Asymmetry After Hip Fracture: A Multi-factorial Problem

Background and Purpose: Sit-to-stand (STS) and static standing mechanics are related to fall risk and function after hip fracture. Often, these patients avoid weight bearing on the fracture side after rehabilitation. The purpose of this study was to use a novel clinically-relevant protocol to examine standing and STS vertical ground reaction force (vGRF) in light of perceptual measures of loading symmetry and muscle torque production in this population. Methods: A person post hip fracture performed 3 different STS conditions and 2 simple load-matching tasks. Motion, force plate, and perceptual data on weight distribution and load were collected. Findings: Standing and STS asymmetry were not explained by strength. A perceptual issue may be limiting performance progress in achieving symmetry. Clinical Relevance: Active task-specific training, augmented by attention to perception of movement, load, or strength, may assist in attaining symmetry in STS. Conclusion: Some patients may benefit when mechanical and perceptual performances are considered together

Effect of Haptic Feedback on Static Standing Sway

Study Goal: To explore the use of proprioceptive input as a means of attenuating postural sway through the development and implementation of a hands-free device, with the ultimate goal of providing sway-reference haptic input located at the upper trunk and shoulders to determine: Does sway-referenced haptic input improve static standing stability

Sit-to-Stand Symmetry in Individuals with Hip Pathology

Hip fractures occur approximately in 300K individuals aged 65+ annually post-fall 53.3% will sustain another fall; Mortality rate \u3e 25% The sit-to-stand (STS) task is impacted by hip fractures. vGRF asymmetry with STS post-hip fracture (Houck et al.) Hip fracture side \u3c non-fractured side Asymmetry not fully explained by LE strength in hip fracture nor CV

The Effects of Haptic Feedback on Postural Sway

Purpose: Effectiveness of haptic feedback on reducing postural sway Hypothesis: Haptic input improves static standing stability. Individuals with increased variability in sway may have an increased risk for falls. Therefore, our haptic feedback device may have the ability to reduce risk of falling. Postural control is a dynamic system involving vision, vestibular system, proprioception, and musculoskeletal system. Postural control enables people to maintain their balance, reduce their sway, and keep an upright posture. Haptic feedback is tactile or vibratory cues that assist a subject in determining where they are in space

Can Cue Location Influence Postural Sway Control in a Post-Concussion Syndrome Case?

Center for Disease Control reports the following as fall risk factors: lower extremity weakness, vision problems, and difficulty maintaining balance during walking. Greatest predictor for a fall, is prior fall within the last year. Injury from a fall leads to: fear of falls, inactivity, atrophy, higher risk for falls. Kouzake and Masani (2008) indicated that improvements in postural sway are attributed to light touch increasing proprioception, rather than through mechanical support. Examples of light touch-enhanced proprioceptive feedback: walls and assistive walking devices. Successful strategy in bimanual tasks

Sit-to-Stand Symmetry in Individuals with Hip Pathology

Post-hip fracture patients continue to exhibit asymmetries during sit-to-stand task following rehabilitation. While strength is thoroughly addressed, perceptual deficits may be a missing component to rehabilitation post-hip fracture

Sit-to-Stand Symmetry

Asymmetric sit-to-stand (STS) and static standing mechanics may be related to fall risk and function after hip fracture. Even in those individuals who achieve an independent status in rising from STS, asymmetric movement strategies are frequently adopted. Previous research has revealed that the asymmetry is not fully explained by strength deficits alone. Stroke literature suggests that STS asymmetry is a function of perceptual deficits, such as sense of effort, however, this concept has not yet been explored following a hip fracture

Size-Weight Illusion: A Proof of Concept

Hypotheses - SWI will be present in full body squat with more force being produced through the lower extremity on the side that has the larger cube initially, with more vertical displacement of the large cube side as well - Pre lift predictions will bias the larger cube, while post predictions will bias the smaller cube - We also anticipate a larger vertical displacement on the side with the larger box following the fatigue protoco

Sit-to-Stand Symmetry in Individuals with Hip Pathology

Why study hip fracture? • Hip fractures occur in approximately 300,000 individuals over 65 years of age and is on the rise • 53.3% of those who fall, fall again • 50% loss of function in involved lower extremity post fracture • 25% increased mortality rate 1 year post hip fracture An asymmetry in force production has been found to exist between fractured/non- fractured sides during a sit-to-stand task post hip fracture, despite having adequate capacity to perform the task symmetrically. Houck 2011 found the asymmetry is a result of weakness in the fractured lower extremity. Briere 2013 found the asymmetry is a result of motor control dysfunction in the nervous system rather than a pure strength deficit. An explanation for these errors could be that patients rated their perceived effort distribution rather than their force/weight distribution through their lower extremities during a functional sit to stand task

Low Frequency Fatigue in Human Quadriceps is Fatigue Dependent and Not Task Dependent

It is well accepted that a low intensity/long duration isometric contraction induces more low frequency fatigue (LFF) compared to a high-intensity/short-duration contraction. However, previous reports examined the intensity/duration of the contraction but did not control the level of fatigue when concluding fatigue is task dependent. The purpose of this study was to determine whether a long duration/low intensity fatiguing contraction would induce greater LFF than a short duration/high-intensity contraction when the quadriceps muscle was fatigued to similar levels. Eighteen healthy male subjects performed quadriceps contractions sustained at 35% and 65% of maximal voluntary contraction (MVC) on separate days, until the tasks induced a similar amount of fatigue (force generating capacity = 45% MVC). Double pulse torque to single pulse torque ratio (D/S ratio) was obtained before, immediately and 5 min after fatigue along with the electromyographic (EMG) signal from vastus medialis (VM) and rectus femoris (RF). The D/S ratio significantly (p \u3c 0.05) increased by 8.7 ± 8.5% (mean ± SD) and 10.2 ± 9.2% after 35% and 65% tasks, respectively, and remained elevated 5 min into recovery; however, there was no significant difference in ratio between the two sessions immediately or 5 min post-fatigue (p \u3e 0.05) even though the endurance time for the 35% fatigue task (124 ± 39.68 s) was significantly longer (p = 0.05) than that of the 65% task (63 ± 17.73 s). EMG amplitude and median power frequency (MPF) analysis also did not reveal any significant differences between these two sessions after fatigue. These findings indicate that LFF fatigue is fatigue dependent as well as task intensity/duration dependent. These findings assist us in understanding task dependency and muscle fatigue