Evaluation of knee cartilage thickness: A comparison between ultrasound and magnetic resonance imaging methods

Measurement Position Influences Sex Comparisons of Distal Femoral Cartilage Thickness With Ultrasound Imaging

The purpose was to examine (1) the effect of measurement position and sex on femoral cartilage outcomes, and (2) the association between gait biomechanics and cartilage outcomes. Fifty individuals participated (25 males and 25 females; age = 20.62 [1.80] y). Ultrasound measured femoral cartilage thickness and echo-intensity at 90°, 115°, and 140° of knee flexion. Gait outcomes included the external knee adduction and knee flexion moments. Cartilage outcomes were compared using 2 (sex) × 3 (position) repeated-measures analysis of variance. Gait and cartilage associations were assessed using stepwise regression. Medial cartilage was thicker when measured at 90° compared with 115° (P = .02) and 140° (P < .01), and 115° compared with 140°, (P < .01) in males but not in females. Cartilage was thicker at 90° compared with 140° across both sexes within all regions (P < .01). Males had thicker cartilage than females in all positions (P < .01). Echo-intensity was lower at 90° than 115° (P < .01) and 140° (P = .01) in the central and lower at 90° than at 115° (P < .01) and 140° (P = .03) in lateral regions. No association was found between gait and cartilage outcomes. Ultrasound imaging position effects cartilage features more in males compared with females. Imaging position and sex influence cartilage outcomes and should be considered in study designs and clinical evaluation.

Ultrasound-guided determination demonstrates influence of age, sex and type of sport on medial femoral condyle cartilage thickness in children and adolescents

PURPOSE

To analyse the reliability of ultrasound-guided measurement of the cartilage thickness at the medial femoral condyle in athletically active children and adolescents before and after mechanical load in relation to age, sex and type of sport.

METHODS

Three successive measurements were performed in 157 participants (median/min-max age: 13.1/6.0-18.0 years, 106 males) before and after mechanical load by squats at the same site of the medial femoral condyle by defined transducer positioning. Test-retest reliability was examined using Cronbach'sα $\alpha $ calculation. Differences in cartilage thickness were analysed with respect to age, sex and type of practiced sports, respectively.

RESULTS

Excellent reliability was achieved both before and after mechanical load by 30 squats with a median cartilage thickness of 1.9 mm (range: 0.5-4.8 mm) before and 1.9 mm (0.4-4.6 mm) after mechanical load. Male cartilages were thicker (p < 0.01) before (median: 2.0 mm) and after (2.0 mm) load when compared to female cartilage (before: 1.6 mm; after: 1.7 mm). Median cartilage thickness was about three times higher in karate athletes (before: 2.3 mm; after: 2.4 mm) than in sports shooters (0.7; 0.7 mm). Cartilage thickness in track and field athletes, handball players and soccer players were found to lay in-between. Sport type related thickness changes after mechanical load were not significant.

CONCLUSION

Medial femoral condyle cartilage thickness in childhood correlates with age, sex and practiced type of sports. Ultrasound is a reliable and simple, pain-free approach to evaluate the cartilage thickness in children and adolescents.

LEVEL OF EVIDENCE

Level III.

Characteristics of Acute Cartilage Response After Mechanical Loading in Patients with Early-Mild Knee Osteoarthritis

This study determined whether the acute cartilage response, assessed by cartilage thickness and echo intensity, differs between patients with early-mild knee osteoarthritis (OA) and healthy controls. We recruited 56 women aged ≥ 50 years with Kellgren-Lawrence (KL) grade ≤ 2 (age, 70.6 ± 7.4 years; height, 153.7 ± 5.2 cm; weight, 51.9 ± 8.2 kg). Based on KL grades and knee symptoms, the participants were classified into control (KL ≤ 1, asymptomatic, n = 27) and early-mild knee OA groups (KL 1 and symptomatic, KL 2, n = 29). Medial femoral cartilage thickness and echo intensity were assessed using ultrasonographic B-mode images before and after treadmill walking (15 min, 3.3 km/h). To investigate the acute cartilage response, repeated-measures analysis of covariance (groups × time) with adjusted age, external knee moment impulse, steps during treadmill walking, and cartilage thickness at pre-walking was performed. A significant interaction was found at the tibiofemoral joint; after walking, the cartilage thickness was significantly decreased in the early-mild knee OA group compared to the control group (p = 0.002). At the patellofemoral joint, a significant main effect of time was observed, but no interaction was detected (p = 0.802). No changes in cartilage echo intensity at either the tibiofemoral or patellofemoral joints, and no interactions were noted (p = 0.295 and p = 0.063). As acute cartilage response after walking, the thickness of the medial tibiofemoral joint in the early-mild knee OA was significantly reduced than that in the control group. Thus, greater acute deformation after walking might be a feature found in patients with early-mild knee OA.

Femoral cartilage ultrasound echo-intensity is a valid measure of cartilage composition

This study aimed to create a conversion equation that accurately predicts cartilage magnetic resonance imaging (MRI) T2 relaxation times using ultrasound echo-intensity and common participant demographics. We recruited 15 participants with a primary anterior cruciate ligament reconstruction between the ages of 18 and 35 years at 1-5 years after surgery. A single investigator completed a transverse suprapatellar scan with the ACLR limb in max knee flexion to image the femoral trochlea cartilage. A single reader manually segmented the femoral cartilage cross-sectional area to assess the echo-intensity (i.e., mean gray-scale pixel value). At a separate visit, a T2 mapping sequence with the MRI beam set to an oblique angle was used to image the femoral trochlea cartilage. A single reader manually segmented the cartilage cross-sectional area on a single MRI slice to assess the T2 relaxation time. A stepwise, multiple linear regression was used to predict T2 relaxation time from cartilage echo-intensity and common demographic variables. We created a conversion equation using the regression betas and then used an ICC and Bland-Altman plot to assess agreement between the estimated and true T2 relaxation time. Cartilage ultrasound echo-intensity and age significantly predicted T2 relaxation time (F = 7.33, p = 0.008, R2 = 0.55). When using the new conversion equation to estimate T2 relaxation time from cartilage echo-intensity and age, there was strong agreement between the estimated and true T2 relaxation time (ICC2,k = 0.84). This study provides promising preliminary data that cartilage echo-intensity combined with age can be used as a clinically accessible tool for evaluating cartilage composition.

The effect of attending rehabilitation after traumatic knee joint injury on femoral articular cartilage morphology in collegiate rugby players with a history of intracapsular knee joint injury during two-year consecutive rugby seasons

Introduction

This present study aimed to compare ultrasonographic measures of femoral articular cartilage during two-year seasons between collegiate rugby players who have attended supervised rehabilitation following intracapsular knee joint injury and those without a history of knee injury.

Methods

Using a prospective observational study design, 12 male collegiate rugby players with a previous history of intracapsular knee joint injury who have received and completed supervised rehabilitation following their injury and 44 players without knee joint injury participated in this study. Ultrasonographic images were used to verify changes in femoral articular cartilage thickness and cross-sectional area (CSA) with or without a previous history of knee joint injury over two consecutive rugby seasons.

Results

Significant time main effects were observed for the lateral condylar thickness (p < 0.001), the intercondylar thickness (p = 0.001), the medial condylar thickness (p < 0.001), and CSA (p < 0.001). No significant interactions nor group main effects were identified for all femoral articular cartilage (p < 0.05).

Conclusions

Collegiate rugby players demonstrated a decrease in femoral articular cartilage thickness and CSA over two-year consecutive rugby seasons. These findings indicate that engaging in collegiate rugby induces alterations in femoral articular cartilage structure. Furthermore, there were no differences in all femoral cartilage outcome measures between rugby players with and without a previous history of traumatic knee joint injury. Therefore, attending supervised rehabilitation at the time of their knee joint injury appeared to reduce the impact of a previous history of intracapsular knee joint injury on the change in femoral articular cartilage thickness and CSA among active rugby players.

The short-term effect of glucosamine-sulfate, nonanimal chondroitin-sulfate, and S-adenosylmethionine combination on ultrasonography findings, inflammation, pain, and functionality in patients with knee osteoarthritis: A pilot, double-blind, randomized, placebo-controlled clinical trial

Objectives

This study aimed to investigate the efficacy of glucosamine-sulfate (GS), nonanimal chondroitin-sulfate (naCS), and S-adenosylmethionine (SAMe) combination on ultrasound findings, inflammation, pain, and functionality in knee osteoarthritis.

Patients and methods

In the prospective, randomized, double-blind, placebo-controlled pilot study conducted between August 2019 and November 2019, 120 participants (28 males, 92 females; mean age: 66.4±7.9 years; range, 42.4 to 74.5 years) were randomized at a 1:1:1 ratio to the placebo group, the first experimental group (a combination of GS, naCS, and SAMe was administered to the experimental groups. The first experimental group received 375 mg of GS, 300 mg of naCS, and 100 mg of SAMe, whereas the second experimental group received 750 mg of GS, 600 mg of naCS, and 200 mg of SAMe). Laboratory (erythrocyte sedimentation rate, C-reactive protein, tumor necrosis factor alpha, interleukin [IL]-1β, IL-6, IL-17), clinical (Visual Analog Scale [VAS], short form health survey [SF-36], the Western Ontario and McMaster Universities Arthritis Index [WOMAC], and the Tegner Lysholm Knee Scoring Scale [TLKS]), and musculoskeletal ultrasound (MSUS) assessments were performed at baseline and after three and six months.

Results

A minor increase was observed in the second experimental group after six months using ultrasonography to evaluate articular cartilage thickness (p<0.05). The investigational product's superiority in reducing osteoarthritis ultrasonographic findings was not proven. A moderately negative association was found between cartilage thickness and VAS scores at baseline (ρ=-0.36, p<0.01), while the presence of massive osteophytes on MSUS showed a low to moderate association with all clinical outcomes. There was no difference in the delta changes between groups for the VAS, TLKS, WOMAC, and SF-36. The only serum inflammatory marker outside the reference range was IL-1β, but no significant changes were observed after six months.

Conclusion

According to the results of our investigation, treatment for knee osteoarthritis should be evaluated using more objective outcomes. The most important conclusion of our study is that IP may result in a slight increase in articular cartilage thickness, which was associated with a decrease in pain intensity at baseline. Clarification of the potential influence of this combination on radiographic progression and laboratory markers of inflammation requires further exploration.

Toward New Assessment of Knee Cartilage Degeneration

OBJECTIVE

Assessment of human joint cartilage is a crucial tool to detect and diagnose pathological conditions. This exploratory study developed a workflow for 3D modeling of cartilage and bone based on multimodal imaging. New evaluation metrics were created and, a unique set of data was gathered from healthy controls and patients with clinically evaluated degeneration or trauma.

DESIGN

We present a novel methodology to evaluate knee bone and cartilage based on features extracted from magnetic resonance imaging (MRI) and computed tomography (CT) data. We developed patient specific 3D models of the tibial, femoral, and patellar bones and cartilages. Forty-seven subjects with a history of degenerative disease, traumatic events, or no symptoms or trauma (control group) were recruited in this study. Ninety-six different measurements were extracted from each knee, 78 2D and 18 3D measurements. We compare the sensitivity of different metrics to classify the cartilage condition and evaluate degeneration.

RESULTS

Selected features extracted show significant difference between the 3 groups. We created a cumulative index of bone properties that demonstrated the importance of bone condition to assess cartilage quality, obtaining the greatest sensitivity on femur within medial and femoropatellar compartments. We were able to classify degeneration with a maximum recall value of 95.9 where feature importance analysis showed a significant contribution of the 3D parameters.

CONCLUSION

The present work demonstrates the potential for improving sensitivity in cartilage assessment. Indeed, current trends in cartilage research point toward improving treatments and therefore our contribution is a first step toward sensitive and personalized evaluation of cartilage condition.

Ultrasonographic echo intensity in the medial femoral cartilage is enhanced prior to cartilage thinning in women with early mild knee osteoarthritis

PURPOSE

We aimed to determine whether altered cartilage echo intensity is associated with knee osteoarthritis (OA) severity and whether the alteration occurs before thinning of the femoral cartilage in knee OA.

METHODS

The medial femoral cartilage thickness and echo intensity of 118 women aged ≥ 50 years were assessed using an ultrasound imaging device. Based on the Kellgren-Lawrence (KL) grade and knee symptoms, participants were classified into five groups: control (asymptomatic grades 0-1), early OA (symptomatic grade 1), grade 2, grade 3, and grade 4. Analysis of covariance, with adjusted age and height, and the Sidak post hoc test were used to assess the differences in cartilage thickness and echo intensity in knees with varying OA severity.

RESULTS

The echo intensity on longitudinal images, equivalent to the tibiofemoral weight-bearing surface, was significantly higher in the grade 2 group than that in the control group (p = 0.049). However, no significant difference was noted in cartilage thickness (n.s.). In the grades 3 and 4 groups, cartilage thickness became thinner as OA progressed (p < 0.001 and p < 0.001, respectively). However, the cartilage echo intensity was not significantly enhanced compared with that of the grade 2 group (n.s.). There were no significant differences in the cartilage thickness and echo intensity between the early OA and control groups on the longitudinal images (n.s.).

CONCLUSIONS

The echo intensity of the medial femoral cartilage was high in patients with KL grade 2, without decreased thickness. Our findings suggested that higher echo intensity is a feature of early cartilage degeneration in mild knee OA. Further studies are needed to establish this feature as a useful screening parameter of early cartilage degeneration in knee OA.

LEVEL OF EVIDENCE

Level III.

Point-of-care ultrasound in musculoskeletal field

The musculoskeletal field is relatively new in point-of-care ultrasound (POCUS), a modality that has been gaining significance with the evolution of ultrasound (US) equipment and high-frequency probes. Images have become progressively clearer over the past decade, making it possible to diagnose many pathological conditions without exposure to radiation. Ultrasonography reveals many soft tissue pathologies that cannot be visualized using plain radiographs, which have historically been the first choice for the evaluation of musculoskeletal disorders. US saves money and time compared to magnetic resonance imaging (MRI). Although it is difficult to diagnose a disorder inside bone, its surface can be visualized very clearly, and it is also possible to visualize cartilage. Furthermore, with POCUS, it is possible to confirm a disorder and the continuity of the fibrous structures of muscles, tendons, and ligaments. In addition, the understanding of pathological conditions of motor disturbances, such as nerve or muscle/tendon injury, nerve paralysis, adhesions of the tendons, and joint instability, is deepened by observing the movement of these structures. Peripheral nerves, even small branches, can be visualized, and pathological conditions can be pinpointed by observing the nerve morphology, continuity, and relationship with the surrounding tissues. Children can be examined in a safe, relaxed environment, without leaving their parents. In addition, US is significantly different from other modalities in that it can be used for both diagnosis and treatment. Being able to visualize target sites improves safety and route accuracy of needle insertion for injection or puncture. Musculoskeletal POCUS is indispensable in routine medical care and is a technique that medical residents should acquire.

Articular surface integrity assessed by ultrasound is associated with biological characteristics of articular cartilage in early-stage degeneration

Early diagnosis of articular cartilage damage and repeated evaluation of treatment efficacy are essential for osteoarthritis treatment. In this study, we established a simple ultrasound grading system for early degenerative articular cartilage and investigated its relationship with cartilage biological characteristics. The ultrasound grading system were based on surface integrity (S1a: continuous high-echo lines, S1b: discontinuous or weak high-echo lines, S2: surface irregular) and cartilage echogenicity (E1: with > 50%, E2: < 50% hypoechoic area of total cartilage layer) and verified by surface roughness (Ra; μm) and histological staining. Ra was lower in S1 than in S2, and the percentage of hypoechoic and safranin O-stained areas was positively correlated. Then we examined its relationship with histopathological evaluation (OARSI grade), gene expression, and protein production in responded to pro-inflammatory cytokine (IL-1ß) stimulation. OARSI grades were different among S grades. The superficial layer of S1 had higher expression of Collagen10, aggrecan, Sox9, and lower expression of Collagen1 and BMP2 than that of S2. S1 responded more pronouncedly to IL-1ß in IL-6, IL-8, and CCL2 production than S2. There was no difference among the E-grades. Taken together, our findings indicate that ultrasound assessment using surface integrity can reflect the biological characteristics of early degenerative articular cartilage.

Reliability and Convergent Construct Validity of Quantitative Ultrasound for Synovitis, Meniscal Extrusion, and Osteophyte in Knee Osteoarthritis With MRI

AIMS

To determine: 1) inter-rater reliability of quantitative measurements of ultrasound-detected synovitis, meniscal extrusion, and osteophytes; and 2) construct (convergent) validity via correlations and absolute agreements between ultrasound- and gold-standard magnetic resonance imaging (MRI)-outcomes in knee osteoarthritis.

METHODS

Dynamic ultrasound images for supra-patellar synovitis, meniscal extrusion, and osteophytes were acquired and quantified by a physician operator, musculoskeletal ultrasonographer, and medical student independently. On the same day, 3T MRI images were acquired. Effusion-synovitis, meniscal extrusion, and osteophytes were quantified on sagittal or coronal proton-density-weighted fat-suppressed noncontrast TSE sequences, respectively. Intra-class correlation coefficients (ICCs), Pearson's correlations (r), and Bland-Altman plots were used to analyze inter-rater reliability, and correlations, and agreements between the two imaging modalities.

RESULTS

Eighty-nine participants [48 females (53.9%)] with mean (standard deviation) age of 61.5 ± 6.9 years were included. The inter-rater reliability was excellent for osteophytes (ICC range = 0.90-0.96), meniscal extrusion (ICC range = 0.90-0.93), and synovitis (ICC range = 0.86-0.88). The correlations between ultrasound pathologies and their MRI counterparts were very strong (ICC range = 0.85-0.98) except for lateral meniscal extrusion [0.66 (95% CI, 0.52-0.76)]. Bland-Altman plots showed 0.01, 0.05, 0.10, 0.53, and 0.60 mm larger size in ultrasound medial tibial and medial femoral osteophytes, medial meniscal extrusions, synovitis, and lateral meniscal extrusions with 95% limits of agreements [±0.39, ±0.44, ±0.85, ±0.70, and ±0.90 (SDs)] than MRI measures, respectively. The lines of equality were within 95% CI of the mean differences (bias) only for medial osteophytes and medial meniscal extrusion.

CONCLUSION

The quantitative assessment of synovitis, meniscal extrusion, and osteophytes generally showed excellent inter-rater reliability and strong correlations with MRI-based measurements. Absolute agreement was strong for medial tibiofemoral pathologies.

Current concept of kinematic alignment total knee arthroplasty and its derivatives

The kinematic alignment (KA) approach to total knee arthroplasty (TKA) has recently increased in popularity. Accordingly, a number of derivatives have arisen and have caused confusion. Clarification is therefore needed for a better understanding of KA-TKA. Calipered (or true, pure) KA is performed by cutting the bone parallel to the articular surface, compensating for cartilage wear. In soft-tissue respecting KA, the tibial cutting surface is decided parallel to the femoral cutting surface (or trial component) with in-line traction. These approaches are categorized as unrestricted KA because there is no consideration of leg alignment or component orientation. Restricted KA is an approach where the periarthritic joint surface is replicated within a safe range, due to concerns about extreme alignments that have been considered ‘alignment outliers’ in the neutral mechanical alignment approach. More recently, functional alignment and inverse kinematic alignment have been advocated, where bone cuts are made following intraoperative planning, using intraoperative measurements acquired with computer assistance to fulfill good coordination of soft-tissue balance and alignment. The KA-TKA approach aims to restore the patients’ own harmony of three knee elements (morphology, soft-tissue balance, and alignment) and eventually the patients’ own kinematics. The respective approaches start from different points corresponding to one of the elements, yet each aim for the same goal, although the existing implants and techniques have not yet perfectly fulfilled that goal.

Deep learning-based segmentation of knee MRI for fully automatic subregional morphological assessment of cartilage tissues: Data from the Osteoarthritis Initiative

Morphological changes in knee cartilage subregions are valuable imaging-based biomarkers for understanding progression of osteoarthritis, and they are typically detected from magnetic resonance imaging (MRI). So far, accurate segmentation of cartilage has been done manually. Deep learning approaches show high promise in automating the task; however, they lack clinically relevant evaluation. We introduce a fully automatic method for segmentation and subregional assessment of articular cartilage, and evaluate its predictive power in context of radiographic osteoarthritis progression. Two data sets of 3D double-echo steady-state (DESS) MRI derived from the Osteoarthritis Initiative were used: first, n = 88; second, n = 600, 0-/12-/24-month visits. Our method performed deep learning-based segmentation of knee cartilage tissues, their subregional division via multi-atlas registration, and extraction of subregional volume and thickness. The segmentation model was developed and assessed on the first data set. Subsequently, on the second data set, the morphological measurements from our and the prior methods were analyzed in correlation and agreement, and, eventually, by their discriminative power of radiographic osteoarthritis progression over 12 and 24 months, retrospectively. The segmentation model showed very high correlation (r > 0.934) and agreement (mean difference < 116 mm³ ) in volumetric measurements with the reference segmentations. Comparison of our and manual segmentation methods yielded r = 0.845-0.973 and mean differences = 262-501 mm³ for weight-bearing cartilage volume, and r = 0.770-0.962 and mean differences = 0.513-1.138 mm for subregional cartilage thickness. With regard to osteoarthritis progression, our method found most of the significant associations identified using the manual segmentation method, for both 12- and 24-month subregional cartilage changes. The method may be effectively applied in osteoarthritis progression studies to extract cartilage-related imaging biomarkers.

A semi-automatic framework based upon quantitative analysis of MR-images for classification of femur cartilage into asymptomatic, early OA, and advanced-OA groups

To develop a semi-automatic framework for quantitative analysis of biochemical properties and thickness of femur cartilage using magnetic resonance (MR) images and evaluate its potential for femur cartilage classification into asymptomatic (AS), early osteoarthritis (OA), and advanced OA groups. In this study, knee joint MRI data (fat suppressed-proton density-weighted and multi-echo T2-weighted images) of eight AS-volunteers (data acquired twice) and 34 OA patients including 20 early OA (16 Grade-I and 4 Grade-II), 14 advanced-OA (Grade-III) were acquired at 3.0T MR scanner. Modified Outerbridge classification criteria was performed for the clinical evaluation of data by an experienced radiologist. Cartilage segmentation, T2-mapping, 2D-WearMap generation, and subregion analysis were performed semi-automatically using in-house developed algorithms. The intraclass correlation coefficient (ICC) and coefficient of variation (CV) were computed for testing the reproducibility of T2 values. One-way analysis of variance with Tukey-Kramer post hoc test was performed for evaluating the differences among the groups. The performance of individual T2 and thickness, as well as their combination using logistic regression, were evaluated with receiver operating characteristics (ROC) curve analysis. The interscan agreement based on the ICC index was 0.95 and the CV was 2.45 ± 1.33%. T2 mean of values greater than 75th percentile showed sensitivity and specificity of 94.1% and 81.3% (AUC = 0.93, cut-off value = 47.9 ms) in differentiating AS volunteers versus OA group, while sensitivity and specificity of 90.0% and 81.3% (AUC = 0.90, cut-off value = 47.9 ms) in differentiating AS volunteers versus early OA groups, respectively. In the differentiation of early OA versus advanced-OA group, ROC results of combination (T2 and thickness) showed the highest sensitivity and specificity of 85.7%, and 70.0% (AUC = 0.79, cut-off value = 0.39) compared with individual T2 and thickness features, respectively. A computer-aided quantitative evaluation of femur cartilage degeneration showed promising results and can be used to assist clinicians in diagnosing OA.

Validation of ultrasonography for measurement of cartilage thickness in the equine carpus

Articular cartilage thinning is an important hallmark of osteoarthritis (OA), and ultrasonography (US) is a clinically accessible tool potentially suitable for repeated evaluation. The aim of the present prospective methods comparison study was to validate US as a tool for measuring cartilage thickness in the carpus of the horse. Eight Standardbred trotters underwent US examination with 9 and 15 MHz linear transducers. Six anatomical locations in the radiocarpal joint (RCJ) and middle carpal joint (MCJ) were examined. The same joints were assessed by ultrahigh field (9.4 Tesla) magnetic resonance imaging (MRI) and histology. Associations between measurements obtained by the different modalities were assessed by ANOVA, Deming regression, Pearson correlation and Bland–Altman plots. Histologically assessed total cartilage thickness (the noncalcified cartilage (NCC) plus the calcified cartilage zone (CCZ)) overestimated thickness compared to MRI (P < 0.01) and US (P < 0.01). US 15 MHz had substantial agreement with MRI and NCC histology, and repeatability was acceptable (coefficient of variation = 8.6–17.9%) when used for assessment of cartilage thickness in the RCJ. In contrast, 9 MHz US showed poorer agreement with MRI and NCC histology, as it overestimated the thickness of thin cartilage and underestimated the thickness of thicker cartilage in the RCJ and MCJ. Moreover, repeatability was suboptimal (coefficient of variation = 10.4–26.3%). A 15 MHz transducer US is recommended for detecting changes in RCJ cartilage thickness or monitoring development over time, and it has the potential for noninvasive assessment of cartilage health in horses.

CT- and MRI-Based 3D Reconstruction of Knee Joint to Assess Cartilage and Bone

For the observation of human joint cartilage, X-ray, computed tomography (CT) or magnetic resonance imaging (MRI) are the main diagnostic tools to evaluate pathologies or traumas. The current work introduces a set of novel measurements and 3D features based on MRI and CT data of the knee joint, used to reconstruct bone and cartilages and to assess cartilage condition from a new perspective. Forty-seven subjects presenting a degenerative disease, a traumatic injury or no symptoms or trauma were recruited in this study and scanned using CT and MRI. Using medical imaging software, the bone and cartilage of the knee joint were segmented and 3D reconstructed. Several features such as cartilage density, volume and surface were extracted. Moreover, an investigation was carried out on the distribution of cartilage thickness and curvature analysis to identify new markers of cartilage condition. All the extracted features were used with advanced statistics tools and machine learning to test the ability of our model to predict cartilage conditions. This work is a first step towards the development of a new gold standard of cartilage assessment based on 3D measurements.

Relationship between individual forces of each quadriceps head during low-load knee extension and cartilage thickness and knee pain in women with knee osteoarthritis

BACKGROUND

This study aimed to clarify the individual forces of each quadriceps head during low-load contractions and to determine the associations between individual muscle force and cartilage thickness and symptoms in female knee osteoarthritis patients.

METHODS

Twenty-two women with painful knee osteoarthritis and 15 asymptomatic age-matched women (control group) participated in this cross-sectional study. Maximal knee extension strength and the cross-sectional area of each quadriceps muscle were measured. Shear modulus was calculated for each muscle during 20-Nm torque production by shear-wave elastography. Muscle force index was defined as the product of the cross-sectional area and shear modulus. Medial femur cartilage thickness was measured using an ultrasound B-mode image. Knee pain during gait was evaluated using a Numerical Rating Scale. Muscle force index, cross-sectional area, and maximal knee extension strength, which were defined as muscle functions, were compared between groups using the unpaired t-test. Correlation coefficients were calculated using muscle function, cartilage thickness, or pain.

FINDINGS

Maximal strength and vastus lateralis force index were smaller in the knee osteoarthritis group than in the control group (p < 0.001 and p = 0.005, respectively). In the knee osteoarthritis group, vastus medialis and vastus lateralis force indexes were positively correlated with cartilage thickness (r = 0.57 and r = 0.45, respectively), whereas the rectus femoris force index was negatively correlated with cartilage thickness (r = -0.45). The vastus lateralis force index was negatively correlated with knee pain (ρ = -0.56).

INTERPRETATION

Vasti force indices were positively associated with cartilage thickness; however, rectus femoris index was negatively associated in female patients with knee osteoarthritis.

Longitudinal Changes in Ultrasound-Assessed Femoral Cartilage Thickness in Individuals from 4 to 6 Months Following Anterior Cruciate Ligament Reconstruction

OBJECTIVE

Diagnostic ultrasound provides a valid assessment of cartilage health that has been used to observe cross-sectional cartilage thickness differences post-ACLR (anterior cruciate ligament reconstruction), but has not been used longitudinally during early recovery post-ACLR.

DESIGN

The purpose of this study was to assess longitudinal changes in femoral cartilage thickness via ultrasound in individuals at 4 to 6 months post-ACLR and compared to healthy controls. Twenty participants (50% female, age = 21.1 ± 5.7 years) completed testing sessions 4 and 6 months post-ACLR. Thirty healthy controls (57% female, age = 20.8 ± 3.8 years) without knee injury history completed 2 testing sessions (>72 hours apart). Femoral cartilage ultrasound images were captured bilaterally in ACLR participants and in the dominant limb of healthy controls during all sessions. Average cartilage thicknesses in the medial, intercondylar, and lateral femoral regions were determined using a semi-automated processing technique.

RESULTS

When comparing cartilage thickness mean differences or changes over time, individuals post-ACLR did not demonstrate between limb differences (P-range = 0.50-0.92), limb differences compared to healthy controls (P-range = 0.19-0.94), or changes over time (P-range = 0.22-0.72) for any femoral cartilage thickness region. However, participants demonstrated cartilage thickening (45%) or thinning (35%) that exceeded minimal detectable change (MDC) from 4 to 6 months post-ACLR, respectively.

CONCLUSIONS

Using MDC scores may help better identify within-subject femoral cartilage thickness changes longitudinally post-ACLR due to bidirectional cartilage thickness changes.

Running kinetics and femoral trochlea cartilage characteristics in recreational and collegiate distance runners

Recreational running can benefit knee cartilage, but the relationship between competitive running and knee cartilage is unclear. We compared femoral cartilage between collegiate runners, recreational runners, and controls; and evaluated the association between running amount, running kinetics and femoral cartilage characteristics. Thirty collegiate runners, 30 recreational runners, and 30 controls completed ultrasound imaging of the femoral cartilage and running gait analysis. Outcomes included cartilage thickness, and echo-intensity from the medial and lateral femoral condyles; and the peak external knee flexion (KFM) and knee adduction moments. Cartilage outcomes were compared via one-way MANOVA. The associations between running kinetics, running amount, and femoral cartilage characteristics were assessed via linear regression models adjusted for sex. No differences were found in cartilage outcomes between groups (p = 0.067). Among recreational runners, a larger peak KFM was associated with lower medial femoral cartilage echo-intensity (ΔR2 = 0.176, Δp = 0.014). In collegiate runners, a greater self-reported running amount was associated with higher medial femoral cartilage (ΔR2 = 0.117, Δp = 0.046) and lateral cartilage (ΔR2 = 0.121, Δp = 0.042) echo-intensity. Cartilage did not differ between groups, but the association between running kinetics, running amount, and knee cartilage may vary between collegiate and recreational runners.

Ultrasonographic Assessment of the Normal Femoral Articular Cartilage of the Knee Joint: Comparison with 3D MRI

Objective

Ultrasonography (US) has a promising role in evaluating the knee joint, but capability to visualize the femoral articular cartilage needs systematic evaluation. We measured the extent of this acoustic window by comparing standardized US images with the corresponding MRI views of the femoral cartilage.

Design

Ten healthy volunteers without knee pathology underwent systematic US and MRI evaluation of both knees. The femoral cartilage was assessed on the oblique transverse axial plane with US and with 3D MRI. The acoustic window on US was compared to the corresponding views of the femoral sulcus and both condyles on MRI. The mean imaging coverage of the femoral cartilage and the cartilage thickness measurements on US and MRI were compared.

Results

Mean imaging coverage of the cartilage of the medial femoral condyle was 66% (range 54%-80%) and on the lateral femoral condyle 37% (range 25%-51%) compared with MRI. Mean cartilage thickness measurement in the femoral sulcus was 3.17 mm with US and 3.61 mm with MRI (14.0% difference). The corresponding measurements in the medial femoral condyle were 1.95 mm with US and 2.35 mm with MRI (21.0% difference), and in the lateral femoral condyle, they were 2.17 mm and 2.73 mm (25.6% difference), respectively.

Conclusion

Two-thirds of the articular cartilage of the medial femoral condyle, and one-third in the lateral femoral condyle, can be assessed with US. The cartilage thickness measurements seem to be underestimated by US. These results show promise for the evaluation of the weight-bearing cartilage of the medial femoral condyle with US.

Changes in anterior femoral articular cartilage structure in collegiate rugby athletes with and without a history of traumatic knee joint injury following a five-month competitive season

This study aimed to examine anterior femoral cartilage morphology before (pre-season) and after (post-season) a 5-month competitive season in collegiate ruby players with and without a previous history of traumatic injury to ligamentous, meniscus, and/or cartilage structures at the knee joint. Using a prospective cohort design, 42 male collegiate rugby players with a previous history of traumatic intracapsular knee joint injury and 124 players without knee injury history were included in this study. Ultrasonography assessments of anterior femoral cartilage were performed before (pre-season) and following a 5-month athletic season (post-season). Rugby players with a history of traumatic knee joint injury had greater lateral condylar thickness (2.37 ± 0.35 mm, p = 0.03), intercondylar thickness (2.51 ± 0.47 mm, p = 0.03), and partial area (44.67 ± 7.28mm², p = 0.02) compared to control players (lateral = 2.23 ± 0.35 mm, intercondylar = 2.32 ± 0.47 mm, partial area = 41.60 ± 7.26 mm²), regardless of pre-and post-season assessment time points. Pre-season ultrasonography assessment of lateral condylar thickness (2.34 ± 0.47 mm, p = 0.02), medial condylar thickness (2.05 ± 0.43 mm, p = 0.03), and partial area (44.10 ± 9.23 mm², p = 0.001) were significantly greater than the post-season ultrasonography assessment time point (lateral = 2.26 ± 0.43 mm, medial = 1.98 ± 0.43 mm, partial area = 42.17 ± 8.82 mm²), regardless of group membership. Rugby players with a history of intracapsular knee joint injury displayed altered anterior femoral cartilage size via ultrasonography assessments. Regardless of a presence of injury history, collegiate rugby players showed a decrease in cartilage thickness and partial area following a 5-month competitive season.

Evaluation of Changes in Condylar Cartilage Thickness Using MRI and Ultrasound Imaging in Patients Treated by Mandibular Advancement With Myofunctional Appliance: An In-Vivo Pilot Study

Introduction

The changes occurring due to growth modulation of the condylar cartilage act as an important mechanism for mandibular advancement using myofunctional appliance therapy. So this study aims to evaluate the condylar cartilage thickness by using MRI and USG in patients undergoing myofunctional appliance therapy for mandibular advancement with the null hypothesis being that there are no changes seen in the thickness of condylar cartilage in growing children.

Materials and methods

A prospective evaluation of samples having skeletal Class-II malocclusion ranging between cervical vertebral maturation index (CVMI) stage II and III, requiring twin block functional therapy was performed. Ten patients were selected randomly who underwent MRI and USG in the open and close positions for the evaluation of condylar cartilage thickness and the dimensional changes in the width of the right and left condyle in mm at T0 and T1.

Result

There was no statistically significant difference between the values interpreted by MRI or USG imaging when compared at T0 and T1 and in the open and closed mouth on the left and right sides. At T0, the mean thickness noted was 0.49 mm and 0.48 mm during opening and closing on the left side and 0.52 mm in both positions on the right side. At T1, the mean thickness noted was 0.8 and 0.79mm during opening and closing on the left side, whereas it was 0.81 mm in both positions on the right side.

Conclusion

The condylar cartilage thickness increases significantly after twin block therapy suggestive of mandibular growth in skeletal class II malocclusion. It can be inferred that both MRI and USG carry equal diagnostic interpretation, as there was no statistically significant difference between the two imaging modalities.

Body mass index moderates the association between gait kinetics, body composition, and femoral knee cartilage characteristics

This study compared femoral cartilage characteristics between age- and sex-matched individuals with (n = 48, age = 22.8 ± 3.5 years; body mass index [BMI] = 33.1 ± 4.1 kg/m² ) and without obesity (n = 48 age = 22.0 ± 2.6 years; BMI = 21.7 ± 1.7 kg/m² ) and evaluated the associations between body composition, quadriceps function, and gait kinetics with femoral cartilage characteristics. Medial and lateral femoral cartilage thickness, medial:lateral thickness ratio and medial and lateral cartilage echo intensity were measured using ultrasound imaging. Body composition was assessed using air displacement plethysmography. Quadriceps function was assessed via maximal isometric knee extension. Three-dimensional gait biomechanics were recorded to extract peak external knee flexion and adduction moments, and peak loading rate of the vertical ground reaction force. Cartilage outcomes were compared between groups using one-way multivariate analysis of variance. Stepwise moderated regression evaluated the association between body composition, quadriceps function, and gait kinetics with femoral cartilage outcomes in individuals with and without obesity. Medial (75.24 vs 65.84; P < .001, d = 1.02) and lateral (58.81 vs 52.22; P < .001, d = 0.78) femoral cartilage echo intensity were higher in individuals with compared with those without obesity. A higher body fat percentage was associated with higher medial and lateral cartilage echo intensity (ΔR²  = 0.09-0.12) in individuals with obesity. A higher knee adduction moment was associated with a larger medial:lateral thickness ratio (ΔR²  = 0.09) in individuals without obesity. No associations were found between quadriceps function and cartilage outcomes. These findings suggest that high body fat in adults with obesity is associated with cartilage echo intensity. The obese body mass index was also associated with a lack of a positive relationship between cartilage thickness and joint loading during walking.

Effects of exercise mode in knee cartilage thickness

BACKGROUND

It is unclear how cycling and running would differ in terms of changes in cartilage thickness. Also, given squats are a popular type of exercise used to strengthen lower limbs, it is critical to assess if loads used during resisted training could lead to changes in cartilage cushioning properties. Therefore, the purpose of this study was to compare the effects of exercise mode in knee cartilage thickness.

METHODS

This study utilized a randomized cross-over design with repeated measures. All sessions were completed between 48hrs and seven days, at the same time of the day. Fourteen (seven males and seven females) apparently healthy participants without musculoskeletal or neurological diseases volunteered for the study. Participants were assessed after squats and functional exercises (n = 18 knees) or after running and cycling (n = 10 knees). All ultrasound images were collected at participants' arrival in the laboratory (Baseline), after warm-up (Pre-exercise), after the completion of each exercise protocol (Post-exercise), and at five (5-min) and 10 minutes (10-min) after exercise.

RESULTS

Cartilage thickness did not change after squats performed with 60% of 1-RM or after a set of three functional exercises (i.e. sit-to-stand, lunges, and step-ups; p = 0.68). However, longer duration exercises (i.e. cycling and running) led to increases in cartilage thickness after 5-min from the completion of the exercise (p = 0.02).

CONCLUSION

Knee cartilage may have capacity to sustain short-term cyclical loads applied during exercise (i.e. squats and functional exercises) but not to moderate duration exercises (i.e. cycling and running).

Sonographic assessment of femoral cartilage thickness in healthy adults

OBJECTIVE

This study was performed to obtain normative data of the distal femoral cartilage thickness in healthy adults by ultrasound.

METHODS

This cross-sectional study included 72 healthy adults. The demographic characteristics of the participants were recorded, and the thickness of the femoral articular cartilage was measured using a 5- to 18-MHz linear probe.

RESULTS

Significant statistical difference towards the male side at left medial condyle (P = 0.001) and left lateral condyle (P = 0.009). Weakly positive statistical difference was noted towards the male side at right medial condyle (P = 0.06) and right lateral condyle (P = 0.07). The femoral cartilage thickness in the study participants did not correlate with weight, body mass index, and age (P >0.05). Positive statistical correlation with height noted in right medial condyle, right lateral condyle, right intercondylar area, and left medial condyle.

CONCLUSION

This study increases the pool of normative data of femoral cartilage thickness measurements. Additionally, the findings of this study emphasize the fact that women have thinner cartilage than men in four of the studied parameters.

Is there a relationship between venous insufficiency and knee osteoarthritis?

Objectives

This study aims to evaluate whether there is a relationship between venous insufficiency (VI) and knee osteoarthritis (OA).

Patients and methods

Between February 2012 and May 2013, a total of 206 knees of 103 participants (14 males, 89 females; mean age 48.6±8.6 years; range, 30 to 69 years) were enrolled. The study group included 59 patients who were diagnosed with knee OA and the control group included 44 healthy volunteers without any complaint in their knee joints. Demographic and clinical characteristics of all participants were recorded. Venous system of the lower extremities was evaluated by Doppler ultrasonography. All knees were evaluated using conventional radiography based on the Kellgren-Lawrence (K&L) grading system and ultrasonography. Pain severity was evaluated using Likert pain scale and functioning was evaluated using Western Ontorio and McMaster Universities Osteoarthritis Index (WOMAC).

Results

Venous insufficiency was detected in 40.6% of the OA group and 15.9% of the control group (p=0.007). There was no statistically significant difference in the cartilage thicknesses and K&L grading regarding the presence of VI (p>0.05); however, the percentage of the radiographic medial tibial sclerosis was higher in patients with VI (60%) in the OA group (p>0.05). The WOMAC total scores were similar in both groups, while the WOMAC pain scores were higher in the patients with deep VI (p>0.05).

Conclusion

Increased radiographic medial tibial sclerosis and higher WOMAC pain scores in patients with venous involvement in OA may lead to the hypothesis that venous system pathologies can affect the intraosseous microenvironment of the bone, resulting in pain and early subchondral bone involvement, consequently presenting as subchondral sclerosis.

Ultrasonographic measurement of femoral cartilage thickness in type II diabetic patients

The aim of this study is to compare the distal femoral cartilage thickness of patients with type II diabetes mellitus with those of healthy subjects using ultrasonography. The study comprised 34 patients and 36 healthy subjects. Demographic characteristics of all the participants were recorded. The thickness of the femoral articular cartilage was measured using a 5-18MHzlinearprobe.Measurements were performed bilaterally from three points (intercondylar area, medial condyle, and lateral condyle). No significant difference could be found between patients and healthy subjects. Two demographic characteristics correlated positively with diabetic patients.

The Transverse Infrapatellar View: A New Ultrasound Technique to Measure Distal Femoral Cartilage Thickness

OBJECTIVES

To examine the reliability and face validity of ultrasound (US) measurements of distal femoral cartilage thickness (CT) using the infrapatellar view (IPV) with knee extension compared to the traditional suprapatellar view (SPV) with knee hyperflexion in young asymptomatic participants and patients with painful knee osteoarthritis (KOA).

METHODS

The IPV was obtained in an extended knee position by placing the US transducer on the patellar tendon at a 60° angle tilted toward the distal femoral condyle in 19 young adults (control group) and 70 patients with KOA. The CT was measured at the medial femoral condyle, the intercondylar notch, and the lateral femoral condyle.

RESULTS

The inter-rater intraclass correlation coefficient was higher for IPV-based CT measurement (range, 0.856-0.858) compared to SPV-based CT measurement (range, 0.315-0.523) among the patients with symptomatic KOA. The IPV-based CT differed significantly between the control group and the KOA group at the intercondylar notch (P < .001) and lateral femoral condyle (P = .006). The SPV-based CT differed significantly between the control group and the KOA group only at the lateral femoral condyle region (P = .014).

CONCLUSIONS

An infrapatellar US evaluation of the distal femoral CT can be a reliable alternative method to a suprapatellar US evaluation for patients with KOA.

Ultrasonographic Measures of Talar Cartilage Thickness Associate with Magnetic Resonance-Based Measures of Talar Cartilage Volume

Our primary goal was to quantify associations between ultrasonographic (US) measurements of talar cartilage apparent thickness and magnetic resonance (MR)-based measures of talar cartilage volume in a heterogeneous sample of those with and without chronic ankle instability. Cartilage volume from MR and normalized cross-sectional area (CSA) and thickness from a transverse US image of the talar cartilage were calculated after 30 min of unloading. Overall talar and region of interest-specific morphology measures (i.e., volume, normalized CSA, thickness) were submitted for statistical analysis. Overall US-normalized CSA positively associated with the overall talar MR volume (r = 0.641, p < 0.001). Medial (r = 0.673, p < 0.001) and lateral US-normalized CSA (r = 0.584, p = 0.001) positively associated with MR volume in the anteromedial and anterolateral MR region of interest, respectively. No differences in US-based normalized CSA, thickness (p > 0.481) or MR-based volume (p > 0.287) were noted between the groups. US appears to be a clinically accessible and cost-effective method for evaluating average ankle cartilage apparent thickness.

Biochemical changes in knee articular cartilage of novice half-marathon runners

Objective

To evaluate changes in knee articular cartilage of novice half-marathon runners using magnetic resonance imaging T2 relaxation time mapping.

Methods

Healthy subjects were recruited from local running clubs who met the following inclusion criteria: (i) age 18–45 years; (ii) body mass index less than 30 kg/m²; (iii) had participated in one half-marathon or less (none within the previous 6 months); (iv) run less than 20 km/week; (v) no previous knee injury or surgery; (vi) no knee pain. T2 signals were measured pre- and post-race to evaluate the biochemical changes in articular cartilage after the subjects run a half-marathon.

Results

A significant increase in the mean ± SD T2 relaxation time was seen in the outer region of the medial tibial plateau (50.1 ± 2.4 versus 54.7 ± 2.6) and there was a significant decrease in T2 relaxation time in the lateral femoral condyle central region (50.2 ± 4.5 versus 45.4 ± 2.9). There were no significant changes in the patella, medial femoral condyle and lateral tibia articular surfaces.

Conclusion

An increase in T2 relaxation time occurs in the medial tibial plateau of novice half-marathon runners. This limited region of increased T2 values, when compared with complete medial compartment involvement seen in studies of marathon runners, may represent an association between distance run and changes seen in articular cartilage T2 values.

Variation in the Thickness of Knee Cartilage. The Use of a Novel Machine Learning Algorithm for Cartilage Segmentation of Magnetic Resonance Images

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 < .001).

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.

Plausible mechanisms of and techniques to assess ankle joint degeneration following lateral ankle sprains: a narrative review

Lateral ankle sprain (LAS) is the most common lower extremity musculoskeletal injury sustained during daily life and sport. The cascade of events that starts with ligamentous trauma leads to clinical manifestations such as recurrent sprains and giving way episodes, hallmark characteristics of chronic ankle instability (CAI). The sequelae of lateral ankle sprains and CAI appear to contribute to aberrant biomechanics. Combined, joint trauma and aberrant biomechanics appear to directly and/or indirectly play a role in talar cartilage degeneration. Up to 80% of all cases of ankle osteoarthritis (OA) are post-traumatic in nature and common etiologies for ankle post-traumatic osteoarthritis (PTOA) are histories of a single and recurrent ankle sprains. Despite known links between LAS, CAI, and PTOA and evidence demonstrating the burden of LAS and its sequelae, early pathoetiological changes of ankle PTOA and how they can be assessed are poorly understood. Therefore, the purpose of this paper is to review the plausible mechanistic links among LAS and its sequelae of CAI and PTOA as well as review non-surgical techniques that can quantify talar cartilage health. Understanding the pathway from ligamentous ankle injury to ankle PTOA is vital to developing theoretically sound therapeutic interventions aimed at slowing ankle PTOA progression. Further, directly assessing talar cartilage health non-surgically provides opportunities to quantify if current and novel intervention strategies are able to slow the progression of ankle PTOA.

Ultrasound Assessment of Weight-Bearing and Non-Weight-Bearing Meniscal Extrusion: A Reliability Study

BACKGROUND

Ultrasound has become a useful instrument in evaluating musculoskeletal pathology. Recent studies suggest that ultrasound imaging of weight-bearing menisci may enhance the assessment of knee pathology, such as osteoarthritis (OA) and meniscal injuries.

OBJECTIVE

The primary aim of this study was to determine the intrarater and interrater reliability of ultrasound measurements of medial meniscal extrusion (MME) after a brief training session.

DESIGN

Prospective reliability study.

SETTING

Physical medicine and rehabilitation (PM&R) department within a tertiary care institution.

PARTICIPANTS

Forty-five participants (29 female, 16 male) were recruited to serve as models, 24 of whom had healthy knees and 21 of whom had radiographically confirmed medial compartment knee OA. Three physician sonographers (1 = experienced, 1 = sports medicine fellow, 1 = post-graduate year [PGY]-4 PM&R resident) were recruited to serve as operators.

METHODS OR INTERVENTIONS

Operators received a brief training session on identifying and measuring MME. All operators measured bilateral MME in each model in the standing and supine positions on two separate days. Operators were blinded to all measurements.

MAIN OUTCOME MEASUREMENTS

Primary outcomes were inter- and intrarater intraclass correlation coefficients (ICCs) of MME measurements among operators with different levels of ultrasound experience.

RESULTS

Supine MME intrarater reliability ICCs were 0.927, 0.885, and 0.780 for the experienced physician, sports medicine fellow, and PGY-4 operators, respectively. Standing MME intrarater reliability ICCs were 0.941, 0.902, and 0.824 for the experienced physician, sports medicine fellow, and PGY-4 operators, respectively. Interrater reliability ICCs were 0.896 and 0.842 for supine and standing measurements, respectively. There was a statistically significant increase in intrarater reliability with experience between the PGY-4 resident and experienced physician operators.

CONCLUSIONS

Operators with different levels of ultrasound experience demonstrated good MME measurement intra- and interrater reliabilities in both supine and standing positions.

Gradual change in knee extension following total knee arthroplasty using ultracongruent inserts

BACKGROUND

Total knee arthroplasty (TKA) using an ultracongruent (UC) insert is widely performed. Lack of the posterior cruciate ligament or post-cam mechanism is a concern in terms of range of motion. The flexion angle of UC TKA had been well investigated; however, natural history and correlation factors of the postoperative extension angle have not been well documented. This study aimed to investigate time-dependent changes in extension after TKA using UC inserts, and to evaluate factors that correlated with the postoperative extension angle.

METHODS

This study reviewed 388 gap-balanced UC TKAs (331 patients) without hyperextension at navigation and performed between November 2010 and December 2014. The extension angle (a positive number indicates hyperextension) was measured on full-extension lateral radiographs. The extension angles from five days post-operation to final follow-up were investigated. Factors correlated with the postoperative extension angle were evaluated using multiple regression analysis.

RESULTS

Mean follow-up duration was 46.2 months. Until two years, the extension angle gradually increased; mean angles at five days/six months/one year/two years/and final follow-up were: -9.2°/-2.6°/0.6°/1.0°/1.0°, respectively. Female sex (β = -0.15, P = 0.002) and pre-operative hyperextension (β = 0.31, P < 0.001) were associated with postoperative hyperextension deformity.

CONCLUSIONS

Following UC TKA, knees became gradually more extended until two years post-operation. Sex and pre-operative extension angle were predictive factors for the postoperative extension angle following UC TKA.

LEVEL OF EVIDENCE

Level 4, Case series.

Segmentation of Femoral Cartilage from Knee Ultrasound Images Using Mask R-CNN

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.

Knee-Cartilage Segmentation and Thickness Measurement from 2D Ultrasound

Ultrasound (US) could become a standard of care imaging modality for the quantitative assessment of femoral cartilage thickness for the early diagnosis of knee osteoarthritis. However, low contrast, high levels of speckle noise, and various imaging artefacts hinder the analysis of collected data. Accurate, robust, and fully automatic US image-enhancement and cartilage-segmentation methods are needed in order to improve the widespread deployment of this imaging modality for knee-osteoarthritis diagnosis and monitoring. In this work, we propose a method based on local-phase-based image processing for automatic knee-cartilage image enhancement, segmentation, and thickness measurement. A local-phase feature-guided dynamic-programming approach is used for the fully automatic localization of knee-bone surfaces. The localized bone surfaces are used as seed points for automating the seed-guided segmentation of the cartilage. We evaluated the Random Walker (RW), watershed, and graph-cut-based segmentation methods from 200 scans obtained from ten healthy volunteers. Validation against manual expert segmentation achieved a mean dice similarity coefficient of 0.90, 0.86, and 0.84 for the RW, watershed, and graph-cut segmentation methods, respectively. Automatically segmented cartilage regions achieved 0.18 mm localization accuracy compared to manual expert thickness measurement.

Effectiveness of Therapeutic Ultrasound on Clinical Parameters and Ultrasonographic Cartilage Thickness in Knee Osteoarthritis: A Double-Blind Trial

Objective:

A double-blind placebo-controlled randomized study was conducted to assess the effectiveness of therapeutic ultrasound (US) in knee OA.

Patients and Methods:

Thirty-three patients (mean age 54.7 ± 14.7) were randomized to receive either continuous US (n = 15) or sham US (n = 18) as a placebo. Continuous ultrasonic waves with 1 MHZ frequency and 1 watt/cm² power were applied for 5 min for 10 sessions. The primary outcome was pain on movement assessed by visual analog scale (VAS). The secondary outcomes were WOMAC scores and measurements of distal femoral cartilage thickness by imaging US.

Results:

Both groups showed reduced knee pain on movement following intervention. The VAS measurements improved significantly both in the treatment and the placebo group patients (P < 0.05 and P < 0.05). WOMAC scores improved statistically significant in all domains (pain, stiffness, physical function, and total score) in the treatment group (P < 0.05). All domains of WOMAC score showed statistically significant change when compared with the placebo group (P < 0.05). There was no change in the cartilage thickness measurements of medial femoral condyle, lateral femoral condyle, and intercondylar area in both groups after intervention.

Conclusion:

Results suggest that US is effective treatment modality in pain relief and improvement of function in patients with knee OA; however, US had no effect on cartilage repair.

The association between habitual walking speed and medial femoral cartilage deformation following 30minutes of walking

Habitual walking speed is a key functional outcome that has implications for knee biomechanics that occur during gait. Lower extremity biomechanics during walking affects the loading of the femoral cartilage. Ultrasonography (US) can be used to assess resting femoral cartilage thickness and acute cartilage deformation in response to walking. The purpose of this study was to determine the association between habitual walking speed and both resting femoral cartilage thickness and deformation. Twenty-four healthy participants with no history of knee injury volunteered for this study. Habitual walking speed was assessed with a 20-m walk test. Femoral cartilage thickness was assessed with US in the medial condyle, lateral condyle, and intercondylar regions prior to and immediately following 30min of walking. Femoral cartilage deformation was calculated as the percent change in cartilage thickness acutely following the walking protocol. Separate Pearson product moment correlations were used to assess the association between habitual walking speed and each US cartilage variable. Slower habitual walking speed was significantly associated with greater medial femoral cartilage deformation (r=0.48, P=0.018), but not with lateral and intercondylar deformation. Habitual walking speed was not significantly associated with the resting cartilage thickness in any cartilage region. These findings highlight the in vivo association between walking speed and medial femoral cartilage deformation. When controlling for body mass index, the association between walking speed and medial cartilage deformation was weakened (Δr=-0.12). Future studies are needed to determine the extent to which BMI influences the association between walking speed and cartilage deformation.

Fixed-flexion view X-ray of the knee superior in detection and follow-up of knee osteoarthritis

A fixed flexion view (FFV) is useful for evaluating joint space when assessing the severity of osteoarthritis (OA) of the knee. We analyzed changes in joint space revealed by standing extended view (SEV) and FFV over a mean 4 years, to compare both views on their capacity to measure joint space width accurately at particular time points during follow-up.SEV and FFV images were acquired in patients with knee OA. The 81 patients (157 knees) followed up for ≥24 months were selected as study subjects. Medial joint space widths (MJSW), Kellgren-Lawrence (KL) grades, and reductions in MJSW on SEV (ΔSEV) and FFV (ΔFFV) were compared in knees evaluated by SEV and FFV.At both time-points, mean MJSW was significantly lower by FFV than by SEV. Mean MJSW was significantly lower at follow-up than at first examination by both SEV and FFV. At both time-points, the KL grade was higher by FFV than by SEV group. The ΔFFV was significantly greater than the ΔSEV. ΔSEV did not differ significantly among KL grades, but ΔFFV was significantly greater in patients with KL grade II than in patients with other KL grades.FFV is not only useful for evaluating joint space in knees with OA, but also for accurately evaluating the progression of OA. The risk of rapid progression of knee OA may be higher in patients with KL grade II, as determined by FFV. FFV may be superior to SEV in determining appropriate treatment strategies for knee OA.

Association of medial meniscal extrusion with medial tibial osteophyte distance detected by T2 mapping MRI in patients with early-stage knee osteoarthritis

Background

Medial meniscal extrusion (MME) is associated with progression of medial knee osteoarthritis (OA), but no or little information is available for relationships between MME and osteophytes, which are found in cartilage and bone parts. Because of the limitation in detectability of the cartilage part of osteophytes by radiography or conventional magnetic resonance imaging (MRI), the rate of development and size of osteophytes appear to have been underestimated. Because T2 mapping MRI may enable us to evaluate the cartilage part of osteophytes, we aimed to examine the association between MME and OA-related changes, including osteophytes, by using conventional and T2 mapping MRI.

Methods

Patients with early-stage knee OA (n = 50) were examined. MRI-detected OA-related changes, in addition to MME, were evaluated according to the Whole-Organ Magnetic Resonance Imaging Score. T2 values of the medial meniscus and osteophytes were measured on T2 mapping images. Osteophytes surgically removed from patients with end-stage knee OA were histologically analyzed and compared with findings derived by radiography and MRI.

Results

Medial side osteophytes were detected by T2 mapping MRI in 98% of patients with early-stage knee OA, although the detection rate was 48% by conventional MRI and 40% by radiography. Among the OA-related changes, medial tibial osteophyte distance was most closely associated with MME, as determined by multiple logistic regression analysis, in the patients with early-stage knee OA (β = 0.711, p < 0.001). T2 values of the medial meniscus were directly correlated with MME in patients with early-stage knee OA, who showed ≥ 3 mm of MME (r = 0.58, p = 0.003). The accuracy of osteophyte evaluation by T2 mapping MRI was confirmed by histological analysis of the osteophytes removed from patients with end-stage knee OA.

Conclusions

Our study demonstrates that medial tibial osteophyte evaluated by T2 mapping MRI is frequently observed in the patients with early-stage knee OA, showing close association with MME, and that MME is positively correlated with the meniscal degeneration.