scholarly journals Relationship between patellofemoral finite helical axis and femoral trans-epicondylar axis using a static magnetic resonance-based methodology

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Zhenguo Yu ◽  
Hong Cai ◽  
Bin Yang ◽  
Jie Yao ◽  
Ke Zhang ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Knee Flexion ◽  
Spline Interpolation ◽  
Helical Axis ◽  
Mr Images ◽  
Full Extension ◽  
Epicondylar Axis ◽  
Maximum Angle ◽  
Finite Helical Axis

Abstract Background To manage patellofemoral joint disorders, a complete understanding of the in vivo patellofemoral kinematics is critical. However, as one of the parameters of joint kinematics, the location and orientation of the patellofemoral finite helical axis (FHA) remains unclear. The purpose of this study is to quantify the location and orientation of the patellar FHA, both in vivo and non-invasively at various flexion angles, and evaluate the relationship of the FHA and the trans-epicondylar axis (TEA). Methods The magnetic resonance (MR) images of 18 unilateral knees were collected at full extension, 30°, 60°, 90°, and maximum angle of knee flexion. Three-dimensional models of the knee joint at different flexion angles were created using the MR images, and then used to calculate the patellar tracking and FHA with a spline interpolation algorithm. By using a coordinate system based on the TEA, the FHA tracking was quantified. Six parameters concerning the location and orientation of the patellar FHA were analysed. Results The average patellar FHA drew an L-shaped tracking on the midsagittal plane moving from the posteroinferior to the anterosuperior side of the TEA with knee flexion. Before 90° flexion, the patellar rotational radius decreased slightly, with an average value of 5.65 ± 1.09 cm. During 20° to 90° knee flexion, the average angle between the patellar FHA and the TEA was approximately 10° and that between the FHA and the coronal plane was maintained at about 0°, while that between the FHA and the level plane fluctuated between − 10° and 10°. Conclusions This study quantitatively reported the continuous location and direction of the patellar FHA during knee flexion. The patellar FHA was close to but not coincident with the femoral TEA both in location and orientation, and the patellar rotational radius decreased slightly with knee flexion. These findings could provide a clear direction for further studies on the difference in patellofemoral FHA among various types of patellofemoral disorders, and provide a foundation for the application of FHA in surgical evaluation, preoperative planning and prosthesis design, thereby assisting in the diagnosis and treatment of patellofemoral disorders.

scholarly journals Relationship Between Patellofemoral Finite Helical Axis and Femoral Trans-Epicondyle Axis Using a Static Magnetic Resonance-Based Methodology

2020 ◽  
Author(s):  
Zhenguo Yu ◽  
Hong Cai ◽  
Bin Yang ◽  
Jie Yao ◽  
Ke Zhang ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Knee Flexion ◽  
Patellofemoral Joint ◽  
Spline Interpolation ◽  
Joint Kinematics ◽  
Helical Axis ◽  
Mr Images ◽  
Maximum Angle ◽  
Finite Helical Axis

Abstract Background: To manage patellofemoral joint disorders, a complete understanding of the in vivo patellofemoral kinematics is critical. However, as one of the parameters of joint kinematics, the location and orientation of patellofemoral finite helical axis (FHA) remains unclear. The purpose of this study is to quantify the location and orientation of the patellar FHA both in vivo and non-invasively at various flexion angles and to relate the FHA to the trans-epicondyle axis (TEA).Methods: The Magnetic resonance (MR) images of 18 unilateral knees were collected at full extension and at 30°, 60°, 90°, and maximum angle of knee flexion. Three-dimensional models of knee joint at different flexion angles were developed with the MR images, and were used to calculate the patellar tracking and FHA with a spline interpolation algorithm. By using a coordinate system based on the TEA, the FHA tracking was quantified. Six parameters concerning the location and orientation of the patellar FHA were analyzed.Results: The average patellar FHA of 18 knees drew an L-shaped tracking on the midsagittal plane moving from the posteroinferior side of the TEA to the anterosuperior with knee flexion. Before 90° flexion, the patellar rotational radius decreased slightly, with an average value of 5.65 ± 1.09 cm. During 20° to 90° knee flexion, the average angle between the patellar FHA and TEA was approximately 10° and that between the FHA and coronal plane was maintained at about 0°, while that between the FHA and level plane fluctuated between -10° and 10°.Conclusions: Patellar FHA was not fixed during flexion, which showed a close relationship with femoral TEA in both location and orientation. The results could help us better understand the patellofemoral joint kinematics and further deal with troublesome patellofemoral disorders.

In vivo measurements of patellar tracking and finite helical axis using a static magnetic resonance based methodology

2014 ◽  
Vol 36 (12) ◽  
pp. 1611-1617 ◽  
Author(s):  
Jie Yao ◽  
Bin Yang ◽  
Wenxin Niu ◽  
Jianwei Zhou ◽  
Yuxing Wang ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Patellar Tracking ◽  
Helical Axis ◽  
In Vivo Measurements ◽  
Finite Helical Axis

The Medial Patellofemoral Ligament Is a Dynamic and Anisometric Structure: An In Vivo Study on Length Changes and Isometry

2019 ◽  
Vol 47 (7) ◽  
pp. 1645-1653 ◽  
Author(s):  
Willem A. Kernkamp ◽  
Cong Wang ◽  
Changzou Li ◽  
Hai Hu ◽  
Ewoud R.A. van Arkel ◽  
...  
Keyword(s):  
Knee Flexion ◽  
Medial Patellofemoral Ligament ◽  
Length Change ◽  
High Rate ◽  
Mpfl Reconstruction ◽  
Full Extension ◽  
3 Dimensional ◽  
Technical Errors ◽  
Length Changes

Background: Medial patellofemoral ligament (MPFL) reconstruction is associated with a high rate of complications, including recurrent instability and persistent knee pain. Technical errors are among the primary causes of these complications. Understanding the effect of adjusting patellofemoral attachments on length change patterns may help surgeons to optimize graft placement during MPFL reconstruction and to reduce graft failure rates. Purpose: To determine the in vivo length changes of the MPFL during dynamic, weightbearing motion and to map the isometry of the 3-dimensional wrapping paths from various attachments on the medial femoral epicondyle to the patella. Study Design: Descriptive laboratory study. Methods: Fifteen healthy participants were studied with a combined computed tomography and biplane fluoroscopic imaging technique during a lunge motion (full extension to ~110° of flexion). On the medial femoral epicondyle, 185 attachments were projected, including the anatomic MPFL footprint, which was divided into 5 attachments (central, proximal, distal, posterior, and anterior). The patellar MPFL area was divided into 3 possible attachments (proximal, central, and distal). The length changes of the shortest 3-dimensional wrapping paths of the various patellofemoral combinations were subsequently measured and mapped. Results: For the 3 patellar attachments, the most isometric attachment, with an approximate 4% length change, was located posterior and proximal to the anatomic femoral MPFL attachment, close to the adductor tubercle. Attachments proximal and anterior to the isometric area resulted in increasing lengths with increasing knee flexion, whereas distal and posterior attachments caused decreasing lengths with increasing knee flexion. The anatomic MPFL was tightest in extension, decreased in length until approximately 30° of flexion, and then stayed near isometric for the remainder of the motion. Changing both the femoral and patellar attachments significantly affected the length changes of the anatomic MPFL ( P < .001 for both). Conclusion: The most isometric location for MPFL reconstruction was posterior and proximal to the anatomic femoral MPFL attachment. The anatomic MPFL is a dynamic, anisometric structure that was tight in extension and early flexion and near isometric beyond 30° of flexion. Clinical Relevance: Proximal and anterior MPFL tunnel positioning should be avoided, and the importance of anatomic MPFL reconstruction is underscored with the results found in this study.

In vivo diffusion–perfusion magnetic resonance imaging of acute cerebral ischemia

1991 ◽  
Vol 69 (11) ◽  
pp. 1719-1725 ◽  
Author(s):  
John Kucharczyk ◽  
Jan Mintorovitch ◽  
Haleh Asgari ◽  
Mitsuharu Tsuura ◽  
Michael Moseley
Keyword(s):  
Cerebral Ischemia ◽  
Magnetic Resonance ◽  
Resonance Imaging ◽  
Mr Images ◽  
Ischemic Brain ◽  
Diffusion Weighted ◽  
Acute Cerebral Ischemia ◽  
Planar Images ◽  
Echo Planar

We compared the anatomic extent and severity of ischemic brain injury shown on diffusion-weighted magnetic resonance (MR) images, with cerebral tissue perfusion deficits demonstrated by a nonionic intravascular T2*-shortening magnetic susceptibility contrast agent used in conjunction with standard T2-weighted spin-echo and gradient-echo echo-planar images. Diffusion-weighted images displayed increased signal intensity in the vascular territory of the middle cerebral artery 25–40 min after permanent occlusion, whereas T2-weighted images without contrast were negative or equivocal for at least 2–3 h after stroke was induced. Contrast-enhanced T2-weighted and echo-planar images revealed perfusion deficits that were spatially closely related to the anatomic regions of ischemic tissue injury. These data indicate that diffusion-weighted MR images are very sensitive to early onset pathophysiologic changes induced by acute cerebral ischemia. Combined sequential diffusion–perfusion imaging enables noninvasive in vivo examination of the relationship between hypoperfusion and evolving ischemic brain injury.Key words: in vivo, diffusion, perfusion, acute cerebral ischemia, magnetic resonance imaging.

scholarly journals Development of a Hybrid Magnetic Resonance and Ultrasound Imaging System

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Victoria Sherwood ◽  
John Civale ◽  
Ian Rivens ◽  
David J. Collins ◽  
Martin O. Leach ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Focused Ultrasound ◽  
Imaging System ◽  
Single Point ◽  
Image Data ◽  
High Intensity Focused Ultrasound ◽  
Thigh Muscle ◽  
Mr Images ◽  
Rf Noise

A system which allows magnetic resonance (MR) and ultrasound (US) image data to be acquired simultaneously has been developed. B-mode and Doppler US were performed inside the bore of a clinical 1.5 T MRI scanner using a clinical 1–4 MHz US transducer with an 8-metre cable. Susceptibility artefacts and RF noise were introduced into MR images by the US imaging system. RF noise was minimised by using aluminium foil to shield the transducer. A study of MR and B-mode US image signal-to-noise ratio (SNR) as a function of transducer-phantom separation was performed using a gel phantom. This revealed that a 4 cm separation between the phantom surface and the transducer was sufficient to minimise the effect of the susceptibility artefact in MR images. MR-US imaging was demonstratedin vivowith the aid of a 2 mm VeroWhite 3D-printed spherical target placed over the thigh muscle of a rat. The target allowed single-point registration of MR and US images in the axial plane to be performed. The system was subsequently demonstrated as a tool for the targeting and visualisation of high intensity focused ultrasound exposure in the rat thigh muscle.

Validation of Cartilage Thickness Calculations Using Indentation Analysis

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Matthew F. Koff ◽  
Le Roy Chong ◽  
Patrick Virtue ◽  
Dan Chen ◽  
Xioanan Wang ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Measurement Techniques ◽  
Magnetic Resonance Images ◽  
Cartilage Thickness ◽  
Mr Images ◽  
Data Set ◽  
Data Points ◽  
Indentation Analysis ◽  
Thickness Measurements

Different methods have been used to cross-validate cartilage thickness measurements from magnetic resonance images (MRIs); however, a majority of these methods rely on interpolated data points, regional mean and/or maximal thickness, or surface mean thickness for data analysis. Furthermore, the accuracy of MRI cartilage thickness measurements from commercially available software packages has not necessarily been validated and may lead to an under- or overestimation of cartilage thickness. The goal of this study was to perform a matching point-to-point validation of indirect cartilage thickness calculations using a magnetic resonance (MR) image data set with direct cartilage thickness measurements using biomechanical indentation testing at the same anatomical locations. Seven bovine distal femoral condyles were prepared and a novel phantom filled with dilute gadolinium solution was rigidly attached to each specimen. High resolution MR images were acquired, and thickness indentation analysis of the cartilage was performed immediately after scanning. Segmentation of the MR data and cartilage thickness calculation was performed using semi-automated software. Registration of MR and indentation data was performed using the fluid filled phantom. The inter- and intra-examiner differences of the measurements were also determined. A total of 105 paired MRI-indentation thickness data points were analyzed, and a significant correlation between them was found (r=0.88, p<0.0001). The mean difference (±std. dev.) between measurement techniques was 0.00±0.23 mm, with Bland–Altman limits of agreement of 0.45 mm and −0.46 mm. The intra- and inter-examiner measurement differences were 0.03±0.22 mm and 0.05±0.24 mm, respectively. This study validated cartilage thickness measurements from MR images with thickness measurements from indentation by using a novel phantom to register the image-based and laboratory-based data sets. The accuracy of the measurements was comparable to previous cartilage thickness validation studies in literature. The results of this study will aid in validating a tool for clinical evaluation of in-vivo cartilage thickness.

A Detailed and Validated Three Dimensional Dynamic Model of the Patellofemoral Joint

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Mohammad Akbar ◽  
Farzam Farahmand ◽  
Ali Jafari ◽  
Mahmoud Saadat Foumani
Keyword(s):  
Knee Flexion ◽  
Patellofemoral Joint ◽  
Muscle Activation ◽  
Model Simulation ◽  
Three Dimensional ◽  
Rigid Bodies ◽  
Patellar Tilt ◽  
Full Extension ◽  
Patellar Stability

A detailed 3D anatomical model of the patellofemoral joint was developed to study the tracking, force, contact and stability characteristics of the joint. The quadriceps was considered to include six components represented by 15 force vectors. The patellar tendon was modeled using four bundles of viscoelastic tensile elements. Each of the lateral and medial retinaculum was modeled by a three-bundle nonlinear spring. The femur and patella were considered as rigid bodies with their articular cartilage layers represented by an isotropic viscoelastic material. The geometrical and tracking data needed for model simulation, as well as validation of its results, were obtained from an in vivo experiment, involving MR imaging of a normal knee while performing isometric leg press against a constant 140 N force. The model was formulated within the framework of a rigid body spring model and solved using forth-order Runge-Kutta, for knee flexion angles between zero and 50 degrees. Results indicated a good agreement between the model predictions for patellar tracking and the experimental results with RMS deviations of about 2 mm for translations (less than 0.7 mm for patellar mediolateral shift), and 4 degrees for rotations (less than 3 degrees for patellar tilt). The contact pattern predicted by the model was also consistent with the results of the experiment and the literature. The joint contact force increased linearly with progressive knee flexion from 80 N to 210 N. The medial retinaculum experienced a peak force of 18 N at full extension that decreased with knee flexion and disappeared entirely at 20 degrees flexion. Analysis of the patellar time response to the quadriceps contraction suggested that the muscle activation most affected the patellar shift and tilt. These results are consistent with the recent observations in the literature concerning the significance of retinaculum and quadriceps in the patellar stability.

Model Studies of Nonsteady Flow Using Magnetic Resonance Imaging

1990 ◽  
Vol 112 (1) ◽  
pp. 93-99 ◽  
Author(s):  
Ding-Yu Fei ◽  
Kenneth A. Kraft ◽  
Panos P. Fatouros
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Velocity Profiles ◽  
Resonance Imaging ◽  
Mr Images ◽  
Model Studies ◽  
Physiological Limits ◽  
Theoretical Predictions ◽  
Magnetic Resonance Imaging Mri

A bolus-tracking magnetic resonance imaging (MRI) method has been employed to measure velocity profiles for oscillatory flow with and without a steady flow component as well as pulsatile flow in an axisymmetric tube model. A range of flow conditions within normal physiological limits was tested. The imaged velocity profiles were observed to be generally in accord with theoretical predictions. Instantaneous flow rates calculated from the MR images agreed well with those assessed using an ultrasonic flowmeter. Because MRI is noninvasive and poses few risks to subjects, this technique is potentially useful for studying vascular hemodynamics in vivo.

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