Cartilage thickness in the hip joint measured by MRI and stereology – a methodological study (original) (raw)
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Determining the volume of hip cartilage by magnetic resonance imaging
Radiography, 2000
Objective: Little progress has been made in developing a non-invasive method for assessing hip cartilage in vivo. The aim of our study was to determine whether the volume of hip cartilage can be determined accurately and reproducibly from routinely performed magnetic resonance images (MRI). Methods: Ten femoral heads obtained at surgery (five men, five women; aged 67-75 years) were used to compare cartilage volume estimates obtained using MRI with direct dissection of cartilage from anatomical samples. Hip MRI from six randomly selected patients having MRI for clinical indications were used to assess the reproducibility of MRI cartilage volume. Articulate cartilage volumes were determined by means of three-dimensional image processing of TI-weighted fat saturated, sagittal MRI. Results: The volume of the cartilage from the 10 hip specimens ranged from 1.8 to 7.8 ml, as determined by the MRI method, and 1.6 to 8.1 ml, as determined by dissection and volume displacement. The average over-and under-estimation of the cartilage volume using MRI was 0.6 (12%) 0.6 ml. The coefficient of variation, as a measure of reproducibility, was 6.6%, based on six subjects, measured five times. Conclusions: The volume of femoral head cartilage can be measured non-invasively with good accuracy and reproducibly from standard diagnostic MRI. As cartilage volume measures are not subject to the same difficulty in reselecting identical section locations in follow-up MRI as other methods examining structural changes in the hip joint, this method may be useful in longitudinal studies examining therapeutic agents and preventive strategies in hip arthritis.
Thickness of the bone-cartilage unit in relation to osteoarthritis severity in the human hip joint
RMD Open
ObjectiveBone formation is a hallmark of osteoarthritis (OA). It has been speculated that bone formation may occur because of ossification at the bone-cartilage unit, that is, bone formation directly involving the calcified cartilage (CC). This study aimed to investigate the thickness of the CC and subchondral bone (SCB) in relation to the severity of the overlying articular cartilage (AC) degeneration.DesignWe investigated femoral heads from 20 patients with OA and 15 healthy subjects with design-based stereology using systematic uniform random sampling of the entire joint surface. This was combined with the Osteoarthritis Research Society International (OARSI) OA cartilage histopathology assessment system, thus obtaining focal OARSI grades paired with thickness measurements of AC, CC and the SCB.ResultsThe patients with OA had thicker CC (mean 159; 95% CI 144 to 177 µm) compared with the healthy subjects (mean 132; 95% CI 113 to 1550 µm; p=0.036), and this difference was even high...
Osteoarthritis and Cartilage, 2005
Objective: The primary goal of this study was to describe and evaluate conditions that could influence the precision and accuracy of measuring in vivo cartilage thickness in the weight bearing regions of the knee from magnetic resonance imaging (MRI). Design: Three-dimensional (3D) models of the femoral cartilage were created from segmented MR images. The weight bearing regions on femoral cartilage were selected for the portion of the tibiofemoral joint that sustains contact during walking. Six regions of interest (three on each condyle) were located on the femur. Average cartilage thickness was calculated over each region. The sensitivity of the precision of the measurements to observer variability was evaluated using intra-and inter-observer reproducibility tests of cartilage thickness measurements from the MRI-derived 3D models. In addition, the quantitative influence of a rule-based protocol for segmentation was evaluated using the inter-observer reproducibility protocol. Accuracy tests were conducted on porcine knees by comparing 3D models from MR images and laser scans across weight bearing and non-weight bearing regions. Results: The precision was substantially better for the intra-observer tests (Coefficient of variation (CV) Z 1e3%) than the inter-observer tests. Adding a rule-based protocol reduced variability in inter-observer tests substantially (CV Z 6.6% vs 8.3%). Accuracy tests showed that the central and weight bearing regions on each condyle were more accurate than boundary and non-weight bearing regions. In addition, these results indicate that care should be taken when determining cartilage thickness of weight bearing regions with cartilage degenerations, since the thickness of thinner cartilage can be systematically overestimated in MR images. Conclusions: A rule-based approach can substantially increase inter-observer reproducibility when measuring cartilage thickness from multiple observers. This improvement in inter-observer reproducibility could be an important consideration for longitudinal studies of disease progression. In quantifying cartilage thickness, central and weight bearing regions on each condyle can provide more accurate measurement than boundary and non-weight bearing regions with average accuracy of G0.2e0.3 mm. An important finding of this study was that the weight bearing regions, which are usually of the greatest clinical interest, were measured most accurately by sagittal plane imaging.
Clinical Orthopaedics and Related Research®, 2010
Background Untreated hip dysplasia can result in a degenerative process joint and secondary osteoarthritis at an early age. While most periacetabular osteotomies (PAOs) are performed to relieve symptoms, the osteotomy is presumed to slow or prevent degeneration unless irreparable damage to the cartilage has already occurred. Questions/purposes We therefore determined (1) whether changes in the thickness of the cartilage in the hip occur after PAO, and (2) how many patients had an acetabular labral tear and whether labral tears are associated with thinning of the cartilage after PAO. Patients and Methods We prospectively followed 22 women and four men with hip dysplasia with MRI before PAO and again 1 year and 2 1 .
Cartilage, 2013
Objective: Before quantitative imaging techniques can become clinically valuable, the method, and more specifically, the regions of locating and reporting these values should be standardized toward reproducibility comparisons across centers and longitudinal follow-up of individual patients. The purpose of this technical note is to describe a rigorous and reproducible method of locating, analyzing, and reporting quantitative MRI values in hip articular cartilage with an approach that is consistent with current orthopedic literature. Design: To demonstrate this localization and documentation, 3 patients (age, 23 ± 5.1 years; 2 males, 1 female) who presented with symptomatic mixed-type femoroacetabular impingement (α angle, 63.3° ± 2.1°; center edge angle, 39° ± 4.2°) were evaluated with T2-mapping at 3 T MRI prior to hip arthroscopy. Manual segmentation was performed and cartilage of the acetabulum and femur was divided into 12 subregions adapted from the geographic zone method. Bone landmarks in the acetabulum and femur, identifiable both in arthroscopy and MR images, were manually selected and the coordinates exported for division of cartilage. Results: Mean T2 values in each zone are presented. Conclusions: The current work outlines a standardized system to locate and describe quantitative mapping values that could aid in surgical decision making, planning, and the noninvasive longitudinal follow-up of implemented cartilage preservation and restoration techniques.
Magnetic Resonance in Medicine, 1996
A method for the assessment of articular cartilage thickness based on MRI is presented and its accuracy and reproducibility tested. Six specimens of human patellae were imaged, using a fat-=pressed FLASH 3D sequence, and sectioned with a high-precision band saw. The regional distribution of articular cadlage thickness was determined from the MR images and from the anatomical sections (intervals of 0.5 mm). With image analysis 5040% of the image points were found to lie within exactly the same thickness interval in corresponding patterns, and less than 17% deviated mom than 0.5 mm. More than 85% of all pixels were reproducible with MRI after new positioning of the joint. No influence of the read-out direction and no important differences between areas of thin and thick cartilage could be detected. The authors conclude that MR chondro-crassometry can provide accurate and reproducible information on cartilage thickness.
Magnetic Resonance in Medicine, 1996
The objective of this article was to analyze the accuracy and precision with which the quantitative distribution of articular cartilage can be determined in the knee joint using MRI. A three-dimensional (3D) technique that accounts for the outof-plane deviation of the interface normal in strongly curved joint surfaces (3D MR-CCM) has been developed for cartilage thickness measurements. Eight cadaveric knee-joint specimens and six volunteers were imaged using a fat-suppressed gradient-echo sequence at a resolution of 2 x 0.31 x 0.31 mm3. Cartilage volumes and topographical thickness maps were obtained and compared with those derived from anatomical sections by image analysis. The deviation of the MR volumes from those of the sections was 1-12%, the coefficient of variation after repositioning ranged from 2.9% (patella) to 8.2% (lateral tibia1 plateau). Between 60% and 80% of all image points could be attributed to identical thickness intervals, less than 20% deviating by more than 0.5 mm. The intraobserver and interobserver reproducibilities were very high in both the specimens and the volunteers. In the knee joint, 3D reconstructions of the cartilages, and measurements that take into account the out-of-plane deviation of the interface normals (3D MR-CCM), are required.