Dynamic Primitives in the Control of Locomotion.

Dynamic primitives in the control of locomotion.

Front Comput Neurosci. 2013; 7: 71
Hogan N, Sternad D

Humans achieve locomotor dexterity that far exceeds the capability of modern robots, yet this is achieved despite slower actuators, imprecise sensors, and vastly slower communication. We propose that this spectacular performance arises from encoding motor commands in terms of dynamic primitives. We propose three primitives as a foundation for a comprehensive theoretical framework that can embrace a wide range of upper- and lower-limb behaviors. Building on previous work that suggested discrete and rhythmic movements as elementary dynamic behaviors, we define submovements and oscillations: as discrete movements cannot be combined with sufficient flexibility, we argue that suitably-defined submovements are primitives. As the term “rhythmic” may be ambiguous, we define oscillations as the corresponding class of primitives. We further propose mechanical impedances as a third class of dynamic primitives, necessary for interaction with the physical environment. Combination of these three classes of primitive requires care. One approach is through a generalized equivalent network: a virtual trajectory composed of simultaneous and/or sequential submovements and/or oscillations that interacts with mechanical impedances to produce observable forces and motions. Reliable experimental identification of these dynamic primitives presents challenges: identification of mechanical impedances is exquisitely sensitive to assumptions about their dynamic structure; identification of submovements and oscillations is sensitive to their assumed form and to details of the algorithm used to extract them. Some methods to address these challenges are presented. Some implications of this theoretical framework for locomotor rehabilitation are considered. HubMed – rehab


Upper and lower limb muscles in patients with COPD: similarities in muscle efficiency but differences in fatigue resistance.

Respir Care. 2013 Jun 25;
Miranda EF, Malaguti C, Marchetti PH, Dal Corso S

Peripheral muscle dysfunction is a common finding in patients with chronic obstructive pulmonary disease (COPD); however, the structural adaptation and functional impairment of the upper and lower limb muscles do not seem to be homogenous.To compare muscle fatigue and recovery time between two representative muscles of the upper limb (middle deltoid, MD) and lower limb (quadriceps femoris, QF).Twenty-one patients with COPD (with forced expiratory volume in 1 s of 46.1 ± 10.3% predicted) underwent maximal voluntary isometric contraction (MVIC) and an endurance test (ET, 60% MIVC) to the limit of tolerance. The MVIC was repeated after 10 minutes, 30 minutes, 60 minutes and 24 hours for both the QF and MD. Surface electromyography was recorded throughout the ET.A significant fall in MVIC was observed only for the MD between ten and sixty minutes after the ET. A significant increase of the root mean square and a greater decline in median frequency throughout the ET occurred for the MD compared with the QF. When dyspnea and fatigue scores were corrected by endurance time, higher values were observed for MD (0.07 and 0.08, respectively) in relation to QF (0.02 and 0.03, respectively).Patients with COPD presented a higher fatigability of a representative upper limb muscle (MD) compared with a lower limb muscle (QF). HubMed – rehab


Implementing patient-reported outcome measures in palliative care clinical practice: A systematic review of facilitators and barriers.

Palliat Med. 2013 Jun 25;
Antunes B, Harding R, Higginson IJ,

Background:Many patient-reported outcome measures have been developed in the past two decades, playing an increasingly important role in palliative care. However, their routine use in practice has been slow and difficult to implement.Aim:To systematically identify facilitators and barriers to the implementation of patient-reported outcome measures in different palliative care settings for routine practice, and to generate evidence-based recommendations, to inform the implementation process in clinical practice.Design:Systematic literature review and narrative synthesis.Data Sources:Medline, PsycInfo, Cumulative Index to Nursing and Allied Health Literature, Embase and British Nursing Index were systematically searched from 1985. Hand searching of reference lists for all included articles and relevant review articles was performed.Results:A total of 3863 articles were screened. Of these, 31 articles met the inclusion criteria. First, data were integrated in the main themes: facilitators, barriers and lessons learned. Second, each main theme was grouped into either five or six categories. Finally, recommendations for implementation on outcome measures at management, health-care professional and patient levels were generated for three different points in time: preparation, implementation and assessment/improvement.Conclusions:Successful implementation of patient-reported outcome measures should be tailored by identifying and addressing potential barriers according to setting. Having a coordinator throughout the implementation process seems to be key. Ongoing cognitive and emotional processes of each individual should be taken into consideration during changes. The educational component prior to the implementation is crucial. This could promote ownership and correct use of the measure by clinicians, potentially improving practice and the quality of care provided through patient-reported outcome measure data use in clinical decision-making. HubMed – rehab


Changes of body balance before and after total knee arthroplasty in patients who suffered from bilateral knee osteoarthritis.

J Orthop Sci. 2013 Jun 26;
Ishii Y, Noguchi H, Takeda M, Sato J, Kishimoto Y, Toyabe SI

It is still controversial whether simultaneous or staged total knee arthroplasty (TKA) is most desirable for patients with bilateral knee osteoarthritis. We retrospectively evaluated changes in balance among patients with bilateral osteoarthritis who underwent staged TKA using a gravicorder.Patients were stratified into two groups: the unilateral group (UG) (22 patients) consisted of patients who did not undergo a second TKA within 24 months of the first TKA, and the bilateral group (BG) (20 patients) were those who had a second TKA within 12 months after initial TKA.The mean gravity center position (GCP), which indicates the translation of GCP in the mediolateral direction between pre- and post-TKA shifted to the operative side in both groups after initial surgery. While the GCP was maintained on the same side in UG over 2 years follow-up, in BG it moved to the opposite side and approached a central position after the second TKA. Locus length of GCP (LG), which indicates postural control function by proprioceptive reflex showed significant improvement after initial TKA in UG, while BG showed significant improvement after the second TKA.The degree of LG improvement after initial TKA may indicate the necessity of a second TKA for patients with bilateral osteoarthritis. The current study suggests that simultaneous bilateral TKA is not always necessary for patients with bilateral knee arthritis, and that properly performed rehabilitation such as improving postural sway after initial TKA might attenuate the timing for the second TKA. HubMed – rehab


Longitudinal Urban-Rural Discrepancies in the US Orthopaedic Surgeon Workforce.

Clin Orthop Relat Res. 2013 Jun 26;
Fu MC, Buerba RA, Gruskay J, Grauer JN

It is unclear whether the supply of orthopaedic surgeons can meet the needs of a growing and aging population. This may be especially concerning in rural areas where there are known disparities in overall healthcare provision.We therefore (1) determined urban-rural trends in the US physician and orthopaedic workforce (including the age of that workforce) from 1995 to 2010; (2) geographically mapped the physician and orthopaedic distribution; and (3) examined urban-rural changes in select nonorthopaedic musculoskeletal provider (chiropractor and podiatrist) workforces from 2000 to 2010.County-level provider data from 1995 to 2010 were obtained from the Department of Health and Human Services. This was aggregated to Hospital Referral Regions and ranked by Rural-Urban Continuum Code. Hospital Referral Region-level data were mapped to identify geographic trends. Total physician and orthopaedic surgeon workforce data were averaged across the most urban and rural regions for the study period.There were urban-rural discrepancies in the physician and orthopaedic workforce from 1995 to 2010 with fewer orthopaedic surgeons in rural areas than urban areas (6.52 versus 8.73 per 100,000 in 2010; p = 0.001). Furthermore, orthopaedic surgeons in rural areas were older than their urban counterparts, with a workforce age ratio (age > 55: age < 55 years) of 0.92 versus 0.65 in 2010 (p = 0.024). From 2000 to 2010, the rural chiropractor and podiatrist workforces showed tremendous growth of 229.6% and 279.9%, respectively.There were significant urban-rural orthopaedic surgeon workforce discrepancies from 1995 to 2010. Concurrent growth in chiropractor and podiatrist numbers shows significant trends in the musculoskeletal provider workforce that warrant continuing observation and analysis.Level IV, economic and decision analyses. See Guidelines for Authors for a complete description of levels of evidence. HubMed – rehab