to total hip replacement. RESULTS: The mean follow-up time was 21.6 years. A satisfactory hip fusion was found in 48 patients (85.7%). Lumbar spine pain was reported by 11 patients (19.6%) and ipsilateral knee osteoarthritis was found in four patients (7.1%). Discussion: Two works, with a longer follow-up time (35 and 38 years) present more prevalent symptoms involving the lumbar spine (57% and 62% ) and ipsilateral knee joint (45% and 57%), and higher conversion surgery rates (17% e 28%). CONCLUSION: hip arthrodesis by the Davis technique presents satisfactory results until the 20th year after surgery, however lumbar spine disease seems to become more prevalent over the years, and the pain in the homolateral knee suggests an association with the initial position in abduction of the hip submitted to arthrodesis. Level of Evidence: Level III clinical study

The effectiveness of walking as an intervention for low back pain: a systematic review

As current low back pain (LBP) guidelines do not specifically advocate walking as an intervention, this review has explored for the effectiveness of walking in managing acute and chronic LBP. CINAHL, Medline, AMED, EMBASE, PubMed, Cochrane and Scopus databases, as well as a hand search of reference lists of retrieved articles, were searched. The search was restricted to studies in the English language. Studies were included when walking was identified as an intervention. Four studies met inclusion criteria, and were assessed with a quality checklist. Three lower ranked studies reported a reduction in LBP from a walking intervention, while the highest ranked study observed no effect. Heterogeneity of study design made it difficult to draw comparisons between studies. There is only low–moderate evidence for walking as an effective intervention strategy for LBP. Further investigation is required to investigate the strength of effect for walking as a primary intervention in the management of acute and chronic LBP