Groove Radius Research Articles

Influence of process layouts of multi-roll solid-liquid cast-rolling bonding process on circumferential performance uniformity during fabricating metal cladding materials

The twin-roll casting (TRC) process is typically used to fabricate laminated metal cladding strips with rectangular cross-sections, and it has the advantages of short flow, low energy consumption, green environmental protection, etc. Recently, a twin-roll solid-liquid cast-rolling bonding (TRSLCRB) process was proposed based on the TRC process to fabricate metal cladding materials with round cross-sections. However, the nonuniformity of heat transfer and mass transfer along the circumferential direction finally influences the performance uniformity. Therefore, a multi-roll solid-liquid cast-rolling bonding (MRSLCRB) process was proposed integrating cast-rolling bonding technology and multi-roll groove rolling technology. The steady-state thermal resistance network was established, and the influences of nominal roll radius, groove radius, and molten pool height on the heat transfer and mass transfer were studied systematically. 3-D steady-state thermal-fluid coupled simulation models of twin-roll, three-roll, and four-roll layouts were established. The results indicate that increasing casting roll number can improve the nominal cast-rolling velocity, service life of the casting roll, temperature uniformity, strain uniformity, and strain rate uniformity through regulating the heat transfer and mass transfer. Considering the manufacturing feasibility, the MRSLCRB equipment based on the three-roll layout was designed. Cu/steel cladding bars with uniform circumferential performance were fabricated, and the forming mechanism was revealed. The multi-field coupled analysis method provides a way to control heat and mass transfer uniformity, and the successful attempts of various typical metal cladding materials inspire exploring new forming processes.

Spontaneous spreading of nanodroplets on partially wetting surfaces with continuous grooves: Synergy of imbibition and capillary condensation

The wetting behavior of nanodroplets deposited on hydrophilic textured surfaces with discontinuous and continuous grooves was investigated by many-body dissipative particle dynamics. For surfaces with discontinuous grooves, the apparent contact angle (θa) can be described by the Wenzel model with an effective area ratio. However, for surfaces with continuous grooves, θa of nanodroplets depends on roughness topology, and spontaneous spreading of nanodroplets can take place even for partially wetting surfaces (θY > 0). That is, the partial-to-total wetting transition can occur on hydrophilic surfaces as surface textures change from discontinuous to continuous grooves. The dynamics of the spreading can be characterized by the apparent radius and groove radius (Rg). While the former is time-invariant at early stage, the latter follows the power law Rg ~ t1/4. This spreading of nanodroplets along continuous grooves can be explained from the synergy of spontaneous imbibition into continuous grooves, arrest by sharp edges, and capillary condensation for resuming the flow.

A computational method for pass design of the four-roll rolling process for sizing of round sections

The four-roll rolling process (4RP) enables the further evolution of sizing processes in rolling mills for round sections. The well-known advantages of the three-roll process over the two-roll process can be further improved using the 4RP. The participation of four rolls in the deformation zone instead of three or two leads to a significant increase in deformation efficiency. The present work shows a pass design method for pass sequences in the four-roll rolling process. Here, three basic types of roll groove geometries are discussed: the flat groove, the non-opened single-radius groove, and a tangentially opened type of a single radius groove. Based on a predefined cross-sectional evolution, grooves are found numerically to satisfy two conditions, i.e., the cross section of the rolled section and the groove filling criterion. The equations of the equivalent pass method, together with a suitable model for lateral spread and the geometric equations of the groove are solved by nonlinear optimization to minimize the sectional and filling errors of a specific pass. Combined for several rolling passes, a complete pass design can be carried out for the reduction of a specified initial section to a final section. The presented results show, how a pass design method for the four-roll rolling process can be constructed. The newly developed model is implemented in a software solution for pass design and analysis of full section rolling mills. An exemplified pass design is discussed to show the possibilities and limitations of the new model.

Evaluation of the brittleness and viscosity of metals upon tensile testing

The indicators of the brittleness and viscosity of metals calculated from their mechanical properties are considered with allowance for the stress state proceeding from the results of tensile testing of cylindrical smooth and notched samples of perlite 16KhSN, martensitic-aging (maraging) 03Kh11N10M2T, and austenitic 10Kh11N23T3MR steels. Tests were carried out on a UEM-10TM tensile strength testing machine, deformation diagrams developed on a scale of ~50:1 at a deformation rate of 5 mm/min. The sample size before and after testing were measured using a micrometer and an ISA-2 comparator with an accuracy of ±10–3 mm. Pendulum impact bending tests were carried out on a MK15 with the same cylindrical notched samples used to plot the plasticity and viscosity diagrams depending on the Bridgman stress state stiffness index. The new indicators of the brittleness λ = εk/η and viscosity η = (Sk/σb) – 1 (where εk = ln(1/(1 – ψk)) is the true limit plasticity) are proposed proceeding from the testing data. The special feature of the brittleness index λ is growth of the index with increase in the metal strength, e.g., due to pre-deformation or strengthening heat treatment procedures. However, a decrease in the groove radius on the samples, i.e., an increase in the Bridgman stress state stiffness, has almost no effect on the brittleness value λ, but is accompanied by a correlation decrease in the values of the viscosity indices η and the ultimate ductility εk of steels. The curves of the temperature dependences of the mechanical properties of steels 16KhSN and 03Kh11N10M2T show that anomalies in the brittleness indices λ observed at elevated test temperatures can be attributed to the structural transformations like increase in the grain size of 16KhSN steel or in the amount of the residual austenite in 03Kh11N10M2T steel due to reverse martensitic transformation. In this case, the temperature dependences of the viscosity η and brittleness λindicators change in the opposite way.

Prediction of Surface Wrinkle Defect of Welding Wire Steel ER70S-6 in Hot Bar Rolling Process Using Finite Element Method and Experiments

High quality products are demanded due to increasingly fierce market competition. In this paper, the generation of surface wrinkle defect of welding wire steel ER70S-6 was studied by the combination of the experimental method and finite element simulation. Firstly, a thermal compression test was conducted on the Gleeble-3500 thermosimulator under different strain rates and temperatures and a strain dependent Arrhenius-type constitutive function was employed to fit the flow stress–strain curves obtained from the experiments. Then, the elastoplastic constitutive relationship was implemented using radial return mapping algorithm by means of the user subroutine VUMAT of Abaqus/Explicit. A new instability criterion was proposed to predict the possibility of the surface wrinkle defect during the multipass hot bar rolling process. In order to verify the reliability of the finite element model of the six-pass continuous rolling process, the simulated results were compared with experimental data. Finally, the effects of groove width and groove radius on the billet were investigated by the orthogonal test method, and the friction coefficient and rolling temperature. The results show that the groove width and groove radius are key factors to suppress the surface wrinkle defect. Decreasing the groove width can be beneficial for improving the surface quality and reducing the fillet radius. The optimized combination of the rolling process parameters was further applied in an industrial test and the surface quality of the billet was greatly improved.

The sagittal geometry of the trochlear groove could be described as a circle: an intraoperative assessment with navigation.

The aim of this study was to describe the sagittal geometry of the trochlear groove in patients who underwent primary TKA, based on intraoperative data acquired with a navigation system. Intraoperative navigation data were collected from 110 patients. All operations were guided by a non-image-based navigation system (BLU-IGS, Orthokey Italia Srl). The trochlear groove has been described on the three anatomical planes; in particular, on the sagittal plane the hypothesis has been verified that the acquired points are referable to a circle. Using the data collected during intraoperative navigation, possible correlation between the radius of the trochlear groove and other femur dimension (length, AP dimension) was analyzed; the orientation of the trochlear sulcus with respect to the mechanical axis and the posterior condyle axis was analyzed too, searching for possible correlation between groove alignment (frontal and axial) or groove radius and the hip-knee-ankle (HKA). The average radius of curvature of the femoral trochlea was 25.5 ± 5.6mm; the difference was not statistically significant between the men and women (n.s. p value). No correlation was found between the trochlear groove radius and the femur length (r = - 0.02) or the HKA-phenotypes (r = 0.03) and between the groove alignment and HKA-phenotypes. On axial plane, the trochlear groove was 3.2° ± 4.3° externally rotated, with respect to the posterior condylar axis; on frontal plane, the trochlear groove was 3.9° ± 5.3° externally rotated, with respect to the mechanical axis. In both cases, no statistically significant differences were found between male and female and between left and right limb (p > 0.05). The present study shows that the sagittal plane geometry of the femoral trochlea in patients affected by osteoarthritis could be described accurately as a circle. The acquisition of the trochlear morphology intraoperatively can lead to more anatomically shape definition, to investigate deeper its radius of curvature and geometry. Trochlear shape could be used as landmarks for femoral component positioning, thus customizing the implant design, optimize the outcomes and improving anterior knee pain after TKA. IV.

Wall suction & slip effect of spherical-grooved bionic metasurface for controlling the aerodynamic noise

The wall suction & slip effect of the bionic metasurface with periodic spherical grooves on the vehicle body surface is proposed for aerodynamic noise control, and physical mechanism is investigated by theoretical analysis and simulation. When fluid flows through the grooved vehicle body surface, wall suction effect occurs due to clockwise pressure difference around the interior groove. The trailing vortex region of the vehicle body is reduced, the fluctuating pressure on the wall surface decreases, and the adverse pressure in the boundary layer is relieved. On the other hand, a slip velocity consistent with flow direction is generated at the interface corresponding to grooves, which results in reduced velocity gradient in the boundary layer and decreased thickness of the boundary layer. Ideally, the boundary layer could disappear when the velocity of slippage is increased to that of the flow by adjusting the grooves parameters, such as, the groove depth, pitch, and radius. Overall, the wall suction & slip effect fundamentally prevents generation of the boundary layer and delays its separation. Finally, effective control of aerodynamic noise within 450–1000 Hz on the vehicle body surface is realized by an average drop of 11.97 dB and up to 100% at 500 Hz. This study opens up a possibility for full control of boundary layer and could have effective applications in controlling aerodynamic noise.

Bionic research on spikes based on the tractive characteristics of ostrich foot toenail

Inspired by the superior fixed and traction characteristics of ostrich foot toenails, we devised, optimized and manufactured the single structure and group arrangement of a new-style bionic spike for sprint shoes to improve athletic performance. The tractive performance of the bionic spike was tested by finite element analysis and experimental verification. The optimized single structure of the bionic spike had a top slope angle of 13° and the radius of the medial groove of 7.3 mm. Compared with the conventional conic spike, the maximal and stable extrusion resistances of the single bionic spike decreased by about 25% and 40% respectively, while the maximal and stable horizontal thrusts increased by about 16% and 10%, respectively. In addition, the arrangement of the bionic spikes was also optimized. Compared with the conventional spike group, the maximal and stable extrusion resistances of the bionic spike group decreased by 11.0% and 6.2%, respectively, while the maximal and stable horizontal thrusts increased by 20.0% and 16.0%, respectively. The current results may provide useful mechanical information that can help develop a better design of athletic shoes with the potential for advanced performance.

Mechanical properties of the grooved-wheel drilling particles under multivariate interaction influenced based on 3D printing and EDEM simulation

The grooved-wheel drilling device is one of the most widely used seeding and fertilizing equipment in developing countries. In the drilling process of the grooved wheel, the particles (fertilizers or seeds) are subject to great force which easily causes the particles broken or the grooved wheel stuck. Therefore, in this paper, the EDEM simulation software was used to analyze the velocity of and force on the particles in the drilling process, to obtain the maximum discharging velocity of and the force on the particles at different helix angles in the drilling process. With the 3D printing technology, a brand new grooved wheel was designed and produced. The response surface methodology was adopted to analysis of the influence of multiple factors on indicators in the grooved-wheel fertilizing process to build a multivariate regression model to obtain the best working parameters. The accuracy of the simulation and regression models was verified with fertilizer amount as an indicator. The simulation and experimental results show that in static and dynamic conditions, the force on the particles decreases first and then increases with the increase of helix angle. In static condition, discharging velocity of the particles increases first and then decrease with the increase of helix angle, followed by fluctuations in a small range. In dynamic condition, discharging velocity of the particles first decreases and then increases with the increase of helix angle, and finally fluctuates in a small range. The best parameters for fertilizing are as follows: groove radius of 13.5 mm, helix angle of 62°, rotational speed of 29.4r/min, tilt angle of fertilizer feeder of 5°, fertilizer amount of 17.810 g, and variation coefficient of fertilizer amount of 5.60%. The relative errors between the EDEM simulation and the regression model and the experiments are 0.90% and 3.55%, respectively. The simulation model and the regression model were built with practical engineering application value.

Characterization of the material-induced elastic–plastic deformations in ultra-precision diamond cutting

Ultra-precision cutting (UPC) technology can directly achieve freeform surfaces with form accuracy in sub-micrometer and surface finishing in nanometer, and the achieved surface quality affects the functionalities of the components. Different from the conventional machining process, the effects of workpiece material properties on surface generation in UPC are ignorable. The influences of plastic side flow and elastic recovery are very important for the surface quality in UPC, while few studies were found to evaluate the extent of the two phenomena. This paper makes theoretical and experimental studies on the factors affecting the side flow and recovery and proposed a method to characterize the extent of plastic side flow and recovery by studying the deviation of the groove radius in single ruling. Experiments are conducted to machine grooves with different cutting parameters on different workpiece materials. The experiment results agree well with the theoretical analyses and show that under the combined effect of side flow and recovery, the generated groove radius may be larger or smaller than the theoretical one. Moreover, the proposed method makes effective evaluation on extend of swelling and recovery in UPC.

An improved dynamic model of defective bearings considering the three-dimensional geometric relationship between the rolling element and defect area

Abstract The accuracy of the vibration response simulated by the dynamic model of the defective bearing depends on the precise expression of the interaction between the rolling elements and defect area in the model. An improved dynamic model considering the three-dimensional geometric relationship between the rolling element and the defect area is developed to investigate the abrupt change of contact force and the corresponding vibration response of the bearing system. The geometry parameters describing the defect area are extended to the radius and groove radius of the raceway, the maximum and minimum depths of the defect area, and the circumferential angular extents of defect area on the radial and axial cross-sections for the first time. During a rolling element passes through the defect area, the contact forms between the rolling element and the defect area are classified into different types depending on whether the rolling element is in contact with the top edges or the bottom surface of defect area. The influence of defect size on contact form was investigated, the changes in contact force of the rolling element under different types of contact forms were compared, and the relationship between defect size and vibration response of the bearing system was quantified. The analysis results indicate that the circumferential angular extent of defect area on the axial cross-section has significant influence on the contact force between the rolling element and defect area, as well as the impulse response of the bearing system. Double-impulse phenomenon appears in both the time domain and time-frequency distribution of the vibration response of bearing system, and the simulation results have a good agreement with the experiments. The comparison of the vibration responses at different defect sizes shows whether the double-impulse phenomenon can be clearly observed in the vibration response depending on the rotational speed of the bearing and the size of the defect area.

Role of optical angular momentum in enhanced transmission process of plasmonic coaxial nanoring aperture

The nano groove can highly improve the transmittance of coaxial nanoring aperture due to the excitation of surface plasmon polariton (SPP). The total angular momentum carried by incident beam is reserved in the whole process and transferred to the SPP, thus the vortex SPP carrying orbital angular momentum is generated. The enhanced transmittance of nano aperture by vortex SPP has a wide range of applications, but its physical mechanism has been ignored for a long time. Here we study the process of the enhanced transmittance of the coaxial nanoring aperture and provide a model to describe the process of photon transmission. When the incident light irradiates on the coaxial nanoring aperture and nano groove, the vortex SPP induced by the groove propagates to coaxial nanoring aperture. Some of the photons in the SPP are coupled into the coaxial nanoring aperture and some are reflected back. The reflected photons travel back and forth multiple times between the coaxial nanoring aperture and nano groove. The vortex SPP interacts with the incident beam at the round of coaxial nanoring aperture, which determines the intensity at the round of the coaxial nano aperture, and thus affecting the transmittance. We systematically study the influence of optical angular momentum and the radius of the nano groove on the transmittance of coaxial nanoring aperture by using theoretical analysis and numerical simulations. The results show that the optical angular momentum and radius of the nano groove both affect the radial propagation phase of vortex SPP from nano groove to coaxial nanoring aperture, hence affecting the intensity of the electric field at the round of coaxial nanoring aperture and consequently determine the transmittance. The transmittance peaks of incident beams with different optical angular momenta will appear at different radii of the nano grooves, which provides a potential way to modulate the transmittance by adjusting the radius of the nano groove. This study is instructive for designing the enhanced optical transmission nano device based on vortex SPP.

Analysis of Backward and Forward Effects on a Grooved Co-axial Heat Exchanger by Response Surface Methodology

In the literature, it is proved that grooved pipe models are thermally more efficient than the smooth pipe model. Different than the previous studies in which the groove dimensions are constant along the pipe, we study the effect of groove radius and the gap between adjacent grooves on the local heat transfer coefficients using computational fluid dynamics software. The grooved section consists of three sub-sections to see the effects of groove dimension in stream-wise flow direction. We vary the radius of circular grooves parametrically in each section to optimize the local groove radius throughout the pipe. We couple the fluid flow (1200<Re<24000) with energy equations, and the grooved sections are set as heated wall at constant temperature of 350 K. The optimal mesh has been selected by performing mesh independence study and finer mesh has been used in heated wall section. The radii of grooves are varied from 2 to 6 mm with an increment of 0.2 mm considering the manufacturability of the pipe, to do so we use the design of experiments (DOE). All DOE tools in ANSYS software are examined and compared with full factorial results. After DOE process, local heat transfer coefficient values of all groove parts are examined by response surface methodology (RSM).

Influence of groove shape on rolling contact fatigue of PEEK-PTFE hybrid radial bearings in dry conditions

In this study, rolling contact fatigue (RCF) tests were performed in order to investigate the effect of groove radius on the life of PEEK-PTFE hybrid radial bearings. Furthermore, solid state NMR spectroscopy was performed in order to investigate the molecular structure of PEEK. It was found that groove radius shape was related to limitations of the bearings, and the molecular structure of the PEEK was not changed by the temperature rise in this test. Furthermore, thermal failure of the PEEK was not affected by oxidation during RCF test.

Poor relationship between frontal tibiofemoral and trochlear anatomic parameters: Implications for designing a trochlea for kinematic alignment

BackgroundThe kinematic alignment (KA) technique for total knee arthroplasty (TKA) is an emerging implant positioning philosophy that aims to restore constitutional knee anatomy to improve knee kinematics. At present, the KA technique aims to reconstruct native femorotibial (FT) joint alignment, however there is still insufficient consideration towards the inter-individual trochlear anatomy variability. Poor trochlear restoration may compromise clinical outcomes. Our study aimed at assessing the anatomical relationship between the native trochlea and other FT anatomical parameters. MethodsFifty-eight preoperative CT scans of low-grade knee arthritic patients were segmented to create 3D bone models. The FT and the PF anatomical parameters were measured using in-house software. Values were compared between different groups of lower limb and FT joint line (JL) orientation, and correlations between FT and PF anatomical parameters were assessed. ResultsWe were unable to detect any significant correlation between groove orientation (frontal and axial) or groove radius and either the hip–knee–ankle (HKA), or the lateral distal femoral (LDFA), or the medial proximal tibial (MPTA), or the FTJL-mechanical axis (FTJLMAA) Angles. When considering the correlation within sub-groups of limb or JL orientation, we only found a positive correlation (r = 0.464, p = 0.022) in the varus lower limb (HKA ≤ 180°) sub-group between groove frontal orientation and LDFA. ConclusionOur study shows that the determination of several limb, knee, and JL parameters is of poor value to predict individual trochlea anatomy. This raises the issue of how to improve femoral component design to achieve individualised FT and PF anatomical restoration with KATKA. Level of evidenceLevel 1 – computational study.

Fretting wear and fatigue in press-fitted railway axle: A simulation study of the influence of stress relief groove

In this paper, a finite element model for the prediction of fretting fatigue crack initiation in the full-scale railway axle was proposed, which took into account the influence of the stress redistribution due to fretting wear on the fretting fatigue. Then, this model was used to investigate the influence of stress relief groove on the fretting wear and fatigue of the railway axle. The simulation results show that the stress concentration at the contact edge is gradually relieved with an increase in fretting cycles due to the fretting wear, while a new stress concentration appears at the edge of fretting wear scar, which gradually increases and moves towards the inner side of the contact area. The stress concentration in the inner side is considered to cause the fatigue crack initiation. Either the increase in groove depth or the decrease in groove radius can reduce the fretting wear and improve the fretting fatigue strength through relieving the stress concentration. Accompanying the improvement of fretting fatigue strength, the potential site of crack initiation gradually moves towards the contact edge. The simulation results stated above agree with the published experimental results.

Effects of groove factor and surface roughness of raceway in ball-bearing-like specimens on tribological behavior and the onsets of two instabilities of dry contacts

Ball-bearing-like specimens are prepared with three groove factors (GF ≡ r/D; r: radius of groove; D: diameter of ball). Analyses of operating conditions are conducted for the thrust loads applied to the dry-contact specimens running with the maximum contact stress close to 2.0 GPa. The combined effect of surface roughness ((Ra)inner) of the inner raceway and groove factor becomes the controlling factor for the slip ratio (SR) arising at the tribocontact of ball and inner raceway, and the average friction coefficient (μ¯) of specimen. Both the inception time (TBR) of the instability in the running-in process and the inception time (TBS) of the instability arising in specimen's base material are governed by the average value (SR¯) of SR. The wavinesses of raceway are the controlling factor for the significant rise of frictional torque in the running-in regime and the TBR value. The fluctuations of frictional torque arising at the time behind TBR are confirmed to be the instability arising in the base material. The theoretical prediction for TBS is determined when μ¯ reaches the threshold value, (μ¯)threshold. For the specimens with the same GF, increasing (Ra)inner can elevate SR¯ and μ¯. In the specimens with a relatively smaller (Ra)inner, GF is the dominant factor for SR¯; however, (Ra)inner becomes the dominant factor for SR¯ if the inner raceway is prepared with a relatively larger (Ra)inner. Increasing GF can result in aμ¯ reduction, irrespective of the (Ra)inner value. Both TBS and TBR are reduced by the increasing SR¯. The wear losses of ball and the two raceways, however, increase as increasing SR¯.

Wire Electrochemical Threading: A Technique for Fabricating Macro/Micro Thread Profiles

In the past decades, wire electrochemical machining (Wire-ECM) has been extensively investigated for machining flat surfaces on varying engineering materials. In the present work, an attempt has been made to develop a novel technique (mask-less as well as through-mask) for generating macro as well as micro thread profiles on cylindrical rotating shafts using wire electrochemical turning process (Wire-ECTrg). Profiles with rounded edges like British Standard Whitworth (BSW) thread profile (Thread angle 55°) are fabricated using the mask-less method. Typical thread profiles are characterized and the impact of various input parameters on two key profile features, thread depth and thread angle are investigated. Generation of ball-full radius thread profile is very cumbersome to make through conventional turning process as it also requires a complex profiled tool. This type of thread profile is machined using the through-mask method. Three different engineering materials namely, copper, stainless steel 304 and a bio-compatible alloy of titanium Ti-6Al-4V are adapted for generating different thread profiles to show the versatility and applicability of the proposed technique. A ball-full radius thread of pitch 450 μm on stainless steel 304 is successfully fabricated using a single pass through-mask wire electrochemical turning process with an average percent error in groove radius of 2.42%.

Minimzing the value of axial forces in the cold tube rolling mills

The aim. Subsequent development of procedure for calculation of the kinematic parameters of the process of tube deformation in the cold tube pilger roll rolling mills with purpose of decreasing the value of axial forces. Methods. The new method (procedure) for the choice of the rational relationship of values of the forced rolling radius and the roll barrel radius in the mill KPW (method of the work minimum) had been assumed as the basis of development of the procedure for calculating the kinematic parameters of the tube deformation process in the cold tube pilger roll rolling mills. The outcome. The main dependencies known for now, which are used for calculating the value of the natural rolling radius and the roll barrel radius had been considered in the present paper, as well as the main practice used for decreasing the value of axial forces in the CTR mills. A procedure had been proposed for calculating the kinematic parameters of the tube deformation process in the mills of the cold tube pilger roll rolling (the method of the work minimum). Basing on the outcomes of industrial exploitation of the given method one drew the conclusion as to effectiveness of the proposed procedure. The scientific novelty. Basing on existing dependencies, the development of procedure had been proposed for calculating the rational relationship of the forced rolling groove radius and the roll barrel radius in the cold tube rolling mills. The procedure is based on the intimate analysis of axial forces, which are determined proceeding from all the basic parameters of the process. The practical importance. The given method allows optimizing not only the maximum values of axial forces at the direct and reverse stroke of the stand, but also the intensity of forces distribution along the cone of deformation. The method (procedure) had been used while calculating a number of roll pass designs for rolling tubes of titanium alloys in the mill KPW–25.

Anatomical Variations of the Extensor Carpi Ulnaris Groove: A New Computed Tomography-based Evaluation.

This study aimed to develop a classification that precisely describes the extensor carpi ulnaris (ECU) groove morphology. Reconstructed axial plane computed tomography scans of the wrists of 200 patients were reviewed. Three groups of groove shape were created based on the position of the deepest point: deviated to the ulnar side (Type U), in the middle of the groove (Type M), and deviated to the radial side (Type R). Groove depth, width, carrying angle, and radius of the curvature were measured using the Picture Archiving and Communication System in a slice in which the ulnar head was the largest. Type U was present in 88 patients (44%), Type M in 74 patients (37%), and Type R in 38 patients (19%). The average depth, width, carrying angle, and radius of curvature were 2.2 mm, 9.2 mm, 135.8° and 7.0 mm, respectively. Depth, width, and carrying angle were normally distributed. Both depth and width were statistically correlated with the carrying angle; groove depth and width were not correlated. ECU groove shape and depth showed excellent intra- and inter-observer reliabilities; the reliabilities for the width were poor. Therefore, depth subgroups were defined using cutoffs of ±2 standard deviations (SD): d1 (≤-2 SD), ≤1.0 mm; d2 (±SD), 1.1-3.3 mm; and d3 (≥+2 SD), ≥3.4 mm. The 200 wrists were classified as follows: 0.5% Ud1, 40.2% Ud2, 1.3% Ud3, 0.8% Md1, 38.3% Md2, 0.8% Md3, 1.5% Rd1, 16.4% Rd2, and 0.2% Rd3. The detailed morphology of the ECU groove was classified using three major types and depth subgroups. The Type R ECU groove, which lacks a medial bony buttress, might be more prone to ECU-related injuries. This classification helps to understand the ECU tendon-related injury pathologies and may provide valuable information for treatment decisions; however, further research is necessary.