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Objectives To evaluate the clinical feasibility of ultrahigh field 7-T SWI to visualize vessels and assess their density in the immature epiphyseal cartilage of human knee joints. Methods 7-T SWI of 12 knees (six healthy volunteers, six patients with osteochondral abnormalities; mean age 10.7 years; 3 female, 9 male) were analysed by two readers, classifying intracartilaginous vessel densities (IVD) in three grades (no vessels, low IVD and high IVD) in defined femoral, tibial and patellar zones. Differences between patients and volunteers, IVDs in different anatomic locations, differences between cartilage overlying osteochondral abnormalities and corresponding normal zones, and differences in age groups were analysed. Results Interrater reliability showed moderate agreement between the two readers (κ = 0.58, p < 0.001). The comparison of IVDs between patients and volunteers revealed no significant difference (p = 0.706). The difference between zones in the cartilage overlying osteochondral abnormalities to corresponding normal zones showed no significant difference (p = 0.564). IVDs were related to anatomic location, with decreased IVDs in loading areas (p = 0.003). IVD was age dependent, with more vessels present in the younger participants (p = 0.001). Conclusions The use of SWI in conjunction with ultrahigh field MRI makes the in vivo visualization of vessels in the growing cartilage of humans feasible, providing insights into the role of the vessel network in acquired disturbances. Key Points • SWI facilitates in vivo visualization of vessels in the growing human cartilage. • Interrater reliability of the intracartilaginous vessel grading was moderate. • Intracartilaginous vessel densities are dependent on anatomical location and age. Electronic supplementary material The online version of this article (10.1007/s00330-017-5290-1) contains supplementary material, which is available to authorized users.

Objective To determine biomechanical effects of knee cartilage defect perimeter morphology based on cartilage strain and opposing subchondral bone contact. Design Articular cartilage defects were created in 5 bovine femoral condyles: group 1, 45° inner bevel with 8-mm rim; group 2, vertical with 8-mm rim; and group 3, 45° outer bevel with 8-mm base. Samples were placed into a custom-machined micro–computed tomography tube and subjected to 800 N of axial loading. DICOM data were used to calculate cartilage thickness 4 and 6 mm from the center, distance between tibial cartilage surface and femoral subchondral bone, and contact width between tibial cartilage and subchondral bone. Strain 4 mm from the center and both absolute and change in distance (mm) to subchondral bone were compared between groups 1 and 2 using paired t tests. Strain at 6 mm and distance changed, loaded distance, and contact width (mm) were compared between groups using the Friedman test with post hoc analysis using Wilcoxon signed rank test. Results No significant differences in rim strain were noted between groups 1 and 2 at 4 mm ( P = 0.10) and between groups 1, 2, and 3 at 6 mm ( P = 0.247) from the defect center. The loaded distance was significantly different between groups 1 and 3 ( P = 0.013). No significant change in distance to the subchondral bone was found between groups ( P = 0.156). The difference in subchondral bone contact area approached but did not reach significance ( P = 0.074). Conclusion When debriding focal articular cartilage defects, establishment of an inner bevel decreases tissue deformation and contact with opposing subchondral bone.

The purpose was to evaluate the feasibility of quantitative MRI T2 mapping based on the quantitative MRI (QRAPMASTER) sequence for the quantitative assessment of knee cartilage. The T2 values from the phantom study showed excellent correlation between the two techniques (r2 = 0.998). The cartilage T2 values exhibited strong correlations (r2 = 0.867-0.982). Quantitative MRI (qMRI) T2 mapping can be used as an alternative to multi-echo T2 mapping, with relatively short scan time.

In previous studies, numerous approaches were proposed that assess knee cartilage volume quantitatively using 3D magnetic resonance (MR) imaging. However, the clinical use of these approaches is limited because 3D MR is prone to metal artifacts in postoperative cases. Our purpose in this study was to validate a method for knee cartilage volume quantification using conventional MR imaging in patients who underwent anterior cruciate ligament (ACL) reconstruction surgery. The study included 16 patients who underwent MR imaging before and 1 year after ACL reconstruction surgery. Knee cartilage volumes were measured by our computer- based method with the use of T1-weighted sagittal images. We classified the cartilage into eight regions and made comparisons between preoperative and postoperative cartilage volumes in each region. There was a significant difference between preoperative and postoperative cartilage volumes with regard to medial posterior weight-bearing, medial posterior, lateral posterior weight-bearing, and lateral posterior portions (p = 0.006, 0.023, 0.017 and 0.002, respectively). These results were consistent with the previous studies showing that knee cartilage loss occurs frequently in these portions due to an anterior subluxation of the tibia accompanied by ACL tear. With our method, knee cartilage volumes could be measured quantitatively with conventional MR imaging in patients who underwent ACL reconstruction surgery.

Purpose: Medial meniscus (MM) posterior root (PR) tear leads to severe MM posterior extrusion (PE), resulting in rapid knee cartilage degeneration. MMPR repairs are recommended to reduce MMPE, especially during knee flexion. However, the difference in MMPE between different repair techniques remains unknown. This study aimed to investigate preoperative and postoperative MMPE following several pullout repair techniques. We hypothesized that a technique using two simple stitches (TSS) would be more useful than FasT-Fix-dependent modified Mason-Allen suture (F-MMA) to prevent the progression of MMPE in knee extension. Methods: This retrospective study included 35 patients who underwent MMPR repair. To compare MMPE, patients were divided into two groups according to the use of F-MMA while grasping the posterior capsule and TSS without grasping it. Open magnetic resonance imaging was performed at 10 degrees and 90 degrees knee flexion preoperatively, and at 3 and 12 months postoperatively, and the MMPE of both groups was evaluated. Results: A significant difference was observed between preoperative and 3-month postoperative MMPE at 90 degrees knee flexion in both groups (p < .01). A significant difference was observed in 3- and 12-month postoperative MMPE at 10 degrees knee flexion between both groups (p = .04/.02), whereas no significant difference in the preoperative MMPE at 10 degrees knee flexion was observed between them (p = .45). Conclusions: Both repairs were found to be useful to reduce MMPE in knee flexion. Further, F-MMA repair increased MMPE in knee extension, unlike TSS repair. These findings suggest that TSS might have more advantages for load distribution when standing or walking.

Background:Osteoarthritis (OA) is the most common form of arthritis, and its impact is increasing year by year due to an aging population and lack of effective treatments. One of the main structural pathological changes of OA is the loss of articular cartilage. Tools that can predict cartilage loss would help identify people at high risk, thus preventing OA development.Objectives:Using a metabolomics approach, the current study aimed to identify serum metabolomic signatures for predicting the loss of knee cartilage volume over 10 years in a well-established community-based cohort - the Tasmania Older Adult Cohort (TASOAC).Methods:TASOAC is an on-going, prospective, population-based study of older adults who were randomly selected from the roll of electors in Southern Tasmania, Australia. Participants had a right knee magnetic resonance imaging (MRI) scan at baseline and a 10-year follow-up. Cartilage volume was measured in the medial, lateral, and patellar compartments and change in cartilage volume over 10 years was calculated as percentage change per year. Fasting serum samples collected at 2.6-year follow-up were metabolomically profiled using the TMIC Prime Metabolomics Profiling Assay which measures a total of 143 metabolites. 129 metabolite concentrations passed the quality control and the pairwise ratios of them as the proxies of enzymatic reaction were calculated. Linear regression models were used to test the association between each of the metabolite ratios and change in cartilage volume in each of the knee compartments with adjustment for age, sex, and body mass index (BMI). The significance was defined at a=3.0×10-6 to control multiple testing of 16,512 ratios with Bonferroni method.Results:A total of 344 participants (51% females) were included. The mean baseline age was 62.83±6.13 years and the mean BMI was 27.48±4.41 kg/m2. The average follow-up time was 10.84±0.66 years. Cartilage volume reduced by 1.34±0.72%, 1.06±0.58%, and 0.98±0.46% per year in the medial, lateral, and patellar compartments, respectively. Our data showed that an increased ratio of hexadecenoylcarnitine (C16:1) to tetradecanoylcarnitine (C14) was associated with a 0.12±0.02% per year reduction in patellar cartilage volume (p = 8.80×10-7). An increased ratio of hexadecenoylcarnitine (C16:1) to dodecanoylcarnitine (C12) was also associated with a 0.12±0.02% per year reduction in patellar cartilage volume (p = 2.66×10-6). While there were several metabolite ratios associated with cartilage volume loss in the medial and lateral compartments, none of them reached the predefined significance level.Conclusion:Our data suggested that alteration of fatty acid β-oxidation is involved in knee cartilage loss, especially in the patellar compartment, and the serum ratio of C16:1 to C14 and to C12 could be used to predict long-term patellar cartilage loss.Acknowledgements:We thank all the study participants who made the study possible. The original TASOAC study was supported by the National Health and Medical Research Council (NHMRC) and the current study was supported by the Canadian Institutes of Health Research (CIHR).Disclosure of Interests:None declared

Aim: The relationship between bone mineral density (BMD) and osteoarthritis (OA) remains controversial. This study aimed to explore the cross-sectional associations between BMD at the total body, hip and spine and joint structural abnormalities including cartilage defects and bone marrow lesions (BMLs) in patients with knee OA. Method: One hundred and eight-five subjects with symptomatic knee OA were included in this study. T2-weighted fast spin echo magnetic resonance imaging was used to assess knee cartilage defects and BMLs. Total body, hip and spine BMD were measured using dual-energy X-ray absorptiometry. Results: After adjustment for potential confounders, total hip BMD was negatively associated with medial tibial cartilage defects, lateral femoral cartilage defects, medial tibial BMLs and lateral tibial BMLs. Spine and total body BMD were negatively associated with lateral femoral cartilage defects, but not with BMLs. Conclusion: We concluded that BMD particularly at the hip was negatively associated with knee cartilage defects and BMLs.

Objective In the present in vitro study, we analyzed the chondrogenic differentiation capacity of human chondrocytes postmortally isolated from unaffected knee cartilage by the addition of transforming growth factor–β1 (TGF-β1) and/or insulin-like growth factor–1 (IGF-1) and different oxygen levels. Design After 14 and 35 days, DNA concentrations and protein contents of Col1, Col2, aggrecan as well as glycosaminoglycans (GAGs) of chondrocytes cultivated as pellet cultures were analyzed. Additionally, expression rates of mesenchymal stem cell (MSC)–associated differentiation markers were assessed in monolayer cultures. Results All cultivated chondrocytes were found to be CD29+/CD44+/CD105+/CD166+. Chondrocytic pellets stimulated with TGF-β1 showed enhanced synthesis rates of hyaline cartilage markers and reduced expression of the non-hyaline cartilage marker Col1 under hypoxic culture conditions. Conclusions Our results underline the substantial chondrogenic potential of human chondrocytes postmortally isolated from unaffected articular knee cartilage especially in case of TGF-β1 administration.

The aims of this review article are (a) to describe the principles of morphologic and compositional magnetic resonance imaging (MRI) techniques relevant for the imaging of knee cartilage repair surgery and their application to longitudinal studies and (b) to illustrate the clinical relevance of pre- and postsurgical MRI with correlation to intraoperative images. First, MRI sequences that can be applied for imaging of cartilage repair tissue in the knee are described, focusing on comparison of 2D and 3D fast spin echo and gradient recalled echo sequences. Imaging features of cartilage repair tissue are then discussed, including conventional (morphologic) MRI and compositional MRI techniques. More specifically, imaging techniques for specific cartilage repair surgery techniques as described above, as well as MRI-based semiquantitative scoring systems for the knee cartilage repair tissue—MR Observation of Cartilage Repair Tissue and Cartilage Repair OA Knee Score—are explained. Then, currently available surgical techniques are reviewed, including marrow stimulation, osteochondral autograft, osteochondral allograft, particulate cartilage allograft, autologous chondrocyte implantation, and others. Finally, ongoing research efforts and future direction of cartilage repair tissue imaging are discussed.

Purpose To evaluate biexponential T2 relaxation mapping of human knee cartilage in vivo in clinically feasible scan times. Materials and Methods T2-weighted magnetic resonance (MR) images were acquired from eight healthy volunteers using a standard 3T clinical scanner. A 3D Turbo-Flash sequence was modified to enable T2-weighted imaging with different echo times. Series of T2-weighted images were fitted using mono- and biexponential models with two- and four-parametric nonlinear approaches, respectively. Results Biexponential relaxation of T2 was detected in the knee cartilage in five regions of interest in all eight healthy volunteers. Short/long relaxation components of T2 were estimated to be 8.27 ± 0.68 / 45.35 ± 3.79 msec with corresponding fractions of 41.3 ± 1.1% / 58.6 ± 4.6%, respectively. The monoexponential relaxation of T2 was measured to be 26.9 ± 2.27 msec. The experiments showed good repeatability with coefficient of variation root mean square (CVrms) < 18% in all regions. The only difference in gender was observed in medial tibial cartilage, where the biexponential T2 in female volunteers was significantly higher compared to male volunteers (P = 0.014). Significant differences were observed in T2 relaxation between different regions on interest. Conclusion Biexponential relaxation of T2 was observed in the human knee cartilage in vivo. The short and long components are thought to be related to the tightly bound and loosely bound macromolecular water compartments. These preliminary results of biexponential T2 analysis could potentially be used to increase the specificity for detection of early osteoarthritis by measuring different water compartments and their fractions. Level of Evidence: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017.

Purpose To introduce a simple analytical formula for estimating T 2 from a single Double-Echo in Steady-State (DESS) scan. Methods Extended Phase Graph (EPG) modeling was used to develop a straightforward linear approximation of the relationship between the two DESS signals, enabling accurate T 2 estimation from one DESS scan. Simulations were performed to demonstrate cancellation of different echo pathways to validate this simple model. The resulting analytic formula was compared to previous methods for T 2 estimation using DESS and fast spin-echo scans in agar phantoms and knee cartilage in three volunteers and three patients. The DESS approach allows 3D (256 × 256 × 44) T 2 -mapping with fat suppression in scan times of 3–4 min. Results The simulations demonstrated that the model approximates the true signal very well. If the T 1 is within 20% of the assumed T 1 , the T 2 estimation error was shown to be less than 5% for typical scans. The inherent residual error in the model was demonstrated to be small both due to signal decay and opposing signal contributions. The estimated T 2 from the linear relationship agrees well with reference scans, both for the phantoms and in vivo. The method resulted in less underestimation of T 2 than previous single-scan approaches, with processing times 60 times faster than using a numerical fit. Conclusion A simplified relationship between the two DESS signals allows for rapid 3D T 2 quantification with DESS that is accurate, yet also simple. The simplicity of the method allows for immediate T 2 estimation in cartilage during the MRI examination.

Compositional measures of articular cartilage are accessible in vivo by magnetic resonance imaging (MRI) based relaxometry and cartilage spin-spin transverse relaxation time (T2) has been related to tissue hydration, collagen content and orientation, and mechanical (functional) properties of articular cartilage. The objective of the current study was therefore to evaluate subregional variation, and sex- and age-differences, in laminar (deep and superficial) femorotibial cartilage T2 relaxation time in healthy adults. To this end, we studied the right knees of 92 healthy subjects from the Osteoarthritis Initiative reference cohort (55 women, 37 men; age range 45-78 years; BMI 24.4±3.1) without knee pain, radiographic signs, or risk factors of knee osteoarthritis in either knee. T2 of the deep and superficial femorotibial cartilages was determined in 16 femorotibial subregions, using a multi-echo spin-echo (MESE) MRI sequence. Significant subregional variation in femorotibial cartilage T2 was observed for the superficial and for the deep (both p

Author(s): Joseph, Gabby B; McCulloch, Charles E; Nevitt, Michael C; Gersing, Alexandra S; Schwaiger, Benedikt J; Kretzschmar, Martin; Heilmeier, Ursula; Link, Thomas M | Abstract: ObjectiveThe purpose of this study was to determine the probability of structural worsening of knee cartilage and whole joint degeneration over 4-8 years based on cartilage T2 Z-scores at baseline.DesignRight knees with Kellgren-Lawrence (KL) grades of 0-2 in 587 participants from the Osteoarthritis Initiative were studied. 3T MR images were used to perform baseline cartilage T2 quantification and assess 4-year changes in cartilage morphology (WORMS scoring) in 5 regions. Changes in joint space narrowing (JSN) and KL were assessed over 8 years. T2 Z-scores were based on a reference database of knees without morphologic cartilage degeneration at baseline. Odds ratios for, and predicted probabilities of any worsening in WORMS cartilage, JSN and KL grade were obtained from logistic regression models.ResultsA one-unit increase in the baseline medial femur T2 Z-score was associated with cartilage worsening in the same region (OR = 1.59; P l 0.0001) and in any region (OR = 1.37; P l 0.0001), and with worsening JSN (OR = 1.82; P l 0.0001) and KL grades (OR = 1.69; P l 0.0001). Predicted probabilities of worsening in knees with a medial femur T2 Z-score from 2-4 were 38% for medial femur cartilage WORMS, 70% for any cartilage region, 28% for increasing JSN and 31% for increasing KL grade.ConclusionKnees with elevated cartilage T2 (especially in the medial femur and those that are 2 to 4 SDs above the mean reference values) are significantly more likely to have structural worsening over 4 to 8 years. Knowing cartilage T2 Z-scores may aid in targeting prevention efforts at early stages of osteoarthritis.Level of evidence2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1128-1136.

Purpose To compare the acute effect of running and bicycling of an equivalent cumulative load on knee cartilage composition and morphometry in healthy young men. A secondary analysis investigated the relationship between activity history and the change in cartilage composition after activity. Methods In fifteen men (25.8±4.2 years), the vertical ground reaction force was measured to determine the cumulative load exposure of a 15-min run. The vertical pedal reaction force was recorded during bicycling to define the bicycling duration of an equivalent cumulative load. On separate visits that were spaced on average 17 days apart, participants completed these running and bicycling bouts. Mean cartilage transverse relaxation times (T2) were determined for cartilage on the tibia and weight-bearing femur before and after each exercise. T2 was measured using a multi-echo spin-echo sequence and 3T MRI. Cartilage of the weight bearing femur and tibia was segmented using a highly-automated segmentation algorithm. Activity history was captured using the International Physical Activity Questionnaire. Results The response of T2 to bicycling and running was different (p=0.019; mean T2: pre-running=34.27 ms, pre-bicycling=32.93 ms, post-running=31.82 ms, post-bicycling=32.36 ms). While bicycling produced no change (−1.7%, p=0.300), running shortened T2 (−7.1%, p

Background Patient compliance to physiotherapy after surgical intervention is key to optimal functional outcome. This has been recognised by published literature over a number of decades. Improving and monitoring patient compliance remains a challenge. This paper explores the use of a website linked iPhone application that may be used to address this issue. Purpose The purpose of this case study was to assess if the D+R Therapy application was of benefit to a patient and to assess the advantages and disadvantages of such a system. Method One patient who underwent knee cartilage resurfacing surgery was followed up in the post-operative period. Results/conclusion The D+R Therapy platform may provide a timely and cost effective method of managing patients undergoing musculoskeletal physiotherapy. Costs may be reduced by exploiting the hardware patients already own, and identifying non-compliant patients who may be of interest to both healthcare providers and insurers. Level of evidence Level IV.

The examination of knee cartilage degradation by magnetic resonance imaging (MRI) data is essential due to the reduction in physical activity of the population and a rising number of patients with osteoarthritis(OA). The main aim of this publication is to show a new approach for analyzing knee tissue by MRI data. The present paper investigates the problems of relaxation times calculation, medical image segmentation and statistical texture features calculation. Proposed paper describes an approach for medical image segmentation, relaxation times calculation and statistical texture features calculation. An important aspect of analysis of articular cartilage relaxation times changing is illustrated in the experimental part. The experimental part of the publication also describes the dependence between organic structure and relaxation times. The proposed approach the obtained results can be useful for early OA diagnostics.

This research aims at designing exercise rehabilitation program for mechanical sensory receptors development after surgical intervention for knee cartilage injury within students of Faculty of physical education, Al-Azhar University, and identify its effect on developing lower limb’s mechanical sensory receptors, injured knee joint range of motion, working muscle strength on injured knee joint, real balance for injured limb. Five (5) students from faculty of physical education, aged between 18-20 years, who have knee cartilage entire cut, participated in the study. Results indicate that the proposed rehabilitative program has a positive effect on mechanical sensory receptors, range of motion, muscle strength and balance variables. Keywords: knee cartilage injury, rehabilitative program

Manual segmentation is the standard procedure in osteoarthritis study. However, this method is infamous for being excessive, time consuming and exhaustive. In this study, we overcame the problem of excessive expert interaction reported in manual segmentation by developing a semi-automated random walks technique with computer-aided labelling system. To minimize expert interaction, non-cartilage seeds were generated by using computer. Then, random walks algorithm would segment knee cartilage based on cartilage seeds and non-cartilage seeds. Finally, segmentation results were revised and refined accordingly. A total of 15 normal images and 10 osteoarthritic images were used in this study. In term of efficiency, we have reduced the processing time to segment normal cartilage by 47.5% (93±21s; P = 0.0000019) for observer 1 and 44% (61±8s; P = 3.52±10-5) for observer 2. We also reduced the processing time to segment diseased cartilage by 48.1% (56±16s; P = 0.00014) for observer 1 and 30.3% (62±14s; P = 0.0070) for observer 2. Besides, the proposed technique have produced good reproducibility in both normal (0.83±0.028 for observer 1 and 0.80±0.040 for observer 2) and diseased (0.80±0.060 for observer 1 and 0.82±0.043 for observer 2) cartilage segmentations. In conclusion, the combination of computer generated seeds and user-friendly random walks method have reduced the amount of expert interaction to necessary level without compromising the accuracy of results.

Nearly nothing is known about the consequences of ultra-long-distance running on knee cartilage. In this mobile MRI field study, we analysed the biochemical effects of a 4,486 km transcontinental multistage ultra-marathon on femorotibial joint (FTJ) cartilage. Serial MRI data were acquired from 22 subjects (20 male, 18 finisher) using a 1.5 T MR scanner mounted on a 38-ton trailer, travelling with the participants of the TransEurope FootRace (TEFR) day by day over 64 stages. The statistical analyses focused on intrachondral T2* behaviour during the course of the TEFR as the main outcome variable of interest. T2* mapping (sagittal FLASH T2* weighted gradient echo) is a validated and highly accurate method for quantitative compositional cartilage analysis of specific weightbearing areas of the FTJ. T2* mapping is sensitive to changes in the equilibrium of free intrachondral water, which depends on the content and orientation of collagen and the proteoglycan content in the extracellular cartilage matrix. Within the first 1,100 km, a significant running load-induced T2* increase occurred in all joint regions: 44.0% femoral-lateral, 42.9% tibial-lateral, 34.9% femoral-medial, and 25.1% tibial-medial. Osteochondral lesions showed no relevant changes or new occurrence during the TEFR. The reasons for stopping the race were not associated with knee problems. As no further T2* elevation was found in the second half of the TEFR but a decreasing T2* trend (recovery) was observed after the 3,500 km run, we assume that no further softening of the cartilage occurs with ongoing running burden over ultra-long distances extending 4,500 km. Instead, we assume the ability of the FTJ cartilage matrix to reorganize and adapt to the load.

Degeneration of articular cartilage (AC) is actively studied in knee osteoarthritis (OA) research via magnetic resonance imaging (MRI). Segmentation of AC tissues from MRI data is an essential step in quantification of their damage. Deep learning (DL) based methods have shown potential in this realm and are the current state-of-the-art, however, their robustness to heterogeneity of MRI acquisition settings remains an open problem. In this study, we investigated two modern regularization techniques -- mixup and adversarial unsupervised domain adaptation (UDA) -- to improve the robustness of DL-based knee cartilage segmentation to new MRI acquisition settings. Our validation setup included two datasets produced by different MRI scanners and using distinct data acquisition protocols. We assessed the robustness of automatic segmentation by comparing mixup and UDA approaches to a strong baseline method at different OA severity stages and, additionally, in relation to anatomical locations. Our results showed that for moderate changes in knee MRI data acquisition settings both approaches may provide notable improvements in the robustness, which are consistent for all stages of the disease and affect the clinically important areas of the knee joint. However, mixup may be considered as a recommended approach, since it is more computationally efficient and does not require additional data from the target acquisition setup.

Knee cartilage segmentation has been challenging task for many years. This task is usually connected with two major issues. First object of interest is automatic detection and extraction of knee cartilage shape. Second important issue is detection of osteoarthritis, especially, in early stages. This early deterioration is badly recognizable from native images segmentation significantly contributes to precise localization, detection and extraction of early osteoarthritis. Generally, the knee cartilage automatic segmentation and extraction can be performed by various approaches including edge tracking, intensity-based methods, supervised learning, energy minimization, statistical methods and multiregional segmentation methods. Using of particular segmentation method depends on a compromise which user is willing to accept with respect to robustness, segmentation purpose, computational time, accuracy and level of user interaction. This review is mainly focused on fully automatic segmentation methods bringing the recent informations about modeling of cartilage structure via segmentation approaches.

Knee cartilage manual segmentation is tedious. Hence, an automated approach is preferable. Convolutional neural networks (CNNs) have various application in automatic medical image segmentation task, including knee cartilage segmentation. Generative adversarial networks are popular recently due to the capability in generating images that are similar to real images. In this paper, we formulate the segmentation problem in an adversarial training approach to improve CNN-based cartilage segmentation. Two individual networks are introduced which are segmentation network and evaluation network. Segmentation network learn the feature of cartilage and generate segmented probability map while evaluation network will benchmark it. This new approach has been evaluated on medical image database and benchmarked with U-Net. The proposed method achieved accuracy of 96.8% when tested on 50 images.

The emergence of physiological magnetic resonance imaging technology provides a wealth of information for the diagnosis and research of knee cartilage lesions. In this paper, the T2 value of degenerative cartilage in the weight-bearing area of the femoral condyle of knee joint was measured in vitro by using 7.0T magnetic resonance T2 mapping sequence. The water content and collagen content of cartilage in the same site were calculated. The collagen fiber orientation was graded under polarized light microscope, and the T2 value was analyzed. Correlation with water content, collagen content and collagen fiber orientation. The results showed that the T2 value of degenerative weight-bearing cartilage was positively correlated with water content (r=0.70, P=0.000), and had no correlation with collagen content (r=0.14, P=0.200), and was positively correlated with collagen fiber orientation. r = 0.56, P = 0.000). The T2 value of degenerative cartilage in the weight-bearing area of human knee joint was positively correlated with the water content of the extracellular matrix component and the biochemical composition of collagen fiber. The magnetic resonance T2-mapping imaging sequence can accurately reflect under non-invasive conditions. Assessment of cartilage lesions.

To systematically analyse post-operative outcomes following enhanced microfracture procedures in focal cartilage injuries of the knee. Database searches were conducted in PubMed, EMBASE and Cochrane Library databases up to 30 November 2018, for clinical studies in humans that assessed surgical outcomes of enhanced microfracture procedures in focal cartilage injuries of the knee. The clinical, functional and imaging outcomes were assessed and summarized. The MINORS scale was used to assess the methodological quality of the studies included. Ten studies were included comprising a total of 331 patients (mean age of 37.0 ± 5.5 years, body mass 25.2 ± 1.7 kg m2, 56% male and 42% left knee), 278 femoral condyle chondral defects (147 medial, 35 lateral and 78 undefined) and 43 chondral defects distributed by the tibial plateau, patella and femoral trochlea. The chondral defects were mostly Outerbridge grade III or IV and the mean defect size was 3.2 ± 0.6 cm2. Studies consistently demonstrated significant improvement in the patient-reported outcome measures from baseline to final follow-up. Overall, imaging outcomes showed inconsistent results. Treatment-related adverse events were poorly reported. Enhanced microfracture techniques significantly result in improved patient-reported outcome measures over the MCID, but provide inconsistent imaging results. Current clinical evidence does not allow for unequivocal recommendation of enhanced microfracture to treat symptomatic focal grade III/IV knee cartilage lesions. IV.

Segmentation of knee cartilage from Ultrasound (US) images is essential for various clinical tasks in diagnosis and treatment planning of Osteoarthritis. Moreover, the potential use of US imaging for guidance in robotic knee arthroscopy is presently being investigated. The femoral cartilage being the main organ at risk during the operation, it is paramount to be able to segment this structure, to make US guidance feasible. In this paper, we set forth a deep learning network, Mask R-CNN, based femoral cartilage segmentation in 2D US images for these types of applications. While the traditional imaging approaches showed promising results, they are mostly not real-time and involve human interaction. This being the case, in recent years, deep learning has paved its way into medical imaging showing commendable results. However, deep learning-based segmentation in US images remains unexplored. In the present study we employ Mask R-CNN on US images of the knee cartilage. The performance of the method is analyzed in various scenarios, with and without Gaussian filter preprocessing and pretraining the network with different datasets. The best results are observed when the images are preprocessed and the network is pretrained with COCO 2016 image dataset. A maximum Dice Similarity Coefficient (DSC) of 0.88 and an average DSC of 0.80 is achieved when tested on 55 images indicating that the proposed method has a potential for clinical applications.

Purpose: To describe the associations of glucose homeostasis measures and metabolic syndrome (MetS) measures with knee cartilage defects and cartilage volume in young adults. Methods: Australian young adults from the Childhood Determinants of Adult Health Study were selected to undergo knee magnetic resonance imaging (MRI) scans during 2008-2010 (aged 31-41 years). Fasting blood sample, waist circumference and blood pressure measures were collected during 2004-2006 (aged 26-36 years). Glucose, insulin, triglyceride and high-density lipoprotein (HDL) were measured using serum samples. Homeostatic model assessment 2-insulin resistance (HOMA2-IR), HOMA2-beta cell function (HOMA2-β), HOMA2-insulin sensitivity (HOMA-S) were calculated using HOMA2 calculator (version 2.2.3 available from http://www.dtu.ox.ac.uk/homacalculator) according to fasting glucose and fasting insulin. MetS was defined when at least three of the following five components were present: waist circumference (male ≥102 cm, female ≥88 cm), fasting glucose (≥5.6 mmol/L), serum triglycerides (≥1.7 mmol/L), HDL (male Results: Among 328 participants (47.3% were females), 40 (12.7%) had hyperglycaemia and 21 (6.7%) had MetS. Glucose homeostasis measures (except fasting glucose) were associated with tibiofemoral cartilage defects (Fasting insulin: relative risk (RR) 1.05/mU/L, 95% confidence interval (CI) 1.01 to 1.09; HOMA2-IR: 1.46, 1.10 to 1.95; HOMA2-β: 2.54, 1.27 to 5.11; HOMA2-S: 0.44, 0.23 to 0.81), but not patellar cartilage defects. MetS measures were not associated with cartilage defects, except associations between hypertriglyceridemia and patellar cartilage defects (RR 1.72, 95% CI 1.09 to 2.72) and between low HDL and tibiofemoral cartilage defects (RR 2.11, 95% CI 1.22 to 3.66). All the significant associations persisted after further adjustment for total physical activity. There were no associations between glucose homeostasis measures or MetS measures and knee cartilage volume. Conclusions: Insulin resistance was associated with higher risk of tibiofemoral cartilage defects, but not patellar cartilage defects amongst young adults. MetS was not associated with cartilage defects; neither glucose homeostasis measures nor MetS were associated with cartilage volume. These suggest that glucose homeostasis, but not MetS, may play a role in cartilage damage in young adults and may lead to knee osteoarthritis in later life.

Background Body composition, physical activity and physical performance may play roles in the incidence of knee osteoarthritis. However, the effects of body composition, physical activity and physical performance on knee cartilage thickness and subchondral bone area in young adults were unknown. Objectives To describe associations of body composition, physical activity and physical performance with knee cartilage thickness and subchondral bone area in young adults. Methods Body composition, physical activity and physical performance were measured 4-5 years prior to knee magnetic resonance imaging (MRI). Cartilage thickness and subchondral bone area of patella and lateral/medial femorotibial compartment were measured quantitatively from MRI. Total knee cartilage thickness was calculated as the weighted-average according to bone area of each compartment; total knee bone area was calculated as the sum of each compartment. Associations were assessed using linear regression analysis. Age, gender, height (if fat mass or lean mass was predictor) and BMI (if physical activity or physical performance measures were predictors) were examined as potential confounders and were included in the regressions. Mediator was identified using mediation analysis (Stata’s medeff command). Results Participants were aged 31-40 years, 48% were female (n=186). Greater lean mass, but not fat mass, was positively associated with total knee cartilage thickness (β=6.50 μm/kg, 95% confidence interval (CI): 0.86 to 12.13) and subchondral bone area (β=13.66 mm2/kg, 95% CI: 5.73 to 21.59). Physical performance measures were positively associated with knee cartilage thickness (long jump: β=2.36 μm/cm, 95% CI 0.68 to 4.04; hand grip strength: 7.65 μm/kg, 1.53 to 13.77; physical work capacity: 1.04 μm/watt, 0.27 to 1.81) and subchondral bone area (long jump: β=4.25 mm2/cm, 95% CI 1.01 to 7.50; hand grip strength: 19.89 mm2/kg, 8.23 to 31.55; leg strength: 3.32 mm2/kg. 1.25 to 5.40; physical work capacity: 3.00 mm2/watt, 1.54 to 4.45). Mediation analysis suggested these associations were mediated by lean mass (effect mediated: 29-95%). Questionnaire based activity measures (including walking, moderate activity, vigorous activity and total activity) were not associated with total knee cartilage thickness or subchondral bone area. Conclusion Greater lean mass and better physical performance measures were associated with greater knee cartilage thickness and subchondral bone area in young adults, and the associations of physical performance were largely mediated by lean mass. These findings suggest lean mass may play an important role in maintaining knee joint health in young adults. Disclosure of Interests Tao Meng: None declared, Benny Antony: None declared, Alison Venn: None declared, Felix Eckstein Shareholder of: Shareholder of Chondrometrics GmbH, Consultant for: Consulting fees from Merck KGaA, Samumed LLC, Abbvie, Bioclinica, TissueGene, Servier, and Roche, Employee of: Employee of Chondrometrics GmbH, Flavia Cicuttini: None declared, Lyn March: None declared, Marita Cross: None declared, Terence Dwyer: None declared, Graeme Jones: None declared, Laura Laslett: None declared, Changhai Ding: None declared

Background The variation in articular cartilage thickness (ACT) in healthy knees is difficult to quantify and therefore poorly documented. Our aims are to (1) define how machine learning (ML) algorithms can automate the segmentation and measurement of ACT on magnetic resonance imaging (MRI) (2) use ML to provide reference data on ACT in healthy knees, and (3) identify whether demographic variables impact these results. Methods Patients recruited into the Osteoarthritis Initiative with a radiographic Kellgren-Lawrence grade of 0 or 1 with 3D double-echo steady-state MRIs were included and their gender, age, and body mass index were collected. Using a validated ML algorithm, 2 orthogonal points on each femoral condyle were identified (distal and posterior) and ACT was measured on each MRI. Site-specific ACT was compared using paired t-tests, and multivariate regression was used to investigate the risk-adjusted effect of each demographic variable on ACT. Results A total of 3910 MRI were included. The average femoral ACT was 2.34 mm (standard deviation, 0.71; 95% confidence interval, 0.95-3.73). In multivariate analysis, distal-medial (−0.17 mm) and distal-lateral cartilage (−0.32 mm) were found to be thinner than posterior-lateral cartilage, while posterior-medial cartilage was found to be thicker (0.21 mm). In addition, female sex was found to negatively impact cartilage thickness (OR, −0.36; all values: P Conclusion ML was effectively used to automate the segmentation and measurement of cartilage thickness on a large number of MRIs of healthy knees to provide normative data on the variation in ACT in this population. We further report patient variables that can influence ACT. Further validation will determine whether this technique represents a powerful new tool for tracking the impact of medical intervention on the progression of articular cartilage degeneration.

Objective To describe associations of body composition, physical activity and physical performance with knee cartilage thickness and subchondral bone area in young adults. Methods Body composition, physical activity and physical performance were measured 4–5 years prior to knee MRI. Cartilage thickness and bone area were measured quantitatively from MRI. Associations were assessed using linear regression analysis, with mediators being identified using mediation analysis. Results Participants (n = 186) were 31–41 years of age when the MRI was acquired and 48% were female. Greater lean mass was positively associated with cartilage thickness [β = 6.52 μm/kg (95% CI 0.86, 12.18)] and bone area [β = 13.37 mm2/kg (95% CI 5.43, 21.31)]. Physical performance measures were positively associated with cartilage thickness [long jump: β = 2.44 μm/cm (95% CI 0.70, 4.18); hand grip strength: 7.74 μm/kg (95% CI 1.50, 13.98); physical work capacity: 1.07 μm/W (95% CI 0.29, 1.85)] and bone area [long jump: β = 3.99 mm2/cm (95% CI 0.64, 7.34); hand grip strength: 19.06 mm2/kg (95% CI 7.21, 30.92); leg strength: 3.18 mm2/kg (95% CI 1.09, 5.28); physical work capacity: 3.15 mm2/W (95% CI 1.70, 4.60)]. Mediation analysis suggested these associations were mediated by lean mass (effect mediated: 27–95%). Conclusion Greater lean mass and better physical performance measured 4–5 years prior were associated with greater knee cartilage thickness and subchondral bone area in young adults, and the associations of physical performance were largely mediated by lean mass. These findings suggest lean mass may play an important role in maintaining knee joint health in young adults.

Objective To determine whether there are differences in symptomatic knee cartilage defects and rates of tobacco use among age-matched athletes versus nonathletes undergoing initial arthroscopic knee surgery who meet demographic and radiographic criteria for cartilage restoration surgery. Design Age-matched athletes ( n = 186) and nonathletes ( n = 159) age 40 or less with a body mass index (BMI) of 35 kg/m2 or less (mean 26.8 SD 4.1) and Results Nonathletes were more likely to smoke ( P < 0.001) and had higher BMI ( P = 0.005). Duration of symptoms prior to surgery was shorter among athletes ( P < 0.001). Grade 4 defects were equally prevalent ( P = 0.96) as were multicompartment grade 3-4 lesions ( P = 0.12). Mean grade 3-4 defect size was similar in lateral ( P = 0.96) and medial compartments ( P = 0.82). There was a trend toward larger anterior compartment defects in nonathletes ( P = 0.07). Conclusions Among age-matched athletes and nonathletes with symptomatic cartilage defects who meet demographic criteria for cartilage restoration, nonathletes were more likely to smoke and have a longer duration of symptoms prior to treatment. Athletes tended to present earlier but with similar size defects compared to nonathletes, supporting accelerated treatment of defects in athletes and caution toward allowing continued athletic participation in patients with known cartilage defects.

Objective Successful clinical outcomes following cartilage restoration procedures are highly dependent on addressing concomitant pathology. The purpose of this study was to document methods for evaluating concomitant procedures of the knee when performed with articular cartilage restoration techniques, and to review their reported findings in high-impact clinical orthopedic studies. We hypothesized that there are substantial inconsistencies in reporting clinical outcomes associated with concomitant procedures relative to outcomes related to isolated cartilage repair. Design A total of 133 clinical studies on articular cartilage repair of the knee were identified from 6 high-impact orthopedic journals between 2011 and 2017. Studies were included if they were primary research articles reporting clinical outcomes data following surgical treatment of articular cartilage lesions with a minimum sample size of 5 patients. Studies were excluded if they were review articles, meta-analyses, and articles reporting only nonclinical outcomes (e.g., imaging, histology). A full-text review was then used to evaluate details regarding study methodology and reporting on the following variables: primary cartilage repair procedure, and the utilization of concomitant procedures to address additional patient comorbidities, including malalignment, meniscus pathology, and ligamentous instability. Each study was additionally reviewed to document variation in clinical outcomes reporting in patients that had these comorbidities addressed at the time of surgery. Results All studies reported on the type of primary cartilage repair procedure, with autologous chondrocyte implantation (ACI) noted in 43% of studies, microfracture (MF) reported in 16.5%, osteochondral allograft (OCA) in 15%, and osteochondral autograft transplant (OAT) in 8.2%. Regarding concomitant pathology, anterior cruciate ligament (ACL) reconstruction (24.8%) and meniscus repair (23.3%) were the most commonly addressed patient comorbidities. A total of 56 studies (42.1%) excluded patients with malalignment, meniscus injury, and ligamentous instability. For studies that addressed concomitant pathology, 72.7% reported clinical outcomes separately from the cohort treated with only cartilage repair. A total of 16.5% of studies neither excluded nor addressed concomitant pathologies. There was a significant amount of variation in the patient reported outcome scores used among the studies, with the majority of studies reporting International Knee Documentation Committee (IKDC) and Knee Injury and Osteoarthritis Outcomes Score (KOOS) in 47.2% and 43.6% of articles, respectively. Conclusions In this study on knee cartilage restoration, recognition and management of concomitant pathology is inadequately reported in approximately 28% of studies. Only 30% of articles reported adequate treatment of concomitant ailments while scoring their outcomes using one of a potential 18 different scoring systems. These findings highlight the need for more standardized methods to be applied in future research with regard to inclusion, exclusion, and scoring concomitant pathologies with regard to treatment of cartilage defects in the knee.