Imaging of osteoarthritis (OA) in the elderly is gaining importance because of the aging population. It requires knowledge about findings relevant for patient management and others which are abnormal findings, but part of normal aging without relevance for patient management due to lack of clinical symptoms. This review will provide information on what imaging techniques are best used for knee OA and how to systematically assess knee joint structures in order to cover the most common asymptomatic and symptomatic MR findings in OA. We will discuss which findings are typically found in older patients and which are likely to progress to severe pain and disability, finally leading to total joint replacement. The review may aid radiologists and referring clinicians to better understand the evolution of symptomatic OA and the current or future clinical significance of the most common symptomatic and asymptomatic findings.

Objectives

To assess (i) normal imaging anatomy of the popliteomeniscal fascicles, (ii) prevalence and natural evolution of popliteomeniscal fascicle tears (PMFT) in subjects with traumatic anterior cruciate ligament (ACL) tears over 2 years and (iii) compare knee cartilage degeneration in subjects with and without PMFT longitudinally.

Methods

57 subjects with ACL tears were screened for PMFT. Morphological (high-resolution 3D fast spin-echo) and compositional (T1ρ and T2 mapping) MR imaging was performed prior to and 2 years after ACL reconstruction. Differences of morphological and compositional parameters were compared between subjects with and without PMFT using logistic regression, adjusting for age, sex and BMI.

Results

In 24% (n = 14) of the subjects with ACL tear a PMFT was detected on baseline MRI. One subject with PMFT developed a meniscal tear over 2 years. Cartilage ∆T1ρ of the lateral femur increased significantly more in subjects with isolated PMFT compared to controls (mean difference, 2.0 ± 2.9 vs. -1.3 ± 1.6, p = 0.027).

Conclusion

PMFT detected by MRI are a common finding in subjects with ACL tears. Subjects with these defects showed higher compositional cartilage deterioration compared to controls, over 2 years in the lateral femoral compartment, indicating accelerated cartilage degeneration.

Key points

• Popliteomeniscal fascicle lesions are a common finding in subjects with ACL tears. • Progression to a meniscal tear over 2 years is not frequent. • Anteroinferior popliteomeniscal fascicle is injured most frequently. • Patients with popliteomeniscal fascicle lesions showed accelerated cartilage degeneration.

Objective

To determine if presence of calcium-containing crystals (CaC) is associated with increased knee joint degeneration over 4 years and assess if total number of CaCs deposited is a useful measure of disease burden.

Design

Seventy subjects with CaCs in right knees at baseline were selected from the Osteoarthritis Initiative and matched to 70 subjects without evidence of CaCs. T1-weighted gradient-echo sequences were used to confirm presence of CaCs and count the numbers of distinct circumscribed CaCs. Morphological abnormalities were assessed at baseline and 4-year follow-up using the modified semi-quantitative Whole-Organ Magnetic Resonance Imaging Score (WORMS). Linear regression models were used to analyze the associations between presence of CaCs at baseline and changes in WORMS and to analyze the associations between numbers of circumscribed CaCs at baseline and changes in WORMS.

Results

Presence of CaCs was associated with increased cartilage degeneration in the patella (coefficient: 0.33; 95% confidence interval (CI): 0.04-0.63), the medial femur (coefficient: 0.51; 95% CI: 0.18-0.83), the lateral tibia (coefficient: 0.36; 95% CI: 0.01-0.71) as well as the medial and lateral meniscus (coefficient: 0.38; 95% CI: 0.00-0.75 and coefficient: 0.72; 95% CI: 0.12-1.32). Knees with higher numbers of CaCs had increased cartilage degeneration in the patella and medial femur (coefficient: 0.09; 95% CI: 0.05-0.14; P < 0.001 and coefficient: 0.08; 95% CI: 0.02-0.14; P = 0.005).

Conclusions

CaCs were associated with increased cartilage and meniscus degeneration over a period of 4 years. Assessing the number of CaC depositions may be useful to evaluate risk of onset and worsening of degenerative disease.

Objective

To investigate compositional cartilage changes measured with 3T MRI-based T2 values over 48 months in overweight and obese individuals with different degrees of weight loss (WL) and to study whether WL slows knee cartilage degeneration and symptom worsening.

Design

We studied participants from the Osteoarthritis Initiative with risk factors or radiographic evidence of mild to moderate knee osteoarthritis with a baseline BMI ≥25 kg/m(2). We selected subjects who over 48 months lost a, moderate (BMI change, 5-10%WL, n = 180) or large amount of weight (≥10%WL, n = 78) and frequency-matched these to individuals with stable weight (<3%, n = 258). Right knee cartilage T2 maps of all compartments and grey-level co-occurrence matrix (GLCM) texture analyses were evaluated and associations with WL and clinical symptoms (WOMAC subscales for pain, stiffness and disability) were assessed using multivariable regression models.

Results

The amount of weight change was significantly associated with change in cartilage T2 of the medial tibia (β 0.9 ms, 95% CI 0.4 to 1.1, P = 0.001). Increase of T2 in the medial tibia was significantly associated with increase in WOMAC pain (β 0.5 ms, 95% CI 0.2 to 0.6, P = 0.02) and disability (β 0.03 ms, 95% CI 0.003 to 0.05, P = 0.03). GLCM contrast and variance over all compartments showed significantly less progression in the >10%WL group compared to the stable weight group (both comparisons, P = 0.04).

Conclusions

WL over 48 months is associated with slowed knee cartilage degeneration and improved knee symptoms.

Purpose

To assess the evolution of MR imaging findings in normal volunteers and subjects with hip osteoarthritis (OA) over 1.5 years described by the semi-quantitative Scoring Hip OA with MRI (SHOMRI) scoring system and their correlation with the evolution of clinical parameters.

Materials and methods

Hip MRI studies of 18 subjects with [Kellgren-Lawrence (KL) score = 2/3; mean age = 54.4 ± 11.2 years; 27.8% women] and 36 controls without radiographic OA [KL = 0/1; mean age = 43.7 ± 12.8 years; 50.0% women] were assessed at baseline and after 1.5 years by using SHOMRI, and their clinical status was evaluated by using Harris Hip Score and Hip Disability and Osteoarthritis Outcome Score (HOOS). Imaging and clinical parameters at baseline and their change over time were compared between groups using Mann-Whitney U and Fisher׳s exact tests. Spearman׳s rank correlations and generalized linear models adjusted for age, sex, BMI, and KL were used to assess associations between imaging and clinical findings.

Results

At baseline, OA subjects had significantly higher SHOMRI total scores than controls [median (IQR): 12.5 (6-19.5) vs. 7 (4-13.5); p = 0.024]. Over 1.5 years, only the progression rate of subchondral cysts was significantly higher in OA subjects than in controls (16.7% vs. 0.0%; p = 0.033), while no significant differences were found for any of the other SHOMRI subscales. Baseline bone-marrow edema pattern (BMEP) was significantly associated with worsening pain (HOOS subscale; p = 0.018) and hip-related quality of life (HOOS subscale; p = 0.044). Progression of subchondral cysts was significantly associated with worsening symptoms other than pain (HOOS subscale, p = 0.030). Baseline KL did not significantly correlate with worsening of any clinical symptoms (each, p > 0.05).

Conclusion

In this relatively young study population without or with mild to moderate radiographic hip OA, only minimal differences were found between groups regarding the progression of hip abnormalities as assessed by SHOMRI over 1.5 years. However, BMEP predicted clinical worsening and subchondral cyst progression was associated with worsening symptoms. Although longer follow-up periods are required, this suggests that SHOMRI is a useful tool to monitor hip abnormalities and their progression longitudinally.

Objective

To analyze associations of suprapatellar fat pad (SPFP) hyperintense signal alterations and mass effect with progression of patellofemoral osteoarthritis (OA) and clinical symptoms over 48 months.

Materials and methods

Subjects from the Osteoarthritis Initiative (n = 426; 51.8 ± 3.8 years; 49.8% women) without radiographic tibiofemoral OA underwent 3T-MRI of their right knees and clinical evaluation using the Knee Injury and Osteoarthritis Outcome Score at baseline and at 48 months. Elevated SPFP signal was assessed on intermediate-weighted, fat-saturated turbo spin-echo (TSE) images. Mass effect was defined as a convex posterior contour. Patellofemoral cartilage, bone marrow lesions (BML), and subchondral cysts were assessed using the Whole-Organ Magnetic Resonance Imaging Score (WORMS). Associations of SPFP imaging findings with MRI and clinical progression were assessed using general linear models and logistic regressions.

Results

Baseline SPFP signal alterations were found in 51% of the subjects (n = 217), of whom 11% (n = 23) additionally had a mass effect. Progression of cartilage lesions was significantly higher in subjects with signal alteration versus without (adjusted mean increases, 95% CI; patella: 0.29, -0.07 to 0.64 vs -0.04, -0.40 to 0.31; p < 0.001; trochlea: 0.47, 0.16 to 0.77 vs 0.31, 0.01 to 0.61; p = 0.007). BML progression was also more likely in subjects with signal alteration (OR 1.75, 95% CI 1.09 to 2.82; p = 0.021). Mass effect was not associated with joint degeneration and SPFP findings were not associated with clinical worsening (p > 0.18 for all).

Conclusion

Patellofemoral joint degeneration over 48 months was significantly increased in subjects with SPFP signal alteration, suggesting an association between SPFP abnormalities and the progression of patellofemoral OA.

Purpose To determine the incidence with which morphologic articular cartilage defects develop over 48 months in cartilage with signal abnormalities at baseline magnetic resonance (MR) imaging in comparison with the incidence in articular cartilage without signal abnormalities at baseline. Materials and Methods The institutional review boards of all participating centers approved this HIPAA-compliant study. Right knees of 90 subjects from the Osteoarthritis Initiative (mean age, 55 years ± 8 [standard deviation]; 51% women) with cartilage signal abnormalities but without morphologic cartilage defects at 3.0-T MR imaging and without radiographic osteoarthritis (Kellgren-Lawrence score, 0-1) were frequency matched for age, sex, Kellgren-Lawrence score, and body mass index with right knees in 90 subjects without any signal abnormalities or morphologic defects in the articular cartilage (mean age, 54 years ± 5; 51% women). Individual signal abnormalities (n = 126) on intermediate-weighted fast spin-echo MR images were categorized into four subgrades: subgrade A, hypointense; subgrade B, inhomogeneous; subgrade C, hyperintense; and subgrade D, hyperintense with swelling. The development of morphologic articular cartilage defects (Whole-Organ MR Imaging Score ≥2) at 48 months was analyzed on a compartment level and was compared between groups by using generalized estimating equation logistic regression models. Results Cartilage signal abnormalities were more frequent in the patellofemoral joint than in the tibiofemoral joint (59.5% vs 39.5%). Subgrade A was seen more frequently than were subgrades C and D (36% vs 22%). Incidence of morphologic cartilage defects at 48 months was 57% in cartilage with baseline signal abnormalities, while only 4% of compartments without baseline signal abnormalities developed morphologic defects at 48 months (all compartments combined and each compartment separately, P < .01). The development of morphologic defects was not significantly more likely in any of the subgrades (P = .98) and was significantly associated with progression of bone marrow abnormalities (P = .002). Conclusion Knee cartilage signal abnormalities detected with MR imaging are precursors of morphologic defects with osteoarthritis and may serve as imaging biomarkers with which to assess risk for cartilage degeneration. (©) RSNA, 2016.

Objective

To investigate compositional cartilage changes measured with 3T MRI-based T2 values over 48 months in overweight and obese individuals with different degrees of weight loss (WL) and to study whether WL slows knee cartilage degeneration and symptom worsening.

Design

We studied participants from the Osteoarthritis Initiative with risk factors or radiographic evidence of mild to moderate knee osteoarthritis with a baseline BMI ≥25 kg/m(2). We selected subjects who over 48 months lost a, moderate (BMI change, 5-10%WL, n = 180) or large amount of weight (≥10%WL, n = 78) and frequency-matched these to individuals with stable weight (<3%, n = 258). Right knee cartilage T2 maps of all compartments and grey-level co-occurrence matrix (GLCM) texture analyses were evaluated and associations with WL and clinical symptoms (WOMAC subscales for pain, stiffness and disability) were assessed using multivariable regression models.

Results

The amount of weight change was significantly associated with change in cartilage T2 of the medial tibia (β 0.9 ms, 95% CI 0.4 to 1.1, P = 0.001). Increase of T2 in the medial tibia was significantly associated with increase in WOMAC pain (β 0.5 ms, 95% CI 0.2 to 0.6, P = 0.02) and disability (β 0.03 ms, 95% CI 0.003 to 0.05, P = 0.03). GLCM contrast and variance over all compartments showed significantly less progression in the >10%WL group compared to the stable weight group (both comparisons, P = 0.04).

Conclusions

WL over 48 months is associated with slowed knee cartilage degeneration and improved knee symptoms.

Objective

The objective of our study was to assess the prevalence and evolution of intrameniscal signal-intensity alteration in subjects with an anterior cruciate ligament (ACL) tear over 24 months and compare clinical outcome and changes of cartilage between subjects with and those without this meniscal abnormality.

Materials and methods

Fifty-seven subjects with an ACL tear were screened for intrameniscal signal-intensity alteration. Morphologic and compositional MRI was performed before ACL reconstruction and 12 and 24 months after ACL reconstruction. Twelve subjects with an intrameniscal signal-intensity alteration and 12 subjects without any meniscal abnormality on MRI were identified. Clinical outcome was measured using the Knee Injury and Osteoarthritis Outcome Score (KOOS), and T1ρ and T2 maps of the cartilage were obtained.

Results

In 10 of 12 subjects (83%) the meniscal signal-intensity abnormality identified on baseline MRI was located at the posterior horn of the medial meniscus. None of these subjects presented with a meniscal tear over 24 months of follow-up. At 12 months after the ACL tear, the intrameniscal signal-intensity alteration detected on baseline MRI had completely resolved in seven of 12 subjects (58%), showed a signal-intensity decrease in four (33%), and remained stable in one subject (8%). Of the 10 subjects who underwent MRI at 24 months, the meniscal signal-intensity alteration had completely resolved in eight (80%), and the signal intensity had decreased in the other two subjects. Changes in the KOOS and cartilage T1ρ and T2 values from baseline and 24 months did not differ significantly between subjects with and those without intrameniscal signal-intensity alteration (p > 0.05).

Conclusion

High intrameniscal signal-intensity alterations are a common finding in subjects with an ACL tear and have a benign course over 24 months after surgical repair of the ACL tear.

Background

Anterior cruciate ligaments (ACL) injuries represent a major risk factor for early osteoarthritis (OA).

Purpose

To evaluate the prevalence and 4-year progression of knee OA measured with 3T MR-imaging in individuals with ruptured, reconstructed or normal ACL and to assess the impact of thigh muscle characteristics.

Methods

A total of 54 knees (23/54 male, 31/54 female) were recruited from the Osteoarthritis Initiative (OAI). At baseline, 15/54 subjects had prevalent ACL ruptures and 15/54 subjects had prevalent ACL reconstruction (24/54 normal ACL). Western Ontario and McMasters Universities Arthritis Index (WOMAC) scores, Physical Activity Scores of the Elderly (PASE) and thigh muscle characteristics including strength, fat infiltration (Goutallier score) and thigh muscle cross-sectional area (CSA) MR measurements were obtained at baseline. Whole-organ MR-imaging Scores (WORMS) were obtained at baseline and at a 4-year follow-up time-point. Multivariate regression models, adjusting for covariates (age, gender, body mass index), were used for statistical analysis.

Results

At baseline, subjects with prevalent ACL ruptures had worse WORMS total scores (mean±SEM, 44.1±3.5) than subjects with ACL reconstruction (30.8±4.0; P = 0.015) and worse than subjects with normal ACL (21.3±3.0; P<0.001). Cartilage scores were worse in both femorotibial compartments in ACL injured knees than in knees with normal ACL (P<0.05). Knees with ACL reconstruction showed an increased degeneration of the medial meniscus (P = 0.036), cartilage degeneration at the medial femoral condyle (P = 0.011). In a multivariate regression model, including both ACL groups and total muscle characteristics as influence parameters, high thigh muscle CSA, high muscle/ fat ratio and low Goutallier scores were associated with less degenerative changes at the knee, independent of ACL status. Knees with ACL reconstruction showed an increased progression of cartilage degeneration at the medial tibia compared to the normal ACL group (P = 0.027).

Conclusions

High thigh muscle CSA is associated with less degenerative changes at the knee, independent of the ACL status and may potentially be advantageous in the prevention of early OA.