Biomechanical Changes Following Knee Arthroplasty During Sit-To-Stand Transfers: Systematic Review

BackgroundKnee arthroplasty (KA) is a common and effective surgical procedure that allows patients with knee osteoarthritis to restore functional ability and relieve pain. Sit-to-stand is a common demanding task during activities of daily living and is performed more than 50 times per day. The purpose of this systematic review is to obtain a comprehensive understanding of biomechanical changes during sit-to-stand transfers following KA.MethodsRelevant articles were selected through MEDLINE (PubMed), Scopus, Embrace, and Web of Science. Articles were included if they met the following inclusion criteria: (1) underwent KA without restriction on the arthroplasty design, (2) involve kinematic, kinetic, or muscle activity variables as the primary outcome measure, (3) evaluated sit-to-stand, and (4) were written in English.ResultsA total of 13 articles were included in the current systematic review. The KA group exhibited altered movement patterns as compared to healthy controls. Considering the time course of recovery, improvement in knee joint kinematics was found up to 2 years but kinetic changes indicate intensified contralateral limb loading. For comparisons for limbs, limb differences were apparent, but those differences were resolved by 1 year.ConclusionDespite the inevitable changes in kinematics, kinetics, and muscle activity in sit-to-stand since KA, it appears to be important to restore quadriceps strength for the operative limb in order to minimize risk for subsequent joint problems.     

A validation study of a smartphone application for functional mobility assessment of the elderly

BackgroundTo minimize the reaction time and position judgment error using stopwatch-timed measures, we developed a smartphone application to measure performance in the five-time sit-to-stand (FTSTS) and timed up-and-go (TUG) tests.ObjectiveThis study aimed to validate this smartphone application by comparing its measurement with a laboratory-based reference condition.MethodsThirty-two healthy elderly people were asked to perform the FTSTS and TUG tests in a randomized sequence. During the tests, their performance was concurrently measured by the smartphone application and a force sensor installed in the backrest of a chair. The intraclass correlation coefficient [ICC_(2,1)] and Bland–Altman analysis were used to calculate the measurement consistency and agreement, respectively, between these two methods.ResultsThe smartphone application demonstrated excellent measurement consistency with the lab-based reference condition for the FTSTS test [ICC_(2,1) = 0.988] and TUG test [ICC_(2,1) = 0.946]. We observed a positive bias of 0.27 seconds (95% limits of agreement, −1.22 to 1.76 seconds) for the FTSTS test and 0.48 seconds (95% limits of agreement, −1.66 to 2.63 seconds) for the TUG test.ConclusionWe cross-validated the newly developed smartphone application with the laboratory-based reference condition during the examination of FTSTS and TUG test performance in healthy elderly.     

Reproducibility and Convergent Validity of the Sitting-Rising Test in People With Multiple Sclerosis

ObjectiveTo evaluate the test-retest reproducibility and convergent validity of the sitting-rising test (SRT) in people with multiple sclerosis (PwMS).DesignObservational study comprising a test-retest design.SettingMultiple Sclerosis Center, Rehabilitation Hospital at Sheba Medical Center, Tel-Hashomer, Israel.ParticipantsA total of 50 PwMS (32 women, 18 men, N=50), mean age 44.8±7.6 years and mean disease duration of 13.8±8.5 years since diagnosis, were enrolled in the study. The median Expanded Disability Status Scale score was 4.5, indicating a mild-moderate neurologic disability.InterventionsNot applicable.Main Outcome MeasuresSRT, posturography measures, 10-repetion sit-to-stand test (10STS), timed Up and Go (TUG) test, hand grip strength, strength of hip flexion/extension/abduction, knee flexion/extension, and Fall Status Questionnaire.ResultsThe intraclass correlation coefficient value for the intrarater test-retest reproducibility (7- to 10-day interval between tests) of the SRT test, was 0.931 (95% confidence interval, 0.796-0.977). Strong correlations were found between the SRT, TUG test (ρ=−0.709), and 10STS (ρ=−0.719), and moderate correlations were found between the SRT and postural control measures (ρ∼0.4). Moderate correlations were found between the SRT and the hip and knee strength (combined) of the weaker limb (ρ=0.344). No differences were found in the SRT score between fallers and nonfallers.ConclusionsThe current study supports the convergent validity and test-retest reproducibility of the SRT in PwMS.     

Various Surfaces Benefited Functional Outcomes and Fall Incidence in Individuals With Spinal Cord Injury: A Randomized Controlled Trial With Prospective Data Follow-up

ObjectivesTo compare effects of walking training on a walking track with different surfaces (WTDS), including artificial grass, soft, and pebbles, as compared to overground walking training on the functional ability necessary for independence and incidence of falls of ambulatory individuals with spinal cord injury (SCI).DesignA randomized controlled trial (single-blinded design) with 6-month prospective fall data follow-up.SettingTertiary rehabilitation centers and several communities.ParticipantsIndependent ambulatory individuals (N=54) with SCI who walked with or without a walking device.InterventionParticipants were randomly arranged into a control group (overground walking training, n=26) or experimental group (walking training over a WTDS, n=28) for 30 min/d, 5 d/wk over 4 weeks.Main Outcome MeasuresThe 10-m walk test, timed Up and Go test, five times sit-to-stand test, and 6-minute walk test were repeatedly measured 4 times, including before training, and after 2 and 4 weeks, and 6 months. In addition, participants were prospectively monitored for the fall data over 6 months.ResultsParticipants who walked with an average speed of 0.52 m/s and postinjury time >7 years could safely walk over a WTDS. They demonstrated significant improvement at 2 and 4 weeks after experimental training (P<.001), but not after control training. During the 6-month follow-up, participants in the experimental group also had the number of those who fell (n=5, 18%) fewer than those in the control group (n=12, 46%).ConclusionsBeing at a chronic SCI with ability of independent walking, participants needed a challenging task to promote their functional outcomes and minimize fall risk. The findings suggest the use of various surfaces as an alternative rehabilitation strategy for these individuals.     

Balance Control and Energetics of Powered Exoskeleton-Assisted Sit-to-Stand Movement in Individuals With Paraplegic Spinal Cord Injury

Objective

To quantify the effects of initial hip angle and angular hip velocity settings of a lower-limb wearable robotic exoskeleton (WRE) on the balance control and mechanical energy requirements in patients with paraplegic spinal cord injuries (SCIs) during WRE-assisted sit-to-stand (STS).

坐下-站立功能测试训练系统数据采集与无线通讯模块的开发

目的:研发一套基于MSP430单片机与蓝牙无线通信的用于人体坐下-站立功能的测试系统。方法:系统采用上下位机结构,通过压力传感器采集坐下-站立过程中的足底和臀部的压力参数,通过蓝牙无线传输将数据传送至上位机。仪器研制成功后,对20位志愿者进行了坐下-站立功能的测试。结果:设计出该系统。利用上位机开发的测试训练软件,实现压力变化的实时显示及评定结果的数值显示。20位志愿者坐下-站立功能测量所得各参数的组内相关系数(ICC)均大于0.8,表明该系统具有很好的可靠性。结论:本研究所设计的坐下-站立功能测试系统可定性定量地测试人体坐下-站立的平衡功能。     

Association between subject functional status, seat height, and movement strategy in sit-to-stand performance

OBJECTIVES: To explore the association between an individual's functional status, movement task difficulty, and effectiveness of compensatory movement strategies within a sit-to-stand (STS) paradigm. DESIGN: Cross-sectional study. SETTINGS: Rehabilitation unit of the Istituto Nazionale Riposo e Cura Anziani Geriatric Hospital of Florence, Italy. PARTICIPANTS: A convenience sample (131 subjects) of the outpatient clinic and day-hospital population. MEASUREMENTS: A performance-based test (repeated chair standing) was used to divide the subjects into five functional groups. Subjects performed a series of single STS tasks across a range of five descending seat heights. They were instructed to stand without using arms or compensatory strategies. If unable, swinging the arms was allowed, and if the inability persisted, subjects could push with their arms during subsequent attempts. The strategy or inability to stand formed the dependent measures. RESULTS: Subjects within the two highest functional groups could complete the single STS task at all seat heights, with a slight increased use of compensatory strategies at the lowest seat height. The effectiveness of the compensatory strategies decreased rapidly as a function of seat height and functional status. One-third (35.5%) of the subjects in the middle functional group swung their arms at the lower seat heights. Across the three least functional groups, 11.8%, 30.6%, and 83.3% of the subjects, respectively, were unable to stand at the lowest seat height. CONCLUSION: The individual's functional status and difficulty of the task influenced the effectiveness of a compensatory strategy to maintain the ability to stand, supporting the idea that disability depends on the interplay between environmental demands and physical ability.     

Postural control during sit-to-stand movement and its relationship with upright position in children with hemiplegic spastic cerebral palsy and in typically developing children

OBJECTIVE:

The purpose of this study was to compare postural control in typically developing (TD) children and children with cerebral palsy (CP) during the sit-to-stand (STS) movement and to assess the relationship between static (during static standing position) and dynamic postural control (during STS movement) in both groups.

METHOD:

The center of pressure (CoP) behavior of 23 TD children and 6 children with spastic hemiplegic CP (Gross Motor Function Classification System [GMFCS] I and II) was assessed during STS movement performance and during static standing conditions with the use of a force plate. The data obtained from the force plate were used to calculate CoP variables: anteroposterior (AP) and mediolateral (ML) amplitudes of CoP displacement and the area and velocity of CoP oscillation.

RESULTS:

According to the Mann-Whitney test, children with CP exhibited higher CoP values in all of the analyzed variables during the beginning of STS movement. Pearson''s correlation verified a positive correlation between the CoP variables during both static conditions and the performance of STS movement.

CONCLUSIONS:

Children with spastic hemiplegic CP present major postural oscillations during the beginning of STS movement compared with typical children. Moreover, the observed relationship between postural control in static and dynamic conditions reveals the importance of body control in the static position for the performance of functional activities that put the body in motion, such as STS movement.     

老年人坐立转换时股骨近端应力分布的有限元分析

目的 通过建立股骨近端有限元模型,分析在坐立（sit-to-stand, STS）转换站立阶段初期,股骨近端在自选速度起立和快速起立条件下的损伤风险。方法 将老年人股骨近端CT影像三维重建、逆向建模完成实体模型。通过材料赋值和网格划分建立有限元模型,基于有限元分析软件ANSYS,通过边界条件约束,并加载1.733、1.837 kN载荷,得到不同起立速度下股骨近端的应力分布和应变。结果 应力集中区域均为大转子内侧边缘和股骨颈。应力和微应变峰值出现在大转子内侧边缘。快速起立下应力峰值为30.16 MPa,微应变峰值为2 553.5;自选速度起立下应力和微应变峰值较低,分别为28.69 MPa和2 430.4。对于股骨颈应力集中区,快速、自选速度起立下应力范围分别为13.42~23.46、12.76~25.51 MPa。结论 频繁的STS转换会使老年人股骨近端有疲劳性骨折的风险;快速STS转换比自选速度STS转换对股骨近端有更高的损伤风险。