Sit-to-stand Transfer Research Articles

Decoupled optimal control of 3D biped for human voluntary motion.

The sit-to-stand (STS) model from a biomechanical point of view is an enormously important subject, with motor controls simulating human intended behavior. Physiological motion-based biomechanical research is important for designing whole-body prosthetics and understanding physical disabilities. The control strategies for biomechanical models can effectively synergize with the central nervous system (CNS) to facilitate the desired movements of individuals with neurological disabilities. In this study, we present our novel 3D biped model by decoupling it into healthy and neurologically deficient joints. The developed 8-segment model (i.e., 2× feet, 2× shanks, 2× thighs, 1× pelvic, and 1× Head Arm Torso (HAT) segment) with 10 joints is decoupled into 6 healthy joints and 4 deficient joints. This decoupling mimics stroke patients or subjects with neuromuscular deficiency. This novel decoupling establishes through asymmetrical torques in frontal and sagittal plane joints on a bipedal design with one foot fixed and the other a sliding tilt joint. In this design, two decoupled controllers collaborate to stabilize the nonlinear model for biped STS transfer. Utilizing the xml files from SOLIDWORKS, the model is linearized in SIMSCAPE / SIMULINK. We further imply the Linear Quadratic Regulator (LQR) optimal controller design in MATLAB / SIMULINK for torques in both the sagittal and frontal planes, respectively, for six healthy and four deficient joints. We also comprehend the forward thrust velocity controls to pragmatically model the STS of stroke patients. This decoupling enhanced the overall stability of the system and simulated more relevant angular and velocity profiles for neurologically deficient substances.

The Role of Muscle Strength in the Sit-to-Stand Task in Parkinson's Disease.

Rising from a chair or the sit-to-stand (STS) task is frequently impaired in individuals with Parkinson's disease (PD). These patients commonly attribute such difficulties to weakness in the lower extremities. However, the role of muscle strength in the STS transfer task has not been fully elucidated. We aim at determining the role of muscle strength in the STS task. We studied 90 consecutive patients with PD and 52 sex- and age-matched controls. Lower limb strength was determined in both legs by clinical examination using the Medical Research Council Scale, dynamometric (leg flexion) and weighting machine (leg pressure) measures. Patients were interrogated regarding the presence of subjective lower limb weakness or allied sensations. There were 20 patients (22.2%) with abnormal STS task (item 3.9 of the MDS-UPDRS-III ≥2 points). These patients had higher modified Hoehn and Yahr stage (P < 0.001) and higher total motor scores of the MDS-UPDRS(P < 0.001), compared with 70 PD patients with normal STS task. Patients with abnormal STS task endorsed lower limb weakness more frequently and had lower muscle strength in the proximal lower extremities, compared to PD patients with normal STS task and normal controls. The presence of perceived lower limb weakness increased the risk of an abnormal STS task, OR: 11.93 (95% C.I. 1.51-94.32), whereas a hip extension strength ≤9 kg/pressure also increased the risk of abnormal STS task, OR: 4.45 (95% C.I. 1.49-13.23). In the multivariate regression analysis, bradykinesia and decreased hip strength were related to abnormal STS task. Patients with PD and abnormal STS task complain more commonly of lower limb weakness and have decreased proximal lower limb strength compared to patients with PD and normal STS task, likely contributing to abnormalities in performing the STS task.

Effect of initial foot angle (IFA) on kinematics and dynamics of body during sit-to-stand transfer.

Sit-to-stand (STS) is considered the most common functional activities in daily life and the basis for other activities. The elderly and patients with lower limb disorders could not complete the STS motion very well due to limb pain and muscle weakness. Physiotherapist find that specific STS transfer strategies can make patients more easily to complete this task. However, few researchers pay attention to the effect of initial foot angle (IFA) on STS motion. Twenty-six healthy subjects were randomly selected to perform STS transfer experiment. The motion characteristic parameters of subjects under 4 different IFAs (nature, 0°, 15°, and 30°) were obtained, including the percentage of duration in each phase, the velocity of joints, rotation angle and angular velocity of joints (shoulder, hip and knee), center of gravity (COG) trajectory. the change of plantar pressure parameters, and dynamic margin of stability. By comparing the motion characteristic parameters obtained under different IFAs and carrying out statistical analysis, the influence of different IFAs on body kinematics and dynamics during STS task was further explored. The kinematic parameters obtained under different IFAs are significantly different. The percentage of duration in each phase of the STS transfer was different with different IFA, the main differences were in phase I and phase II. The phase I of U15 took 24.5% T, while phase I of N, U0 and U30 took about 20% T, and the maximum difference was (U15-U0) 5.4%. The phase II of U15 took the least time, about 30.8% T. When the IFA is nature (N) and 15°(U15), the trajectories of COG are basically in coincidence; when the IFA is 0°(U0) and 30°(U30), the displacement of COG in anterior-posterior direction is larger. The larger the IFA, the smaller the plantar pressure parameter. When the IFA is 15°, the COG is close to the center of limits of stability, which can provide a better stability. This paper summarizes the influence under 4 different experimental conditions of IFAs on STS transfer, so as to provide a starting point and bases for clinicians to develop rehabilitation training protocols and STS motion strategies for patient.

Effect of a Passive Exosuit on Sit-to-Stand Performance in Geriatric Patients Measured by Body-Worn Sensors—A Pilot Study

Standing up from a seated position is a prerequisite for any kind of physical mobility but many older persons have problems with the sit-to-stand (STS) transfer. There are several exosuits available for industrial work, which might be adapted to the needs of older persons to support STS transfers. However, objective measures to quantify and evaluate such systems are needed. The aim of this study was to quantify the possible support of an exosuit during the STS transfer of geriatric patients. Twenty-one geriatric patients with a median age of 82 years (1.-3.Q. 79-84 years) stood up at a normal pace (1) from a chair without using armrests, (2) with using armrests and (3) from a bed with pushing off, each condition with and without wearing an exosuit. Peak angular velocity of the thighs was measured by body-worn sensors. It was higher when standing up with exosuit support from a bed (92.6 (1.-3.Q. 84.3-116.2)°/s versus 79.7 (1.-3.Q. 74.6-98.2)°/s; p = 0.014) and from a chair with armrests (92.9 (1.-3.Q. 78.3-113.0)°/s versus 77.8 (1.-3.Q. 59.3-100.7)°/s; p = 0.089) compared to no support. There was no effect of the exosuit when standing up from a chair without using armrests. In general, it was possible to quantify the support of the exosuit using sensor-measured peak angular velocity. These results suggest that depending on the STS condition, an exosuit can support older persons during the STS transfer.

The effects of anterior and posterior ankle-foot orthoses on sit-to-stand transfer performance in stroke patients

BackgroundNonarticulated and low-temperature thermoplastic ankle–foot orthoses (AFOs) have a semirigid design and are effective in improving the postural control mechanism (PCM) in individuals with poststroke hemiparesis. AFOs with an anterior leaf (AAFOs) are more often prescribed than are AFOs with a posterior leaf (PAFOs); however, the effects of AAFOs on the PCM during sit-to-stand transfer (STST) have not been explored. Research questionsDo AAFOs and PAFOs change the PCM differently during STST? MethodsA cross-sectional quasi-experimental design was adopted in this study. Fourteen individuals with poststroke hemiparesis (10 men and 4 women, aged between 38 and 71 years, stroke onset between 1 and 17 months) performed STST with shoes only, an AAFO with shoes, or a PAFO with shoes. Vertical ground reaction force (VGRF) and center-of-pressure (CoP) coordinates were collected using a pressure mat to calculate PCM parameters. A single-factor repeated measures analysis of variance was performed to answer the research question. Results(1) The weight-bearing percentage of the paretic leg was significantly lower when the participants wore a PAFO (p = 0.018) than when they wore an AAFO (p = 0.019) during the first 5 and 5–10 s after rising. (2) A small rate of change of the VGRF increment (dF/dT) was detected when participants wore AFOs, particularly AAFO. (3) The maximum mediolateral displacement of the CoP when standing up was significantly different among the three conditions (p = 0.012). SignificanceFor patients with poststroke hemiparesis, AAFO and PAFOs change the PCM during STST performance. Only AAFO improved the PCM possibly because of the rigidity and clearance of the heel region, which provide somatic sensory feedback. Therefore, rehabilitation professionals should educate hemiplegic patients who use AAFOs or PAFOs to perform dynamic daily tasks slowly for their safety.

Compensatory biomechanics and spinal loading during dynamic maneuvers in patients with chronic low back pain

PurposeThis study explores the biomechanics underlying the sit-to-stand (STS) functional maneuver in chronic LBP patients to understand how different spinal disorders and levels of pain severity relate to unique compensatory biomechanical behaviors. This work stands to further our understanding of the relationship between spinal loading and symptoms in LBP patients.MethodsWe collected in-clinic motion data from 44 non-specific LBP (NS-LBP) and 42 spinal deformity LBP (SD-LBP) patients during routine clinical visits. An RGB-depth camera tracked 3D joint positions from the frontal view during unassisted, repeated STS maneuvers. Patient-reported outcomes (PROs) for back pain (VAS) and low back disability (ODI) were collected during the same clinical visit.ResultsBetween patient groups, SD-LBP patients had 14.3% greater dynamic sagittal vertical alignment (dSVA) and 10.1% greater peak spine torque compared to NS-LBP patients (p < 0.001). SD-LBP patients also had 11.8% greater hip torque (p < 0.001) and 86.7% greater knee torque (p = 0.04) compared to NS-LBP patients. There were no significant differences between patient groups in regard to anterior or vertical torso velocities, but anterior and vertical torso velocities correlated with both VAS (r = − 0.38, p < 0.001) and ODI (r = − 0.29, p = 0.01). PROs did not correlate with other variables.ConclusionPatients with LBP differ in movement biomechanics during an STS transfer as severity of symptoms may relate to different compensatory strategies that affect spinal loading. Further research aims to establish relationships between movement and PROs and to inform targeted rehabilitation approaches.

Proxy-Based Control of Intelligent Assistive Walker for Intentional Sit-to-Stand Transfer

Sit-to-stand (STS) transfer is an easy everyday activity for healthy people, but it is a challenging task for the elderly, and patients with lower-limb weaknesses. This article presents an intelligent assistive walker, which assists the user to accomplish safe STS transfers. An STS intention recognition method is proposed based on an optimized adaptive network-based fuzzy inference system (ANFIS), where the walker is able to accurately detect a voluntary STS and to apply an appropriate control accordingly. The walker is controlled by using a proxy-based controller with respect to the detected human intention, that is measured using thin-film force sensing resistors. During the STS transfer, the assistance force is generated on-line using a virtual spring-damper between the proxy and the linear actuator of the assistive walker. The stability of the proposed controller is theoretically analyzed, and verified by simulations. Experiments with five young healthy subjects and one elderly subject demonstrated that the proposed assistive walker is able to efficiently follow the user’s intention to complete stable and compliant STS transfers.

What are the effects of simulated muscle weakness on the sit-to-stand transfer?

Populations with lower extremity muscle weakness have difficulty performing the sit-to-stand (STS) transfer. The degree of weakness that can be tolerated before compromising the ability to perform this task is unknown. Using dynamic simulations, we investigated the effects of weakness before changes in kinematics/kinetics would be required. Lower extremity muscles were weakened globally and individually and muscle forces were re-estimated as the model tracked original task kinematics/kinetics. The STS transfer was sensitive to quadriceps and plantarflexor weakness, suggesting that strengthening these muscles or changing kinematics are essential for populations who have difficulty rising from a chair independently.

Knee torque estimation in sit to stand transfer

Multi-body formulations of human body has been a major approach in biomechanics to study the kinematics and dynamics of human movements. This paper discuss an inverse dynamics model of human body for the estimation of knee torque requirement during a sit to stand (STS) transfer. The study was carried out in two parts. In the first part of the study, angular deviations of trunk and knee were recorded in the sagittal plane, while one participant performed STS transfer. In the second part of the study, a five segment human model was designed in SolidWorks and later analysed in MSC/ADAMS for computation of knee torque in STS transfer. The maximum knee torque was found to be 1.34 Nm/kg at 59.2° knee extension.

Human sit-to-stand transfer modeling towards intuitive and biologically-inspired robot assistance

Sit-to-stand (STS) transfers are a common human task which involves complex sensorimotor processes to control the highly nonlinear musculoskeletal system. In this paper, typical unassisted and assisted human STS transfers are formulated as optimal feedback control problem that finds a compromise between task end-point accuracy, human balance, energy consumption, smoothness of motion and control and takes further human biomechanical control constraints into account. Differential dynamic programming is employed, which allows taking the full, nonlinear human dynamics into consideration. The biomechanical dynamics of the human is modeled by a six link rigid body including leg, trunk and arm segments. Accuracy of the proposed modelling approach is evaluated for different human healthy and patient/elderly subjects by comparing simulations and experimentally collected data. Acceptable model accuracy is achieved with a generic set of constant weights that prioritize the different criteria. Finally, the proposed STS model is used to determine optimal assistive strategies suitable for either a person with specific body segment weakness or a more general weakness. These strategies are implemented on a robotic mobility assistant and are intensively evaluated by 33 elderlies, mostly not able to perform unassisted STS transfers. The validation results show a promising STS transfer success rate and overall user satisfaction.

Movement analysis of sit-to-stand – research informing clinical practice

Background:Sit-to-stand (STS) is a crucial transfer influencing a person's independence in daily activities, as well as safety and quality of life, and is thus vital to evaluate in research and in practice. Clinical STS tests provide single values in seconds or numbers of STS. There is, however, increasing numbers of research papers reporting spatial and temporal kinematic and kinetic process STS data.Objectives:To provide an overview of research findings from laboratory-based movement analyses regarding phases and determinants of typical STS, characteristics of successful versus failed STS transfers, and finally STS performance in some neurological conditions.Major Findings:The STS transfer, previously regarded as mainly requiring lower limb muscle strength, is increasingly recognized as a complex transfer skill. Muscle strength, balance, foot position, chair height and the movement strategy are major determinants influencing STS performance. Scaling and timing of momentum generation throughout STS seems critical for success or failure. Sit-to-stand in stroke and Parkinson's disease (PD) is characterized by asymmetry in force generation and difficulties in switching movement direction, respectively. In-depth, knowledge regarding mechanisms of momentum control during STS sub-phases, STS failures, as well as exploration of variability in normal and atypical STS is still lacking.Conclusions:Recent research based on instrumented movement analyses has generated better understanding of movement control during STS, but the specifics are not yet reflected in clinical assessments. There seems to be a call for clinical tools capturing determinants and process characteristics of the STS transfer for a more comprehensive evaluation in rehabilitation.

Coordinating Upper and Lower Body During FES-Assisted Transfers in Persons With Spinal Cord Injury in Order to Reduce Arm Support.

The goal of this study is to minimize arm forces applied during sit-to-stand (STS) transfers in persons with spinal cord injury (SCI) by using functional electrical stimulation (FES) applied to lower limbs muscles. A new FES system has been used to automatically trigger muscle stimulation of the lower limbs, at the desired moment in regards to trunk motion. The objective was to decrease arm participation during STS motion of a person with complete paraplegia and low-level tetraplegia. Six participants with chronic SCI participated in the study. Participants with SCI were recruited to complete STS movement using a new system for FES-assisted STS transfer. All participants attended one muscle mapping session to test their muscles condition, two training sessions to become familiarized with the experimental setup, and two measurement sessions using the proposed system for FES-assisted STS movement. The applied arm forces during STS movement were recorded and analyzed for different stimulation onset values with respect to the maximal trunk acceleration signal using one-way ANOVA statistical test. Post-hoc analysis was performed using Tukey's method. The results of this study showed that the moment of the stimulation onset has an influence on the arm forces applied during the STS motion. The lowest values of arm forces were obtained for STS movements where the electrical stimulation was triggered before and around the time corresponding to the maximal value of the trunk acceleration signal. Lowest arm forces values were obtained for STS motions that were similar to those of healthy persons in terms of trunk movements and beginning of lower limb movements in regards to maximal trunk acceleration signal. The FES system was able to mimic the rising motion of a healthy individual by triggering the FES at the appropriate moment. This method could prove useful for pivot transfer, therapeutic or functional verticalization.

Effect of bed height and use of hands on trunk angular velocity during the sit-to-stand transfer

The ability to rise from a chair or bed is critical to an individual's quality of life because it determines functional independence. This study was to investigate the effect of bed height and use of hands on trunk angular velocity and trunk angles during the sit-to-stand (STS) performance. Twenty-four older persons (median age 74 years) were equipped with a body-fixed gyroscopic sensor and stood up from a bed adjusted to different heights, with and without the use of hands at each height. Peak angular velocity and trunk range of motion decreased with increasing bed height (all p ≤ 0.038) and were lower using hands during STS transfer indicating less effort. In conclusion, gyroscopic sensor data of the STS transfer of older persons show differences as an effect of bed height and use of hands. These results provide the rationale for recommending a relatively high bed height for most of the older persons.

Sit-To-Stand (STS) timing among older adults in their homes: Two measurement approaches

Sit-to-stand (STS) times required by older adults exiting from their beds at home were compared simultaneously using under mattress pressure sensor technology and video analysis. Six older adults consented to participate in the study and had under mattress pressure technology installed in their homes. Participants were visited monthly over a period of 2-10 months by a researcher who asked them to perform three bed exits which were videotaped. The pressure sensor technology calculated a portion of STS time based on changes in pressure between the end of stable sitting on the edge of the bed and pressure leaving the bed. The video analysis approach calculated this corresponding initial phase of the same STS transfer by determining the difference between the first forward movement from the quiet sitting position and the initiation of vertical rise. The remaining period of vertical rise into a complete standing position was calculated using video analysis but not pressure sensor technology. A Spearman’s rank order correlation analysis revealed that there was a moderate, positive correlation between the video and pressure-sensor measures of the initial phase of STS which was statistically significant (r s =0.50, n=97, p<0.001). Wilcoxon signed-rank tests indicated that pressure sensor times were longer (Z=-7.91, p<0.000) and more variable than video times (Z=-3.14, p=0.002). Analysis of video data revealed that this initial phase of STS represented between 15 to 81% of the total STS time among the 97 sampled STS in this study. Results highlight how the home environment presents a number of conditions affecting differences in STS values obtained by each of these measurement approaches.

Minimization of body loads during sit-to-stand movement by continuous genetic algorithm

Sit-to-stand (STS) rehabilitation equipment traditionally simulates natural movements of unspecified healthy people. This type of movement may not place the lowest load on a patient's body. These factors let us develop a novel and widely applicable system for rehabilitation purposes that suggests a motion that places low body loads at the lower limb joints. This paper describes the core computation in the system that calculates a STS movement that places a minimum body load by using Continuous Genetic Algorithm (CGA). The minimization process starts from measurement of kinematic and kinetic data of a human subject by using gyroscopic sensors and reaction force plates, and then estimation and evaluation of the body load are followed. The body load which is minimized during STS movement was quantified by an index value. The index value strongly correlates with the chair height. Decreasing this index value by changing the movement during STS transfer could reduce the impact on the body, which is the same amount of load placed on the body while standing up from a higher chair height. The angular displacements of the averaged natural STS movement of the subject were considered as one of the several ways to stand up and the movements were assessed by means of the index value in CGA. A modified STS movement that can minimize the body load was computed after the optimization and it could be a personalized optimum movement allowing users to conduct rehabilitation with lesser unnecessary body load.

Characterizing asymmetry across the whole sit to stand movement in healthy participants

Sit-to-stand transfer (STS) is a common yet critical prerequisite for many daily tasks. Literature conducted on healthy STS often assume the body to behave symmetrically across the left and right side; yet only a few studies have been conducted to investigate this supposition. These studies have focused on a single numerical indicator such as peak joint moment (JM) values to describe symmetricity; however, STS is a dynamic and time dependent movement. This study addresses the validity of peak value analyses through the introduction of a time based peak-offset measure and proposes two time-dependent techniques to further characterize asymmetry and assesses their feasibility in ten (10) healthy male participants. JM and joint power (JP) over the whole STS movement was determined using motion capture and inverse dynamics. Using a paired one-tailed t-test differences were found in the time at which the left and right side reached peak values in all lower extremity joints (p<0.05) with exception of the hip JM. Using a measure of JM and JP straight-difference it was determined that the ankle joint displayed the largest number of JM and JP development strategies of all the lower extremity joints. Finally, through numerical integration of the JM and JP data with respect to time, it was found that the longer one side spends dominating the movement, the larger the excess angular impulse and work that can be expected from that side. The results suggest that when analyzing STS movements, one must be aware of the potential asymmetry present even in healthy movements. Furthermore, a simple peak JM or JP analysis may not fully describe the extent of these asymmetries.

A bio-inspired modular hierarchical structure to plan the sit-to-stand transfer under varying environmental conditions

Human motion planning studies are of considerable importance in producing human-like trajectories for various industrial or clinical applications (e.g. assistive robots). In this case, the capability of Central Nervous System (CNS) in generating a large repertoire of actions can be inspirational to develop more efficient motion planning approaches. Here, inspired by structural and functional modularity in the CNS, a novel modular and hierarchical model is developed to plan the sit-to-stand (STS) transfer under varying environmental conditions. In this model, the planning process is distributed among several functionally simple modules. The cooperation of modules enables the model to plan the motion under a variety of conditions. The proposed model is assessed by planning the STS transfer under two types of environmental conditions: varying seat heights and varying base of support areas. The results revealed a suitable fit between the planned trajectories and the experimental trajectories for different conditions. It is demonstrated that a modular motion planner provides a higher accuracy and flexibility for the model to extend the planning process to various new conditions, yet still requires less computational complexity when compared with previous approaches. The proposed model is also supported by several behavioral and neurophysiological evidences.

Effect of a Cane on Sit-to-Stand Transfer in Subjects with Hemiparesis

The aim of this study was to determine the effect of using a cane on movement time, joint moment, weight symmetry, and muscle activation patterns during sit-to-stand (STS) transfer in healthy subjects and subjects who have had a stroke. Nine subjects with hemiparesis (mean [SD] age, 61.11 [12.83] yrs) and nine healthy adults (mean [SD] age, 63.11 [10.54] yrs) were included. The subjects with hemiparesis performed STS transfer in two randomly assigned conditions: (1) without a cane and (2) with a cane. The healthy subjects performed only STS transfer without a cane. A three-dimensional motion system, force plates, and eletromyography were used to examine STS transfer. The symmetry index between the two limbs was calculated. The movement time of the subjects with hemiparesis in both conditions without a cane and with a cane was longer than that of the healthy subjects without a cane (P < 0.025). However, STS transfer with a cane in the subjects with hemiparesis resulted in shorter movement time, greater knee extensor moment of the paretic limb, and more symmetry of weight bearing than in those without a cane (P < 0.05). The sequence of muscle onset tended to improve with a cane in the subjects with hemiparesis. Cane use may promote more symmetrical STS transfers rather than compensation by the unaffected limb.

Functional Muscle Power Testing in Young, Middle-Aged, and Community-Dwelling Nonfrail and Prefrail Older Adults

Zech A, Steib S, Freiberger E, Pfeifer K. Functional muscle power testing in young, middle-aged, and community-dwelling nonfrail and prefrail older adults. Objective To evaluate the stair climb (SC) and sit-to-stand (STS) transfer test for functional power assessment in young, middle-aged, and community-dwelling nonfrail and prefrail older adults. Design Cross-sectional study. Setting Sport science institute providing health-related exercise programs for older people. Participants Participants (N=60; age, 22–81y) were divided into groups of young (n=15; 20–30y), middle-aged (n=16; 40–60y), nonfrail older (n=16; >65y), and prefrail older adults (n=13; >65y). Interventions Not applicable. Main Outcome Measures SC and STS transfer power were measured on 2 separate occasions. Results Age and height correlated positively ( P<.001) with both power measures. Multiple linear regression analysis showed that 67.9% ( R 2) of the variance in SC power and 31.3% ( R 2) of the variance in STS transfer power can be attributed to age and height. Significant age-related subgroup differences were found for SC power ( P=.001). Nonfrail and prefrail older adults differed significantly in both power measures ( P<.001). Conclusions The findings indicate that SC and STS transfer power are sensitive enough to distinguish between nonfrailty and prefrailty. This suggests that both tests are relevant clinical measures in older people.

Investigating joint kinematics during a hoist-assisted sit-to-stand activity

Assisting individuals to stand up from a chair, or sit-to-stand (STS), is a physically demanding task restricted by manual handling regulations. If a hoist was able to produce a normal STS movement pattern this would offer a safe option for both therapist and patient, satisfying both therapeutic and manual handling criteria. Twenty-two healthy subjects participated in the study. Each subject completed STS with and without hoist assistance. Two hoists were used: the Sara 3000 and the Encore. The STS movements were captured on digital camera and the knee and trunk angles were calculated at point of seat-off for unassisted STS, Sara 3000 STS and Encore STS. Data were analysed using a repeated measures ANOVA. Trunk angles during STS using both hoists were found to be different (P &lt; 0.001) from that seen during normal STS. Knee angles measured when using the Sara 3000 hoist were different to those seen during unassisted (or normal) STS; however, knee angles at seat-off for the Encore hoist were similar to those seen during normal STS. This study analysed the movement patterns re-created by two hoists used in the clinical setting. Results showed that the Encore hoist is effective at re-creating normal knee angles at seat-off during the STS transfer, however, neither hoist is able to encourage the required normal trunk angle for independent STS.