Magnitude Of Deformation Research Articles

ANATOMICAL AND FUNCTIONAL PREREQUISITES FOR THE DEVELOPMENT OF ENDOPROSTHESIS INSTABILITY AFTER MONOCANDYLAR KNEE ARTHROPLASTY

Monocondylar knee arthroplasty allows to restore normal kinematics and function of the knee joint in the case of osteoarthritis limited to the medial or lateral part of the joint. Objective. To identify the patterns and features of secondary anatomical and functional changes in the knee joint after monocandylar arthroplasty depending on the patientʼs gender, weight, etiology of gonarthrosis, the magnitude of the primary joint deformity and bone tissue condition. Methods. The results of the examination of 71 patients (age 37–83 years, follow-up period 3–10 years) were analyzed. In 20 (28.2 %) patients, problems with the arthroplasty joint occurred. joint: increased frontal deformity angle — 8 (40 %), decreased joint mobility — 12 (60 %), pain in the implantation area — 10 (50 %). Results. Preoperative factors that may affect the outcome of monocandylar knee arthroplasty were identified. The main one is reduced bone density, especially localized osteoporosis. In the presence of osteoporotic areas in the area of arthroplasty, the risk of endoprosthesisinstability can reach 100 %. The second important factor is frontal deformities of the knee joint of more than 10°. Other factors, such as obesity, meniscal and crossed ligament injuries, fractures of the femoral and tibial condyles, also affect the development of complications, especially with a simultaneousdecrease in bone mineral density and/or significant frontal deformity of the knee joint. Conclusions. Monocondylar knee arthroplasty is a reliable, costeffective, low-traumatic method of treating gonarthrosis, but subject to clear indications for its implementation. In the long term, patients with osteoporosis, meniscal and ligamentous injuries, fractures of the condyles, and frontal deformities of more than 10° may develop signs of endoprosthesis instability.

Dense optic nerve head deformation estimated using CNN as a structural biomarker of glaucoma progression.

To present a new structural biomarker for detecting glaucoma progression based on structural transformation of the optic nerve head (ONH) region over time. Dense ONH deformation was estimated using deep learning methods namely DDCNet-Multires, FlowNet2, and FlowNetCorrelation, and legacy computational methods namely the topographic change analysis (TCA) and proper orthogonal decomposition (POD) methods. A candidate biomarker was estimated as the average magnitude of deformation of the ONH and evaluated using longitudinal confocal scans of 12 laser treated and 12 contralateral normal eyes of 12 primates from the LSU Experimental Glaucoma Study (LEGS); and 36 progressing eyes and 21 longitudinal normal eyes from the UCSD Diagnostic Innovations in Glaucoma Study (DIGS). Area under the ROC curve (AUC) was used to assess the diagnostic accuracy of the biomarker. AUROC (95% CI) for LEGS were: 0.83 (0.79, 0.88) for DDCNet-Multires; 0.83 (0.78, 0.88) for FlowNet2; 0.83 (0.78, 0.88) for FlowNet-Correlation; 0.94 (0.91, 0.97) for POD; and 0.86 (0.82, 0.91) for TCA methods. For DIGS: 0.89 (0.80, 0.97) for DDCNet-Multires; 0.82 (0.71, 0.93) for FlowNet2; 0.93 (0.86, 0.99) for FlowNet-Correlation; 0.86 (0.76, 0.96) for POD; and 0.86 (0.77, 0.95) for TCA methods. Lower diagnostic accuracy of the learning-based methods for LEG study eyes were due to image alignment errors in confocal sequences. Deep learning methods trained to estimate generic deformation were able to estimate ONH deformation from image sequences and provided a higher diagnostic accuracy. Our validation of the biomarker using ONH sequences from controlled experimental conditions confirms the diagnostic accuracy of the biomarkers observed in the clinical population. Performance can be further improved by fine-tuning these networks using ONH sequences.

Application of redefined J-integral range ΔJ for ultra-low cycle fatigue problems with large magnitude of elastic-plastic deformation

The redefined J-integral range ΔJ by a domain integral representation was applied to the ultra-low cycle fatigue problem of a 1 T compact tension (1TCT) specimen. The specimen was subject to large magnitude of cyclic deformation. The redefined J-integral range ΔJ is unconditionally independent of size and shape of its integral domain. The subloading surface plasticity model was adopted to appropriately reproduce the cyclic stress-strain behavior of the material. Finite element analyses on and evaluations of ΔJ were performed on the ultra-low cycle fatigue problem of a 1TCT specimen made of stainless steel SUS316. The outcomes of present study show the followings: (i) use of the redefined J-integral range ΔJ under the assumption of finite deformation theory, ductile crack propagations in ultra-low cycle fatigue problems can be characterized and (ii) deformation and load-displacement hystereses of the experiments can appropriately be reproduced by the use of the subloading surface plasticity model.

Reconstructive surgeries in the case of the knee joint osteoarthritis

Objective. To clarify the indications and volume of reconstructive surgeries under conditions of knee joint arthritis and to improve the methods of surgical correction of peri-articular deformations using an external rod fixator. Methods. During the last 10 years (2012‒2022), reconstructive surgeries were performed in 45 patients (49 joints). Indications for surgery were based on the study of pain and its localization, peri-articular deformation of the limb, ultrasound (USD) and X-ray examinations. Results. Indications for certain reconstructive surgical interventions on the knee joint are substantiated. The role of pathological changes of the meniscus in the development of knee joint arthritis has been determined. The positive clinical effect of paracapsular resection of the front part of the meniscus with hyperplastic growths of synovial tissue is shown. Deformation of the extremety (43 patients — with varus deformity, 2 — with valgus deformity) limited the function of the limb and caused pain. Surgical treatment in such cases were aimed at eliminating the deformation of the proximal part of the tibia. The types of osteotomies, the features of the author's rod external fixation device application, and the postoperative management of patients are presented. Due to external fixator, it is possible to perform, if necessary, angular correction of the limb axis during the period when the patient begins to walk with partial weight bearing, and the functional load of the limb makes it possible to achieve fusion of fragments within 3.5–4 months. A long-term positive clinical effect was obtained in 42 (93 %) patients. Conclusions. Indications for pathogenetic treatment should be based, first of all, on the identification of the source (or pathogenesis) of the pain syndrome, then on the analysis of the type and magnitude of peri-articular deformation of the limb, signs of functional insufficiency of the limb associated with it. In the third place, the X-ray signs should be analyzed. Elimination of angular peri-articular deformation of the limb has a positive effect on the course of knee arthritis, reduces pain, increases physical activity, and slows down the progression of cartilage destruction.

Ground deformation induced by shield tunneling posture in soft soil

Constructing tunnels in soft soil using shield machines would induce soil deformation. Several factors, such as support pressure, ground loss, grouting pressure may affect the soil deformation. In engineering practice, the ground deformation could also vary with the posture of the shield machine. This study proposed an approach for estimating the soil deformation considering shield posture. Firstly, the shield-soil interaction displacement was obtained by considering shield geometry and its kinematic behavior, such as shield diameter and length, articulation, and shield deviation. Secondly, based on the elastic half-space theory, a calculation method for mapping the shield-soil interaction displacement to soil deformation was established. Finally, the proposed model was verified by the field measurement in the tunnel of Suzhou Metro line S1, and the results confirm that the postures of the shield machine in the soil influence the magnitude, distribution, and evolution of the soil deformation.

Picometer-scale optical vortex interferometer using azimuthal complex spectrum analysis.

An interferogram demodulation method based on azimuthal complex spectrum analysis is proposed for achieving picometer-scale accuracy with an optical vortex interferometer (OVI). The OVI uses conjugated p-radial-order Laguerre-Gaussian beams to produce a high-order petal-like interferogram. A camera with a multi-ring pattern written on its sensor is used to convert the interferogram into multiple azimuthal intensity profiles. A phase shift subjected to either uniform surface displacement or axisymmetric non-uniform surface deformation can be retrieved from the complex spectra of the azimuthal intensity profiles at the main frequency components. The experiment verified that the measurement error is 84 pm for a displacement of 10 nm and 0.359 nm for a deformation magnitude of 100 nm. The effect of surface misalignment on the measurement result is also discussed. The proposed method provides an effective and highly accurate method of interferogram demodulation for the OVI and extends the applicability of OVI from uniform surface displacement measurement to axisymmetric non-uniform surface deformation measurement.

Observation of spatial and temporal patterns of seasonal ground deformation in central Yakutia using time series InSAR data in the freezing season

The seasonal freeze/thaw variations of the active layer cause seasonal ground deformation, such as thaw subsidence in summer and frost heave in winter due to the cyclic phase changes of soil water. The Synthetic Aperture Radar (SAR) remote sensing, especially interferometric SAR (InSAR) techniques, has been proven to be a very useful tool for observing surface displacements of permafrost environments. Most previous studies on seasonal InSAR displacement have been concentrated in several study sites in the Arctic tundra regions. The objective of this study is to extend the InSAR analysis of seasonal ground deformations to boreal forest regions, where monitoring ground deformation is particularly important in terms of better understanding active layer dynamics under various ecological and geological conditions. In this study, we presented a strategy to analyze the time series SAR data in the freezing season to estimate the differential phase for seasonal ground deformation while overcoming the problem of coherence losses due to the rapid growth of vegetation during the short growing season. We applied the SBAS-based InSAR processing method to Sentinel-1 SAR in the central Yakutian lowlands, where boreal forests and thermokarst landforms are widely distributed, and retrieved frost-related displacement signals successfully. In addition to the magnitude of ground deformation in the freezing season, we further examined the temporal deformation pattern related to the progression of the freezing front in the soil during active freezing. Based on the Stefan solution, we proposed a piecewise linear model for the time series deformation. The proposed model divides the time series displacement according to the progression of freezing into three linear segments, and the slope parameter of each linear model can be interpreted as indicating the hydrological characteristics of the upper, middle, and lower parts of the soil. The results for the Yakutian lowlands illustrated the potential of SAR remote sensing to observe and quantify spatial details of the thermal and hydrological properties inside the active layer soil even in highly vegetated subarctic boreal forest areas.

Sinkhole risk mapping and early warning: the case of Camaiore (Italy)

Introduction: Sinkholes are ground collapses that can cause significant damage to infrastructure and buildings. Part of the risk represented by sinkholes is related to their abruptness and the difficulty in spotting in advance their exact location within a sinkhole-prone area. For this reason, urban planning informed by an accurate risk mapping and monitoring is one of the most effective ways to reduce the risk.Methods: In this study, we propose a two-folded procedure based on the examination of ground displacement data measured by a ground-based interferometric radar and on the generation of a sinkhole risk zonation map. We examined 11 years’ worth of ground displacement data measured by a ground-based interferometric radar to search for sinkhole precursors. The analysis was based on averaged displacement time series retrieved from high-coherence pixels scattered around Camaiore, Italy, a test site where a catastrophic sinkhole occurred in 1995. To generate a sinkhole risk map, we evaluated the susceptibility map as derived from a set of predisposing environmental parameters, the vulnerability derived from the thickness of the sedimentary cover that can be linked to the abruptness of the collapse, and the value of the elements at risk from the Italian Real Estate Market Observatory integrated with land cover information for the non-built up areas.Results: The analysis of ground displacement data revealed that Camaiore had not experienced subsidence relatable to incoming sinkholes in the monitored period. However, few cm of vertical movements, which are well correlated with water table oscillations, have been measured and are expected to be of the same order of magnitude of sinkhole precursor deformations. This implies that a phenomenon of the size and velocity of the 1995 event could have likely been detected before its final collapse. The sinkhole risk map identified specific areas that should be closely monitored using in situ and remote sensing instrumentation.Discussion: The sinkhole risk zonation map generated in this study can be used to inform urban planning and risk management strategies. The study also shows the potential of ground-based interferometric radar to detect sinkhole precursors and the importance of integrating different mitigation approaches. Overall, this study can provide insights for sinkhole risk assessment and management in sinkhole-prone areas.

Tracing the “missing shortening” in fold-and-thrust belts: Insights from structural analyses of the Hotan-Mazatagh transect in the West Kunlun foreland, NW China

Use of balanced cross-section methods, which assume length and area conservation in two dimensions, to quantitatively analyze fold-and-thrust belts is vital in structural analyses. However, layer-parallel shortening is beyond this assumption and thus indescribable by balanced cross-section methods. The contribution of layer-parallel shortening in accommodating shortening has rarely been quantitatively determined, especially in sections hundreds of kilometers in scale. In this study, we conducted structural analyses on the ∼230-km-long Hotan-Mazatagh transect along the West Kunlun foreland of the NW Tibetan Plateau, based on interpretations of seismic reflection profiles. The results reveal that the transect forms a long thrust sheet detaching along the basal Cenozoic detachment, with deformation localized in the Hotan, Manan, and Mazatagh belts. Out of the ∼23.82 km of cutoff displacement translating into the thrust sheet, only ∼1.4 km and ∼4.94 km are absorbed by the Hotan anticline and the Mazatagh detachment thrust, respectively. The remaining ∼17.48 km extent of shortening is absorbed by layer-parallel shortening in the ∼180-km-long section between the Hotan and Mazatagh belts. The layer-parallel shortening produces a strain rate of ∼2.43 × 10−8 yr−1 and absorbs ∼77.97% of the shortening of the segment. Our results argue for caution when using balanced cross-section methods to determine deformation magnitudes. We suggest that localized deformation and layer-parallel shortening function together to shape the ∼230-km-long Hotan-Mazatagh transect into a combined discrete-and-distributed deformation style.

Numerical modeling of ice–seabed interaction in layered soil: stiff over soft clay

This study presents a numerical investigation of free field ice gouging in layered cohesive seabeds comprising stiff over soft clay. A three-dimensional, half-space, dynamic large deformation finite element analysis was conducted using the Coupled Eulerian Lagrangian approach. To simulate the seabed, a Tresca soil model with the strain rate and strain-softening effects was coded into a user subroutine. The accuracy of the model was verified by comparing its results with those of published experimental studies. Additionally, a comprehensive parametric study was conducted to examine the effect of various ice gouging scenarios and seabed soil parameters on the subgouge soil deformation and the ice keel reaction forces. Our findings revealed that an interactive response occurs between the soil layers and the ice keel that may cause the peak subgouge soil deformation and keel reaction magnitudes to differ from those observed under uniform soil condition. The developed model was found to be an efficient tool for free field ice gouging analysis in cohesive layered seabeds.

Numerical studies on Vibro-creep of PEM fuel cell elements used in mobile applications

The wide use of fuel cells in mobile applications carries significant risks caused by accompanying vibrations, the origin of which can be found in the interaction of the ground or other vibration-generating components. The classical approach treated vibration and creep as two separate phenomena. One generated pulses, and the other caused durable deformations under the influence of temperature and static loads. This work combines both phenomena, describing the impact of vibrations on the material's structure and estimating the magnitude of durable deformations caused by the aggregation of alloy inclusions and dislocations in the material mesh. The Norton creep model and the failure model described by Kachanov were used for this. In addition, Stobyriev's reduced stresses were used to reflect the failure spectrum of the material: from brittle to ductile.

Spatiotemporal characteristics of upper-crust seasonal velocity changes in North–South Seismic Belt and South China block in China

Investigating mechanisms and characteristics of the non-tectonic deformation has crucial implications for evaluating the subsurface stress evolution. In this study, we continuously tracked the seasonal velocity changes of Rayleigh wave at 2–10 s with the ambient noise interferometry and discrete wavelet decomposition, in different regions along the actively deforming North–South Seismic Belt (NSSB) and the stable Guangdong region in the South China block in China. The seasonal velocity changes exhibit strong lateral variations across different regions, with much larger seasonality (annual periodicity) and amplitude along the NSSB than those in the stable Guangdong region. There are also small-scale lateral variations inside of each region and generally larger amplitudes of the seasonal velocity changes at greater depth, but the phases (peaks, mostly in winter or summer) at different depths are consistent. The mechanism of the seasonal changes is most likely the direct loading effect of the precipitation, as indicated by consistency in their phases. However, the amplitudes of the seasonal velocity changes seem not controlled by the amount of precipitation, but are more dependent on the tectonic deformation at the different scales, from the correlation between the amplitude of the velocity change and the absolute strain rate. We demonstrate that the crustal media in the regions with larger tectonic background stress are more sensitive to the seasonal loadings. The new finding also highlights the role of the external seasonal loadings in the modulation of seismic activities and risk evaluations. Keypoints•Seasonal seismic velocity variations are found in different regions in China, likely from direct hydrological loadings of precipitation.•The spatial pattern of the seasonal velocity changes is consistent with the distribution of tectonic deformation at multi-scales.•The amplitude of the seasonal velocity changes is more dependent on the magnitude of local deformation than the amount of precipitation.

Об одном способе построения сорбционной изотермы угольного пласта

Sorption isotherm is dependence between the specific mass of methane contained in a unit volume of coal and its pore pressure, and it is constructed based on the Langmuir dependence. Two coefficients included in this dependence are determined from the solution of the system of equations after the values of the specific mass of methane in two different places of the reservoir are determined. In this regard, a control well is drilled from the face of mining working, and measurements of methane parameters are made from it at two different depths. These parameters include the initial rate of gas release from the well and the pressure of methane in it. The initial outgassing rate is determined using a flow meter. And for pressure measurements, capital sealing of the well is required since the pressure of methane in it can squeeze out the sealer. Therefore, for these purposes, it is proposed to use not a sealer, but a spherical shell into which methane enters from the well. The shell material is adopted with low stiffness characteristics therefore it is easy to measure its dimensions. Deformation of the shell under the action of excessive pressure of methane is associated with its geometric and physical-mechanical parameters, which are determined by the well-known formulas of the theory of shells. Knowing the magnitude of shell deformation, it is easy to calculate the methane excess pressure. According to the conclusions of Academician S.A. Khristianovich the filtration processes in a coal seam with a moving free edge are stationary, and isothermal. Therefore, it is not difficult to switch from the excess pressure in the shell to the pressure in the well, and, consequently, to the pore pressure of methane. With known values of the initial gas release rate and methane pressure, it is easy to calculate the specific mass of the methane in the well in two of its sections, and then determine the porosity coefficients from the Langmuir equation.

Bioinspired bistable dielectric elastomer actuator based on low-melting-point alloy phase change regulation

Soft bistable actuators that exhibit flexibility, fast response, and low energy consumption are key components for applications such as fast grippers, shape reconfiguration actuators, and deployable soft robots. Inspired by the structure of rhododendron leaves, we designed a bistable dielectric elastomer actuator (BDEA) by integrating a dielectric elastomer with a low-melting-point alloy. The developed BDEA can operate reversibly between two stable states through the synergistic application and control of high voltage and Joule heating. The transition process between the two stable states of the actuator was elucidated using finite element analysis. The bending angles of the actuator in the two deformation directions were measured, and grasping experiments were performed. The experimental results show that the direction and magnitude of deformation of the bistable actuator can be tuned to conform to the shape of the target object. The developed BDEA has enhanced shape adaptability and higher bearing capacity compared to conventional soft actuators.

An Enhanced Offset Tracking Method: Providing Auxiliary Information for DInSAR Phase Filtering in Urban Areas.

In the application of synthetic aperture radar differential interferometry in urban environments, it is easy to regard the phase change in the deformation band of buildings under construction as noise that requires filtering. This introduces an error into the surrounding area while over-filtering, resulting in an error in the magnitude of the deformation measurement results for the entire region and the loss of deformation details in the surrounding area. Based on the traditional DInSAR workflow, this study added a deformation magnitude identification step, determined the deformation magnitude by using enhanced offset tracking technology, supplemented the filtering quality map and removed the construction areas that affect the interferometry in the filtering stage. The enhanced offset tracking technique adjusted the ratio of contrast saliency and coherence via the contrast consistency peak in the radar intensity image, which was used as the basis for adjusting the adaptive window size. The method proposed in this paper was evaluated in an experiment on a stable region using simulated data and in an experiment on a large deformation region using Sentinel-1 data. The experimental results show that the enhanced method has a better anti-noise ability than the traditional method, and the accuracy rate is improved by about 12%. The supplemented quality map can effectively remove the large deformation area to prevent over-filtering while ensuring the filtering quality, and it can achieve better filtering results.

Innervation of Sensing Microchannels for Three‐Dimensional Stimuli Perception

AbstractStimuli perception enables animals and robots to interact with unknown environments safely and predictably. For the sensing of soft robotics and wearable devices, although electronic skins have already been widely accepted and studied, their planar geometries are not applicable for multi‐direction volume sensing. Herein, the innervation of sensing microchannel networks into elastic matrices to mimic the exteroception and proprioception of the human bodies is employed. Soft actuators with interlaced actuating and sensing microchannels resembling the distribution of muscle fiber and proprioceptors are fabricated and the internal stimuli perception of deformation configurations (bending, elongating, and bending directions) and magnitudes (bending angle and elongation) of the soft actuators are demonstrated. It is also demonstrated that a soft cubic sensor containing 3D microchannels (diameter: 400 µm) is capable of identifying 3D external stimuli, including force types (pressing, squeezing, shearing, and twisting) and real‐time directions by measuring the resistance variation, and its application in the virtual reality field is exhibited.

Statistical Assessments of InSAR Tropospheric Corrections: Applicability and Limitations of Weather Model Products and Spatiotemporal Filtering

Tropospheric correction is a crucial step for interferometric synthetic aperture radar (InSAR) monitoring of small deformation magnitude. However, most of the corrections are implemented without a rigorous evaluation of their influences on InSAR measurements. In this paper, we present three statistical metrics to evaluate the correction performance. Firstly, we propose a time series decomposition method to estimate the tropospheric noise and mitigate the bias caused by ground displacement. On this basis, we calculate the root-mean-square values of tropospheric noise to assess the general performance of tropospheric corrections. Then, we propose the use of semi-variograms with model-fitted range and sill to investigate the reduction of distance-dependent signals, and Spearman’s rank correlation between phase and elevation to evaluate the mitigation of topography-correlated signals in hilly areas. The applicability and limitations were assessed on the weather model-derived corrections, a representative spatiotemporal filtering method, and the integration of the two mainstream methods. Furthermore, we notice that the persistent scatter InSAR processing resulted in two components, the primary and secondary images’ contribution to the tropospheric and orbit errors. To the best of our knowledge, this paper for the first time analyzes the respective roles of the two components in the InSAR tropospheric corrections.

Interaction of open-top, short, cylindrical tank with wind-driven rain

Driving rain or wind-driven rain (WDR) is defined as rain, falling in an inclined manner due to the driving force of the wind, inflicting damage to the envelope of building, due to rain droplet impingement, hygrothermal effect, and, rain water ingress. When rain is driven by wind, especially high wind (during storm, cyclone, etc.), the rain droplet impact can increase. There is no availability of literatures on the interaction of shell structures with driving rain, which incurs damage to the thin wall of the tank through droplet impact. This scope is the main motivation behind the present study, which is focused on fluid–structure interaction analysis of an open-top, ground-supported, cylindrical tank with a slenderness ratio of 1.0, affected by wind driven rain. The thickness of the tank wall is varied, and, open terrain condition is considered. The study exhibits that the force coefficient (Cf) of WDR is higher between 0° to 53° peripheral position and decreasing upto 140° circumferential location. Maximum 28% increase of force coefficient of WDR noticed for 45° position in comparison to the wind force coefficient. Also, the top of the tank wall exhibits greater deformation and vulnerable under the effect of wind-driven rain load. Also, it is evident that 0° to 18°, and, 0° to 27° circumferential area exhibit higher deformation for radius: thickness (R/t) ratios 500, and 250, respectively. In case of R/t ratios 125, and 166.67, the higher deformation zone is distributed 0° to 15° and 77° to 82° peripherally. This deformation behaviour of the tank wall, shows that the open-top tanks need to be stiffened at the top to withstand the wind-driven rain force. The magnitude of deformation exhibits increments with the decrease in the thickness of wall of the tank. Maximum deformation is observed for lowest thickness of the tank wall.

Application of Cad Systems to Accounting for Mechanical Stresses in the Development of Uncooled Thermal Detectors of the Bolometric Type

A comparative analysis of the characteristics of the main types of bolometers is indicated in the article. The constructive solution of an uncooled thermal detector of the bolometric type, formed using the technology of microelectromechanical systems, is studied. By means of computer simulation in modern computer-aided design systems in microelectronics, a static mechanical analysis was performed to assess the effect of mechanical stresses arising in structural materials during their formation on the magnitude of deformation. It has been established that to ensure the normal functioning of the microbolometer (to reduce the maximum deviation value of the film from the nominal value), it is necessary to reduce the internal mechanical stresses in the NiCr film. For the Si3N4 films, on the contrary, this value should be increased.

Predicting Rates of Angular Correction After Hemiepiphysiodesis in Patients With X-Linked Hypophosphatemic Rickets.

Patients with X-linked hypophosphatemic rickets (XLH) often develop coronal plane knee deformities despite medical treatment. Hemiepiphysiodesis is an effective way to correct coronal plane knee deformities in skeletally immature patients, but a full understanding of the rate of angular correction after hemiepiphysiodesis in XLH patients, compared with idiopathic cases is lacking. We retrospectively reviewed charts of 24 XLH patients and 37 control patients without metabolic bone disease who underwent hemiepiphysiodesis. All patients were treated with standard-of-care medical therapy (SOC=active vitamin D and phosphate salt supplementation) in our clinical research center and had a minimum of 2-year follow-up after hemiepiphysiodesis. Demographic data as well as complications, repeat procedures, or recurrence/overcorrection were recorded. Standing lower extremity radiographs were evaluated before the surgical intervention and at subsequent hardware removal or skeletal maturity, whichever came first. Mean axis deviation, knee zone, mechanical lateral distal femoral angle (mLDFA), and medial proximal tibial angle were measured on each radiograph. The rate of angular correction was calculated as the change in mLDFA and medial proximal tibial angle over the duration of treatment. The magnitude of the initial deformity of the distal femur was greater in XLH patients as compared with control for varus (XLH mLDFA 97.7 +/- 4.9 vs. Control mLDFA 92.0 +/- 2.0 degrees) and valgus (XLH mLDFA 78.7 +/- 6.2 vs. Controls mLDFA 83.6 +/- 3.2 degrees). The rate of correction was dependent on age. When correcting for age, XLH patients corrected femoral deformity at a 15% to 36% slower rate than control patients for the mLDFA (>3y growth remaining XLH 0.71 +/- 0.46 vs. control 0.84 +/- 0.27 degrees/month, <3y growth remaining XLH 0.37 +/- 0.33 vs. control 0.58 +/- 0.41 degrees/month). No significant differences were seen in the rate of proximal tibia correction. XLH patients were less likely to end treatment in zone 1 (55.0% XLH vs. 77.8% control). XLH patients had longer treatment times than controls (19.5 +/- 10.7 vs. 12.6 +/- 7.0mu, P value <0.001), a higher average number of secondary procedures than controls (1.33 +/- 1.44 vs. 0.62 +/- 0.92 number of procedures), a higher rate of overcorrection than controls (29.2% vs. 5.4%), and a higher rate of subsequent corrective osteotomy than controls (37.5% vs. 8.1%). There was no significant difference in the rate of complications between groups (8.3% vs. 5.4%). Patients with XLH undergoing hemiepiphysiodesis have a 15% to 36% slower rate of femoral deformity correction that results in longer treatment times, a higher likelihood to undergo more secondary procedures, and a lower likelihood to reach neutral mechanical alignment. This study provides important information to guide the timing and treatment of patients with XLH and coronal plane knee deformities. In addition, results from this study can be educational for families and patients with respect to anticipated treatment times, success rates of the procedure, complication rate, and likelihood of needing repeat procedures.