Thresholds of ultrasound synovial abnormalities for knee osteoarthritis – a cross sectional study in the general population

Abstract

SummaryObjectiveTo establish “normal” ranges for synovial thickness and effusion detected by ultrasound (US) and to determine cut-offs associated with knee pain (KP) and radiographic knee osteoarthritis (RKOA) in the community.Methods147 women and 152 men ≥40 years old were randomly selected from the Nottingham KP and Related Health in the Community (KPIC) cohort (n = 9506). The “normal” range was established using the percentile method in 163 participants who had no KP and no RKOA. Optimal (maximum sensitivity and specificity) and high specificity (90%) cut-offs were established using receiver operating characteristic (ROC) curve analysis in a comparison between people with both KP and RKOA and normal controls.ResultsEffusion and synovial hypertrophy differed by gender but not by age or laterality, therefore gender-specific reference limits were estimated. However, the “normal” ranges between men and women were similar for effusion (0–10.3 mm vs 0–9.8 mm), but different for synovial hypertrophy (0–6.8 mm vs 0–5.4 mm). Power Doppler Signal (PDS) in the healthy controls was uncommon (1.2% in men and 0.0% in women). The optimal cut-off was 7.4 mm for men and 5.3 mm for women for effusion, and 3.7 and 1.6 for hypertrophy respectively. The high specificity cut-off was 8.9 for men and 7.8 for women for effusion, and 5.8 and 4.2 for hypertrophy respectively.ConclusionsUS effusion and synovial hypertrophy but not PDS are common, but differ by gender, in community-derived people without painful knee OA. Currently used cut-offs for abnormality need reappraisal.

Effect of ultrasound-detected synovitis on therapeutic efficacy of hyaluronic acid injection for symptomatic knee osteoarthritis

“…In addition, studies have stated that effusion-related synovitis is a better surrogate marker for structural damage in knees affected by OA [ 31 ]. This result is also consistent with a study by Sarmanova et al that proposed cutoff values for synovial abnormality (7.4 mm in men; 5.3 mm in women) for US-detected effusion in patients with knee pain and OA [ 32 ]. This supports our finding of a significant association between an increased amount of SF and clinical improvement.…”

Osteoarthritis year in review 2019: imaging

“…Studies have investigated US findings in subjects with knee OA. Sarmanova et al compared inflammatory features on US in 199 subjects from the Nottingham KP and Related Health in the Community (KPIC) cohort in order to establish normal reference ranges for effusion and synovial thickening 69 . The optimal and high specificity cut-off values for distinguishing between knees with and without OA was 7.4 mm and 8.9 mm, respectively in men and 5.3 mm and 7.8 mm, respectively in women for effusion and 3.7 mm and 5.8 mm, respectively in men and 1.6 mm and 4.2 mm, respectively in women for synovial thickening.…”

Prevalence of ultrasound-detected knee synovial abnormalities in a middle-aged and older general population—the Xiangya Osteoarthritis Study

“…The prevalence of synovial abnormalities in our study was comparable with these previous studies, suggesting similar findings in diverse populations (China, USA, UK, and Italy). Several previous studies also reported higher prevalence of synovial hypertrophy and effusion in men than women [ 20 , 21 , 33 ]. This finding may be partly explained by the fact that men normally have thicker synovium and more synovial fluid than women [ 21 ].…”

“…Several previous studies also reported higher prevalence of synovial hypertrophy and effusion in men than women [ 20 , 21 , 33 ]. This finding may be partly explained by the fact that men normally have thicker synovium and more synovial fluid than women [ 21 ]. The high prevalence of abnormal ultrasound values in this and previous general population samples suggest that, rather than using a fixed cut-off of ≥ 4 mm for “abnormal” synovial hypertrophy and effusion, different cut-offs for presence of hypertrophy and effusion, and for men and women, might be calculated from normal ranges and incorporated into future studies.…”

“…In the Italian Bruneck population-based cohort, the prevalence of synovial hypertrophy, effusion, and PDS were 43.9%, 60.4%, and 22.6%, respectively, among 433 survivors in the fourth follow-up (927 participants at baseline) [ 20 ]. In the Nottingham Knee Pain and Related Health in the Community Study in the UK, the prevalence was 23.9% for synovial hypertrophy, 50.9% for effusion, and 0.7% for PDS in 163 participants with no knee pain or ROA [ 21 ]. In the Johnston County Osteoarthritis Project, evidence of effusion/synovitis on ultrasound was found in 80.3% of 396 knees of 203 participants using a semi-quantitative assessment atlas [ 22 ].…”