Torsional Resistance Research Articles

Elastic Limits in Torsion of Reciprocating Nickel-Titanium Instruments

IntroductionReciprocating angle and torsional load at the superelastic limit were investigated for nickel-titanium (NiTi) instruments used with reciprocating movements. MethodsTwo reciprocating NiTi instruments (Reciproc R25 [VDW, Munich, Germany] and WaveOne Primary [Dentsply Maillefer, Ballaigues, Switzerland]) and ProTaper F2 (Dentsply Maillefer) were tested for 2 torsional conditions using a custom-designed testing device. Rotational angles were applied, and generated torque values were recorded. The first test condition fixed the files at 5 mm and repetitively rotated them with gradually increasing angles up to 250° (n = 10). The second test subjected the files to a single continuous rotation until fracture (n = 10). The superelastic limits of the instruments were determined from their torque-rotation curves. Statistical analysis was performed (Kruskal-Wallis) at a 95% significance level. The tested specimens were examined under a scanning electron microscope. ResultsIt was found that the angle at the superelastic limit was higher for R25 and Primary files than the ProTaper file (P < .05). Repetitive torsional loading with a gradually increasing rotational angle reduced the torsional resistance compared with the single rotation motion. At the 5-mm fixation level all files had superelastic limit angles higher than the 170° set in the dedicated reciprocating motor. The scanning electron microscopic analysis showed features of torsional failure. ConclusionsUnder the conditions of this study, the 170° set angle of dedicated motors for reciprocating file systems is safe at the 5-mm level. Reuse of reciprocating systems, even with the movements within the elastic limit, may cause deterioration of the instruments.

Torsional and cracking characteristics of steel fiber-reinforced oil palm shell lightweight concrete

The study presents the investigations of the torsional behavior and crack resistance of a sustainable lightweight oil palm shell (OPS) concrete. In the comparison between the OPS concrete (OPSC) and normal weight concrete (NWC), the torsional failure of the NWC was sudden and brittle, while the OPSC exhibited post-cracking behavior. The second part of the study examines the effect of steel fibers of 0.25–1.00% in the OPSC to produce OPS fiber-reinforced concrete (OPSFRC). Improved mechanical properties and reduced brittleness were reported in the OPSFRC mixes. The addition of 1% steel fibers in the OPSC-100 mix produced the highest compressive and flexural strengths of 47 MPa and 8.2 MPa, respectively. The steel fibers up to 1% enhanced the ultimate torque, torsional toughness, and twist at failure of the OPSFRC specimens by 60%, 1000%, and 550%, respectively. The addition of steel fibers significantly improved the crack resistance of the OPSFRC specimens.

Torsional Behavior Design of UHPC Box Beams Based on Thin-Walled Tube Theory

This study proposed a prediction formula for the torsional strength enabling to reflect the tensile strength of ultra high performance concrete (UHPC) beams based upon the thin-walled tube theory. The remarkable ductile behavior of UHPC can also be attributed to the steel fiber reinforcement. This feature must be considered to provide rational explanation of the torsional behavior of UHPC structures. In this study, the proposed torsional design adopts a modified thin-walled tube theory so as to consider the tensile behavior of UHPC. And torsion test was conducted on thin-walled UHPC box beams to validate the proposed formula through comparison of the predicted torsional strength with the experimental results. The comparison of the predicted values of the cracking torque and torsional moment resistance with those observed in the torsional test of UHPC verified the validity of the design method. The contribution of the steel fibers to the torsional strength and cracking load was larger than that of the stirrups, but the stirrups appeared to contribute additionally to the torsional ductility. Accordingly, it is recommended that design should exploit effectively the contribution of the steel fiber rather than arrange a larger number of stirrups in UHPC structures subjected to torsion.

Deformations and cyclic fatigue resistance of nickel-titanium instruments inside a sequence

To compare the effect of brushing motion on torsional and cyclic fatigue resistance of TF Adaptive instruments after clinical use. 20 packs of TFA small sequence (SybronEndo, Orange, CA, USA) were used for this study and divided into two groups. Each instrument prepared one resin tooth, consisting in 4 canals with a complex anatomy. In group A, no brushing motion was performed. In group B, after the green instrument reached the working length, brushing motion with circumferential filing was performed for 15 seconds in each canal (overall 1 minute). All the instruments were then subjected to cyclic fatigue test and mean values and standard deviation for time to fracture were evaluated. Data were subjected to one-way analysis of variance and Bonferroni t-test procedure with a significance set at P < 0.05. No instruments were broken during preparation of root canals. Two TF Adaptive green and 5 yellow showed unwinding after intracanal clinical use. No statistically significant differences were found between green instruments of both groups (P > 0.05), while a statistically significant difference was found between the yellow instruments (P < 0.05), with group B showing an higher resistance to cyclic fatigue. A prolonged passive brushing motion did not adversely affected mechanical resistance of the instrument used for this purpose. Resistance to both deformations and cyclic fatigue of the second instrument within the TFA small sequence was enhanced by the coronal flaring provided by the brushing action of the first instrument used.

Torsion and Bending Properties of OneShape and WaveOne Instruments

IntroductionThe purpose of this study was to compare the torsion and bending properties of OneShape (OS; Micro Mega, Besançon, France) and WaveOne (WO; Dentsply Maillefer, Ballaigues, Switzerland) single-file systems. MethodsThe torsional strength of OS size #25, 0.06 taper and WO primary size #25, 0.08 taper was measured by using a torsiometer after fixing the apical 5 mm of the instrument rigidly. A scanning electron microscope was used to characterize the topographic features of the fracture surfaces of broken files. The files were tested for bending resistance by using the cantilever bending test. Data were statistically analyzed using the independent t test. Statistical significance level was set at P < .05. ResultsWO had a significantly higher torsional resistance than OS (P < .001). The average bending resistance as measured by the maximum force (gf) to bend instruments revealed that the WO had a significantly lower resistance to bend than OS (P < .001). Scanning electron microscopic analysis of the fractured cross-sectional surfaces revealed typical features of torsional failure including skewed dimples near the center of the fracture surface and circular abrasion streaks. ConclusionsThe WO single-file system showed higher torsional resistance and flexibility than the OS single-file system. Different cross-sectional geometry and the alloy from which the instrument is manufactured could have significant influence on the torsional resistance and flexibility of the instruments.

Effect from surface treatment of nickel-titanium rotary files on the fracture resistance.

This study was aimed to compare the cyclic fatigue resistance and torsional resistance of rotary instruments with and without surface treatment. G6 A2 (Group A2) with and G6 A2 without surface treatment after machining (Group AN) were compared in this study. ProTaper F2 (Group F2) which has similar dimension and shape was also used for comparison. To evaluate the torsional resistance, ultimate torsional strength and distortion angle until fracture were recorded, and the toughness was calculated. The cyclic fatigue resistance was compared by evaluating the number of cycles to failure in a simulated canal. Statistical analysis was performed by one-way analysis of variance and Tukey post hoc test (p = 0.05). After torsional and cyclic fatigue tests, all fracture fragments were observed under a scanning electron microscope. Group A2 showed higher cyclic fatigue resistance than the groups AN and F2 (p < 0.05). Although group A2 demonstrated lower ultimate torsional strength than the others, there were no significant differences in toughness among the groups. While obvious machining grooves were seen in groups AN and F2, group A2 showed smooth surface resulting from the surface treatment. The specimens of fracture fragments showed typical features of cyclic failure such as micro-cracks, overloaded fast fracture zone, and torsional fracture such as unwinding helix, circular abrasion marks and dimples. Under the conditions of this study, the surface treated instruments may improve cyclic fatigue resistance while maintaining the torsional resistances and mechanical properties.

Lateral–torsional buckling resistance of cellular beams

The evenly spaced circular web openings in I-section cellular beams have an advantageous effect on the material use if these beams are loaded in strong-axis bending. However, not all aspects of the behaviour of such beams have been studied adequately, such as the lateral–torsional buckling failure. For the latter failure mode, the existing design approaches conflict.Furthermore, the detrimental effect of the modification of the residual stresses by the production process, as recently demonstrated by the authors in previous work, was never taken into account.In this paper, the lateral–torsional buckling behaviour of cellular beams is investigated using a numerical model that was validated based on experimental results. In this model, the effect of the modified residual stress pattern was aptly taken into account. Using the results of the parametric study, a preliminary design approach was proposed. This approach is based on the currently existing European guidelines for the calculation of the lateral–torsional buckling resistance of I-section beams, but with a modified calculation of the cross-sectional properties and a modified buckling curve selection.

Effect of a Combination of Torsional and Cyclic Fatigue Preloading on the Fracture Behavior of K3 and K3XF Instruments

IntroductionThe purpose of this study was to evaluate the effect of various degrees of cyclic fatigue on torsional failure and torsional preloading on the cyclic fatigue life of heat-treated K3XF nickel-titanium (NiTi) instruments (SybronEndo, Orange, CA). MethodsThe mean number of cycles until failure (Nf) of K3XF and K3 NiTi instruments was examined in a 3-point bending apparatus with a 7-mm radius and 45° curve. Torque and distortion angles at failure of new instruments and instruments stressed to 25%, 50%, and 75% of the Nf were measured according to ISO 3630-1. Other new files were preloaded at 25%, 50%, and 75% of the mean distortion angles before the fatigue test. After torsional preloading, the Nf was examined. The fracture surface of each fragment was examined with a scanning electron microscope. ResultsThe fatigue resistance of K3XF instruments was 2 times higher than that of K3 instruments (P < .05). The torque and angle of rotation at fracture of K3XF instruments were similar to those of K3 instruments. The 25%, 50%, and 75% torsional preloading significantly lowered the Nf of both K3 and K3XF instruments (P < .05). In the fatigue prestressed groups, K3 instruments with 75% preloading had significantly lower torque and distortion angles than unused K3 instruments (P < .05). The fractographic patterns corresponded to the pattern defined by the last stage test. ConclusionsA low amount of torsional preloading reduced the fatigue resistance of K3 and K3XF instruments. A high amount of precycling fatigue significantly reduced the torsional resistance of K3 instruments. The torsional resistance of K3XF instruments was less affected by previous load cycling even after extensive precycling.

Torsion design implications from shake‐table responses of an RC low‐rise building model having irregularities at the ground story

SummaryA 1:5 scale five‐story RC building model having the irregularities of a soft/weak story and torsion at the ground story was subjected to a series of earthquake simulation tests. The test results reveal the following: The eccentricity varied from zero to infinity with the values of base shear and torque bounded by some limits. As the intensity of table excitations increased, representing earthquakes with return periods from 50 to 2500 years in Korea, the range of eccentricities at the peak values in the time histories of drift and base shear decreased from approximately ±30% to within ±10% of the transverse dimension of the model. The inertial torque was resisted by both longitudinal and transverse frames, in proportion to their instantaneous rigidity. Yielding of the longitudinal frames under severe table excitations caused a substantial loss in their instantaneous torsional resistance and thereby transferred most of the large torque to the transverse frames, resulting in a significantly degraded torsional stiffness with an enlarged torsional deformation despite almost zero eccentricity. From these observations, it is clear that the eccentricity in itself cannot represent the critical torsional behaviors. To overcome this problem, the demand in torque shall be determined in a direct relationship with the base or story shear, given as an ellipse constructed with the maximum points in its principal axes located by the two adjacent torsion‐dominant modal spectral values. This approach provides a simple but transparent design tool by enabling comparison between demand and supply in shear force–torque diagrams. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Retracted: Relationship between Installation Torque and Axial Capacities of Helical Piles in Cohesionless Soils

AbstractWith the rapid growth of the helical piling industry, reliable installation torque estimates and measurements become crucial. This paper presents a theoretical model developed to estimate the torsional resistance of cohesionless soils to helical pile installation. The theoretical torque model was verified using installation records collected from different sites. The paper also highlights factors that affect helical pile installation including soil properties, fluctuation in groundwater levels, shape of pile shaft, pile geometry, and method of helical pile installation. Torque factors, Kt, commonly used in the industry to correlate between installation torque and pile capacities, were also assessed and presented in the paper. The results of the study indicated that the torque factor is a function of the load path (i.e., tension or compression). Therefore torque factors in compression and tension, Kc and Kt, were formulated and presented in the paper.

Static analysis of a Guastavino helical stair as a layered masonry shell

An analytical structural study of general helicoidal timbrel shells is presented. The study is concerned in particular with Guastavino staircases based on a circular planform. Such stairs are composite masonry structures formed by a two or three layers of tiles disposed in a herringbone-pattern. The analysis is based on the assumption that the material is unilateral, namely a No-Tension material in the sense of Heyman; in particular the safe theorem of Limit Analysis is employed. In the spirit of the safe theorem the structure is stable if a statically admissible stress field can be constructed; for the unilateral material here employed, singular stress fields, that is stress concentrated on surfaces (membranes) or lines (arches) are allowed. The statically admissible stress fields that are constructed, combining membrane stresses and 3d diffuse uniaxial stresses, are purely compressive and balance transverse loads either uniformly distributed or localized. A simple order-of-magnitude calculation confirm that bending and torsion resistance is small compared to the structural demand, and that a purely compressive membrane equilibrium stress field is required; the level of compressive stresses required to balance the load is below the limit compressive threshold.

Nonlinear Deformation Behavior of Bolted Flanges Under Tensile, Torsional, and Bending Loads

A bolted flange may be subjected to the axial tensile, torsional, and bending external loads in service. The axial tensile, torsional, and bending resistance of the bolted flange is vital for the system vibration, dynamic strength, and reliability. This paper investigates the nonlinear deformation behavior of bolted flanges under tensile, torsional, and bending loads, using finite element analysis (FEA). Even though the bolted flange materials may still deform elastically, the variation in contact area due to the external loading may still cause nonlinear deformation of the flanges. In this study, finite element simulation is used for investigating the respective nonlinear deformation behavior of a preloaded bolted flange under tensile, torsional, and bending loads, and to determine the corresponding stiffness values for each loading.

Assessment of the Mechanical Properties of ProTaper Next Nickel-Titanium Rotary Files

IntroductionThe purpose of this study was to compare the torsional resistance, flexibility, and surface microhardness of ProTaper Next files (PTN) with Twisted Files (TF) and RaCe (RC). MethodsA metal block with a cubical hole was used to evaluate the torsional resistance. Five millimeters of the tip of each file was securely held in place by filling the mold with a resin composite, and the files were driven clockwise at 300 rpm. The number of load applications before fracture was recorded for each file. A scanning electron microscope was used to characterize the topographic features of the fracture surfaces of the broken files. The files were tested for bending resistance by using cantilever-bending test. Vickers microhardness was measured on the cross section of instruments with 300-g load and 15-second dwell time. Torsional resistance data were analyzed by using the nonparametric Kruskal-Wallis and Mann-Whitney U tests. Bending resistance and microhardness data were analyzed by using analysis of variance and Tukey tests. ResultsPTN showed the highest torsional resistance and microhardness, followed by RC (P < .05). The fracture cross sections of all brands showed dimpling near the center of fracture surface. The ranking in the bending resistance values was as follows: RC > PTN > TF. ConclusionsPTN improved its resistance to torsional stresses and wear compared with TF and RC. TF showed improved flexibility compared with other tested brands.

Improvement of open and semi-open core wall system in tall buildings by closing of the core section in the last story

Increasing number of tall buildings in urban population caused development of tall building structures. One of the main lateral load resistant systems is core wall system in high-rise buildings. Core wall system has two important behavioral aspects where the first aspect is related to reduce the lateral displacement by the core bending resistance and the second is governed by increasing of the torsional resistance and core warping of buildings. In this study, the effects of closed section core in the last story have been considered on the behavior of models. Regarding this, all analyses were performed by ETABS 9.2.v software (Wilson and Habibullah). Consid- ering (a) drift and rotation of the core over height of buildings, (b) total and warping stress in the core body, (c) shear in beams due to warping stress, (d) effect of closing last story on period of models in various modes, (e) relative displacement between walls in the core system and (f) site effects in far and near field of fault by UBC97 spectra on base shear coefficient showed that the bimoment in open core is negative in the last quarter of building and it is similar to wall-frame structures. Furthermore, analytical results revealed that closed section core in the last story improves behavior of the last quarter of structure height, since closing of core section in the last story does not have significant effect on reducing base shear value in near and far field of active faults.

Safety of the Factory Preset Rotation Angle of Reciprocating Instruments

IntroductionThis study aimed to investigate the torsional resistance of 2 reciprocating nickel-titanium instruments (Reciproc [VDW, Munich, Germany] and WaveOne [Dentsply Maillefer, Ballaigues, Switzerland]) operated at the maximum rotating angle in a proprietary motor. MethodsWith the file tip secured at various levels (3, 4, or 5 mm) of Reciproc R25 and WaveOne Primary, the distortion angles and torsional loads were monitored during counterclockwise movement at 2 rpm until fracture (n = 10 at each level) for a load-distortion graph. The rotation angles and loads at the beginning point of the plateau, the ultimate torsional strength, final fracture angle, and toughness were determined. The data were analyzed using 1-way analysis of variance and the Tukey post hoc test at α = .05. The lateral longitudinal aspect and the fracture cross-section of each specimen were examined by scanning electron microscopy after the test. ResultsThe rotation angle at the beginning point of the plateau was significantly greater for a binding site farther away from the tip of the instrument for both systems (P < .05), and all were greater than 170° (preset in the dedicated motor from manufacturer). The ultimate strength and toughness also increased significantly at levels farther away from the instrument tip (P < .05). All specimens showed typical topographic features of torsional fracture, including the circular abrasion marks and fibrous dimples near the rotation center after the test. ConclusionsIt was determined that the 2 brands of reciprocating files are safe when operated at the rotational angle in the proprietary motor.

HSS-to-HSS seismic moment connection performance and design

Abstract Hollow structural sections (HSS) provide an alternative to typical wide flange sections in low-rise seismic moment resisting frames. Their beneficial strength-to-weight ratio as well as bending, compression, and torsional resistance increases the versatility of moment frames and potentially improves performance under earthquake loads. With an understanding of current design requirements for seismic moment connections and static HSS-to-HSS connections, 39 fully welded unreinforced HSS-to-HSS connections are explored through finite element analyses. However, performance is limited due to column face plastification and inability to develop the plastic moment capacity of the beam. To rectify this problem, 24 through plate and 24 external diaphragm plate HSS-to-HSS moment connections are analyzed. Several important geometric parameters, such as the beam width–column width ratio, beam thickness–column thickness ratio, plate length, and plate thickness are considered to understand their effect on the connection moment capacity and sources of inelastic rotation. The through plate and external diaphragm reinforcement greatly improve the connection behavior moving yielding away from the column face and into the beam member. The results from the reinforced connections are used in combination with current seismic design provisions to develop a design procedure that optimizes the performance of these connections. The reinforced connections can be detailed to develop plastic hinging in the HSS beam member while minimizing the likelihood of a non-ductile weld failure.

Biomechanical and histological evaluation of roughened surface titanium screws fabricated by electron beam melting.

BackgroundVarious fabrication methods are used to improve the stability and osseointegration of screws within the host bone. The aim of this study was to investigate whether roughened surface titanium screws fabricated by electron beam melting can provide better stability and osseointegration as compared with smooth titanium screws in sheep cervical vertebrae.MethodsRoughened surface titanium screws, fabricated by electron beam melting, and conventional smooth surface titanium screws were implanted into sheep for 6 or 12 weeks (groups A and B, respectively). Bone ingrowth and implant stability were assessed with three-dimensional imaging and reconstruction, as well as histological and biomechanical tests.ResultsNo screws in either group showed signs of loosening. Fibrous tissue formation could be seen around the screws at 6 weeks, which was replaced with bone at 12 weeks. Bone volume/total volume, bone surface area/bone volume, and the trabecular number were significantly higher for a define region of interest surrounding the roughened screws than that surrounding the smooth screws at 12 weeks. Indeed, for roughened screws, trabecular number was significantly higher at 12 weeks than at 6 weeks. On mechanical testing, the maximum pullout strength was significantly higher at 12 weeks than at 6 weeks, as expected; however, no significant differences were found between smooth and roughened screws at either time point. The maximum torque to extract the roughened screws was higher than that required for the smooth screws.ConclusionsElectron beam melting is a simple and effective method for producing a roughened surface on titanium screws. After 12 weeks, roughened titanium screws demonstrated a high degree of osseointegration and increased torsional resistance to extraction over smooth titanium screws.

Torsional and cyclic fatigue resistances of glide path preparation instruments: G-file and PathFile.

This study aimed to compare cyclic fatigue and torsional resistances of glide path creating instruments with different tapers and tip sizes. Two sizes (G1 and G2) from G-File system and three sizes (PathFile #1, #2, and #3) from PathFile system were used for torsional resistance and cyclic fatigue resistance tests (n = 10). The torsional resistance was evaluated at 2-, 3-, 4-, 5-, and 6-mm from the file tip by plotting the torsional load changes until fracture by rotational loading of 2 rpm. The cyclic fatigue resistance was compared by measuring the number of cycles to failure. Data were analyzed statistically using one-way ANOVA and Duncan's post-hoc comparison. The length of the fractured file fragment was also measured. All fractured fragments were observed under a scanning electron microscope (SEM). Although G-2 file showed a lower torsional strength than PathFile #3 at 2- and 3-mm levels (p < 0.05), they had similar ultimate strengths at 4-, 5-, and 6-mm levels (p > 0.05). The smaller files of each brand had a significantly higher cyclic fatigue resistance than the bigger ones (p < 0.05). PathFile #1 and #2 had higher fatigue resistances than G-files (p < 0.05). While G-1 had a similar fatigue resistance as PathFile #3, G-2 showed the lowest and PathFile #1 showed the highest resistances among the tested groups (p < 0.05). The SEM examination showed typical appearances of cyclic fatigue and torsional fractures, regardless of the tested levels. Clinicians may consider the instruments' sizes for each clinical case in order to get efficient glide path with minimal risk of fracture.

Parametric studies on the lateral restraints of pile caps in soil

The general behaviours of pile caps with vertical rectangular faces embedded in soil mass idealised as a semi-infinite elastic continuum under lateral shears and on-plan torsions are discussed in this paper. Approaches based on the elastic continuum theory with consideration of the soil pressure limited to the passive pressure values have been formulated for the estimation of lateral displacements and on-plan rotations of the pile cap. Based on the findings, parametric studies are then conducted with the production of tables for users to estimate the lateral translational and torsional resistances of pile caps and subsequently, their displacements and rotations under lateral shears and/or on-plan torsions. These tables, though not exactly reflecting the true elasto-plastic behaviour, give conservative results which are also fairly accurate as compared with that yielded by the elasto-plastic theory. The tables can therefore serve as a quick check for users without going into more sophisticated analyses suc...

Shoe torsional resistance related to medial knee oa

Purpose: Recent evidence suggests that footwear can significantly affect dynamic knee loading and that flat, flexible shoes may result in lower knee loads compared to more supportive, stiff-soled shoes. Here, we evaluate the torsional stiffness of the shoe compared longitudinal effects on knee loading over 6 months. Methods: Subjects with radiographic (KL grades ≥ 2) and symptomatic (at least 30mm pain of 100mm scale while walking) medial compartment knee OA were recruited and randomized to receive a flexible soled shoe (mobility shoe) or identical appearing “control” shoe with stiffer sole. The frontal plane torsional stiffness of the shoe was evaluated using a biomaterial testing system. Investigators and participants were blinded to shoe assignment. Baseline gait analyses were performed using an optoelectronic camera system and multi-component force plate in subjects’ “own shoes”, study shoes, and barefoot. Subjects were instructed to wear the study shoes at least 6 hours/day for 6 days/week. Gait analysis was repeated at 6, 12 and 24 weeks. The peak knee adduction moment (KAM), a validated marker of medial compartment loading, was evaluated. An intent-to-treat analysis was performed with imputation of missing data using a hot deck method (Rubin, 1987). Repeated measures analysis of variance compared the two arms and planned contrasts were used to further analyze the data and load reductions at various time points. Results: 22 participants (13 women, mean age 55±7 years) were assigned to the mobility shoe and 28 (21 women, mean age 55±8 years) to the control shoe. The median modulus of elasticity of the treatment group shoes was 0.25±0.07 compared to the control shoe 0.94±1.05 (p=0.009). There was a strong correlation between the reduction in the KAM and torsional stiffness from baseline to 24 months in treatment group and control group (0.88 and 0.89 respectively p=0.03) There were differences in Peak KAM over time in the treatment group vs. control with the more flexible shoe producing reductions while the control increased moments (-0.25 ±0.95 and 0.09 ±0.95 %BW*ht respectively, rmANOVA, p=0.002). Conclusions: This double-blind randomized controlled trial suggests that loading of the medial knee is directly related to the torsional stiffness the shoe. The use of shoes with flexibility in the frontal plane over 6 months results in significant reductions in medial knee loading compared to stiffer shoes with greater torsional resistance. Thus, evaluating the shoe for torsional resistance may help determine which shoe would be an effective biomechanical intervention for the management of knee OA.