T-Flex: A fully flexure-based large range of motion precision hexapod

The safe-zones for combined cup and neck anteversions that fulfill the essential range of motion and their optimum combination in total hip replacements

Stretch-shortening cycle characteristics during vertical jumps carried out with small and large range of motion

The increasing aging of the world population is accompanied by a rise in the incidence of knee osteoarthritis (KOA). There has been a growing interest in shockwave treatment for orthopedic diseases, including KOA. In previous trials, extracorporeal shockwave therapy (ESWT) was compared to physical therapy or placebo in the treatment of KOA. However, the efficacy and safety of ESWT for KOA remains disputed. The present meta-analysis assessed the effects of ESWT in KOA. The PubMed, Medline, Embase, Web of Science, Research Gate and the Cochrane Library were searched to identify comparative studies involving ESWT for patients with KOA. The outcome indicators included the visual analog scale (VAS) score, range of motion (ROM), the Lequesne index (LI) and the Western Ontario and McMaster Universities osteoarthritis index (WOMAC). In the comparison of the ESWT vs. placebo groups, the primary outcomes included the VAS score and ROM, while the LI was the secondary outcome. In the comparison of the ESWT vs. physical therapy groups, the primary outcomes included the pain score and ROM, while the secondary outcome was the WOMAC index. Relevant data were analyzed using RevMan v5.3. The ESWT group had a lower VAS core, larger ROM and a better LI than the placebo group after 1 month of therapy (P<0.05). Furthermore, at 1 month post-therapy, the ESWT group had a lower VAS score, larger ROM and a better WOMAC than the physical therapy group (P<0.05). The outcomes regarding pain, ROM, LI and WOMAC were significantly different between the two different groups (P<0.05). The present meta-analysis suggested that ESWT may achieve a better therapeutic effect for patients with KOA as compared to physical therapy. However, high-quality trials with large sample sizes are essential to substantiate these results.

BackgroundHorses commonly show asymmetries that manifest as left (L)-right (R) differences in vertical excursion of axial body segments. Moving on a circle confounds inherent individual asymmetries. Our goals were to evaluate individual and group asymmetry patterns and compare objective data with subjective impressions of side preference/laterality in horses walking on L and R circles.MethodsFifteen horses walked on L and R circles unridden and ridden on long and short reins. Optical motion capture (150 Hz) tracked skin-fixed markers. Variables were trunk horizontal angle; neck-to-trunk angle; vertical range of motion (ROM) for the head, withers and sacrum; ROM for pelvic roll, pitch, and yaw; mean pelvic pitch; and ROM for hip, stifle and tarsal joints. Differences between inside and outside hind steps were determined for vertical minima and maxima of the head (HMinDiff/HMaxDiff), withers (WMinDiff/WMaxDiff) and sacrum (PMinDiff/PMaxDiff). Subjective laterality was provided by owners. Data analysis used mixed models, first without and then with subjective laterality. Iterative k-means cluster analysis was used to associate biomechanical variables with subjective laterality.ResultsPMaxDiff, PMinDiff and WMaxDiff indicated R limb asymmetry in both directions. WMinDiff indicated L (inside) fore asymmetry for L direction but was close to zero for R direction. Hip ROM was significantly smaller for the inside limb in both directions (L inside/outside: 16.7° vs. 20.6°; R: 17.8° vs. 19.4°). Stifle ROM was significantly larger for the inside limb in both directions (L: 43.1° vs. 39.0°; R: 41.9° vs. 40.4°). Taking the general direction effect into account the R hip and L stifle had larger ROM. Adding laterality to the models (seven horses L- vs. six horses R-hollow), PMaxDiff R hind asymmetry was more obvious for L-hollow horses than for R-hollow horses. L-hollow horses had greater pelvic roll ROM moving in L vs. R direction. L-hollow horses had smaller inside and greater outside hip joint ROM in L vs. R direction. R-hollow horses had a significant difference in HMinDiff between L (0 mm) and R (−14 mm) directions, indicating less head lowering at outside forelimb midstance in R direction, and larger outside tarsal ROM in R (38.6°) vs. L (37.4°) direction (p ≤ 0.05). The variables that agreed most frequently with subjective laterality in cluster analysis were pelvic roll ROM, followed by HMinDiff and PMaxDiff.ConclusionDifferences between horses walking in L and R directions were found both at group and individual levels, as well as evidence of associations with subjective laterality. Horses maintained more symmetric hip and stifle ROM and withers vertical motion when walking on the R circle. Findings suggest that left and right lateralised horses may not be perfect mirror images. Pelvic roll ROM emerged as a promising variable to determine laterality in walk as perceived by the rider, especially when considered together with other variables.

Stretching techniques like proprioceptive neuromuscular facilitation (PNF) or tissue work, like foam rolling (FR), are assumed to increase the range of motion (ROM), but little is known about consecutive adaptations in complex movement techniques. The study aimed to quantify short-term adaptations in the squat movement due to the potentially raised ROM after FR or PNF stretching. Forty young adults (20 females) participated in the study. The intervention group applied PNF stretching or FR in a cross-over design between the first and the second set of five squats, whereas the control group rested. After each set of squats, a questionnaire measured easiness, smoothness, and enjoyment using visual analog scales. Ankle ROM and hamstring flexibility were tested using the Weight-Bearing Lunge Test (WBLT) and the Stand and Reach Test (SaR). The squat movement was assessed through joint angles, specifically including the pelvis motion, utilizing a motion capture system (250 Hz). Results of rANOVAs show a significantly higher ROM increase in the intervention group than in the controls (p = 0.006 for FR and p &lt; 0.003 for PNF in WBLT and SaR, respectively). Angle pathways did not change. After the second set, all groups recorded enhanced perceptions of ease, smoothness, and enjoyment. Interestingly, the larger ROM did not change the squatting motion. In conclusion, both interventions increased ROM in direct ROM tests. However, ankle dorsiflexion and pelvic tilt in squatting, hypothesized to be constrained by ROM, did not change.

Background Previous studies on computed tomography (CT) in patients with a suspected triangular fibrocartilage complex (TFCC) injury have not been successful in assessing distal radioulnar joint (DRUJ) laxity. The aim of this study was to develop a novel servomotor-driven device for the assessment of DRUJ by applying increasing torque to the DRUJ in pronation and supination. Methods A custom-built device was designed to function during four-dimensional (4D) CT of the wrist. A torque meter, positioned between the incoming hand holder, and a direct current (DC) servomotor were used for angular positioning and for applying rotational force to the patient's arm. A total of 110 healthy participants were recruited to gather reference values for the range of motion (ROM), maximum torque in neutral and supinated/pronated position, and the ability to withstand an increasing, device-generated torque in these positions. The device was also used during 4D DRUJ CT in five patients with suspected TFCC injuries. Results A gender- and age-relevant reference chart for ROM and torque was created. Men showed a tendency (ns) toward having a larger ROM and increasing strength with increasing age, whereas women showed the opposite. Also, the dominant hand showed a tendency toward having a larger ROM and being stronger than the nondominant hand (ns). A smaller cohort of patients ( n = 5) with suspected TFCC injuries showed a significantly decreased ability to withstand increasing torque in both supination (2.1 ± 0.3 vs. 3.1 ± 0.2 s; p < 0.005) and pronation (2.3 ± 0.5 vs. 3.1 ± 0.4 s; p < 0.0005) and also showed a clear laxity on real-time 4D CT image sequences. Decreased strength at all positions was also found (average 74% decrease compared to noninjured side). Conclusion Reference values for torque strength and ability to withstand increasing torque can be used clinically in the assessment of patients with symptoms that could represent ligamentous injuries to the TFCC. The ability to use the device during CT enables radiographic evaluation of instability during increasing torque. Level of Evidence This is a Level II study.

Biomechanical effect of implantation of an artificial disc (AD) was investigated using the nonlinear three-dimensional finite element model of L4-L5. The SB CHARITE and the Prodisc were chosen as the representative prosthesis of unconstrained and constrained ADs (UADs and CADs) and compared with the intact human intervertebral disc. To investigate the effect of implantation of an AD to spinal functional unit and to evaluate the difference between the unconstrained and constrained models. Intact osteoligamentous L4-L5 finite element model was created with 1-mm computed tomography scan of a cadaveric spine and known material property of each element. Two models implanted with ADs, unconstrained or constrained model, were also developed. The implanted model predictions were compared with that of the intact. Range of motion, force on the spinal ligaments, force on the facet joint, stress on the vertebral body and vertebral endplate with flexion/extension, lateral bending, and axial rotation under 400 N compressive preload were compared among the models. The implanted models showed increased range of motion in flexion/extension, lateral bending, and axial rotation compared with that of the intact. Under 6-Nm moment, the range of motion were 140%, 170%, and 200% of intact in the UAD model and 133%, 137%, and 138% in the CAD model to each direction of loading. The forces on each ligament were different among the models with various loading conditions. Force on the facet, stress on the vertebral body and vertebral endplate were much larger in implanted model, especially in the CAD model. By the result of this study it is obvious that implanted segment with AD has large range of motion and suffers from increased loading to surrounding bone and ligaments. The UAD has larger range of motion but exert less loading to the implanted segment than the CAD. It seems that the mobile center of rotation of the UAD has the ability to lessen the facet contact force and stress on the vertebral body.

Three-dimensional movements of the pelvis and the lumbar intervertebral joints in walking and trotting dogs

Objective: To complement the clinical assessment of motor impairment after incomplete spinal cord injury (iSCI) by introducing a test that reliably distinguishes between muscle weakness (paresis) and impairment of dexterity in a simple foot motor task.Methods: Auditory-paced ankle dorsi- and plantarflexion, in a supine position, was studied in 30 controls (to establish control values and to test reliability) and in 16 iSCI patients (test validation). The subjects were instructed to initiate dorsi- and plantarflexion as accurately in timing and with the largest range of motion (ROM) possible. For each frequency, accuracy of timing, ROM, peak velocity of dorsi- and plantarflexion and a time quotient for changing from dorsi- to plantarflexion and vice versa were determined. In iSCI subjects, these parameters were related to clinical measures of paresis, spasticity and proprioception.Results: The test parameters showed good to very good reliability. The iSCI subjects were able to follow the target frequency with high accuracy, while ROM and peak velocity for dorsi- and plantarflexion were significantly reduced. Furthermore, there was a strong correlation between ROM/peak velocities and motor scores within the iSCI patients.Discussion: Repetitive foot dorsi- and plantarflexion enables a distinction to be made between muscle weakness and reduced dexterity as the underlying cause of affected foot control. This distinction between and quantification of these two movement components complements the existing clinical examination, and in follow-up works, the recovery of these components may provide further insight into the mechanisms underlying motor function improvement after iSCI.

Large stroke high off-axis stiffness three degree of freedom spherical flexure joint

In developing a shoulder prosthesis, in addition to appropriate payload and range of motion under the constraints of weight and shape, impact absorption is very important for safe use. Hybridization of two different actuators (pneumatic elastic actuators with the features of lightness and intrinsic visco-elasticity, and servo motors that have stable torque and a large range of motion in combination with an antagonistic mechanism) was employed to achieve the development of the shoulder prosthesis. A two-link, two-degree-of-freedom arm was used to test the different hybridization configurations in order to investigate the impact absorption. A dynamic simulation platform based on four bimanual activities of daily living was established to obtain the required range of motion and torque for joints of a two-link, four-degree-of-freedom arm. The number of pneumatic elastic actuators required and the dimension of the antagonistic mechanism mechanical structures were optimized using the dynamic simulation platform. The best configuration of the two types of actuators was determined using the dynamic simulation based on the impact absorption results and other criteria. Moreover, a simplified prototype driven by hybrid actuation was made. It was shown that the pneumatic elastic actuator joint could improve impact absorption, and the actuator configuration of shoulder prostheses is activity of daily living dependent. The prototype could reproduce a certain activity of daily living motion, indicating its feasibility in daily living.

Reaching movements are often used to assess selective trunk control in people with neurological conditions. Also, it is known that reaching performance after stroke is increased through training on a mobile seat compared to conventional physical therapy. However, the effect of a mobile seat on joint kinematics has not yet been investigated. This study aimed to quantify differences in the range of motion of the hip and trunk during reaching exercises on a mobile and stable sitting surface. Fifteen healthy participants performed reaching beyond arm's length on a mobile and a stable seat in four different directions: ipsilateral, anterior, contralateral, and contralateral diagonal. Biomechanical data were collected, including kinematics of the hip and trunk, and surface electromyography of the trunk muscles. The mobile sitting surface led to a higher range of motion in the trunk and the hip in the frontal and sagittal plane, but not in the rotational plane. Differences between reaching directions were found in all joint directions, except that of trunk flexion. Hence, movement patterns of the hip and trunk differ during reaching on different sitting surfaces and in different directions. A larger range of motion in the frontal or sagittal plane while training on the mobile seat provides added neuromuscular stimuli to the trunk muscles (= a higher demand on trunk muscles), which could result in more efficient training and therefore, increased trunk control after stroke. However, this has to be investigated in a future study with people after stroke.

This paper presents a flexure revolute joint with a large range of motion which can be used as a joint in a parallel robot with a large workspace. We proposed a new structure of flexure revolute joint. The joint consists of leaf springs which are symmetrically arranged between two frames. The shape of the frame is like a spiral stairs. Arrangement of leaf springs was proposed taking into consideration the axis drift and stiffness characteristics of the joint while achieving a large range of motion. Characteristics of the proposed joint were investigated by Finite Element Analysis (FEA) and experiments. A planar parallel robot with two degrees of freedom using the proposed joints was designed and fabricated. Its workspace, position repeatability and stiffness were experimentally investigated.

The flexure hinge is a key element in compliant mechanisms to achieve continuous motion; however the motion range of a flexure hinge is severely restricted by the material’s allowable strain. Due to the superelasticity effect, shape memory alloys (SMAs) can undergo much larger strain than other metals; this means that they are excellent candidates for the fabrication of flexure hinges with a large motion range. In this paper, a simple static deformation modeling approach is proposed for a flexure hinge made of a SMA. The superelastic behavior of the SMA is described by Brinson’s constitutive model. The flexure hinge is considered as a non-prismatic cantilever beam associated with geometrical and material nonlinearities. Govern equations of the flexure hinge are derived and solved numerically by applying the nonlinear bending theory of the Euler–Bernoulli beam. Experimental tests show that the proposed modeling approach can predict the deformation of the flexure hinge precisely; the maximum relative error is less than 6.5%. Based on the static deformation model, the motion capacity, the stiffness characteristic and the rotational error of the flexure hinge are also investigated. The results reveal that the flexure hinge made of a SMA has great potential to construct compliant mechanisms with a large motion range.

Objective To investigate biomechanical analysis of poly DL-lactic acid (PDLLA)biodegradable fusion cage of the lumbar vertebrae in vivo degradation. Methods Forty-eight healthy adult porcine were divided into experimental group and control group at randomly. PDLLA cage full of autogenous bone and bone block with the same size were planted in L45 intervertebrae respectively. At the 1st, 3rd, 6th,9th, 12th, and 18th month postoperatively, the animals were sacrificed and the surgical spinal segment was observed. The range of motion (ROM) was measured. Results The ROMs had no statistical differences at all motion directions between the two froups at the 1st month postoperatively. But the ROMs of experimental group were greater than those of control group at extension direction at the 3rd and 6th month postoperatively. The ROMs of extension was the greatest while the ROMs of right rotation was the least in both groups. At the 9th month postoperatively: the ROMs of experimental group greater than those of control group except at rotation. The ROMs of right rotation was the least in both groups. The greatest ROMs was at extension in experimental group and at right bending in control group. ALL ROMs tended to decrease and the ROMs of extension had comparability between tow groups. At the 12th month postoperatively, experimental group had greater ROMs at extension and left bending and less ROMs at other directions. Likewise statistical differences showed only at extension. 18th month postoperatively all ROMs were close between two groups. Conclusion After PDLLA cage is planted, the first 3 months is autologous stable stage. The period of 3rd to 6th months is easily released stage. The operative segments are stable from 9th to 12th months and acquired.Critical period between stability and instability is from 6th to 9th months. Bone fusion is from 12th to 18th months postoperatively. Key words: Lumbar vertebrae; Spinal fusion; Biomechanics