Measurement Of Joint Space Width Research Articles

Subtle Radiographic Progression at Six Months Can Be Detected Using Automated Quantitative Software in Rheumatoid Arthritis While Receiving Tocilizumab.

We investigated whether our in-house software equipped with partial image phase-only correlation (PIPOC) can detect subtle radiographic joint space narrowing (JSN) progression at six months and predict JSN progression in rheumatoid arthritis (RA) patients receiving Tocilizumab. The study included 39 RA patients who were treated with Tocilizumab. Radiological progression of the metacarpophalangeal and the proximal interphalangeal joints was evaluated according to the Genant-modified Sharp score (GSS) at 0, 6, and 12 months. Automatic measurements were performed with the software. We validated the software in terms of accuracy in detecting the JSN progression. The success rate of the software for joint space width (JSW) measurement was 96.8% (449/464). The 0-12-month JSW change by the software was significantly greater in joints with the 0-6-month PIPOC (+) group than the 0-6-month PIPOC (-) group (p < 0.001). The 0-12-month JSW change by the software was 0-12-month GSS (+) than with 0-12-month GSS (-) (p = 0.02). Here, "(+)" indicates the JSN progression during the follow-up period. Meanwhile, "(-)" indicates no JSN progression during the follow-up period. Linear regression tests showed significant correlations between the 0-6-month and the 0-12-month PIPOC in the left 2nd and 3rd MCP joints (R2 = 0.554 and 0.420, respectively). Our in-house software equipped with PIPOC could predict subsequent JSN progression with only short-term observations.

Estimation of radiographic joint space of the trapeziometacarpal joint with computed tomographic validation.

Joint space width (JSW) is a common metric used to evaluate joint structure on plain radiographs. For the hand, quantitative techniques are available for evaluation of the JSW of finger joints; however, such techniques have been difficult to establish for the trapeziometacarpal (TMC) joint. This study aimed to develop a validated method for measuring the radiographic joint space of the healthy TMC joint. Computed tomographic scans were taken of 15 cadaveric hands. The location of a JSW analysis region on the articular surface of the first metacarpal was established in 3D space and standardized in a 2D projection. The standardized region was applied to simulated radiographic images. A correction factor was defined as the ratio of the CT-based and radiograph-based joint space measurements. Leave-one-out validation was used to correct the radiograph-based measurements. A t-test was used to evaluate the difference between CT-based and corrected radiograph-based measurements (). The CT-based and radiograph-based measurements of JSW were and , respectively. The correction factor for radiograph-based joint space was . Before correction, the difference between the CT-based and radiograph-based joint space was 1.43mm [95% CI: ; ]. After correction, the difference was [95% CI: ; ]. Corrected measurements of radiographic TMC JSW agreed well with CT-measured JSW. With in-vivo validation, the developed methodology has potential for automated and accurate radiographic measurement of TMC JSW.

An accurate method for measuring knee joint space width despite variations in beam projection angles

BackgroundAssessing knee osteoarthritis (OA) severity through joint space width (JSW) measurements can be difficult due to anatomical variations, beam projection angle (BPA) errors, and patient posture during X-rays. Although various methods address these issues, a consensus on the reference point for accurate measurement is lacking. Therefore, establishing a precise evaluation method for JSW is imperative. MethodsSimulation on 30 knees with advanced OA to measure the JSW using digital reconstruction radiographs from computed tomography (CT) images was conducted. The distance between the medial femoral condyle and the anterior and posterior borders of the medial tibial plateau (represented by DAB and DPB, respectively) and their average (AVD) were used to evaluate JSW. Discrepancies were analyzed for various BPAs. Additionally, the reliability of measuring JSW using DAB, DPB, and AVD was evaluated in a proof-of-concept study on 100 knees using anteroposterior X-rays at three BPAs (neutral, 5° caudal, and 5° cephalic tilt). ResultsIn the simulation study, the AVD method had discrepancies below 1 mm from BPA 0° of 5°, 10° caudal tilt, and 5° cephalic tilt (P = 0.066, P = 0.120, and P < 0.001, respectively). However, the values of DAB and DPB showed significant discrepancies from BPA 0° (all over 1 mm and all P < 0.001) for various BPAs. The AVD measurement demonstrated the least discrepancy in JSW measurements based on BPA variations compared with DAB and DPB methods in the proof-of-concept study. ConclusionsA simple method for accurately measuring joint space width, even when X-rays are taken at unintended angles can be applied in clinical practice.

Radiographic joint space width in individuals with hand osteoarthritis: Are their “healthy” joints really healthy?

We aimed to investigate the systemic nature of hand osteoarthritis (OA). We hypothesized that people who suffer from hand OA will display narrower radiographic joint space width (JSW) - not only in joints with apparent radiographic OA but also in their unaffected "healthy" joints. We examined 3394 participants from the Osteoarthritis Initiative (OAI) with available dominant hand radiographs at baseline. Cases were defined as having interphalangeal OA (IPOA) based on a Kellgren and Lawrence (KL) score of ≥2 in two or more finger joints, whereas controls did not have IPOA. We used custom software to make JSW measurements of the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints in fingers 2-5 per hand. In joint-level analyses, we included only KL score = 0, allowing us to compare all joints without IPOA in cases and controls. We used generalized estimating equation (GEE) models to compare JSW between both groups, adjusted for age, gender, metacarpal length, and joint type. Finger joints without radiographic OA had significantly narrower JSW in the IPOA group compared to finger joints in the control group (p<0.001). The differences were significant across all joint types and for both total JSW measurements as well as for central and lateral sub-regions within each joint group (p<0.001). Unaffected finger joints in people with IPOA had narrower joint space than joints of healthy controls. This implies a systemic nature of hand OA, in which people may have a predisposition for general cartilage deterioration.

Defining Normal Articular Characteristics of the Primary Joints of the Foot and Ankle: A 3D Hounsfield Algorithm Weight Bearing CT Study

Category: Ankle Arthritis; Hindfoot Introduction/Purpose: To properly treat osteoarthritis-(OA) patients, a grading-system is used to diagnose the stage-of-the- disease. The current gold-standard system, which relies on plain-2D-radiographs, is subjective, categorical, and lacks reliability. Using WBCT-images, 3D-Hounsfield-Unit-(HU) algorithms have been developed to measure the intensity of each image voxel across the joint-space, highlighting transitions between cancellous/subchondral bone and joint-space. The purpose of this study was to analyze and define normal standard values of joint-space-width (JSW) in the four essential joints of the foot-and-ankle (tibiotalar (ankle), subtalar (ST), talonavicular (TN), and first-metatarsophalangeal- (MTP) -joints) using an objective computational WBCT-HU algorithm in healthy non-arthritic feet. We hypothesized that the measurements of JSW and HU distributions across each of the four-essential-joints of the foot-and-ankle would be significantly different from each other, respecting local anatomy and unique functional characteristics of each joint. Methods: Retrospective-comparative-study, we evaluated WBCT-scans of 30 healthy ankle-joints, 28 ST-joints, 26-TN joints, and 30 1st-MTP-joints of control volunteers with no radiographic signs of foot-and-ankle OA. For each-joint, we used dedicated software to define a volume-of-interest (VOI) cube centered on the joint space. Five HU linear search arrays were then defined within this 3D VOI perpendicular to the articular-surface of each-joint, including four projections in each quadrant, and one in the center of the VOI (Figure 1). Image intensity profiles were generated for each search array crossing the transition from cancellous- to-subchondral bone, across the joint-space, back to subchondral-and-cancellous-bone (Figure 2). This profile was used to calculate JSW and to measure HU contrast in the region. Comparisons between the JSW of each joint and within each-joint were accordingly performed using paired t-tests or paired Wilcoxon. Significance was considered for p-values &lt; 0.05. Results: The median-value and 95%-Confidence-Intervals-(CI) for JSW were 4.07mm [CI:3.73–4.20] for the ankle-joint; 4.07mm [3.95–4.44] for the ST-joint; 3.24mm [3.19–3.46] for the TN-joint; and 3.70mm [3.64–4.12] for the 1st-MTP-joint. The TN JSW was significantly narrower than the JSW in the ankle (p=0.0007), ST (p &lt; 0.0002), and 1st-MTP-joints (p=0.0034) (Figure-3). JSW- values were similar across the entire ankle, ST and 1st-MTP-joints. In the TN-joint, the dorsal aspect of the joint was found to be slightly but significantly wider-than the plantar-aspect (p &lt; 0.001). Regarding HU-contrast, we found a progressive increase in the overall contrast from proximal-to-distal (p &lt; 0.001), with a mean HU contrast-value and 95%-CI of respectively 71.8[67.3–76.3] for ankle, 92.4[87.8–97.1] for ST, 84.1[79.2–88.9] for TN, and 101.3[96.9 – 106.8] for 1st-MTP-joints. The only joints with similar HU-contrast were ST and TN. Conclusion: We utilized a novel WBCT-3D-HU measurement algorithm to assess the normal JSW and HU contrast of the four- essential mobile joints of the foot-and-ankle. We found the JSW to be similar (~4mm) in the ankle, ST, and 1st-MTP joints. The TN-joint however, demonstrated a significantly narrower JSW when compared to the other 3 joints. HU-contrast increased progressively from proximal-to-distal, being less prominent in the ankle, similarly increased in TN and ST, and maximum at the 1st-MTP joint. This study's joint characteristic normality data provide a foundation for future-work developing an objective WBCT-based 3D HU-algorithm staging-system for OA-disease-progression in the foot-and-ankle joints.

Three-dimensional Weight-Bearing CT Distance and Coverage Mapping Assessment of the 1st MTPJ and Sesamoid Joints in Patients with Hallux Valgus Deformity

Category: Bunion Introduction/Purpose: Three-dimensional (3D) Distance-Mapping (DM) and Coverage-Mapping (CM) use WBCT images to evaluate multiplanar elements of Hallux Valgus (HV), such as sesamoid subluxation, through analyzing joint space and joint coverage across entire bony interfaces. Previous methods have struggled to characterize sesamoid subluxation consistently, and the reliable assessment of these deformity patterns is essential in guiding HV treatment and impacts recurrence rates following correction. The objective was to (1) develop a 3D WBCT CM and DM algorithm to characterize the surface interaction of the 1st metatarsophalangeal-joint (MTPJ) and metatarsal-sesamoid joints in HV patients and controls (2) correlate DM and CM measurements with WBCT semi-automatic angular measurements in HV patients and controls (3) correlate DM, CM, and angular measurements with Visual Analog Scale (VAS) scores in HV patients. Methods: Retrospective case-control study assessing HV patients. 51-feet with HV who underwent a WBCT of the affected foot and 54-feet were included. Semi-automatic segmentation protocol extracted bone models, which were analyzed with specialized software. The 1st-MTPJ surface was divided into two-by-two grids to provide a more detailed analysis. Distance measurements obtained were used to create color-coded distance maps. Blue color represented expected distances in joint interaction (1 to 5 mm), red or yellow color represented arthritis or impingement (0 to 1mm), and pink color represented subluxation (&gt;5mm). Further, color-coded coverage maps highlighted areas of relative coverage ( &lt; 5mm) or uncoverage (&gt;5mm) contrasting areas with normal joint interaction or subluxation (Figure). Pearson’s correlations were used to describe association between intraarticular distances, or JSW (joint space width), and coverage measurements with the following: intermetatarsal angle (IMA), Hallux-Valgus- Angle (HVA), Distal-Metatarsal-Articulation-Angle (DMAA), Visual-Analog-Scale (VAS), and Body-Mass-Index (BMI). P-values less than 0.05 were statistically significant. Results: Interobserver reliability was high for 1st-metatarsal-head (ICC 0.846,p &lt; 0.001), medial-sesamoid-articulation (ICC 0.854,p &lt; 0.001), and lateral-sesamoid-articulation (ICC 0.832,p &lt; 0.001). HV patients demonstrated significantly decreased coverage in comparison to controls (42.7% vs. 50.1%,p &lt; 0.001) and a relative decrease in 1st-MTPJ-coverage (-14.7%,p &lt; 0.001) in comparison to controls. In HV, articular coverage was higher in patients for the plantar lateral quadrant (HV 88.6% vs. 83.0% Controls,p=0.0002) and decreased in dorsal-medial (HV 8.8% vs. 18.7% Controls,p &lt; 0.0001) and plantar-medial quadrants. (HV 46.2% vs. 78.8% Controls,p &lt; 0.0001). Significantly decreased coverage was observed in HV-patients in both the medial sesamoid- articulation (HV 31.1% vs. 54.4%, p&lt; 0.0001) and lateral sesamoid-articulation (HV 22.6% vs. 46.0%,p &lt; 0.0001). Correlations between the first-metatarsal-head distance/coverage measurements and BMI, pre-op VAS, IMA, HVA, and DMAA are summarized in figure. Conclusion: We developed a quantifiable WBCT distance and coverage map algorithm to assess 3D-joint-interaction, joint- coverage, and subluxation in patients with HV. We observed significant subluxation of the 1st-MTPJ in patients with HV when compared to controls, as well as significant subluxation of the metatarsal-sesamoid joint at the medial and lateral sesamoid-joints, with an apparent medial and dorsal deviation of the first-metatarsal, lateral and plantar deviation of the proximal-hallux-phalanx and Lateral subluxation of the sesamoids. Increased coverage of the 1st-metatarsal-head was associated with decreased IMA and DMAA. However, we found no significant correlation between the Visual-Analogue-Scale-(VAS) and DM, CM, and semi-automatic measurements.

Objective Analysis of Regional Tibiotalar Joint Changes in Ankle Osteoarthritis Assessed by Semi- Automated 3D Distance Mapping

Category: Ankle Arthritis; Ankle Introduction/Purpose: Ankle osteoarthritis is a degenerative joint disease characterized by the narrowing of the tibiotalar joint space and in late stages, eventual tibiotalar contact and subchondral bone loss. Traditional methods of assessing changes in the joint space (such as assessment on 2D radiographs) are subjective and do not fully consider the three-dimensional nature of articular surfaces. Weight-bearing CT (WBCT) provides a unique perspective by placing the joints of the lower extremity in a loaded, functional position, and may help to better quantify changes in joint space. Determining the presence and progression of ankle arthritis is difficult. It is our hope that novel 3D distance mapping technologies using images acquired from WBCT may assist with the detection and characterization of progression of ankle osteoarthritis. Methods: In this IRB-approved, retrospective case-control study, we analyzed WBCT data of 9 ankle osteoarthritis patients and 20 healthy controls. Patients included in this study had no identifiable talar tilt. Segmentations were created using an automated segmentation software package (DISIOR Bonelogic 2.0) Principal component analysis was used to divide the talar dome into nine subregions. The articular facet of the medial malleolus was also analyzed. We used 3D distance mapping to objectively measure joint space width across the tibiotalar joint and assessed changes in distance in each of the nine subregions of the talar dome articular surface. Overall mean distances for each subregion analyzed were calculated. Comparisons between the control and ankle arthritis cases were performed with independent t-tests, assuming unequal variances. P-values &lt; 0.05 were considered significant. Results: Changes in the mean distances are reported in the attached figure. The medial side of the talar experienced significant decreases in mean joint space width. The middle medial subregion experienced the largest decrease in mean joint space width with a reduction of 35% when compared to controls (p = 0.017). Increases in joint space width were observed on the lateral aspect of the talar dome, However, these increases were not found to be significant. Conclusion: The purpose of this study is twofold: to quantify changes in joint space using 3D distance mapping technique and to evaluate the utility of a commercial automated segmentation software package. In this cohort, there was a significant decrease on the medial side of the talar dome – this change can be attributed to cartilage degeneration. To our knowledge, this is the first study to analyze changes in ankle osteoarthritis using a fully automated segmentation method. Automated segmentation and 3D distance mapping provide a useful tool for the quantification of osteoarthritis-associated joint space changes.

Poster 216: Comparison of Joint Space Narrowing to the Contralateral Side During Hip Arthroscopy: Predictor of Conversion to THA?

Objectives: Reduced joint space at the time of joint-preserving hip arthroscopy has been shown to be correlated with rates of eventual conversion to total hip arthroplasty (THA). With an increasingly aging population and increased utilization of hip arthroscopy, it is important to identify factors that may predict early failure and the eventual need for arthroplasty. For some patients, hip arthroscopy may provide symptomatic relief for years, while others garner limited benefit and require conversion THA soon after their index surgery. This study sought to determine if quantitative differences in joint space width (JSW) between the operative and non-operative hip predicted the likelihood of conversion to THA at the time of hip arthroscopy. Methods: After obtaining institutional review board approval, a retrospective review identified 105 patients treated for labral tears with arthroscopic hip surgery by a single-surgeon with a minimum of 5- year follow-up. Patients were stratified into cohorts based on whether they received a subsequent THA. Preoperative, anteroposterior pelvic radiographs were obtained for each patient and semi-automated, quantitative JSW measurements were performed at 3 predefined fixed locations per hip (10, 30, and 50 degrees with respect to a polar coordinate system; Figure 1). All measurements were obtained by an independent assessor blinded to other radiographic or clinical information, with high reliability (intra- class correlations &gt; 0.8), as previously described in literature. Differences in JSW at each prefixed angle were calculated by subtracting the width (millimeters) of each patient’s operative hip from the measurements obtained from their non-operative hip. Categorical variables were analyzed using chi- square test or Fisher exact test, as appropriate. After assessing for normality with Shapiro-Wilk tests, continuous variables were compared using Student t-tests or Mann-Whitney U tests to determine baseline differences between patients that converted to THA and those that did not. Logistic regression was run for JSW at each prefixed angle, followed by adjusted, multivariable logistic regression to determine independent predictors of conversion to THA. Results: Mean [standard deviation (SD)] follow-up was 8.81 [2.68] years, identifying 16 (15.2%) patients that converted to THA and 89 (84.8%) that did not. When comparing baseline demographic and intraoperative characteristics between cohorts, THA patients were found to have higher mean [SD] age 41.8 [13.4; p=0.003], BMI 29.3 [4.2; p&lt;0.001], Tönnis grade (p&lt;0.001), Outerbridge grade (p=0.002) and higher percentage of males (p=0.014; Tables 1&amp;2). THA patients were found to have a significantly greater difference in JSW at 30° compared to those that did not require subsequent hip arthroplasty (0.566 ± 0.883mm versus 0.038 ± 0.499mm, p=0.035). Differences in JSW between cohorts were not significant at the 10° (p=0.104) or 50° (p=0.096) locations. When adjusting for significantly different covariates, the difference in JSW at 30° was correlated with an increased likelihood of conversion to THA (Adjusted Odds Ratio [AOR]: 4.00; 95% Confidence Interval [CI]: 1.06 to 15.13; p =0.041). Finally, adjusted analysis controlling for differences in JSW at all predefined angles found that narrowing at 30° was significantly associated with increased odds of conversion ([AOR]: 3.88; [CI]: 1.06 to 14.22; p=0.041), while 10° (p=0.630) and 50° (p=0.995) were not. Conclusions: To best educate patients on the risk of THA following hip arthroscopy, identifying objective predictors of early failure is imperative during preoperative evaluation. This study identified that differences in JSW at 30° between the operative and non-operative hip were significantly associated with increased risk of conversion after controlling for demographic and intraoperative factors. Analysis was limited by predetermined locations for JSW and future studies may identify stronger correlations by incorporating additional measurements within the acetabular sourcil. Quantitative differences in JSW comparing the operative hip to the contralateral side predicts patients progressing to THA at the time of hip arthroscopy. [Table: see text] [Table: see text]

3-D joint space mapping at the ankle from weight-bearing CT: reproducibility, repeatability, and challenges for standardisation

ObjectivesWe present a 3-D approach to joint space width (JSW) measurement across the ankle from weight-bearing CT (WBCT) to demonstrate inter-operator reproducibility, test-retest repeatability, and how differences in angulation affect ankle JSW distribution.MethodsOne side from repeat WBCT imaging of both feet and ankles was analysed from 23 individuals as part of their routine clinical care pathway. Joint space mapping was performed at four facets across the talus: talonavicular, talar dome and medial gutter (dome-medial), lateral gutter, and posterior subtalar. Inter-operator reproducibility was calculated for two users, while test-retest repeatability was calculated by comparing the two visits, both presented as Bland-Altman statistics. Statistical parametric mapping determined any significant relationships between talocrural joint space angulation and 3-D JSW distribution.ResultsThe average ± standard deviation interval between imaging was 74.0 ± 29.6 days. Surface averaged bias ± limits of agreement were similar for reproducibility and repeatability, the latter being: talonavicular 0.01 ± 0.26 mm, dome-medial 0.00 ± 0.28 mm, lateral gutter − 0.02 ± 0.40 mm, and posterior subtalar 0.02 ± 0.34 mm. Results are presented as 3-D distribution maps, with optimum test–retest repeatability reaching a smallest detectable difference of ± 0.15 mm.ConclusionsJoint space mapping is a robust approach to 3-D quantification of JSW measurement, inter-operator reproducibility, and test–retest repeatability at the ankle, with sensitivity reaching a best value of ± 0.15 mm. Standardised imaging protocols and optimised metal artefact reduction will be needed to further understand the clinical value of these 3-D measures derived from WBCT.Clinical relevance statementWeight-bearing computed tomography is an increasingly important tool in the clinical assessment of orthopaedic ankle disorders. This paper establishes the performance of measuring 3-D joint space width using this technology, which is an important surrogate marker for severity of osteoarthritis.Key Points• Joint space width values and error metrics from across the ankle measured from weight-bearing CT can be presented as 3-D maps that show topographic variation.• The best sensitivity for detecting meaningful change in 3-D joint space width at the ankle was ± 0.15 mm, a value less than the isotropic imaging voxel dimensions.• Standardised imaging protocols and optimised metal artefact reduction will be needed to understand the clinical value of 3-D measures from weight-bearing CT.

JOINT REPAIR EVALUATED ON RADIOGRAPHS IS ASSOCIATED WITH PAIN AND SYNOVIAL FLUID MARKER CHANGES AFTER KNEE JOINT DISTRACTION TREATMENT

Knee joint distraction (KJD) has been associated with clinical and structural improvement and synovial fluid (SF) marker changes. However, structural changes have not yet been shown satisfactorily in regular care, since radiographic acquisition was not fully standardized. AI-based modules have shown great potential to reduce reading time, increase inter-reader agreement and therefore function as a tool for treatment outcome assessment. The objective was to analyse structural changes after KJD in patients using this AI-based measurement method, and relate these changes to clinical outcome and SF markers.20 knee OA patients (&lt;65 years old) were included in this study. KJD treatment was performed using an external fixation device, providing 5 mm distraction for 6 weeks. SF was aspirated before, during and immediately after treatment. Weight-bearing antero-posterior knee radiographs and WOMAC questionnaires were collected before and ~one year after treatment. Radiographs were analysed with the Knee Osteoarthritis Labelling Assistant (KOALA, IB Lab GmbH, Vienna, Austria), and 10 pre-defined biomarker levels in SF were measured by immunoassay. Radiographic one-year changes were analysed and linear regression was used to calculate associations between changes in standardized joint space width (JSW) and WOMAC, and changes in JSW and SF markers.After treatment, radiographs showed an improvement in Kellgren-Lawrence grade in 7 of 16 patients that could be evaluated; 3 showed a worsening. Joint space narrowing scores and continuous JSW measures improved especially medially. A greater improvement in JSW was significantly associated with a greater improvement in WOMAC pain (β=0.64;p=0.020). A greater increase in MCP1 (β=0.67;p=0.033) and lower increase in TGFβ1 (β=-0.787;p=0.007) were associated with JSW improvement.Despite the small number of patients, also in regular care KJD treatment shows joint repair as measured automatically on radiographs, significantly associated with certain SF marker change and even with clinical outcome.

Structural changes after ankle joint distraction in haemophilic arthropathy: an explorative study investigating biochemical markers and 3D joint space width.

Ankle joint distraction (AJD) is a promising treatment for patients with severe haemophilic ankle arthropathy (HAA). However, some patients showed no clinical improvement after AJD and these differences may be related to structural differences. Primarily to quantify the structural changes after AJD in patients with HAA by the use of 3D joint space width (JSW) measurements and biochemical markers and secondarily to correlate these findings with clinical pain/function. Patients with haemophilia A/B who underwent AJD were included for this study. Bone contours on MRI (performed before and 12 and 36 months after AJD) were drawn manually and percentage change in JSW was calculated. Blood/urine (before and 6, 12, 24 and 36 months after AJD) was collected for biomarker measurement (COMP, CS846, C10C, CALC2, PRO-C2, CTX-II) and combined indexes of markers were calculated. Mixed effects models were used for analyses on group level. Structural changes were compared with clinical parameters. Eight patients were evaluated. On group level, percentage changes in JSW showed a slight decrease after 12 months followed by a non-statistically significant increase in JSW after 36 months compared to baseline. Biochemical marker collagen/cartilage formation also showed an initial decrease, followed by a trend towards net formation 12, 24 and 36 months after AJD. On individual patient level, no clear correlations between structural changes and clinical parameters were observed. Cartilage restoration activity on group level in patients with HAA after AJD was in concordance with clinical improvements. Correlating structural modifications with clinical parameters in the individual patient remains difficult.

Automatic measuring of finger joint space width on hand radiograph using deep learning and conventional computer vision methods

Hand osteoarthritis (OA) severity can be assessed visually through radiographs using semi-quantitative grading systems. However, these grading systems are subjective and cannot distinguish minor differences. Joint space width (JSW) compensates for these disadvantages, as it quantifies the severity of OA by accurately measuring the distances between joint bones. Current methods used to assess JSW require users’ interaction to identify the joints and delineate the initial joint boundary, which is time-consuming. To automate this process and offer a robust measurement for JSW, we proposed two novel methods to measure JSW: (1) The segmentation-based (SEG) method, which uses traditional computer vision techniques to calculate JSW; (2) The regression-based (REG) method, which is a deep learning approach employing a modified VGG-19 network to predict JSW. On a dataset with 3591 hand radiographs, 10,845 DIP joints were cut as ROI and served as input to the SEG and REG methods. The bone masks of the ROI images generated by a U-Net model were sent as input in addition to the ROIs. The ground truth of JSW was labeled by a trained research assistant using a semi-automatic tool. Compared with the ground truth, the REG method achieved a correlation coefficient (r) of 0.88 and a mean square error (MSE) of 0.02 mm on the testing set; the SEG method achieved a correlation coefficient of 0.42 and an MSE of 0.15 mm. Results show the REG method has promising performance in JSW measurement and, in general, Deep Learning approaches can facilitate the automatic quantification of distance features in medical images.

WEIGHT BEARING 3-D JOINT SPACE WIDTH DISTRIBUTION AT THE KNEE VARIES ACCORDING TO LOCATION AND EXTENT OF MENISCAL EXTRUSION: A MOST INVESTIGATION

Quantitative 3-D measurement of joint space width (JSW) from weight bearing computed tomography (WBCT) allows analysis of knee tibiofemoral compartments in a loaded stance without subregional constraints on analysis. The relationship between 3-D JSW distribution and meniscal extrusion is yet to be established. To demonstrate topographic variations in 3-D JSW distribution at the knee derived from WBCT imaging data according to meniscal extrusion location and extent. WBCT knee imaging was acquired at the 144-month visit of the Multicenter Osteoarthritis Study (MOST). A subset of individuals had medial and lateral meniscal extrusion grading according to the MRI Osteoarthritis Knee Score to identify medial extrusion of the medial meniscus (MMmed), anterior extrusion of the medial meniscus (MMant), anterior extrusion of the lateral meniscus (LMant), and lateral extrusion of the lateral meniscus (LMlat). The extent of extrusion was graded as 0: <2 mm; 1: 2 to 2.9 mm, 2: 3 to 4.9 mm; and 3: >5 mm. After semi-automatic segmentation of 663 baseline knees, joint space mapping was performed to create 3-D JSW maps for each knee registered to a template surface. Statistical parametric mapping (SPM) was performed using a general linear model to test the dependence of 3-D JSW distribution on each of meniscal extrusion type in turn. SPM results were plotted on the canonical joint surface, with unmasked regions demonstrating the topographic difference in JSW for each increment in extrusion score. 568 knees from 330 participants had meniscal extrusion grading available. Participants (178 female) had mean ± SD age 62.0 ± 9.3 years, body mass 82.2 ± 17.4 kg, height 170 ± 9.5 cm, and BMI 28.3 ± 4.8 kg/m2. Analysed knees were bilateral for 238 participants and unilateral for 92 participants. For MMmed (cohort score range 0-3), the central-to-posterior medial compartment had significantly lower JSW by up to 0.4 mm for each increment in meniscal extrusion grade. Both MMmed and MMant (score range 0-3) were associated with a small region of similarly significantly lower JSW along the medial margin of the lateral compartment, but also with significantly greater JSW at the anterior medial compartment of up to 0.6 mm per grade. The posterior medial joint space was significantly narrower (up to 3 mm) comparing knees with LMant scores of 0 vs 1. This same magnitude of narrowed JSW was detected along the periphery of the lateral joint space comparing grades in the lateral tibiofemoral compartment, but this was not statistically significant. LMlat (score range 0-2) was associated with a trend for greater reduction in JSW in the central lateral compartment of up to 0.5 mm per grade, but this was not statistically significant. Direction of meniscal extrusion is represented by the black arrowhead in the figure. Both medial and anterior extrusion of the medial meniscus are associated with significant reduction in JSW at the medial margin of the lateral joint space and widening of the anterior margin, likely from a posteromedial shift of the femoral condyles with respect to the tibia. Medial extrusion of the medial meniscus is also associated with narrowed JSW in the central to posterior medial joint space, likely as a direct effect of the loss of meniscal hoop tension. Anterior (but not lateral) extrusion of the lateral meniscus is associated with significantly lower JSW in the posterior medial joint space. These findings confirm that the extent and location of meniscal extrusion are key factors in weight bearing 3-D JSW distribution.

Can modified Dunn radiographs be an alternative to standing AP pelvis radiographs in the evaluation of pincer femoroacetabular impingement?

The purpose of this study was to compare modified Dunn radiographs with standing anteroposterior (AP) pelvis radiographs in respect of the tilt ratio, lateral centre-edge angle (LCEA), crossover sign, crossover percentage and joint space width measurements. The study hypothesis was that modified Dunn radiographs could be an alternative method to standing AP pelvis images in the evaluation of pincer-type femoroacetabular impingement (FAI). The study included 31 patients with a mean age of 42 years (range: 29-55 years) who had modified Dunn and standing AP pelvis radiographs taken in the radiological evaluation of non-traumatic hip pain between July 2018 and September 2022. Similar tilt ratio values were obtained on standing AP and modified Dunn images (P = 0.986). Joint space width showed a decrease in the transition from the modified Dunn position to the standing position, but the difference was not statistically significant (P = 0.161). The mean LCEA was measured as 34° ± 4° in the standing position and as 35° ± 5° in the modified Dunn position. No statistically significant difference was determined in the number of patients with a crossover sign or the crossover percentage values in these patients (P > 0.05). The data obtained in this study showed that there was no significant difference between images taken in the standing and modified Dunn positions in respect of radiological findings of pelvic tilt and pincer-type FAI. The modified Dunn radiograph is equivalent to the standing AP pelvis radiograph for the evaluation of pincer FAI.

Improved responsiveness to change in joint space width over 24-month follow-up: comparison of 3D JSW on weight-bearing CT vs 2D JSW on radiographs in the MOST study

Radiographic joint space width (JSW) has been a standard for measuring knee osteoarthritis (OA) structural change. Limitations in the responsiveness of this approach might be overcome by instead measuring 3D JSW on weight-bearing CT (WBCT). This study compared the responsiveness of 3D JSW measurements using WBCT with the responsiveness of radiographic 2D JSW. Standing, fixed-flexion knee radiographs (XR) and WBCT were acquired ancillary to the 144- and 168-month Multicenter Osteoarthritis Study visits. Tibiofemoral JSW was measured on both XR and WBCT. Responsiveness to change was defined by the standardized response mean (SRM) for change in JSW (1) at predetermined mediolateral locations (JSWx) on both modalities and (2) in the following subregions measured on WBCT images: central medial and lateral femur (CMF/CLF) and tibia (CMT/CLT), and anterior and posterior tibia (AMT/ALT, PMT/MLT). Baseline and 24-month follow-up JSWx measurements were completed for 265 participants (58.1% women). Responsiveness of 3D JSWx for medial tibiofemoral compartment on coronal WBCT (SRM range:-0.18,-0.24) exceeded that for 2D JSWx (-0.10,-0.16). Responsiveness of 3D JSW subregional mean (-0.06,-0.36) and maximal (-1.14,-1.75) CMF and CMT and maximal CLF/CLT 3D JSW changes were statistically significantly greater in comparison with respective medial and lateral 2D JSWx (P≤0.002). Subregional 3D JSW on WBCT is substantially more responsive to 24-month changes in tibiofemoral joint structure compared to radiographic measurements. Use of subregional 3D JSW on WBCT could enable improved detection of OA structural progression over a 24-month duration in comparison with measurements made on XR.

Developing Objective Computational Methods for Quantifying Ankle Osteoarthritis using Low-Dose Weight Bearing CT

Category: Ankle Arthritis; Ankle; Other Introduction/Purpose: Decision regarding ankle osteoarthritis (OA) management varies depending on the severity and distribution of the associated joint degeneration. Disease staging is typically based on subjective grading of appearance on conventional plain radiographs, with reported sub-par reproducibility and reliability. Weight-bearing computed tomography (WBCT) offers clinical advantages in the setting of OA, where thinning of the ankle cartilage, softening of the cartilage, and other deformities become more apparent under load. WBCT also provides a better geometric representation of the ankle and allows for more accurate measurements when compared to a conventional radiograph. The purpose of this study was to develop and describe computational methods to objectively quantify radiographic changes associated with ankle OA apparent on low-dose WBCT images. Methods: We analyzed two patients with ankle OA and one healthy control that had all undergone WBCT of the foot and ankle. The severity of OA in the ankle of each patient was scored using the Kellgren-Lawrence (KL) classification by plain weight-bearing radiographs. For each ankle, the subsequent analysis focused on a volume of interest (VOI) centered on the tibiotalar joint. Within the VOI, the initial computational analysis focused on measuring the 3D joint space width (JSW). Subsequent analyses utilized WBCT image intensity (Hounsfield Unit, or HU) profiles along lines perpendicular to the subchondral bone/cartilage interface of the distal tibia extending across the entire VOI. The HU intensity profiles were recorded, and graphical plots of the HU distributions were generated for each line. These plots were then used to calculate the HU contrast, a novel measure of the regional variation in bone density. Results: The average JSW was 3.89 mm for the healthy control ankle, 2.69 mm for the mildly arthritic ankle (KL 2), and 1.57 mm for the severely arthritic ankle (KL 4). The average HU contrast was 72.31 for the healthy control ankle, 62.69 for the mildly arthritic ankle, and 33.98 for the severely arthritic ankle. The use of four projections at different locations throughout the joint allowed us to visualize specifically which quadrants have reduced joint space width and contrast. One projection in the severely arthritic ankle had JSW and contrast values of 0 due to complete joint space loss along with projection 4, which corresponds in this case to the posterolateral part of the joint (Figure). Conclusion: We presented a novel computational assessment of ankle osteoarthritis using low-dose WBCT imaging. We were able to demonstrate differences between normal ankles and ankles with mild and severe OA using JSW and HU contrast measurements. This methodology represents an important step towards a more reliable OA assessment when compared to the current standard qualitative evaluations, potentially serving as a starting point for the development of a more robust osteoarthritis staging system. Additional studies are needed to assess the algorithm more rigorously over a variety of radiographic presentations.

A novel magnetic resonance imaging scoring system for active and chronic changes in children and adolescents with juvenile idiopathic arthritis of the hip

BackgroundHip involvement predicts severe disease in juvenile idiopathic arthritis (JIA) and is accurately assessed by MRI. However, a child-specific hip MRI scoring system has not been validated.ObjectiveTo test the intra- and interobserver agreement of several MRI markers for active and chronic hip changes in children and young adults with JIA and to examine the precision of measurements commonly used for the assessment of growth abnormalities.Materials and methodsHip MRIs from 60 consecutive children, adolescents and young adults with JIA were scored independently by two sets of radiologists. One set scored the same MRIs twice. Features of active and chronic changes, growth abnormalities and secondary post-inflammatory changes were scored. We used kappa statistics to analyze inter- and intraobserver agreement for categorical variables and a Bland–Altman approach to test the precision of continuous variables.ResultsAmong active changes, there was good intra- and interobserver agreement for grading overall inflammation (kappa 0.6–0.7). Synovial enhancement showed a good intraobserver agreement (kappa 0.7–0.8), while the interobserver agreement was moderate (kappa 0.4–0.5).Regarding acetabular erosions on a 0–3 scale, the intraobserver agreement was 0.6 for the right hip and 0.7 for the left hip, while the interobserver agreement was 0.6 for both hips. Measurements of joint space width, caput–collum–diaphyseal angle, femoral neck–head length, femoral width and trochanteric distance were imprecise.ConclusionWe identified a set of MRI markers for active and chronic changes in JIA and suggest that the more robust markers be included in future studies addressing clinical validity and long-term patient outcomes.

AB1330 AUTOMATIC SUBPIXEL MEASUREMENT OF RADIOGRAPHIC FINGER JOINT SPACE NARROWING IN RHEUMATOID ARTHRITIS PATIENTS UNDER TOCILIZUMAB TREATMENT

BackgroundThe conventional scoring methods of radiographic joint space narrowing (JSN) in rheumatoid arthritis (RA) such as the Genant-modified Sharp score (GSS) are widely accepted but include subjective and time-consuming nature1. Therefore, we have developed an in-house software equipped with partial image phase-only correlation (PIPOC)2 which can automatically quantify joint space width (JSW) change.ObjectivesThe purpose of this study was to investigate whether the in-house software can predict the inhibitory effect of tocilizumab on joint destruction in a short period of time.MethodsThe study included 39 RA patients (35 female) who were treated with tocilizumab (Table 1). Radiological progression of the metacarpophalangeal and the proximal interphalangeal joints was evaluated according to the GSS at 0, 6, and 12 months. Automatic measurement was performed by the in-house software (Figure 1). We then validated in-house software in terms of accuracy in detecting the JSN.Figure 1.The algorithm flow of in-house software equipped with PIPOCTable 1.Clinical characteristics of RA patientsvariablebaseline6 months12 monthsTotal number of patients39Sex, female/male35/4Rheumatoid factor status, positive/negative29/10Age, mean (SD) years61.5 (14.6)Duration of disease, mean (SD) months111.4 (85.0)Swollen joint count, mean (SD)6.0 (4.7)3.5 (3.5)2.9 (4.0)Tender joint count, mean (SD)6.4 (3.5)2.9 (2.2)1.9 (2.0)DAS28-ESR, mean (SD)4.9 (1.2)3.0 (1.1)2.6 (1.0)DAS28-CRP, mean (SD)4.4 (1.1)3.0 (0.9)2.6 (0.8)RA, rheumatoid arthritis; SD, standard deviation; DAS28, disease activity score with 28 joints; ESR, erythrocyte sedimentation rate; CRP, C-reactive proteinResultsTo ensure homogeneity of the subjects, we targeted the joints with GSS = 0 at baseline in the software analysis. The success rate of the in-house software for JSW measurement was 96.8% (449/464). Here, the GSS (+)/PIPOC (+) were defined as joints with JSN progression according to the GSS and the software analysis, respectively. Otherwise, joints were defined as the GSS (-)/PIPOC (-) namely non-progressive JSN. The 0–12-month GSS with the 0–6-month GSS (+) group was significantly more JSN progression than the 0–6-month GSS (-) group (Mann-Whitney U test, p &lt; 0.001). Similarly, the 0–12-month PIPOC with the 0–6-month PIPOC (+) group was significantly more JSN progression than the 0–6-month PIPOC (-) group (p &lt; 0.001). The 0–12-month JSW change of finger joints with the 0–12-month GSS (+) detected by the in-house software was significantly greater than the 0–12-month GSS (-) (p = 0.02).ConclusionOur in-house software equipped with PIPOC might be able to predict the subsequent joint destruction with 6 months observations.

FINGER JOINT SEGMENTATION USING MACHINE LEARNING AND MINIMIZED TRAINING SET

Purpose: Hand Osteoarthritis (HOA) is a common form of OA disease. About half of all women and one-quarter of all men will experience the stiffness and pain of HOA by the time they are 85 years old. The 29 bones of hands and wrists come together to form many small joints that can be affected by HOA. One common HOA evaluation is to measure joint space width (JSW) on hand X-ray for each finger joint. This measurement usually requires manual labeling of finger joint bone edge, which is time-consuming.

3-D JOINT SPACE WIDTH FROM WEIGHT BEARING COMPUTED TOMOGRAPHY IS BETTER THAN 2-D RADIOGRAPHIC MEASURES AT PREDICTING FUTURE LATERAL JOINT SPACE NARROWING AT THE KNEE: A MULTICENTER OSTEOARTHRITIS STUDY INVESTIGATION

3-D joint space width (JSW) measured from weight bearing CT (WBCT) has been suggested to be more sensitive than radiographic 2-D measurement in detecting joint space narrowing (JSN), but its diagnostic value in osteoarthritis is yet to be established. To determine the predictive validity of 3-D JSW measurement from baseline WBCT compared to 2-D radiographic measures in identifying structural disease progression at the knee. WBCT knee imaging was acquired at the 144-month visit of the Multicenter Osteoarthritis Study (MOST) with radiographic Kellgren and Lawrence grade (KLG), medial and lateral tibiofemoral radiographic OARSI JSN grades. Progression in medial and lateral JSN grade was recorded 2 years subsequent. After semi-automatic segmentation of 663 available knees, joint space mapping was performed to create 3-D JSW maps. A template was registered to each individual joint surface, a 3-D statistical shape model created, and JSW measurements transferred to the template. A statistical parametric mapping (SPM) general linear model adjusted for age, sex, BMI, and the first 5 shape modes (controlling for effects of systematic misregistration) was used to test the dependence of baseline 3-D JSW on baseline medial and lateral JSN in turn. One knee per participant was included in the SPM model, when required selecting side according to worst baseline compartmental JSN grade or randomly if equal. Mean JSW values from significantly narrower SPM ROIs were taken for all knees and used in receiver operating characteristic analysis to deliver areas under the curve (AUC) in a leave-one-out cross-validation classifier predictive model for future worsening of medial and lateral JSN at 2 years. This prediction model also tested baseline KLG, medial and lateral JSN grade. All predictive models were controlled by inclusion of age, sex, and BMI and compared against each other. 10 knees did not have radiographic grading, so the study set consisted of 653 knees from 394 individuals. 218 participants were female, mean ± SD age was 63.5 ± 9.6 years, mass 82.7 ± 17.7 kg, height 170 ± 9 cm, and BMI 28. 5 ± 5.0 kg/m 2 . SPM revealed regions of significantly narrower baseline medial JSW up to ∼0.75 mm per increment in medial JSN grade (unmasked medial compartment red zone in fig. 1) and narrower baseline lateral JSW up to ∼1 mm per increment in baseline lateral JSN grade (unmasked lateral compartment red zone in fig. 2). Mean medial and lateral ROI JSW values were taken at all available knees for predictive modelling. AUC values with 95% confidence limits showed that baseline mean medial ROI JSW (0.68, 0.61-0.74) was worse than baseline KLG (0.75, 0.68-0.81) and no better than medial JSN (0.73, 0.65-0.79) or lateral JSN (0.66, 0.6-0.71) in predicting future medial JSN. However, baseline mean lateral ROI JSW (0.84, 0.72-0.91) was better than medial JSN (0.61, 0.49-0.72) and lateral JSN (0.71, 0.54-0.86) in prediction of future lateral JSN. It was also better than baseline KLG (0.77, 0.76-0.86) but not outside the 95% confidence limits, however combining baseline lateral ROI JSW and KLG in the model further improved the AUC (0.87, 0.78-0.92) beyond the limits for just KLG (0.77, 0.76-0.86). Baseline 3-D lateral compartment JSW from WBCT is better than 2-D radiographic measures at predicting progression in lateral compartment JSN, but the same was not seen for medial JSN. This suggests an important role for 3-D weight bearing JSW in assessment of knee osteoarthritis according to disease phenotype. National Institutes of Health, University of Kansas (R01AR071648), University of Iowa (U01AG18832) and University of California-San Francisco (U01AG19069). NS is a consultant for Integra BioLife, Trice Medical and Pacira Biosciences. The authors would like to thank participants and staff of the MOST study. CORRESPONDENCE ADDRESS: tom@turmezei.com