Prevalence of intra-articular mineralization on knee computed tomography: the multicenter osteoarthritis study

OBJECTIVE

The aim of this work was to report the prevalence of computed tomography (CT)-detected intra-articular mineralization.

DESIGN

We included participants from the Multicenter Osteoarthritis (MOST) Study. At the 12th year visit of the MOST study, bilateral knee CTs were first obtained. All participants also had posteroanterior and lateral radiographs of bilateral knees and completed standard questionnaires. Knee radiographs were assessed for Kellgren & Lawrence grade (KLG) and radiographic evidence of intra-articular mineralization. CT images were scored using the Boston University Calcium Knee Score (BUCKS) for cartilage, menisci, ligaments, capsule, and vasculature. Prevalence of intra-articular mineralization was computed for the total sample, and stratified by age, sex, race, Body Mass Index (BMI), presence of frequent knee pain, and KLG. We also determined distribution of mineralization in the cartilage and meniscus, and co-localization.

RESULTS

4140 bilateral knees from 2070 participants were included (56.7% female, mean age 61.1 years, mean BMI: 28.8 kg/m2). On radiographs 240 knees (5.8%) had intraarticular mineralization, while CT-detected mineralization was present in 9.8% of knees. Prevalence of hyaline articular and meniscus mineralization increased with age and KL grade, and was similar by sex, BMI categories, and comparable in subjects with and without frequent knee pain. Mineralization tended to be ubiquitous in the joint, most commonly involving all three (medial/lateral tibiofemoral and patellofemoral) compartments (3.1%), while the patellofemoral compartment was the most involved compartment in isolation (1.4%).

CONCLUSIONS

CT of the knee provides greater visualization of intra-articular mineralization than radiographs and allows better localization of the crystal deposition within the joint. Further studies should focus on the co-localization of intra-articular crystal deposition and corresponding magnetic resonance imaging (MRI)-features of knee osteoarthritis (OA).

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

OBJECTIVE

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.

DESIGN

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).

RESULTS

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).

CONCLUSIONS

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.

The morphology of proximal tibiofibular joint (PTFJ) predicts incident radiographic osteoarthritis: data from Osteoarthritis Initiative

OBJECTIVE

To determine whether the morphology of proximal tibiofibular joint (PTFJ) is associated with increased risk of incident radiographic osteoarthritis (iROA) over 4 years in the OA Initiative (OAI) study.

METHODS

A nested matched case-control study design was used to select participants from OAI study. Case knees were defined as those with iROA. Control knees were matched one-to-one by sex, age and radiographic status with case knees. T2-weighted MR images were assessed at P0 (the visit when incident ROA was found on radiograph), P1 (1 year prior to P0) and at OAI baseline. The contacting area of PTFJ (S) and its projection areas onto the horizontal (load-bearing area, Sτ), sagittal (lateral stress-bolstering area, Sφ) and coronal plane (posterior stress-bolstering area, Sυ) were assessed, respectively.

RESULTS

354 case knees and 354 matched control knees were included, with a mean age of 60 and a mean body mass index (BMI) of 28 kg/m². Baseline PTFJ morphological parameters (S, Sτ and Sυ) were significantly associated with iROA over 4 years, and these associations remained unchanged after adjustment for BMI, number of knee bending activities, self-reported knee injury and surgery. S, Sτ and Sυ were also significantly associated with iROA at P1 and P0. In subgroup analysed, S, Sτ and Sυ were associated with risks of incident joint space narrowing in the medial, but not the lateral tibiofemoral compartment.

CONCLUSION

Greater contacting area, load-bearing area and posterior stress-bolstering area of PTFJ were associated with increased risks of iROA, largely in the medial tibiofemoral compartment.

Is the atrophic phenotype of tibiofemoral osteoarthritis associated with faster progression of disease? The MOST study

OBJECTIVE

To assess the associations of atrophic tibiofemoral osteoarthritis (OA) with progression of radiographic joint space narrowing (JSN) and magnetic resonance imaging (MRI)-defined progression of cartilage damage.

DESIGN

Participants of the Multicenter Osteoarthritis (MOST) Study with available radiographic and MRI assessments at baseline and 30 months were included. The atrophic OA phenotype was defined as Osteoarthritis Research Society International (OARSI) grades 1 or 2 for JSN and grade 0 for osteophytes. Based on MRI, atrophic OA was defined as tibiofemoral (TF) cartilage damage grades ≥3 in at least 2 of 10 subregions with absent or tiny osteophytes in all TF subregions. Progression of JSN and cartilage loss on MRI, was defined as (1) no, (2) slow, and (3) fast progression. Co-variance and logistic regression with generalized estimated equations were performed to assess the association of atrophic knee OA with any progression, compared to non-atrophic OA knees.

RESULTS

A total of 476 knees from 432 participants were included. There were 50 (10.5%) knees with atrophic OA using the radiographic definition, and 16 (3.4%) knees with atrophic OA using MRI definition. Non-atrophic OA knees more commonly exhibited fast progression of JSN and cartilage damage. Logistic regression showed that the atrophic phenotype of knee OA was associated with a decreased likelihood of progression of JSN and cartilage loss.

CONCLUSION

In this sample, the atrophic phenotype of knee OA was associated with a decreased likelihood of progression of JSN and cartilage loss compared to the non-atrophic knee OA phenotype.

Baseline trabecular bone and its relation to incident radiographic knee osteoarthritis and increase in joint space narrowing score: directional fractal signature analysis in the MOST study

PURPOSE

To explore the association of baseline trabecular bone structure with incident tibiofemoral (TF) osteoarthritis (OA) and with increase in joint space narrowing (JSN) score.

METHODS

The Multicenter Osteoarthritis Study (MOST) includes subjects with or at risk for knee OA. Knee radiographs were scored for Kellgren-Lawrence (KL) grade and JSN at baseline, 30, 60 and 84 months. Knees (KL ≤ 1) at baseline were assessed for incident OA (KL ≥ 2) and increases in JSN score. For each knee image at baseline, a variance orientation transform method (VOT) was applied to subchondral tibial bone regions of medial and lateral compartments. Seventeen fractal parameters were calculated per region. Associations of each parameter with OA incidence and with medial and lateral JSN increases were explored using logistic regression. Analyses were stratified by digitized film (DF) vs computer radiography (CR) and adjusted for confounders.

RESULTS

Of 894 knees with CR and 1158 knees with DF, 195 (22%) and 303 (26%) developed incident OA. Higher medial bone roughness was associated with increased odds of OA incidence at 60 and 84 months and also, medial and lateral JSN increases (primarily vertical). Lower medial and lateral anisotropy was associated with increased odds of medial and lateral JSN increase. Compared to DF, CR had more associations and also, similar results at overlapping scales.

CONCLUSION

Baseline trabecular bone texture was associated with incident radiographic OA and increase of JSN scores independently of risk factors for knee OA. Higher roughness and lower anisotropy were associated with increased odds for radiographic OA change.

Value of micro-CT as an investigative tool for osteochondritis dissecans: A preliminary study with comparison to histology

Purpose: To evaluate micro computed tomography (micro-CT) for the assessment of osteochondritis dissecans in comparison with histology.

Material and Methods: Osteochondritis dissecans lesions of 3 patients were evaluated using micro-CT (0.125 mA, 40 keV, 60 μm slice thickness, 60 μm isotropic resolution, entire sample) and light microscopy (toluidine blue, 3–5 μm slice thickness). The methods were compared regarding preparation time, detectability of tissue types and morphologic features of bone and cartilage.

Results: Non-destructive micro-CT imaging of the entire sample was faster than histologic preparation of a single slice for light microscopy. Morphologic features of bone and cartilage could be imaged in a comparable way to histology. It was not possible to image cells or different tissue types of bone and cartilage with micro-CT.

Conclusion: Micro-CT is a fast, non-destructive tool that may be a supplement or, if detailed histologic information is not necessary, an alternative to light microscopy for the investigation of osteochondritis dissecans.

Association of Physical Activity Measured by Accelerometer, Knee Joint Abnormalities, and Cartilage T2 Measurements Obtained From 3T Magnetic Resonance Imaging: Data From the Osteoarthritis Initiative

OBJECTIVE

To study the cross-sectional association between physical activity measured with an accelerometer, structural knee abnormalities, and cartilage T2 values assessed with 3T magnetic resonance imaging (MRI).

METHODS

We included 274 subjects from the Osteoarthritis Initiative cohort without definite radiographic osteoarthritis (Kellgren/Lawrence grades 0 and 1) and with at most mild pain, stiffness, and functional limitation in the study knee (Western Ontario and McMaster Universities Osteoarthritis Index scale 0-1), which had not limited their activity due to knee pain. Physical activity was measured over 7 days with an ActiGraph GT1M accelerometer. Subjects were categorized by quartile of physical activity based on the average daily minutes of moderate to vigorous physical activity (mv-PA). MRI images of the right knee (at 48-month visit) were assessed for structural abnormalities using a modified Whole-Organ Magnetic Resonance Imaging Score (WORMS) and for T2 relaxation times derived from segmented cartilage of 4 femorotibial regions and the patella. WORMS grades and T2 measurements were compared between activity quartiles using a linear regression model. Covariates included age, sex, body mass index, knee injury, family history of knee replacement, knee symptoms, hip and ankle pain, and daily wear time of the accelerometer.

RESULTS

Higher mv-PA was associated with increased severity (P = 0.0087) and number of lesions of the medial meniscus (P = 0.0089) and with severity of bone marrow edema lesions (P = 0.0053). No association between cartilage lesions and mv-PA was found. T2 values of cartilage (loss, damage, and abnormalities) tended to be greater in the higher quartiles of mv-PA, but the differences were nonsignificant.

CONCLUSION

In knees without radiographic osteoarthritis in subjects with no or mild knee pain, higher physical activity levels were associated with increases in meniscal and bone marrow edema pattern lesions.

Novel statistical methodology reveals that hip shape is associated with incident radiographic hip osteoarthritis among African American women

INTRODUCTION

Hip shape is a risk factor for the development of hip osteoarthritis (OA), and current methods to assess hip shape from radiographs are limited; therefore this study explored current and novel methods to assess hip shape.

METHODS

Data from a prior case-control study nested in the Johnston County OA Project were used, including 382 hips (from 342 individuals). Hips were classified by radiographic hip OA (RHOA) status as RHOA cases (baseline Kellgren Lawrence grade [KLG] 0 or 1, follow-up [mean 6 years] KLG ≥ 2) or controls (KLG = 0 or 1 at both baseline and follow-up). Proximal femur shape was assessed using a 60-point model as previously described. The current analysis explored commonly used principal component analysis (PCA), as well as novel statistical methodologies suited to high dimension low sample size settings (Distance Weighted Discrimination [DWD] and Distance Projection Permutation [DiProPerm] hypothesis testing) to assess differences between cases and controls.

RESULTS

Using these novel methodologies, we were able to better characterize morphologic differences by sex and race. In particular, the proximal femurs of African American women demonstrated significantly different shapes between cases and controls, implying an important role for sex and race in the development of RHOA. Notably, discrimination was improved with the use of DWD and DiProPerm compared to PCA.

CONCLUSIONS

DWD with DiProPerm significance testing provides improved discrimination of variation in hip morphology between groups, and enables subgroup analyses even under small sample sizes.

Brief Report: Cartilage Thickness Change as an Imaging Biomarker of Knee Osteoarthritis Progression: Data From the Foundation for the National Institutes of Health Osteoarthritis Biomarkers Consortium

OBJECTIVE

To investigate the association of cartilage thickness change over 24 months, as determined by magnetic resonance imaging (MRI), with knee osteoarthritis (OA) progression at 24-48 months.

METHODS

This nested case-control study included 600 knees with a baseline Kellgren/Lawrence (K/L) grade of 1-3 from 600 Osteoarthritis Initiative (OAI) participants. Case knees (n = 194) had both medial tibiofemoral radiographic joint space loss (≥0.7 mm) and a persistent increase in the Western Ontario and McMaster Universities Osteoarthritis Index pain score (≥9 on a 0-100 scale) 24-48 months from baseline. Control knees (n = 406) included 200 with neither radiographic nor pain progression, 103 with radiographic progression only, and 103 with pain progression only. Medial and lateral femorotibial cartilage was segmented from sagittal 3T MRIs at baseline, 12 months, and 24 months. Logistic regression was used to assess the association of change in cartilage thickness, with a focus on the central medial femorotibial compartment, and OA progression.

RESULTS

Central medial femorotibial compartment thickness loss was significantly associated with case status, with an odds ratio (OR) of 1.9 (95% confidence interval [95% CI] 1.6-2.3) (P < 0.0001). Association with case status reached P < 0.05 for both the central femur (OR 1.8 [95% CI 1.5-2.2]) and the central tibia (OR 1.6 [95% CI 1.3-1.9]). Lateral femorotibial compartment cartilage thickness loss, in contrast, was not significantly associated with case status. A reduction in central medial femorotibial compartment cartilage thickness was strongly associated with radiographic progression (OR 4.0 [95% CI 2.9-5.3]; P < 0.0001) and only weakly associated with pain progression (OR 1.3 [95% CI 1.1-1.6]; P < 0.01).

CONCLUSION

Our findings indicate that loss of medial femorotibial cartilage thickness over 24 months is associated with the combination of radiographic and pain progression in the knee, with a stronger association for radiographic progression.

Do persons with asymmetric hip pain or radiographic hip OA have worse pain and structure outcomes in the knee opposite the more affected hip? Data from the Osteoarthritis Initiative

PURPOSE

To determine if asymmetry between hips in pain or radiographic osteoarthritis (RHOA) is associated with worse pain and joint space narrowing (JSN) at baseline and longitudinally in knees contralateral to more affected hips.

METHODS

We studied 279 participants in the Osteoarthritis Initiative with baseline asymmetry between hips in pain and 483 with asymmetry in RHOA none of whom had a hip replacement for ≥4 years after baseline. RHOA assessed from pelvis radiographs was categorized as none, possible or definite and hip pain on most days of a month in the past year as present/absent. Knee pain (WOMAC scale) and JSN (fixed flexion radiographs) were categorized as none, mild and moderate-severe. We compared knees contralateral and ipsilateral to more affected hips on baseline knee pain and JSN using clustered multinomial regression and on change in knee pain and JSN over 4-5 years using generalized linear and logistic estimating equations.

RESULTS

Knees contralateral to painful hips had less baseline pain ("moderate-severe" vs "none", relative risk ratio [RRR]: 0.39, 95% CI = 0.27-0.57), but greater baseline JSN ("moderate-severe" vs "none", RRR: 1.62, 95% CI = 1.09-2.38) and greater worsening of pain during follow-up (P = 0.001). Knees contralateral to hips with worse RHOA had nonsignificant trends for greater baseline JSN (P = 0.10) and JSN progression (P = 0.17).

CONCLUSION

These findings provide limited support for the hypothesis that early asymmetry in hip pain and RHOA is associated with worse pain and structural outcomes in knees contralateral to the more affected hip.

Knee joint subchondral bone structure alterations in active athletes: a cross-sectional case-control study

OBJECTIVE

It has been shown that trabecular bone structure parameters extracted from radiographs known as fractal signature analysis (FSA) are able to predict structural outcomes such as radiographic osteoarthritis (OA) progression. Little is known about their involvement in early disease or about differences between subjects exposed to increased joint loading such as young active athletes compared to non-athletes. Aim was to compare horizontal and vertical dimensions of bone texture considering athlete status, gender, previous anterior cruciate ligament (ACL) surgery and age.

DESIGN

Included were 685 patients of which 135 consecutive athletes (82% soccer players) 18-36 years old and 550 non-athletes controls in the same age range had knee radiography for assessment of subacute or chronic knee complaints. Regions of interest (ROI) were placed in the subchondral medial and lateral tibial plateaus. Fractal signatures were calculated in the horizontal and vertical dimensions. Curve fitting algorithms were applied taking into account all four risk factors in the same model adjusting for each other.

RESULTS

For the horizontal dimensions significant differences were observed for gender (estimate (E) 0.098 (95% confidence interval(CI)) (-0.009, 0.008), P < .0001), previous ACL surgery (E -0.031, 95% CI (-0.043, -0.019), P < .0001) and highest age group (E -0.039, 95% CI (-0.048, -0.029), P < .0001). For vertical dimensions, significant differences were shown for athletes (E -0.012, 95% CI (-0.020, -0.004), P < .0001), gender (E 0.056, 95% CI (0.049, 0.062), P < .0001), and age range from 28 to 32 years (E -0.028, 95% CI (-0.037, -0.019), P < .0001).

CONCLUSIONS

Trabecular bone structure differs between athletes and non-athletes, in regard to previous ACL surgery, gender and higher age.

A reference database of cartilage 3 T MRI T2 values in knees without diagnostic evidence of cartilage degeneration: data from the osteoarthritis initiative

OBJECTIVE

1) To establish a gender- and BMI-specific reference database of cartilage T2 values, and 2) to assess the associations between cartilage T2 values and gender, age, and BMI in knees without radiographic osteoarthritis or MRI-based (WORMS 0/1) evidence of cartilage degeneration.

DESIGN

481 subjects aged 45-65 years with Kellgren-Lawrence Scores 0/1 in the study knee were selected. Baseline morphologic cartilage 3T MRI readings (WORMS scoring) and T2 measurements (resolution = 0.313 mm × 0.446 mm) were performed in the medial and lateral femurs, medial and lateral tibias, and patella compartments. To create a reference database, a logarithmic transformation was applied to the data to obtain the 5th-95th percentile values for T2.

RESULTS

Significant differences in mean cartilage T2 values were observed between joint compartments. Although females had slightly higher T2 values than males in a majority of compartments, the differences were only significant in the medial femur (P < 0.0001). A weak positive association was seen between age and T2 in all compartments, most pronounced in the patella (3.27% increase in median T2/10 years, P = 0.009). Significant associations between BMI and T2 were observed, most pronounced in the lateral tibia (5.33% increase in median T2/5 kg/m(2) increase in BMI, P < 0.0001), and medial tibia (4.81% increase in median T2 /5 kg/m(2) increase in BMI, P < 0.0001).

CONCLUSIONS

This study established the first reference database of T2 values in a large sample of morphologically normal cartilage plates in knees without radiographic knee osteoarthritis (OA). While cartilage T2 values were weakly associated with age and gender, they had the highest correlations with BMI.

A new method to measure anatomic knee alignment for large studies of OA: data from the osteoarthritis initiative

OBJECTIVE

To develop and validate a new and improved software method to rapidly determine femur-tibia angle (FTA).

METHODS

Three readers, two skilled and one unskilled, without any formal medical training, measured FTA in 142 subjects from the Osteoarthritis Initiative (OAI). The reader reliability was assessed using the intra-class correlation coefficient (ICC), root mean square standard deviation (RMSSD), and Bland-Altman plots, comparing the existing and new FTA methods. Gender-specific linear regression assessed the relationship of FTA with the hip-knee-ankle angle (HKA).

RESULTS

The ICC (RMSSD) for intra- and inter-reader reproducibility of the existing FTA method was 0.96 (0.77°) and 0.92 (1.38°), respectively, and for the new technique was 0.98 (0.25°) and 0.98 (0.37°), with similar results for all three readers. Bland-Altman 95% limits of agreement were greater than ±2° for the existing, and ±1° for the new method. The r-value for the relation of FTA to HKA was 0.68 and 0.72 for the existing and new methods, respectively. Varus (HKA ≤ -2°)/neutral (-2° < HKA < 2°)/valgus (HKA ≥ 2°) alignment based on predicted HKA agreed moderately with measured HKA (weighted kappa = 0.53), and had moderate sensitivity (73%) and specificity (84%) for varus malalignment. The new FTA was related to HKA using a linear equation with a slope of 0.98 and an offset of 4.0°.

CONCLUSIONS

Since it is largely automated and uses unambiguous anatomical landmarks, the new method is highly reproducible and can be made on a standard posteroanterior (PA) knee radiograph by a relatively unskilled reader.

Progression of cartilage damage and meniscal pathology over 30 months is associated with an increase in radiographic tibiofemoral joint space narrowing in persons with knee OA--the MOST study

PURPOSE

To determine the association of MRI-assessed worsening of tibiofemoral cartilage damage, meniscal damage, meniscal extrusion, separately and together, with progression of radiographic joint space narrowing (JSN).

METHOD AND MATERIALS

The Multicenter Osteoarthitis Study (MOST) Study is a cohort study of subjects with or at risk for knee osteoarthritis (OA). Knees with radiographic OA Kellgren-Lawrence grade 2 at baseline and with baseline and 30-month 1.0 T MRIs were selected for reading using the WORMS system for cartilage damage, meniscal damage, and meniscal extrusion. The association of worsening of cartilage damage, meniscal damage, and/or meniscal extrusion with increases in the JSN was performed using logistic regression.

RESULTS

A total of 276 knees (one per subject) were included (women 68.5%, mean age 62.9 ± 7.8, mean body mass index (BMI) 30.2 ± 5.0). Worsening of each MRI feature was associated with any increase in JSN (P < 0.01). Worsening of cartilage damage was more frequently observed than worsening of meniscal damage and extrusion, and was significantly associated with both slow and fast progression of JSN. An increasing risk of JSN worsening was associated with increasing number of worsening MRI features (P for trend < 0.0001).

CONCLUSION

Worsening of tibiofemoral cartilage damage, meniscal damage, and meniscal extrusion are independent predictors of JSN progression in the same compartment. Worsening of cartilage damage is more frequently observed in JSN when compared to meniscal worsening. A strong cumulative effect on JSN progression is observed for worsening of more than one MRI feature.

Association of hip and pelvic geometry with tibiofemoral osteoarthritis: multicenter osteoarthritis study (MOST)

OBJECTIVE

Lateral tibiofemoral osteoarthritis (OA) is overall less common than medial tibiofemoral OA, but it is more prevalent in women. This may be explained by sex differences in hip and pelvic geometry. The aim of this study is to explore sex differences in hip and pelvic geometry and determine if such parameters are associated with the presence of compartment-specific knee OA.

METHODS

This case-control study reports on 1,328 hips/knees from 664 participants and is an ancillary to the Multicenter Osteoarthritis Study (MOST). Of the 1,328 knees, 219 had lateral OA, 260 medial OA, and 849 no OA. Hip and pelvic measurements were taken from full-limb radiographs on the ipsilateral side of the knee of interest. After adjusting for covariates, means were compared between sexes and also between knees with medial and lateral OA vs no OA using separate regression models.

RESULTS

Women were shown to have a reduced femoral offset (FO) (mean 40.9 mm vs 45.9 mm; P = 0.001) and more valgus neck-shaft angle (mean 128.4° vs 125.9°; P < 0.001) compared to men. Compared to those with no OA, knees with lateral OA were associated with a reduced FO (P = 0.012), increased height of hip centre (HHC) (P = 0.003), more valgus neck-shaft angle (P = 0.042), and increased abductor angle (P = 0.031). Knees with medial OA were associated with a more varus neck-shaft angle (P = 0.043) and a decreased abductor angle (P = 0.003).

CONCLUSION

These data suggest anatomical variations at the hip and pelvis are associated with compartment-specific knee OA and may help to explain sex differences in patterns of knee OA.

Association of metabolic risk factors with cartilage degradation assessed by T2 relaxation time at the knee: data from the osteoarthritis initiative

OBJECTIVE

To evaluate the association of metabolic risk factors with severity and 2-year progression of early degenerative cartilage changes at the knee, measured with T2 relaxation times in middle-aged subjects from the Osteoarthritis Initiative.

METHODS

Cartilage segmentation and T2 map generation were performed in knee 3T magnetic resonance images from 403 subjects ages 45-60 years without radiographic osteoarthritis (OA). The influence of risk factors on baseline T2 and longitudinal progression of T2 was analyzed using linear regression, adjusting for age, sex, and other OA risk factors.

RESULTS

Four metabolic risk factors, i.e., high abdominal circumference (P < 0.001), hypertension (P = 0.041), high fat consumption (P = 0.023), and self-reported diabetes mellitus (P = 0.010), were individually associated with higher baseline T2. When the 4 metabolic risk factors were considered in a multivariate regression model, higher T2 remained significantly associated with abdominal circumference (P < 0.001) and diabetes mellitus (P = 0.026), and there was a trend for high fat consumption (P = 0.096). For the individual risk factors, only diabetes mellitus remained associated with higher baseline T2 after adjustment for body mass index (BMI). After adjustment for BMI, baseline T2 increased in a dose-response manner with the number of metabolic risk factors present (P = 0.032 for linear trend), and subjects with ≥3 metabolic factors (versus <3) had significantly higher baseline T2 (mean difference 1.2 msec [95% confidence interval 0.3, 2.1]; P = 0.011). Metabolic risk factors were not significantly associated with increases in T2 during followup.

CONCLUSION

Metabolic risk factors are associated with higher T2, suggesting that increased cartilage degeneration may be caused by modifiable metabolic disorders.

Prevalent cartilage damage and cartilage loss over time are associated with incident bone marrow lesions in the tibiofemoral compartments: the MOST study

OBJECTIVE

To assess the association of prevalent cartilage damage and cartilage loss over time with incident bone marrow lesions (BMLs) in the same subregion of the tibiofemoral compartments as detected on magnetic resonance imaging (MRI).

METHODS

The Multicenter Osteoarthritis Study is an observational study of individuals with or at risk for knee osteoarthritis (OA). Subjects whose baseline and 30-month follow-up MRIs were read for findings of OA were included. MRI was performed with a 1.0 T extremity system. Tibiofemoral compartments were divided into 10 subregions. Cartilage morphology was scored from 0 to 6 and BMLs were scored from 0 to 3. Prevalent cartilage damage and cartilage loss over time were considered predictors of incident BMLs. Associations were assessed using logistic regression, with adjustments for potential confounders.

RESULTS

Medially, incident BMLs were associated with baseline cartilage damage (adjusted odds ratio (OR) 3.9 [95% confidence interval (CI) 3.0, 5.1]), incident cartilage loss (7.3 [95% CI 5.0, 10.7]) and progression of cartilage loss (7.6 [95% CI 5.1, 11.3]) Laterally, incident BMLs were associated with baseline cartilage damage (4.1 [95% CI 2.6, 6.3]), incident cartilage loss (6.0 [95% CI 3.1, 11.8]), and progression of cartilage loss (11.9 [95% CI 6.2, 23.0]).

CONCLUSION

Prevalent cartilage damage and cartilage loss over time are strongly associated with incident BMLs in the same subregion, supporting the significance of the close interrelation of the osteochondral unit in the progression of knee OA.

IDH1 and IDH2 mutations in pediatric acute leukemia

To investigate the frequency of isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) mutations in pediatric acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL), we sequenced these genes in diagnostic samples from 515 patients (227 AMLs and 288 ALLs). Somatic IDH1/IDH2 mutations were rare in ALL (N=1), but were more common in AML, occurring in 3.5% (IDH1 N=3 and IDH2 N=5), with the frequency higher in AMLs with a normal karyotype (9.8%). The identified IDH1 mutations occurred in codon 132 resulting in replacement of arginine with either cysteine (N=3) or histidine (N=1). By contrast, mutations in IDH2 did not affect the homologous residue but instead altered codon 140, resulting in replacement of arginine with either glutamine (N=4) or tryptophan (N=1). Structural modeling of IDH2 suggested that codon 140 mutations disrupt the enzyme's ability to bind its substrate isocitrate. Accordingly, recombinant IDH2 R140Q/W were unable to carry out the decarboxylation of isocitrate to α-ketoglutarate (α-KG), but instead gained the neomorphic activity to reduce α-KG to R(-)-2-hydroxyglutarete (2-HG). Analysis of primary leukemic blasts confirmed high levels of 2-HG in AMLs with IDH1/IDH2 mutations. Interestingly, 3/5 AMLs with IDH2 mutations had FLT3-activating mutations, raising the possibility that these mutations cooperate in leukemogenesis.

Association between patella alta and the prevalence and worsening of structural features of patellofemoral joint osteoarthritis: the multicenter osteoarthritis study

OBJECTIVE

To examine the relationship between patella alta and the prevalence and worsening at followup of structural features of patellofemoral joint (PFJ) osteoarthritis (OA) on magnetic resonance imaging (MRI).

METHODS

The Multicenter Osteoarthritis Study is a cohort study of persons ages 50-79 years with or at risk for knee OA. Patella alta was measured using the Insall-Salvati ratio (ISR) on the baseline lateral radiograph, and cartilage damage, bone marrow lesions (BMLs), and subchondral bone attrition (SBA) were graded on MRI at baseline and at 30 months of followup in the PFJ. We examined the association of the ISR with the prevalence and worsening of cartilage damage, BMLs, and SBA in the PFJ using logistic regression.

RESULTS

A total of 907 knees were studied (mean age 62 years, body mass index 30 kg/m(2), ISR 1.10), 63% from female subjects. Compared with knees in the lowest ISR quartile at baseline, those in the highest quartile had 2.4 (95% confidence interval [95% CI] 1.7-3.3), 2.9 (95% CI 2.0-4.3), and 3.5 (95% CI 2.3-5.5) times the odds of having lateral PFJ cartilage damage, BMLs, and SBA, respectively, and 1.5 (95% CI 1.1-2.0), 1.3 (95% CI 0.9-1.8), and 2.2 (95% CI 1.4-3.4) times the odds of having medial PFJ cartilage damage, BMLs, and SBA, respectively. Similarly, those with high ISRs were also at risk for worsening of cartilage damage and BMLs over time than those with low ISRs.

CONCLUSION

A high ISR, indicative of patella alta, is associated with structural features of OA in the PFJ. Additionally, the same knees have an increased risk of worsening of these same features over time.

Pre-radiographic MRI findings are associated with onset of knee symptoms: the most study

OBJECTIVE

Magnetic resonance imaging (MRI) has greater sensitivity to detect osteoarthritis (OA) damage than radiographs but it is uncertain which MRI findings in early OA are clinically important. We examined MRI abnormalities detected in knees without radiographic OA and their association with incident knee symptoms.

METHOD

Participants from the Multicenter Osteoarthritis Study (MOST) without frequent knee symptoms (FKS) at baseline were eligible if they also lacked radiographic features of OA at baseline. At 15 months, knees that developed FKS were defined as cases while control knees were drawn from those that remained without FKS. Baseline MRIs were scored at each subregion for cartilage lesions (CARTs); osteophytes (OST); bone marrow lesions (BML) and cysts. We compared cases and controls using marginal logistic regression models, adjusting for age, gender, race, body mass index (BMI), previous injury and clinic site.

RESULTS

36 case knees and 128 control knees were analyzed. MRI damage was common in both cases and controls. The presence of a severe CART (P=0.03), BML (P=0.02) or OST (P=0.02) in the whole knee joint was more common in cases while subchondral cysts did not differ significantly between cases and controls (P>0.1). Case status at 15 months was predicted by baseline damage at only two locations; a BML in the lateral patella (P=0.047) and at the tibial subspinous subregions (P=0.01).

CONCLUSION

In knees without significant symptoms or radiographic features of OA, MRI lesions of OA in only a few specific locations preceded onset of clinical symptoms and suggest that changes in bone play a role in the early development of knee pain. Confirmation of these findings in other prospective studies of knee OA is warranted.

The association of proximal femoral shape and incident radiographic hip OA in elderly women

PURPOSE

Variations in femoral head shape are reported to predict incident hip osteoarthritis (OA). This study evaluated if proximal femur shape at baseline was a risk factor for incident radiographic hip OA (RHOA) after 8.3 years of follow-up in a cohort of elderly Caucasian women.

METHODS

Supine pelvic radiographs were obtained as part of the Study of Osteoporotic Fractures (SOF) at baseline and Visit 5 (8.3 years later), and were scored for RHOA. A nested case-control study was performed: hips were eligible for inclusion if they had no prevalent RHOA in either hip at baseline. Cases of incident RHOA were defined as no RHOA at baseline and RHOA in their right hip present at Visit 5 [or right total hip replacement (THR) for OA between baseline for follow-up] and a random selection of one half of all incident RHOA cases plus right THR cases (n=102) were chosen. A random selection (n=249) of control subjects who had no RHOA in their right hip at both baseline and follow-up visit were included for comparison. The shape of the right proximal femur was outlined on a digitized baseline radiograph and a statistical image analysis technique, Active Shape Modeling (ASM), was used to generate 10 unique and independent "modes" or variations in shape, which explained 95% of the variance in the shape of the proximal femurs studied. Any hip shape was therefore described as the average shape plus a linear combination of these 10 independent modes of variation. The values for each of these 10 modes for each hip analyzed were entered into a logistic regression model as independent predictors of incident RHOA adjusting for covariates.

RESULTS

The incident RHOA cases were slightly taller, heavier and had higher total hip bone mineral density (BMD) than control subjects (P<0.05), but were otherwise similar demographically. Results of ASM showed that Modes 1, 2 and 3 together explained 81% of the variance in proximal femur shape among all subjects analyzed. Modes 3, 5, 9 which accounted for 8.9%, 3.3% and 0.8% of the variance respectively, were significant predictors of incident RHOA with adjusted odds-ratios ranging from 1.61 to 1.99 (P<0.001) for every 1 standard deviation (SD) increase in the mode score.

CONCLUSION

These results suggest that variations in the relative sizes of the femoral head and neck at baseline are modest determinants of incident RHOA in elderly Caucasian women.

Contrast-enhanced MRI of subchondral cysts in patients with or at risk for knee osteoarthritis: the MOST study

OBJECTIVE

The aim of the study was (1) to evaluate contrast enhancement patterns of subchondral cysts on magnetic resonance imaging and (2) to discuss possible radiological explanations of cyst enhancement based on existing theories of subchondral cyst formation in osteoarthritis.

MATERIALS AND METHODS

The Multicenter Osteoarthritis Study (MOST) is a NIH-funded longitudinal observational study for individuals who have or are at high risk for knee osteoarthritis. All subjects with available non-enhanced and contrast-enhanced MRI were included. The tibiofemoral and patellofemoral joints were divided in 14 subregions. The presence and size of subchondral cysts and bone marrow edema-like lesions (BMLs) were scored semiquantitatively in each subregion on non-contrast-enhanced MRI from 0 to 3. Enhancement of subchondral cysts was evaluated on contrast-enhanced MRI as grade 0 (absent), grade 1 (partial enhancement), or grade 2 (full enhancement). The adjacent articular cartilage was scored in each subregion on non-enhanced MRI as grade 0 (intact), grade 1 (partial thickness loss), or grade 2 (full thickness loss).

RESULTS

Four hundred knees were included (1 knee per person, 5600 subregions). Subchondral cysts were detected in 260 subregions (4.6%). After intravenous contrast administration, 245 cysts (94.2%) showed full enhancement, 12 (4.6%) showed partial enhancement and 3 (1.2%) showed no enhancement. Enhancing BMLs were found in 237 (91.2%) subregions containing cysts, which were located adjacent or in the middle of BMLs. In 121 subregions (46.5%) having cysts, no adjacent full thickness cartilage loss was detected.

CONCLUSION

Most subchondral cysts demonstrated full or partial contrast enhancement, and were located adjacent or in the midst of enhancing BMLs. As pure cystic lesions are not expected to enhance on MRI, the term "subchondral cyst-like bone marrow lesion" might be appropriate to describe these lesions.

The association of meniscal damage with joint effusion in persons without radiographic osteoarthritis: the Framingham and MOST osteoarthritis studies

OBJECTIVE

To assess the cross-sectional association between meniscal status and joint effusion on magnetic resonance imaging (MRI) in knees without radiographic osteoarthritis (OA).

DESIGN

Knees without OA (Kellgren/Lawrence grade 0) from the Framingham and MOST studies were examined by MRI. Meniscal status was assessed with a score of 0-4 in the anterior horn/body/posterior horn of the medial/lateral meniscus and effusion was assessed using a score of 0-3. The odds ratios (ORs) of joint effusion in those with meniscal damage were estimated using a logistic regression model. A subanalysis was performed for knees without MRI-detected cartilage damage.

RESULTS

Of 1368 knees, 296 (21.6%) showed meniscal pathology in at least one subregion. Effusion was present in 133 (44.9%) of knees with meniscal damage vs 328 (30.6%) in those without meniscal damage. The adjusted OR of effusion in a knee with meniscal damage was 1.8, 95% confidence intervals (CI) [1.4, 2.4]. The OR of effusion for the group with meniscal pathology in two compartments was 5.4, 95% CI [2.1, 14.3]. For knees without any cartilage lesions but with meniscal damage in any compartment the OR was 2.3, 95% CI [1.1, 4.5].

CONCLUSIONS

Knees without OA but with meniscal pathology exhibit joint effusion to a significantly higher degree than knees without meniscal damage. The association persists for knees without cartilage damage. The prevalence of effusion is further increased when present in two compartments. Concomitant occurrence of synovial activation and meniscal damage contributes to understanding the pathophysiology of early degenerative joint disease.

Change in MRI-detected subchondral bone marrow lesions is associated with cartilage loss: the MOST Study. A longitudinal multicentre study of knee osteoarthritis

OBJECTIVES

To describe the natural history of subchondral bone marrow lesions (BMLs) in a sample of subjects with knee osteoarthritis (OA) or at risk of developing it. Additionally, to examine the association of change in BMLs from baseline to 30-month follow-up with the risk of cartilage loss in the same subregion at follow-up.

METHODS

1.0 T MRI was performed using proton density-weighted, fat-suppressed sequences. BML size and cartilage status were scored in the same subregions according to the WORMS system. Subregions were categorised based on comparison of baseline and follow-up BML status. A logistic regression model was used to assess the association of change in BML status with cartilage loss over 30 months using stable BMLs as the reference group.

RESULTS

395 knees were included. 66% of prevalent BMLs changed in size; 50% showed either regression or resolution at follow-up. The adjusted odds ratios (95% confidence intervals) of cartilage loss in the same subregion at follow-up for the different groups were 1.2 (0.5 to 1.6) for regressing BMLs, 0.9 (0.5 to 1.6) for resolving BMLs, 2.8 (1.5 to 5.2) for progressing BMLs, 0.2 (0.1 to 0.3) for subregions with no BMLs at baseline and follow-up and 3.5 (2.1 to 5.9) for newly developing BMLs. BML size at baseline was associated with risk of subsequent cartilage loss.

CONCLUSIONS

The majority of pre-existing BMLs decreased in size at follow-up. Absence of BMLs was associated with a decreased risk of cartilage loss, while progressing and new BMLs showed a high risk of cartilage loss in the same subregion.