Comparison of fixed-flexion positioning with fluoroscopic semi-flexed positioning for quantifying radiographic joint-space width in the knee: test-retest reproducibility

Quantitative measurement of medial femoral knee cartilage volume - analysis of the OA Biomarkers Consortium FNIH Study cohort

OBJECTIVE

Large studies of knee osteoarthritis (KOA) require well-characterized efficient methods to assess progression. We previously developed the local-area cartilage segmentation (LACS) software method, to measure cartilage volume on magnetic resonance imaging (MRI) scans. The present study further validates this method in a larger patient cohort and assesses predictive validity in a case-control study.

METHOD

The OA Biomarkers Consortium FNIH Project, a case-control study of KOA progression nested within the Osteoarthritis Initiative (OAI), includes 600 subjects in four subgroups based on radiographic and pain progression. Our software tool measured change in medial femoral cartilage volume in a central weight-bearing region. Different sized regions of cartilage were assessed to explore their sensitivity to change. The readings were performed on MRI scans at the baseline and 24-month visits. We used standardized response means (SRMs) for responsiveness and logistic regression for predictive validity.

RESULTS

Cartilage volume change was associated strongly with radiographic progression (odds ratios (OR) = 4.66; 95% confidence intervals (CI) = 2.85-7.62). OR were significant but of lesser magnitude for the combined radiographic and pain progression outcome (OR = 1.70; 95% CI = 1.40-2.07). For the full 600 subjects, theSRM was -0.51 for the largest segmented area. Smaller areas of cartilage segmentation were also able to predict the case-control status. The average reader time for the largest area was less than 20 min per scan. Smaller areas could be assessed with less reader time.

CONCLUSION

We demonstrated that the LACS method is fast, responsive, and associated with radiographic and pain progression, and is appropriate for existing and future large studies of KOA.

Acromegalic arthropathy in various stages of the disease: an MRI study

BACKGROUND

Arthropathy is a prevalent and invalidating complication of acromegaly with a characteristic radiographic phenotype. We aimed to further characterize cartilage and bone abnormalities associated with acromegalic arthropathy using magnetic resonance imaging (MRI).

METHODS

Twenty-six patients (23% women, mean age 56.8 ± 13.4 years), with active (n = 10) and controlled acromegaly (n = 16) underwent a 3.0 T MRI of the right knee. Osteophytes, cartilage defects, bone marrow lesions and subchondral cysts were assessed by the Knee Osteoarthritis Scoring System (KOSS) method. Cartilage thickness and cartilage T2 relaxation times, in which higher values reflect increased water content and/or structural changes, were measured. Twenty-five controls (52% women, mean age: 59.6 ± 8.0 years) with primary knee OA were included for comparison.

RESULTS

Both in active and controlled acromegaly, structural OA defects were highly prevalent, with thickest cartilage and highest cartilage T2 relaxation times in the active patients. When compared to primary OA subjects, patients with acromegaly seem to have less cysts (12% vs 48%, P = 0.001) and bone marrow lesions (15% vs 80%, P = 0.006), but comparable prevalence of osteophytosis and cartilage defects. Patients with acromegaly had 31% thicker total joint cartilage (P < 0.001) with higher cartilage T2 relaxation times at all measured sites than primary OA subjects (P < 0.01).

CONCLUSIONS

Patients with active acromegaly have a high prevalence of structural OA abnormalities in combination with thick joint cartilage. In addition, T2 relaxation times of cartilage are high in active patients, indicating unhealthy cartilage with increased water content, which is (partially) reversible by adequate treatment. Patients with acromegaly have a different distribution of structural OA abnormalities visualized by MRI than primary OA subjects, especially of cartilage defects.

Fixed-flexion knee radiography using a new positioning device produced highly repeatable measurements of joint space width: ELSA-Brasil Musculoskeletal Study (ELSA-Brasil MSK)

OBJECTIVE

To describe the performance of a non-fluoroscopic fixed-flexion PA radiographic protocol with a new positioning device, developed for the assessment of knee osteoarthritis (OA) in Brazilian Longitudinal Study of Adult Health Musculoskeletal Study (ELSA-Brasil MSK).

MATERIAL AND METHODS

A test-retest design including 19 adults (38 knee images) was conducted. Feasibility of the radiographic protocol was assessed by image quality parameters and presence of radioanatomic alignment according to intermargin distance (IMD) values. Repeatability was assessed for IMD and joint space width (JSW) measured at three different locations.

RESULTS

Approximately 90% of knee images presented excellent quality. Frequencies of nearly perfect radioanatomic alignment (IMD ≤1mm) ranged from 29% to 50%, and satisfactory alignment was found in up to 71% and 76% of the images (IMD ≤1.5mm and ≤1.7mm, respectively). Repeatability analyses yielded the following results: IMD [SD of mean difference=1.08; coefficient of variation (%CV)=54.68%; intraclass correlation coefficient (ICC) (95%CI)=0.59 (0.34-0.77)]; JSW [SD of mean difference=0.34-0.61; %CV=4.48%-9.80%; ICC (95%CI)=0.74 (0.55-0.85)-0.94 (0.87-0.97)]. Adequately reproducible measurements of IMD and JSW were found in 68% and 87% of the images, respectively.

CONCLUSIONS

Despite the difficulty in achieving consistent radioanatomic alignment between subsequent radiographs in terms of IMD, the protocol produced highly repeatable JSW measurements when these were taken at midpoint and 10mm from the medial extremity of the medial tibial plateau. Therefore, measurements of JSW at these locations can be considered adequate for the assessment of knee OA in ELSA-Brasil MSK.

Radiographic Measurement of Joint Space Width Using the Fixed Flexion View in 1,102 Knees of Japanese Patients with Osteoarthritis in Comparison with the Standing Extended View

Purpose

The fixed flexion view (FFV) of the knee is considered useful for evaluating the joint space when assessing the severity of osteoarthritis (OA) of the knee. To clarify the usefulness of FFV for evaluation of the joint space and severity of knee OA, this study evaluated changes in the joint space on the FFV and standing extended view (SEV) in patients with knee OA.

Materials and Methods

The SEV and FFV images were acquired in 567 patients (1,102 knees) who visited the hospital with a chief complaint of knee joint pain. Medial joint space width (MJSW) and Kellgren-Lawrence (K-L) classification assessed using the SEV and FFV images were compared.

Results

Mean MJSW was significantly smaller when assessed on the FFV than on the SEV (3.02±1.55 mm vs. 4.31±1.30 mm; p<0.001). The K-L grade was the same or higher on the FFV than on the SEV.

Conclusions

The FFV is more useful than the SEV for evaluating the joint space in OA knees. Treatment strategies in patients with knee OA should be determined based on routinely acquired FFV images.

Physical Activity Minimum Threshold Predicting Improved Function in Adults With Lower-Extremity Symptoms

OBJECTIVE

To identify an evidence-based minimum physical activity threshold to predict improved or sustained high function for adults with lower-extremity joint symptoms.

METHODS

Prospective multisite data from 1,629 adults, age ≥49 years with symptomatic lower-extremity joint pain/aching/stiffness, participating in the Osteoarthritis Initiative accelerometer monitoring substudy were clinically assessed 2 years apart. Improved/high function in 2-year gait speed and patient-reported outcomes (PROs) were based on improving or remaining in the best (i.e., maintaining high) function quintile compared to baseline status. Optimal thresholds predicting improved/high function were investigated using classification trees for the legacy federal guideline metric requiring 150 minutes/week of moderate-vigorous (MV) activity in bouts lasting 10 minutes or more (MV-bout) and other metrics (total MV, sedentary, light intensity activity, nonsedentary minutes/week).

RESULTS

Optimal thresholds based on total MV minutes/week predicted improved/high function outcomes more strongly than the legacy or other investigated metrics. Meeting the 45 total MV minutes/week threshold had increased relative risk (RR) for improved/high function (gait speed RR 1.8, 95% confidence interval [95% CI] 1.6, 2.1 and PRO physical function RR 1.4, 95% CI 1.3, 1.6) compared to less active adults. Thresholds were consistent across sex, body mass index, knee osteoarthritis status, and age.

CONCLUSION

These results supported a physical activity minimum threshold of 45 total MV minutes/week to promote improved or sustained high function for adults with lower-extremity joint symptoms. This evidence-based threshold is less rigorous than federal guidelines (≥150 MV-bout minutes/week) and provides an intermediate goal towards the federal guideline for adults with lower-extremity symptoms.

Radiological and biochemical effects (CTX-II, MMP-3, 8, and 13) of low-level laser therapy (LLLT) in chronic osteoarthritis in Al-Kharj, Saudi Arabia

Inflammation of synovial membrane and degeneration of articular cartilage in osteoarthritis (OA) lead to major changes in joint space width (JSW) and biochemical components such as collagen-II telopeptide (CTX-II) and matrix metallo protineases (MMP-3, 8, and 13). Low-level laser therapy (LLLT) is thought to have an analgesic effect as well as biomodulatory effect on microcirculation and cartilage regeneration in animal studies. The objective of this study was to examine the analgesic and biochemical effect of LLLT in patients with knee osteoarthritis. Subjects (n = 34) who fulfilled the selection criteria were randomly divided into active group (n = 17) and placebo group. Subjects in active group were irradiated laser with the frequency of 3 days per week for 4 weeks with the specific parameters on 8 different points on the joint at 1.5 J per point for 60 s for 8 points for a total dose of 12 J in a skin contact method. The placebo group was treated with the same probe with minimum emission of energy. Visual analog scale for pain intensity, joint space width, collagen-II telopeptide, and matrix metallo protinease-3, 8, and 13 was measured before treatment and at 4 and 8 weeks following treatment. Data are analyzed with mean values and standard deviation with p < 0.05. Baseline values of all outcome measures show insignificant difference (p > 0.05) in both groups which shows homogeneity. After 4- and 8-week treatment, active laser group shows more significant difference (p < 0.001) in all the parameters than the placebo laser group (p > 0.05). Our results show that low-level laser therapy was more efficient in reducing pain and improving cartilage thickness through biochemical changes.

The association of waist circumference with walking difficulty among adults with or at risk of knee osteoarthritis: the Osteoarthritis Initiative

OBJECTIVE

Excess weight is a known risk factor for functional limitation and common in adults with knee osteoarthritis (OA). We asked to what extent high waist circumference was linked with developing difficulty with walking speed and distance over 4 years in adults with or at risk of knee OA.

METHOD

Using data from the Osteoarthritis Initiative (OAI), we employed World Health Organization (WHO) categories for Body Mass Index (BMI) and waist circumference (small/medium and large). Difficulty with speed was defined by slow gait: <1.2 m/s during a 20-m walk, and difficulty with distance was defined by an inability to walk 400 m. We calculated risk ratios (RR) to examine the likelihood of developing difficulty with distance and speed using obesity and waist circumference as predictors with RRs adjusted for potential confounders (i.e., age, sex, race, education, physical activity, and OA status).

RESULTS

Participants with obesity and large waists were 2.2 times more likely to have difficulty with speed at 4 years compared to healthy weight and small/medium waisted participants (Adjusted RR 2.2 [95% Confidence interval (CI) 1.6, 3.1], P < .0001). Participants with obesity and a large waist circumference had 2.4 times the risk of developing the inability to walk 400 m compared with those with a healthy BMI and small/medium waist circumference (Adjusted RR 0.9 [95% CI 1.6, 3.7], P < .0001).

CONCLUSIONS

Waist circumference may be a main risk factor for developing difficulty with speed in adults with or at risk of knee OA.

The incident tibiofemoral osteoarthritis with rapid progression phenotype: development and validation of a prognostic prediction rule

OBJECTIVES

No clinical prediction rules were found for estimating the likelihood of developing incident radiographic tibiofemoral osteoarthritis (OA) with rapid progression. Such a tool would enhance prognostic capability for clinicians and researchers.

DESIGN

We used two longitudinal datasets to independently derive (Multicenter Osteoarthritis Study) and validate (Osteoarthritis Initiative) a prognostic clinical prediction rule for estimating the probability of incident rapidly progressing radiographic knee OA in the following 4-5 years. Eligible subjects had at least one knee with a Kellgren and Lawrence (K&L) graded tibiofemoral joint of 0 or 1. Several potential risk factors were examined including obesity, age, knee alignment, frequent knee symptoms, contralateral knee OA and knee injury history. Multiple logistic regression was used to identify significant predictors and area under the receiver operating characteristic curve (AUC) was used to assess discrimination.

RESULTS

A total of 1690 subjects participated in the derivation and 2422 subjects participated in the validation of the clinical prediction rule. The multivariable model displayed good discrimination with AUC of 0.79 in the derivation dataset and 0.81 in the validation dataset.

CONCLUSIONS

Persons with contralateral knee OA, a baseline index knee OA grade of 1, higher body mass index (BMI) and higher baseline Western Ontario and McMaster Universities arthritis index total scores were more likely to develop K&L grade of 3 or 4 within 5 years. Frequent knee symptoms at baseline were not a significant predictor. The prediction rule and nomogram can assist clinicians in estimating the probability of rapidly progressing radiographic knee OA and the nomogram can assist researchers conducting epidemiologic studies and clinical trials.

Evaluation of Chondrocalcinosis and Associated Knee Joint Degeneration Using MR Imaging: Data from the Osteoarthritis Initiative

OBJECTIVES

To evaluate the ability of different MRI sequences to detect chondrocalcinosis within knee cartilage and menisci, and to analyze the association with joint degeneration.

METHODS

Subjects with radiographic knee chondrocalcinosis (n = 90, age 67.7 ± 7.3 years, 50 women) were selected from the Osteoarthritis Initiative and matched to controls without radiographic chondrocalcinosis (n = 90). Visualization of calcium-containing crystals (CaC) was compared between 3D T1-weighted gradient-echo (T1GE), 3D dual echo steady-state (DESS), 2D intermediate-weighted (IW), and proton density (PD)-weighted fast spin-echo (FSE) sequences obtained with 3T MRI and correlated with a semiquantitative CaC score obtained from radiographs. Structural abnormalities were assessed using Whole-Organ MRI Score (WORMS) and logistic regression models were used to compare cartilage compartments with and without CaC.

RESULTS

Correlations between CaC counts of MRI sequences and degree of radiographic calcifications were highest for GE (r_T1GE = 0.73, P < 0.001; r_DESS = 0.68, P < 0.001) compared to other sequences (P > 0.05). Meniscus WORMS was significantly higher in subjects with chondrocalcinosis compared to controls (P = 0.005). Cartilage defects were significantly more frequent in compartments with CaC than without (patella: P = 0.006; lateral tibia: P < 0.001; lateral femur condyle: P = 0.017).

CONCLUSIONS

Gradient-echo sequences were most useful for the detection of chondrocalcinosis and presence of CaC was associated with higher prevalence of cartilage and meniscal damage.

KEY POINTS

• Magnetic resonance imaging is useful for assessing burden of calcium-containing crystals (CaC). • Gradient-echo sequences are superior to fast spin echo sequences for CaC imaging. • Presence of CaC is associated with meniscus and cartilage degradation.

Both systemic and local lipopolysaccharide (LPS) burden are associated with knee OA severity and inflammation

OBJECTIVE

The microbiome is recognized as a new frontier in medicine with connections to a variety of diseases. We aimed to evaluate the association of lipopolysaccharide (LPS), a key pro-inflammatory product of the microbiome, with severity of inflammation, symptoms and radiographic abnormalities of knee osteoarthritis (OA).

DESIGN

LPS was measured using a recombinant Factor C (rFC) assay, carefully optimized for systemic and synovial fluid (SF) analyses. LPS binding protein (LBP) was tested in both serum and SF of 25 patients (31 knees) from the Etarfolatide cohort for association with OA phenotypic outcomes. Models were adjusted for age, gender and body mass index.

RESULTS

Based on LPS spike-and-recovery, both serum and SF dilutions of 0.1% were required to achieve recovery rates of at least 75% in all test specimens. Low coefficients of variation (CVs) (<10%) were achieved with both serum and SF dilutions <0.2%. Serum LPS and LBP were associated with the abundance of activated macrophages in the knee joint capsule and synovium. SF LPS and LBP were associated with the abundance of activated macrophages in the synovium. Serum LPS, LBP and SF LPS were associated with knee osteophyte severity. SF LPS was positively associated with knee joint space narrowing (JSN) severity and total WOMAC score. SF LBP was positively associated with self-reported knee pain score.

CONCLUSION

These data strongly support a role for LPS in the pathogenesis and severity of structural abnormalities and symptoms of knee OA.

Longitudinal validation of periarticular bone area and 3D shape as biomarkers for knee OA progression? Data from the FNIH OA Biomarkers Consortium

OBJECTIVE

To perform a longitudinal validation study of imaging bone biomarkers of knee osteoarthritis (OA) progression.

METHODS

We undertook a nested case-control study within the Osteoarthritis Initiative in knees (one knee per subject) with a Kellgren and Lawrence grade of 1-3. Cases were defined as knees having the combination of medial tibiofemoral radiographic progression and pain progression at the 24-month, 36-month or 48-month follow-up compared with baseline. Controls (n=406) were eligible knees that did not meet both endpoint criteria and included 200 with neither radiographic nor pain progression, 103 with radiographic progression only and 103 with pain progression only. Bone surfaces in medial and lateral femur, tibia and patella compartments were segmented from MR images using active appearance models. Independent variables of primary interest included change from baseline to 24 months in (1) total area of bone and (2) position on three-dimensional (3D) bone shape vectors that discriminate OA versus non-OA shapes. We assessed the association of bone markers changes over 24 months with progression using logistic regression.

RESULTS

24-month changes in bone area and shape in all compartments were greater in cases than controls, with ORs of being a case per 1 SD increase in bone area ranging from 1.28 to 1.71 across compartments, and per 1 SD greater change in 3D shape vectors ranging from 1.22 to 1.64. Bone markers were associated most strongly with radiographic progression and only weakly with pain progression.

CONCLUSIONS

In knees with mild-to-moderate radiographic OA, changes in bone area and shape over 24 months are associated with the combination of radiographic and pain progression over 48 months. This finding of association with longer term clinical outcome underscores their potential for being an efficacy of intervention biomarker in clinical trials.

Norwegican Cartilage Project - a study protocol for a double-blinded randomized controlled trial comparing arthroscopic microfracture with arthroscopic debridement in focal cartilage defects in the knee

Background

Focal lesions to the articular cartilage in the knee might have demolishing consequences to the knee. There exists a wide range of possible surgical procedures targeting these injuries, however no significant differences have been found between these procedures. This may support that the improvement is a result of rehabilitation, and not the surgery itself. Arthroscopic microfracture (MF) treatment has gained popularity, and has become the treatment of choice in patients with knee cartilage defects globally. In this study we want to increase knowledge, both clinical and economic, about arthroscopic microfracture (AF) compared to arthroscopic debridement (AD) and physical rehabilitation both in the short run, and in the long run.

Methods/Design

To compare arthroscopic microfracture with arthroscopic debridement and physiotherapy for the treatment of focal cartilage lesions in the knee, a long-term, double-blinded, randomized controlled multicenter trial will be conducted. A total of 114 men and non-pregnant women with a symptomatic focal full thickness cartilage lesion in the knee less than 2 cm2 will be included in the study. The two treatment allocations will receive identical rehabilitation, which is made up of 3 phases: accommodation, rehabilitation and return to activity. Follow up is 24 months, where all will be invited to participate in late follow ups after 5 and 10 years.

The Knee Injury and Osteoarthritis Outcome Score (KOOS) knee-related quality of life (QoL) subscore is the primary endpoint. Clinical parameters, questionnaires and radiologic modalities (Magnetic Resonance Imaging (MRI) and x-ray) will be used as secondary endpoints.

Discussion

This is an ongoing multicenter study with a high level of evidence to compare arthroscopic microfracture with arthroscopic debridement and physiotherapy for the treatment of isolated symptomatic full thickness cartilage lesions in the knee joint.

Trial registration

ClinicalTrials.gov ID: NCT02637505 (December 15, 2015).

Effect of Matching or Overconstraining Knee Laxity During Anterior Cruciate Ligament Reconstruction on Knee Osteoarthritis and Clinical Outcomes: A Randomized Controlled Trial With 84-Month Follow-up

BACKGROUND

The "initial graft tension" applied at the time of graft fixation during anterior cruciate ligament (ACL) reconstruction surgery modulates joint contact mechanics, which in turn may promote posttraumatic osteoarthritis (OA).

PURPOSE/HYPOTHESES

The study objectives were to compare clinical, functional, patient-reported, and OA imaging outcomes between 2 different initial laxity-based graft tension cohorts and a matched uninjured control group as well as to evaluate the effects of laxity-based graft tension on OA development at 84-month follow-up. The 2 laxity-based tension protocols were (1) to restore normal anteroposterior (AP) laxity at the time of surgery relative to the contralateral uninjured knee (low-tension group) or (2) to overconstrain AP laxity by 2 mm relative to the contralateral uninjured knee (high-tension group). The hypotheses were that (1) the high-tension group would have improved outcomes and decreased OA compared with the low-tension group after 84 months, and (2) the outcomes for the high-tension group would be equivalent to those for an age-, sex-, race-, and activity-matched group of control participants with uninjured knees.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

Patients had their ACLs reconstructed with either a bone-patellar tendon-bone or 4-stranded hamstring autograft, and outcomes were compared with a matched control group. Outcomes were evaluated preoperatively and at 60 and 84 months postoperatively and included clinical (KT-1000 arthrometer AP laxity measurement and International Knee Documentation Committee [IKDC] examination score), functional (1-legged hop for distance and knee extensor torque), patient-reported (Knee injury and Osteoarthritis Outcome Score [KOOS], Short Form-36 [SF-36], and patient satisfaction survey), and OA imaging (measurement of joint space width [JSW], Osteoarthritis Research Society International [OARSI] radiographic score, and Whole-Organ Magnetic Resonance Imaging Score [WORMS]) components. Repeated-measures analyses of variance were used to evaluate differences in outcomes between the treatment groups and the control group.

RESULTS

There were significant differences between the 2 tension groups in 1 of 5 KOOS subscales (sports and recreation; P = .04) and 2 of 8 SF-36 subscales (vitality, mental health; P < .04) at 84 and 60 months, respectively. Both tension groups scored significantly worse than the control group in the IKDC examination (P < .001), 1-legged hop (P ≤ .017), KOOS quality of life and symptoms subscales (P < .03), and OARSI radiographic score (P ≤ .02) at 84 months. The low-tension group performed significantly worse than the control group on the KOOS pain subscale (P = .03), SF-36 general health and social functioning (P < .04), OARSI radiographic score (P < .001), and WORMS (P = .001), while the high-tension group had statistically different results than the control group in AP knee laxity (P < .001), radiographic JSW (P = .003), and OARSI radiographic score (P = .02) as well as significantly more subsequent knee injuries (P = .02) at 84 months.

CONCLUSION

The results do not support the hypotheses that the high-tension group would have improved outcomes when compared with the low-tension group after 84 months of healing or that the outcomes for the high-tension group would be equivalent to those for the matched control group. While there were minor differences in patient-reported outcomes between the 2 laxity-based tension groups, all other outcomes were similar.

REGISTRATION

NCT00434837.

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.

Change in Physical Activity and Sedentary Time Associated With 2-Year Weight Loss in Obese Adults With Osteoarthritis

BACKGROUND

We examined if changes in moderate-to-vigorous physical activity (MVPA), light activity, and sedentary behavior are related to weight change over a 2-year period in obese adults with/elevated risk for knee osteoarthritis.

METHODS

Weight, physical activity, and sedentary time at baseline and 2 years were obtained from 459 obese participants from the Osteoarthritis Initiative. Weight change was categorized as ≥ 10 lbs, 5.0 to 9.9 lbs, 4.9 to -4.9 lbs, -5.0 to -9.9 lbs, and ≤ -10 lbs. We examined the association between 2-year weight change categories and changes in activity/sedentary time from accelerometer monitoring by multiple linear regression adjusted for baseline weight, demographic, and health factors.

RESULTS

Across the 5 weight categories (loss to gain), average 2-year change ranged from -7.4 to 28.0 sedentary minutes/ day, 4.2 to -23.1 light activity minutes/day, and 3.2 to -4.9 MVPA minutes/day, respectively. Higher weight loss categories were separately associated with increased MVPA (P for trend < 0.001) and less sedentary gain (P for trend = 0.01). Weight loss categories had a strong trend with light activity gain but not statistically significant (P for trend = 0.06).

CONCLUSIONS

Small increases in MVPA and decreases in sedentary time over 2 years were associated with weight loss among adults with obesity and with or at elevated risk for knee osteoarthritis.

Differences in subchondral bone size after one year in osteoarthritic and healthy knees

OBJECTIVE

Increase of subchondral bone area (tAB) in OA has been reported, but it remains unclear if this is specific to OA. We investigated differences in knee tAB after one year in healthy subjects and in those with radiographic OA (rOA).

METHOD

MR images of 899 right knees from the OA Initiative were acquired at baseline and one year follow-up (year-1). Medial and lateral tibial cartilage (MT and LT) and weight-bearing femoral cartilage (cMF and cLF) were segmented and tAB computed. Subjects were stratified into: healthy controls, pre-rOA (K&L grades 0 and 1, with OA risk factors), established rOA (K&L grades 2-4), and independently with regards to joint space narrowing (without, with medial, lateral and bilateral JSN). Primary analysis tested if tAB was different between baseline and year-1 in rOA. Exploratory analyses investigated whether: (1) tAB changes differed between healthy controls and those with rOA; (2) tAB differences were greater in higher K&L grades; and (3) tAB was different between baseline and year-1 in JSN. Significance was set at P < 0.0125.

RESULTS

Differences in tAB were found in rOA in MT, cMF and cLF (ranging from +0.2% to +0.4%; P < 0.001), but not in healthy controls or pre-rOA. Rates of change did not differ between groups. Within the JSN groups differences of 0.2-0.4% were found in the femur (P < 0.05).

CONCLUSION

We find that knee tABs differ in rOA between baseline and year-1, but the change was not greater than in healthy knees, and is restricted to the femur in JSN.

Focal cartilage defects in the knee - a randomized controlled trial comparing autologous chondrocyte implantation with arthroscopic debridement

BACKGROUND

Focal cartilage injuries in the knee might have devastating effect due to the predisposition of early onset osteoarthritis. Various surgical treatment options are available, however no statistically significant differences have been found between the different surgical treatments. This supports the suggestion that the improvement might be a result of the post-operative rehabilitation rather than the surgery itself. Autologous chondrocyte implantation (ACI) has become a recognized treatment option for larger cartilage lesions in the knee. Although ACI has been compared to other surgical treatment such as microfracture and mosaicplasty, it has never been directly compared to simple arthroscopic debridement and rehabilitation alone. In this study we want to increase clinical and economic knowledge about autologous chondrocyte implantation compared to arthroscopic debridement and physical rehabilitation in the short and long run.

METHODS/DESIGN

We will conduct a randomized controlled trial to compare ACI with simple arthroscopic debridement (AD) and physiotherapy for the treatment of cartilage lesions in the knee. The study will include a total of 82 patients, both men and non-pregnant women, with a full thickness cartilage defect in the weight bearing area of the femoral condyles or trochlea larger than 2 cm2. The lesion must be symptomatic, with a Lysholm score less than 75. The two treatment groups will receive identical rehabilitation protocol according to a modification of Wondrasch et al., which is an active rehabilitation and education program divided into 3 phases: accommodation, rehabilitation and return to activity. The patients will be followed for 24 months, with additional late follow-ups at 5 and 10 years to monitor the potential onset of osteoarthtitis. The primary outcome measure will be the difference in the KOOS knee-related quality of life (QoL) subscore in the ACI group compared to the AD group at 2 years. A combination of self-explanatory questionnaires, clinical parameters, clinical hop tests and radiographs and Magnetic Resonance Imaging (MRI) will be used as secondary endpoints.

DISCUSSION

This is the first study with a high level of evidence to compare ACI with simple debridement and physiotherapy for the treatment of isolated symptomatic full thickness lesions of the knee.

TRIAL REGISTRATION

ClinicalTrial NCT02636881 (21 December 2015).

Upright Magnetic Resonance Imaging Tasks in the Knee Osteoarthritis Population: Relationships Between Knee Flexion Angle, Self-Reported Pain, and Performance

OBJECTIVE

To characterize the ability of patients with symptomatic knee osteoarthritis (OA) to perform a weight-bearing activity compatible with upright magnetic resonance imaging (MRI) scanning and how this ability is affected by knee pain symptoms and flexion angles.

DESIGN

Cross-sectional observational study assessing effects of knee flexion angle, pain level, and study sequence on accuracy and duration of performing a task used in weight-bearing MRI evaluation. Visual feedback of knee position from an MRI compatible sensor was provided. Pain levels were self-reported on a standardized scale.

SETTING

Simulated MRI setup in a research laboratory.

PARTICIPANTS

Convenience sample of individuals (N=14; 9 women, 5 men; mean, 69±14y) with symptomatic knee OA.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Averaged absolute and signed angle error from target knee flexion for each minute of trial and duration tolerance (the duration that subjects maintained position within a prescribed error threshold).

RESULTS

Absolute targeting error increased at longer trial durations (P<.001). Duration tolerance decreased with increasing pain (mean ± SE, no pain: 3min 19s±11s; severe pain: 1min 49s±23s; P=.008). Study sequence affected duration tolerance (first knee: 3min 5s±9.1s; second knee: 2min 19s±9.7s; P=.015).

CONCLUSIONS

The study provided evidence that weight-bearing MRI evaluations based on imaging protocols in the range of 2 to 3 minutes are compatible with patients reporting mild to moderate knee OA-related pain.

Trajectories of functional decline in knee osteoarthritis: the Osteoarthritis Initiative

OBJECTIVE

To describe trajectories of functional decline over 84 months and study associated risk factors among adults initially without limitation who had or were at risk of knee OA.

METHODS

We used annual measures of WOMAC physical function over 84 months from the OA Initiative. We included knees with no functional limitation (i.e. WOMAC = 0) at baseline. Knee-based trajectories of functional decline from WOMAC were identified from a group-based trajectory model (PROC TRAJ).

RESULTS

We identified five trajectories from 2110 knees (1055 participants, age 61.0 ± 9.3, BMI 27.1 ± 4.4, 52% women). Half of the knees (54%) remained free of limitation over 84 months, 26% slowly declined to a WOMAC of 1.5, 9% were limitation free for the first 36 months and declined to a WOMAC of 11.3, 6% rapidly declined over the first 12 months and gradually recovered to a WOMAC of 3.3 and 5% steadily declined to a WOMAC of 13.2. Baseline radiographic disease, knee pain, obesity and depressive symptoms at baseline were associated with trajectories of worse functional decline.

CONCLUSION

Five per cent of our sample initially without limitation was on a trajectory of progressive functional decline over 84 months later. We found worse disease and health status at baseline to be associated with faster decline over time.

Proceedings from The 8th Annual International Society for Musculoskeletal Imaging in Rheumatology (ISEMIR) Conference

The International Society for Musculoskeletal Imaging in Rheumatology (ISEMIR) was founded in 2005 with the goal of discussing matters related to imaging in rheumatology, particularly, validation, education, and use in both clinical practice and research. The field of musculoskeletal (MSK) imaging is continuously evolving; therefore, education for healthcare providers in this field is of paramount importance. ISEMIR's international faculty and world-renowned experts presented the newest information as it relates to the use of magnetic resonance imaging (MRI) and ultrasound (US) at the 8th annual ISEMIR meeting that took place on April 17-18 in Santa Monica, California. Presentations from the meeting can be viewed at www.isemir.org.

Femoro-tibial knee osteoarthritis: One or two X-rays? Results from a population-based study

OBJECTIVE

Our objective was to compare the use of both anteroposterior (AP) extended-knee X-ray and semi-flexed X-ray (current gold standard) versus the use of semi-flexed X-ray alone to detect femoro-tibial osteoarthritis (OA).

METHODS

Individuals 40 to 75 years of age with symptomatic hip and/or knee OA (Kellgren/Lawrence [KL] score≥2) were recruited using a multiregional prevalence survey in France. Both AP and schuss X-rays were performed and read; two years later, the same examiner, blinded to the results of the first reading, performed a second reading of the schuss X-ray. We compared the KL stages of each knee and analyzed osteophyte detection and localization, joint space narrowing (JSN), and the relationship to obesity.

RESULTS

The analysis included 350 participants with OA of various stages. Comparing the two readings showed that a higher proportion of patients had KL≥2 when the two X-ray views were combined (right knee: P<0.0001; left knee: P<0.001). There were no differences when using the schuss X-ray alone versus in combination with an AP X-ray in terms of detecting JSN, osteophytes. A comparison of schuss X-ray alone versus AP X-ray alone demonstrated the superiority of the schuss view for evaluating JSN (P=0.0001 and P=0.0001) and no difference in osteophyte detection.

CONCLUSION

Our study shows that the schuss view alone was sufficient for detecting knee osteophytes and JSN. Using one X-ray rather than two will reduce medical costs and irradiation burden. Using two views seems preferable for epidemiological studies.

What comes first? Multitissue involvement leading to radiographic osteoarthritis: magnetic resonance imaging-based trajectory analysis over four years in the osteoarthritis initiative

OBJECTIVE

To assess whether the presence of structural osteoarthritis (OA) features over as many as 4 years prior to incident radiographic OA increases the risk of radiographic OA in a nested, case-control design.

METHODS

We studied 355 knees from the Osteoarthritis Initiative cohort that developed radiographic OA before the 48-month visit. They were matched one-to-one by sex, age, and contralateral knee radiographic status with a control knee. Magnetic resonance images (MRIs) were read for bone marrow lesions (BMLs), cartilage damage, meniscal damage (including tears and extrusion), Hoffa synovitis, and effusion synovitis. Conditional logistic regression was applied to assess the risk of radiographic OA with regard to the presence of BMLs (score ≥2), cartilage lesions (score ≥1.1), meniscal damage (any) and extrusion of ≥3 mm ± (score ≥2), and Hoffa and effusion synovitis (any). Time points were defined as incident radiographic OA visit (P0), 1 year prior to the detection of radiographic OA (P -1), 2 years prior to the detection of radiographic OA (P -2), etc.

RESULTS

The presence of Hoffa synovitis (hazard ratio [HR] 1.76 [95% confidence interval (95% CI) 1.18-2.64]), effusion synovitis (HR 1.81 [95% CI 1.18-2.78]), and medial meniscal damage (HR 1.83 [95% CI 1.17-2.89]) at P -2 predicted radiographic OA incidence. At P -1, all features but meniscal extrusion predicted radiographic OA, with highest odds for medial BMLs (HR 6.50 [95% CI 2.27-18.62]) and effusion synovitis (HR 2.50 [95% CI 1.76-3.54]). The findings at P -3 and P -4 did not reach statistical significance.

CONCLUSION

Our findings indicate that the presence of specific structural features of MRI-detected joint damage 2 years prior to incident radiographic OA increases the risk of incident radiographic OA. However, 1 year prior to radiographic OA, the presence of almost any abnormal morphologic feature increases the risk of radiographic OA in the subsequent year.

Serum periostin is associated with prevalent knee osteoarthritis and disease incidence/progression in women: the OFELY study

OBJECTIVE

Our aim was to investigate the relationships between serum periostin (POSTN) and both prevalence and incidence/progression of knee osteoarthritis (OA) in women.

METHODS

We investigated 594 women (62.7 ± 11.2 yr) from the OFELY cohort. Knee radiographs were scored according to the Kellgren & Lawrence (KL) grading system at baseline and 4 years later. Spine, hip and hand OA were assessed at baseline. Prevalent knee OA was defined by a KL score higher or equal in 2. Progression of KL was defined as an increase of the KL score ≥1 during the 4 years follow-up. Serum POSTN was measured at baseline by ELISA.

RESULTS

By non-parametric tests, POSTN was significantly lower in 83 women with a KL score ≥2 at baseline, compared to those with a KL score <2 (n = 511; 1101 ± 300 vs 1181 ± 294 ng/ml, P = 0.002) after adjustment for age, body mass index (BMI), treatments and diseases, prevalent hand OA and prevalent lumbar spine OA. By logistic regression analyses, the odds-ratio of knee OA incidence/progression was significantly reduced by 21% (P = 0.043) for each quartile increase in serum POSTN at baseline, after adjustment for age, BMI, prevalent knee OA, prevalent hand OA and prevalent lumbar spine OA.

CONCLUSIONS

We show for the first time that serum POSTN is associated with prevalence and the risk of development/progression of knee OA in women.

Validity and sensitivity to change of three scales for the radiographic assessment of knee osteoarthritis using images from the Multicenter Osteoarthritis Study (MOST)

OBJECTIVES

The purpose of this study was to assess the concurrent validity and sensitivity to change of three knee osteoarthritis (OA) grading scales. The Kellgren-Lawrence (KL) and the Osteoarthritis Research Society International (OARSI) joint space narrowing (JSN) grading scales are well-established. The third scale, the compartmental grading scale for OA (CG) is a novel scale which grades JSN, femoral osteophytes, tibial erosion and subluxation to create a total score.

METHODS

One sample of 72 posteroanterior (PA) fixed-flexion radiographs displaying mild to moderate knee OA was selected from the Multicenter Osteoarthritis Study (MOST) to study validity. A second sample of 75 radiograph pairs, which showed an increase in OA severity over 30 months, was selected to study sensitivity to change. The three radiographic grading scales were applied to each radiograph in both samples. Spearman's rank correlation coefficients were used to correlate the radiographic grades and the change in grades over 30 months with a Whole-organ Magnetic Resonance Imaging Score (WORMS)-based composite score which included five articular features of knee OA.

RESULTS

Correlations between the KL, OARSI JSN and CG grading scales and the magnetic resonance image (MRI)-based score were 0.836, 0.840 and 0.773 (P < 0.0001) respectively while correlations between change in the radiographic grading scales and change in the MRI-based score were 0.501, 0.525 and 0.492 (P < 0.0001).

CONCLUSIONS

All three radiographic grading scales showed high validity and are suitable to assess knee OA severity. They showed moderate sensitivity to change; therefore caution should be taken when using ordinal radiographic grading scales to monitor knee OA over time.

Diagnostic performance of 3D standing CT imaging for detection of knee osteoarthritis features

OBJECTIVE

To determine the diagnostic performance of standing computerized tomography (SCT) of the knee for osteophytes and subchondral cysts compared with fixed-flexion radiography, using MRI as the reference standard.

METHODS

Twenty participants were recruited from the Multicenter Osteoarthritis Study. Participants' knees were imaged with SCT while standing in a knee-positioning frame, and with postero-anterior fixed-flexion radiography and 1T MRI. Medial and lateral marginal osteophytes and subchondral cysts were scored on bilateral radiographs and coronal SCT images using the OARSI grading system and on coronal MRI using Whole Organ MRI Scoring. Imaging modalities were read separately with images in random order. Sensitivity, specificity and accuracy for the detection of lesions were calculated and differences between modalities were tested using McNemar's test.

RESULTS

Participants' mean age was 66.8 years, body mass index was 29.6 kg/m(2) and 50% were women. Of the 160 surfaces (medial and lateral femur and tibia for 40 knees), MRI revealed 84 osteophytes and 10 subchondral cysts. In comparison with osteophytes and subchondral cysts detected by MRI, SCT was significantly more sensitive (93 and 100%; p < 0.004) and accurate (95 and 99%; p < 0.001 for osteophytes) than plain radiographs (sensitivity 60 and 10% and accuracy 79 and 94%, respectively). For osteophytes, differences in sensitivity and accuracy were greatest at the medial femur (p = 0.002).

CONCLUSIONS

In comparison with MRI, SCT imaging was more sensitive and accurate for detection of osteophytes and subchondral cysts than conventional fixed-flexion radiography. Additional study is warranted to assess diagnostic performance of SCT measures of joint space width, progression of OA features and the patellofemoral joint.

Early T2 changes predict onset of radiographic knee osteoarthritis: data from the osteoarthritis initiative

OBJECTIVE

To evaluate whether T2 relaxation time measurements obtained at 3 T MRI predict the onset of radiographic knee osteoarthritis (OA).

MATERIALS AND METHODS

We performed a nested case-control study of incident radiographic knee OA in the Osteoarthritis Initiative cohort. Cases were 50 knees with baseline Kellgren-Lawrence (KL) grade of 0 that developed KL grade of 2 or more over a 4-year period. Controls were 80 knees with KL grade of 0 after 4 years of follow-up. Baseline T2 relaxation time measurements and laminar analysis of T2 in deep and superficial layers were performed in all knee compartments. The association of T2 values with incident OA was assessed with logistic regression and differences in T2 values by case-control status with linear regression, adjusting for age, sex, body mass index (BMI) and other covariates.

RESULTS

Baseline T2 values in all compartments except the medial tibia were significantly higher in knees that developed OA compared with controls and were particularly elevated in the superficial cartilage layers in all compartments. There was an increased likelihood of incident knee OA associated with higher baseline T2 values, particularly in the patella, adjusted OR per 1 SD increase in T2 (3.37 (95% CI 1.72 to 6.62)), but also in the medial femur (1.90 (1.07 to 3.39)), lateral femur (2.17 (1.11 to 4.25)) and lateral tibia (2.23 (1.16 to 4.31)).

CONCLUSIONS

These findings suggest that T2 values assessed when radiographic changes are not yet apparent may be useful in predicting the development of radiological tibiofemoral OA.

Comparative radiographic analysis on the anatomical axis in knee osteoarthritis cases: inter and intraobserver evaluation

OBJECTIVE

To make a comparative inter and intraobserver analysis on measurements of the anatomical axis between panoramic radiographs of the lower limbs in anteroposterior (AP) view with bipedal weight-bearing, on short film.

METHODS

An accuracy study comparing radiographic measurements on 47 knees of patients attending the knee surgery outpatient clinic due to osteoarthritis. The radiographic evaluation used was as standardized for the total knee arthroplasty program, including panoramic AP views of the lower limbs and short radiographs of the knees in AP and lateral views, all with bipedal weight-bearing. Following this, the anatomical axis of the lower limbs or the femorotibial angle was measured by five independent examiners on the panoramic and short AP radiographs; three of the examiners were considered to be more experienced and two, less experienced. All the measurements were made again by the same examiners after an interval of not less than 15 days. The statistical analysis was performed using the intraclass correlation coefficient, in order to evaluate the inter and intraobserver concordance of the anatomical axis measurements.

RESULTS

From the statistical analysis, it was observed that there was strongly significant concordance between the anatomical axis measurements on the panoramic and short radiographs, for all the five examiners and for both measurements.

CONCLUSIONS

Under the conditions studied, short radiographs were equivalent to panoramic radiographs for evaluating the anatomical axis of the lower limbs in patients with advanced osteoarthritis. The measurements used also showed high rates of inter and intraobserver concordance and reproducibility.

OARSI Clinical Trials Recommendations: Knee imaging in clinical trials in osteoarthritis

Significant advances have occurred in our understanding of the pathogenesis of knee osteoarthritis (OA) and some recent trials have demonstrated the potential for modification of the disease course. The purpose of this expert opinion, consensus driven exercise is to provide detail on how one might use and apply knee imaging in knee OA trials. It includes information on acquisition methods/techniques (including guidance on positioning for radiography, sequence/protocol recommendations/hardware for magnetic resonance imaging (MRI)); commonly encountered problems (including positioning, hardware and coil failures, sequences artifacts); quality assurance (QA)/control procedures; measurement methods; measurement performance (reliability, responsiveness, validity); recommendations for trials; and research recommendations.

Soluble macrophage biomarkers indicate inflammatory phenotypes in patients with knee osteoarthritis

OBJECTIVE

To evaluate the ability of the macrophage markers CD163 and CD14 to predict different osteoarthritis (OA) phenotypes defined by severity of joint inflammation, radiographic features and progression, and joint pain.

METHODS

We evaluated 2 different cohorts totaling 184 patients with radiographic knee OA. These included 25 patients from a cross-sectional imaging study for whom there were data on activated macrophages in the knee joint, and 159 patients (134 with 3-year longitudinal data) from the longitudinal Prediction of Osteoarthritis Progression study. Multivariable linear regression models with generalized estimating equations were used to assess the association of CD163 and CD14 in synovial fluid (SF) and blood with OA phenotypic outcomes. Models were adjusted for age, sex, and body mass index. P values less than or equal to 0.05 were considered significant.

RESULTS

SF CD14, SF CD163, and serum CD163 were associated with the abundance of activated macrophages in the knee joint capsule and synovium. SF CD14 was positively associated with severity of joint space narrowing and osteophytes in both cohorts. SF and plasma CD14 were positively associated with self-reported knee pain severity in the imaging study. Both SF CD14 and SF CD163 were positively associated with osteophyte progression.

CONCLUSION

Soluble macrophage biomarkers reflected the abundance of activated macrophages and appeared to mediate structural progression (CD163 and CD14) and pain (CD14) in OA knees. These data support the central role of inflammation as a determinant of OA severity, progression risk, and clinical symptoms, and they suggest a means of readily identifying a subset of patients with an active inflammatory state and worse prognosis.

Sex-differences of the healthy infra-patellar (Hoffa) fat pad in relation to intermuscular and subcutaneous fat content--data from the Osteoarthritis Initiative

The infra-patellar fat pad (IPFP) is composed of intra-articular adipose tissue; it represents a potential source of pro-inflammatory cytokines and has been associated with osteoarthritis of the knee. Yet, to what extent the size of the IPFP differs between healthy men and women, and how sex differences compare to those in inter-muscular and subcutaneous fat tissue content is unknown. We studied healthy reference subjects from the Osteoarthritis Initiative, without knee pain, without radiographic signs or without risk factors of femorotibial osteoarthritis. Sagittal magnetic resonance images (MRIs) of 99 right knees were used to segment the IPFP; in a subset, axial images of the thigh were available to segment inter-muscular and subcutaneous fat. Healthy men (n=40) displayed a 41% greater (p<0.001) IPFP volume and a 9% greater (p<0.01) ratio of IPFP volume/body weight than women (n=59). Men (n=13) displayed 15% greater intermuscular fat content (not significant), and a 50% lesser (p<0.01) subcutaneous fat content than women (n=12); when related to total thigh cross-sectional areas, these sex differences were +2% (not significant) and -53% (p<0.001). This is the first study to explore quantitative measures of the IPFP in healthy men and women, and to relate these to sex differences of inter-muscular and subcutaneous fat tissue content. Men displayed a significantly greater ratio of IPFP volume/body weight than women, similar amounts of inter-muscular fat, and strikingly less subcutaneous fat. These data provide a basis for further systematic studies of the variability of the IPFP with the body mass index and its role in knee osteoarthritis.

Accelerometer-monitored sedentary behavior and observed physical function loss

OBJECTIVES

We examined whether objectively measured sedentary behavior is related to subsequent functional loss among community-dwelling adults with or at high risk for knee osteoarthritis.

METHODS

We analyzed longitudinal data (2008-2012) from 1659 Osteoarthritis Initiative participants aged 49 to 83 years in 4 cities. Baseline sedentary time was assessed by accelerometer monitoring. Functional loss (gait speed and chair stand testing) was regressed on baseline sedentary time and covariates (baseline function; socioeconomics [age, gender, race/ethnicity, income, education], health factors [obesity, depression, comorbidities, knee symptoms, knee osteoarthritis severity, prior knee injury, other lower extremity pain, smoking], and moderate-to-vigorous activity).

RESULTS

This cohort spent almost two thirds of their waking hours (average=9.8 h) in sedentary behaviors. Sedentary time was significantly positively associated with subsequent functional loss in both gait speed (-1.66 ft/min decrease per 10% increment sedentary percentage waking hours) and chair stand rate (-0.75 repetitions/min decrease), controlling for covariates.

CONCLUSIONS

Being less sedentary was related to less future decline in function, independent of time spent in moderate-to-vigorous activity. Both limiting sedentary activities and promoting physical activity in adults with knee osteoarthritis may be important in maintaining function.

Is loss in femorotibial cartilage thickness related to severity of contra-lateral radiographic knee osteoarthritis?--longitudinal data from the Osteoarthritis Initiative

OBJECTIVE

Anti-catabolic disease modifying drugs (DMOADs) aim to reduce cartilage loss in knee osteoarthritis (KOA). Testing such drugs in clinical trials requires sufficient rates of loss in the study participants to occur, preferably at a mild disease stage where cartilage can be preserved. Here we analyze a "progression" model in mild radiographic KOA (RKOA), based on contra-lateral radiographic status.

METHODS

We studied 837 participants (62.4 ± 9 yrs; 30 ± 4.9 kg/m²; 61.8% women) from the Osteoarthritis Initiative (OAI) with mild to moderate RKOA (Kellgren Lawrence grade [KLG] 2-3) and with/without Osteoarthritis Research Society International (OARSI) atlas radiographic joint space narrowing (JSN). These had quantitative measurements of subregional femorotibial cartilage thickness from magnetic resonance imaging (MRI) at baseline and 1-year follow-up. They were stratified by contra-lateral knee status: no (KLG 0/1), definite (KLG2) and moderate RKOA (KLG 3/4).

RESULTS

KLG2 knees with JSN and moderate contra-lateral RKOA had (P = 0.008) greater maximum subregional cartilage loss -220 μm [95% confidence interval (CI) -255, -184 μm] than those without contra-lateral RKOA -164 μm [-187, -140 μm]. Their rate of subregional cartilage loss was similar and not significantly different (P = 0.61) to that in KLG 3 knees without contra-lateral RKOA (-232 μm; [-266; -198 μm]). The effect of contra-lateral RKOA status was less in KLG2 knees without JSN, and in KLG3 knees.

CONCLUSION

KLG2 knees with JSN and moderate contra-lateral RKOA, display relatively high rates of subregional femorotibial cartilage loss, despite being at a relatively mild stage of RKOA. They may therefore provide a unique opportunity for recruitment in clinical trials that explore the efficacy of anti-catabolic DMOADs on structural progression.

The effect on knee-joint load of instruction in analgesic use compared with neuromuscular exercise in patients with knee osteoarthritis: study protocol for a randomized, single-blind, controlled trial (the EXERPHARMA trial)

BACKGROUND

Knee osteoarthritis (OA) is a mechanically driven disease, and it is suggested that medial tibiofemoral knee-joint load increases with pharmacologic pain relief, indicating that pharmacologic pain relief may be positively associated with disease progression. Treatment modalities that can both relieve pain and reduce knee-joint load would be preferable. The knee-joint load is influenced by functional alignment of the trunk, pelvis, and lower-limb segments with respect to the knee, as well as the ground-reaction force generated during movement. Neuromuscular exercise can influence knee load and decrease knee pain. It includes exercises to improve balance, muscle activation, functional alignment, and functional knee stability. The primary objective of this randomized controlled trial (RCT) is to investigate the efficacy of a NEuroMuscular EXercise (NEMEX) therapy program, compared with optimized analgesics and antiinflammatory drug use, on the measures of knee-joint load in people with mild to moderate medial tibiofemoral knee osteoarthritis.

METHOD/DESIGN

One hundred men and women with mild to moderate medial knee osteoarthritis will be recruited from general medical practices and randomly allocated (1:1) to one of two 8-week treatments, either (a) NEMEX therapy twice a week or (b) information on the recommended use of analgesics and antiinflammatory drugs (acetaminophen and oral NSAIDs) via a pamphlet and video materials. The primary outcome is change in knee load during walking (the Knee Index, a composite score of the first external peak total reaction moment on the knee joint from all three planes based on 3D movement analysis) after 8 weeks of intervention. Secondary outcomes include changes in the external peak knee-adduction moment and impulse and functional performance measures, in addition to changes in self-reported pain, function, health status, and quality of life.

DISCUSSION

These findings will help determine whether 8 weeks of neuromuscular exercise is superior to optimized use of analgesics and antiinflammatory drugs regarding knee-joint load, pain and physical function in people with mild to moderate knee osteoarthritis.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01638962 (July 3, 2012).

Daily walking and the risk of incident functional limitation in knee osteoarthritis: an observational study

OBJECTIVE

Physical activity is recommended to mitigate functional limitations associated with knee osteoarthritis (OA). However, it is unclear whether walking on its own protects against the development of functional limitation.

METHODS

Walking over 7 days was objectively measured as steps/day within a cohort of people with or at risk of knee OA from the Multicenter Osteoarthritis Study. Incident functional limitation over 2 years was defined by performance-based (gait speed <1.0 meter/second) and self-report (Western Ontario and McMaster Universities Osteoarthritis Index physical function score >28 of 68) measures. We evaluated the association of steps/day at baseline with developing functional limitation 2 years later by calculating risk ratios adjusted for potential confounders. The number of steps/day that best distinguished risk for developing functional limitation was estimated from the maximum distance from chance on receiver operating characteristic curves.

RESULTS

Among 1,788 participants (mean age 67 years, mean body mass index 31 kg/m(2) , 60% women), each additional 1,000 steps/day was associated with a 16% and 18% reduction in incident functional limitation by performance-based and self-report measures, respectively. Walking <6,000 and <5,900 steps/day were the best thresholds to distinguish incident functional limitation by performance-based (sensitivity 67.3%, specificity 71.8%) and self-report (sensitivity 58.7%, specificity 68.9%) measures, respectively.

CONCLUSION

More walking was associated with less risk of functional limitation over 2 years. Walking >6,000 steps/day provides a preliminary estimate of the level of walking activity to protect against developing functional limitation in people with or at risk of knee OA.

Imaging of cartilage and bone: promises and pitfalls in clinical trials of osteoarthritis

Imaging in clinical trials is used to evaluate subject eligibility, and/or efficacy of intervention, supporting decision making in drug development by ascertaining treatment effects on joint structure. This review focusses on imaging of bone and cartilage in clinical trials of (knee) osteoarthritis. We narratively review the full-text literature on imaging of bone and cartilage, adding primary experience in the implementation of imaging methods in clinical trials. Aims and constraints of applying imaging in clinical trials are outlined. The specific uses of semi-quantitative and quantitative imaging biomarkers of bone and cartilage in osteoarthritis trials are summarized, focusing on radiography and magnetic resonance imaging (MRI). Studies having compared both imaging methodologies directly and those having established a relationship between imaging biomarkers and clinical outcomes are highlighted. To make this review of practical use, recommendations are provided as to which imaging protocols are ideal for capturing specific aspects of bone and cartilage tissue, and pitfalls in their usage are highlighted. Further, the longitudinal sensitivity to change, of different imaging methods is reported for various patient strata. From these power calculations can be accomplished, provided the strength of the treatment effect is known. In conclusion, current imaging methodologies provide powerful tools for scoring and measuring morphological and compositional aspects of most articular tissues, capturing longitudinal change with reasonable to excellent sensitivity. When employed properly, imaging has tremendous potential for ascertaining treatment effects on various joint structures, potentially over shorter time scales than required for demonstrating effects on clinical outcomes.

Use of a validated algorithm to judge the appropriateness of total knee arthroplasty in the United States: a multicenter longitudinal cohort study

OBJECTIVE

In previous studies conducted outside the US, ∼20% of total knee arthroplasty (TKA) surgeries were judged to be inappropriate. The present study was undertaken to determine the prevalence rates of TKA surgeries classified as appropriate, inconclusive, and inappropriate in a knee osteoarthritis population in the US.

METHODS

We used a modification of a validated appropriateness classification system and applied it to patients in the Osteoarthritis Initiative data set who underwent TKA. A variety of preoperative data were used in the classification, including Western Ontario and McMaster Universities Osteoarthritis Index pain and physical function scores, radiographic features, knee motion and laxity measures, and age.

RESULTS

Data on 205 patients who underwent TKA were examined. The prevalence rates for classification of the procedure as appropriate, inconclusive, and inappropriate were 44.0% (95% confidence interval [95% CI] 37-51%), 21.7% (95% CI 16-28%), and 34.3% (95% CI 27-41%), respectively.

CONCLUSION

Approximately one-third of TKA surgeries were judged to be inappropriate. Variation in the characteristics of patients undergoing TKA was extensive. These data support the need for consensus development of criteria for patient selection among US practitioners treating patients who are potential candidates for TKA. Among the important issues, consensus development needs to address variation in patient characteristics and the relative importance of preoperative status and subsequent outcome.

Relationship of meeting physical activity guidelines with health-related utility

OBJECTIVE

Health-related utility measures overall health status and quality of life and is commonly incorporated into cost-effectiveness analyses. This study investigates whether attainment of federal physical activity guidelines translates into better health-related utility in adults with or at risk for knee osteoarthritis (OA).

METHODS

Cross-sectional data from 1,908 adults with or at risk for knee OA participating in the accelerometer ancillary study of the Osteoarthritis Initiative were assessed. Physical activity was measured using 7 days of accelerometer monitoring and was classified as 1) meeting guidelines (≥150 bouted moderate-to-vigorous [MV] minutes per week); 2) insufficiently active (≥1 MV bout[s] per week but below guidelines); or 3) inactive (zero MV bouts per week). A Short Form 6D health-related utility score was derived from patient-reported health status. Relationship of physical activity levels to median health-related utility adjusted for socioeconomic and health factors was tested using quantile regression.

RESULTS

Only 13% of participants met physical activity guidelines, and 45% were inactive. Relative to the inactive group, median health-related utility scores were significantly greater for the meeting guidelines group (0.063; 95% confidence interval [95% CI] 0.055, 0.071) and the insufficiently active group (0.059; 95% CI 0.054, 0.064). These differences showed a statistically significant linear trend and strong cross-sectional relationship with physical activity level even after adjusting for socioeconomic and health factors.

CONCLUSION

We found a significant positive relationship between physical activity level and health-related utility. Interventions that encourage adults, including persons with knee OA, to increase physical activity even if recommended levels are not attained may improve their quality of life.

Correlation of WOMAC and KOOS scores to tibiofemoral cartilage loss on plain radiography and 3 Tesla MRI: data from the osteoarthritis initiative

PURPOSE

The purpose of this study was to determine the correlation between the Western Ontario and McMasters Universities Osteoarthritis Index (WOMAC) and Knee Injury Osteoarthritis Outcomes scores (KOOS) and the degree of tibiofemoral cartilage loss on plain radiography and 3T magnetic resonance imaging (MRI). We hypothesize that these subjective outcome scores will have a significant correlation to quantitative joint space loss.

METHODS

Data used in the preparation of this article were obtained from the osteoarthritis initiative (OAI) database (OAI public use data sets kMRI_QCart_Eckstein18 and kXR_QJSW_Duryea16). Four hundred and forty-five patients had WOMAC/KOOS scores, quantitative tibiofemoral joints space width on plain radiographs and quantitative tibiofemoral cartilage thickness and per cent full thickness cartilage loss on 3T MRI. Joint space width on plain radiographs was correlated to cartilage thickness on MRI, and WOMAC/KOOS scores were correlated to the degree of cartilage loss using Pearson correlation coefficients.

RESULTS

There was a statistically significant correlation between medial and lateral compartment cartilage thickness on MRI and medial and lateral joint space width on plain radiography (r = 0.86, r = 0.80) (p < 0.001). KOOS knee pain score was significantly correlated to increasing per cent full thickness cartilage loss in the medial femoral compartment (r = 0.34) (p < 0.001). KOOS symptom score was significantly correlated to decreasing joint space width in the medial (r = 0.16) and lateral (r = 0.15) compartment and increasing per cent full thickness cartilage loss in the medial femoral compartment (r = 0.36) (p < 0.001). No WOMAC score was correlated to degree of joint space width, cartilage thickness or per cent full thickness cartilage loss (n.s).

CONCLUSION

The WOMAC and KOOS scores are poor indicators of tibiofemoral cartilage loss, with only the KOOS symptom and knee pain score being weakly correlated. Osteoarthritis is a multifactorial process and the need to treat patients based off their symptoms and rely on radiographs as confirmatory modalities, and not diagnostic modalities, when talking about OA and medical intervention.

Relationship of meeting physical activity guidelines with quality-adjusted life-years

OBJECTIVE

The quality-adjusted life-year (QALY) is a standard outcome measure used in cost-effectiveness analyses. This study investigates whether attainment of federal physical activity guidelines is associated with higher QALY estimates among adults with or at an increased risk for knee osteoarthritis.

METHODS

This is a prospective study of 1794 Osteoarthritis Initiative participants. Physical activity was measured using accelerometers at baseline. Participants were classified as (1) Meeting Guidelines [≥150min of moderate-to-vigorous (MV) activity per week acquired in sessions ≥10min], (2) Insufficiently Active (≥1 MV session[s]/week but below the guideline), or (3) Inactive (zero MV sessions/week). A health-related utility score was derived from participant responses to the 12-item Short-Form Health Survey at baseline and 2 years later. The QALY was calculated as the area under utility curve over 2 years. The relationship of physical activity level to median QALY adjusted for socioeconomic and health factors was estimated using quantile regression.

RESULTS

Relative to the Inactive group, median QALYs over 2 years were significantly higher for the Meeting Guidelines (0.112, 95% CI: 0.067-0.157) and Insufficiently Active (0.058, 95% CI: 0.028-0.088) groups, controlling for socioeconomic and health factors.

CONCLUSION

We found a significant graded relationship between greater physical activity level and higher QALYs. Using the more conservative estimate of 0.058, if an intervention could move someone out of the Inactive group and costs <$2900 over 2 years, it would be considered cost effective. Our analysis supports interventions to promote physical activity even if recommended levels are not fully attained.

Effect of oral glucosamine on joint structure in individuals with chronic knee pain: a randomized, placebo-controlled clinical trial

OBJECTIVE

To determine the short-term efficacy of oral glucosamine supplementation by evaluating structural lesions in the knee joints, as assessed using 3T magnetic resonance imaging (MRI).

METHODS

This study was designed as a randomized, double-blind, placebo-controlled trial. Recruitment was performed via mass mailings and an arthritis registry in southwestern Pennsylvania. In total, 201 participants with mild-to-moderate pain in one or both knees, as defined by a Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain score ≥25 and ≤100, were enrolled. Of these subjects, 69.2% had a Kellgren/Lawrence grade ≥2 in at least 1 knee. Participants received 24 weeks of treatment with 1,500 mg glucosamine hydrochloride in beverage form or a placebo beverage. The primary outcome was decreased worsening of cartilage damage on 3T MRI of both knees, assessed according to a validated scoring system, the Whole-Organ MRI Score (WORMS). Secondary outcomes included change in bone marrow lesion (BML) scores in all knees and change in excretion of urinary C-terminal crosslinking telopeptide of type II collagen (CTX-II).

RESULTS

The adjusted odds ratio (OR) for the likelihood of decreased cartilage damage over 24 weeks in any WORMS-scored subregion of the knee in the glucosamine treatment group compared to the control group was 0.938 (95% confidence interval [95% CI] 0.528, 1.666). Compared to subjects treated with glucosamine, control subjects showed more improvement in BMLs (adjusted OR 0.537, 95% CI 0.291, 0.990) but no difference in worsening BMLs (adjusted OR 0.691, 95% CI 0.410, 1.166) over 24 weeks. There was no indication that treatment with glucosamine decreased the excretion of urinary CTX-II (β = -0.10, 95% CI -0.21, 0.002).

CONCLUSION

The results of this short-term study provide no evidence of structural benefits (i.e., improvements in MRI morphologic features or urinary CTX-II excretion) from glucosamine supplementation in individuals with chronic knee pain.

Can standing knee radiographs predict chondral lesions in young- and middle-aged population?

PURPOSE

The aim of the study is to investigate the correlation between arthroscopic findings and joint space width on the standing knee radiographs at various flexion degrees in the young- and middle-aged patients with complaints of knee pain.

METHODS

Middle-aged patients with complaint of knee pain ongoing more than 6 months and failure in conservative treatment methods were included. Weight-bearing full extension, 30 and 45° of flexion radiographs were obtained. Joint space width was calculated on radiograms. Arthroscopy was performed to evaluate the chondral pathologies. Correlation analysis was performed.

RESULTS

Fourty-three patients (18 female, 25 male) with a mean age of 44.6 (20-63) were included. Mean joint space width was 4.87 mm ± 1.45 (2-10) mm in medial and 5.43 mm ± 1.47 (1-9) in lateral on standing extension radiographs. In 30° flexion radiographs, mean joint space width was 4.33 mm ± 1.25 (1.5-7.5) in medial and 5.36 mm ± 1.69 (1-9) in lateral. In 45° flexion radiographs, medial joint space was 4.28 mm ± 1.59 (2-9) in medial and 5.15 mm ± 1.59 (1.5-9) in lateral. In arthroscopic evaluation, one knee had grade 1 (2.3%), three knees had grade 2 (7%), nine knees had grade 3 (20.9%), and twelve knees had grade 4 (27.9%) lesions in the medial compartment. In the lateral compartment, two knees had grade 3 (4.7%) and one knee had grade 4 lesion (2.3%). Radiological data did not correlate with the arthroscopic findings.

CONCLUSION

Standing knee radiographs do not correlate with the arthroscopic findings in the middle-aged population with chondral lesions in knee joint.

LEVEL OF EVIDENCE

Case series with no comparison group, Level IV.

Effect of bisphosphonate use in patients with symptomatic and radiographic knee osteoarthritis: data from the Osteoarthritis Initiative

OBJECTIVES

Bisphosphonates have some reported beneficial effects in treating osteoarthritis (OA). This study examined the effects of bisphosphonate use on symptoms and structural progression of knee OA in participants from the NIH Osteoarthritis Initiative cohort.

METHODS

People with typical OA trial entry criteria (KL2/3, minimum joint space width 2.5-5.0 mm and pain ≥4 on a numeric rating scale) were classified as bisphosphonate users (≥3 of the 5 years; n=55) or non-users (no use in the preceding 5 years or during follow-up; n=268). Annual data over 4 years were analysed using linear mixed modelling and generalised estimating equations.

RESULTS

Bisphosphonate compliance was 85% at year 1, reducing to 76% by year 4. Numeric rating scale pain scores were significantly reduced among bisphosphonate users at years 2 and 3 (year 3, -0.9 vs -2.2, p=0.004), though not year 4, after adjustment for baseline pain and analgesic use. Differences in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and disability scores did not reach statistical significance at any time point. There was a trend to less joint space narrowing in bisphosphonate users over time (year 4, 0.51 vs 0.29 mm; p=0.06).

CONCLUSIONS

Significant reduction in numeric rating scale pain was observed in the first 3 years with bisphosphonate use; diminution of effects by year 4 may reflect reduced compliance. Differences in results obtained using numeric rating scale and WOMAC may reflect different constructs measured by these tools. The beneficial trend on structural progression should be considered in terms of the sample size.

Relation of physical activity time to incident disability in community dwelling adults with or at risk of knee arthritis: prospective cohort study

OBJECTIVE

To investigate whether objectively measured time spent in light intensity physical activity is related to incident disability and to disability progression.

DESIGN

Prospective multisite cohort study from September 2008 to December 2012.

SETTING

Baltimore, Maryland; Columbus, Ohio; Pittsburgh, Pennsylvania; and Pawtucket, Rhode Island, USA.

PARTICIPANTS

Disability onset cohort of 1680 community dwelling adults aged 49 years or older with knee osteoarthritis or risk factors for knee osteoarthritis; the disability progression cohort included 1814 adults.

MAIN OUTCOME MEASURES

Physical activity was measured by accelerometer monitoring. Disability was ascertained from limitations in instrumental and basic activities of daily living at baseline and two years. The primary outcome was incident disability. The secondary outcome was progression of disability defined by a more severe level (no limitations, limitations to instrumental activities only, 1-2 basic activities, or ≥3 basic activities) at two years compared with baseline.

RESULTS

Greater time spent in light intensity activities had a significant inverse association with incident disability. Less incident disability and less disability progression were each significantly related to increasing quartile categories of daily time spent in light intensity physical activities (hazard ratios for disability onset 1.00, 0.62, 0.47, and 0.58, P for trend=0.007; hazard ratios for progression 1.00, 0.59, 0.50, and 0.53, P for trend=0.003) with control for socioeconomic factors (age, sex, race/ethnicity, education, income) and health factors (comorbidities, depressive symptoms, obesity, smoking, lower extremity pain and function, and knee assessments: osteoarthritis severity, pain, symptoms, prior injury). This finding was independent of time spent in moderate-vigorous activities.

CONCLUSION

These prospective data showed an association between greater daily time spent in light intensity physical activities and reduced risk of onset and progression of disability in adults with osteoarthritis of the knee or risk factors for knee osteoarthritis. An increase in daily physical activity time may reduce the risk of disability, even if the intensity of that additional activity is not increased.

Increased clinical symptoms of acromegalic arthropathy in patients with long-term disease control: a prospective follow-up study

Arthropathy is an invalidating complication of acromegaly. This arthropathy deteriorates radiographically despite long-term disease control. However, the clinical course and its relationship to the radiographic course are currently unknown. We aimed to investigate the clinical course of arthropathy during follow-up and its relationship to radiographic progression in long-term controlled acromegaly patients. Prospective follow-up study. We studied 58 patients (mean age 62 years, women 41 %) with controlled acromegaly for a mean of 17.6 years. Clinical progression of joint disease was defined at baseline and after 2.6 years, by the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) and Australian/Canadian Osteoarthritis Index (AUSCAN) questionnaires for lower limb and hand OA, respectively, and performance tests. Potential risk factors for progression were assessed. The clinical course of arthropathy was related to the radiographic course. On average, hand and lower limb function deteriorated during follow-up, despite large interindividual variations. Joint pain was stable over time. High levels of pain and functional impairment at baseline were related to clinical progression of hand pain and functional limitations. High baseline BMI was a risk factor for functional deterioration in the lower limb. The changes in symptoms and radiographic progression during follow-up were not related. In treated acromegaly patients, joint function deteriorates during prolonged follow-up, despite biochemical disease control, although there was interindividual variation. Clinical and radiographic course of arthropathy were not related. Therefore, in clinical practice, a combination of clinical and radiographic assessment is necessary to evaluate the course of acromegalic arthropathy.

High plasma levels of vitamin C and E are associated with incident radiographic knee osteoarthritis

BACKGROUND

Previous studies suggest that the antioxidants vitamins C and E may protect against development of knee osteoarthritis (OA). We examined the association of circulating levels of vitamin C and E with incident whole knee radiographic OA (WKROA).

METHODS

We performed a nested case-control study of incident WKROA in MOST, a cohort of 3,026 men and women aged 50-79 years with, or at high risk of, knee OA. Incident cases were knees without either tibiofemoral (TF) or patellofemoral (PF) OA at baseline that developed TF and/or PF OA by 30-month follow-up. Two control knees per case were selected from those eligible for WKROA that did not develop it. Vitamin C and E (alpha-tocopherol) assays were done on baseline supernatant plasma (PCA) and serum samples, respectively. We examined the association of gender-specific tertiles of vitamin C and E with incident WKROA using logistic regression with GEE, adjusting for age, gender, and obesity.

RESULTS

Subjects without WKROA at baseline who were in the highest tertile of vitamin C had a higher incidence of WKROA [adjusted OR = 2.20 (95% CI: 1.12-4.33); P-value = 0.021], with similar results for the highest tertile of vitamin E [adjusted OR = 1.89 (1.02-3.50); P-value = 0.042], compared to those in the lowest tertiles. P-values for the trend of vitamin C and E tertiles and incident WKROA were 0.019 and 0.030, respectively.

CONCLUSIONS

Higher levels of circulating vitamin C and E did not provide protection against incident radiographic knee OA, and may be associated with an increased risk of knee OA.

Minimum joint space width (mJSW) of patellofemoral joint on standing "skyline" radiographs: test-retest reproducibility and comparison with quantitative magnetic resonance imaging (qMRI)

OBJECTIVE

To assess the intraobserver, interobserver, and test-retest reproducibility of minimum joint space width (mJSW) measurement of medial and lateral patellofemoral joints on standing "skyline" radiographs and to compare the mJSW of the patellofemoral joint to the mean cartilage thickness calculated by quantitative magnetic resonance imaging (qMRI).

MATERIALS AND METHODS

A couple of standing "skyline" radiographs of the patellofemoral joints and MRI of 55 knees of 28 volunteers (18 females, ten males, mean age, 48.5 ± 16.2 years) were obtained on the same day. The mJSW of the patellofemoral joint was manually measured and Kellgren and Lawrence grade (KLG) was independently assessed by two observers. The mJSW was compared to the mean cartilage thickness of patellofemoral joint calculated by qMRI.

RESULTS

mJSW of the medial and lateral patellofemoral joint showed an excellent intraobserver agreement (interclass correlation (ICC) = 0.94 and 0.96), interobserver agreement (ICC = 0.90 and 0.95) and test-retest agreement (ICC = 0.92 and 0.96). The mJSW measured on radiographs was correlated to mean cartilage thickness calculated by qMRI (r = 0.71, p < 0.0001 for the medial PFJ and r = 0.81, p < 0.0001 for the lateral PFJ). However, there was a lack of concordance between radiographs and qMRI for extreme values of joint width and KLG. Radiographs yielded higher joint space measures than qMRI in knees with a normal joint space, while qMRI yielded higher joint space measures than radiographs in knees with joint space narrowing and higher KLG.

CONCLUSIONS

Standing "skyline" radiographs are a reproducible tool for measuring the mJSW of the patellofemoral joint. The mJSW of the patellofemoral joint on radiographs are correlated with, but not concordant with, qMRI measurements.