Background/Purpose

Ultrasound (US) signs of inflammation in joints are synovial hypertrophy, effusion, and Doppler activity (increased perfusion), which have been demonstrated in both osteoarthritis (OA) and rheumatoid arthritis (RA).  It might be expected that inflammatory signs are more pronounced in patients with RA however, a comparison of RA and OA with respect to US changes remains to be performed. 

Methods

A standardized US examination and scoring technique in patients with OA has been developed and validated in a group of patients with knee OA. This validated technique was applied on a group of RA patients and a group of OA patients – both with knee involvement. The diagnoses of OA and RA were according to the ACR criteria. RA and OA patients were examined by US according to the standardized procedure at baseline before onset of biologics. In the present study the validated US scoring were performed in all patients (RA and OA).  All US images were scored by the same person (KE).  The amount of synovial hypertrophy (mm) and Doppler (+/- scored as 1/0) were measured in five positions (supra patellar; medial and lateral joint space and recess). Synovial hypertrophy measures for all 5 positions were summed and Doppler presence was summed for the medial and lateral joint space and recess (4 positions). Presence and size of Baker`s cyst were registered and any Doppler activity in or around the cyst was registered. Statistics: The difference between US findings in the two diseases was evaluated with both non-parametric and parametric statistics. The level of significance was 2α=0.05.

Results

Eighteen RA patients were included, the percentage of women was 66% and mean age was 66 years (range26.3-73). The mean DAS28 was 4.9 (range 3.5-7.0). The OA group consisted of 99 patients the percentage of women was 59 and the mean age was 64 (range42.3-84.4). See table

Conclusion

On US examination statistically significantly more synovial hypertrophy and more Baker`s cysts were seen in the OA knees as compared to the RA knees. Little Doppler activity (increased blood flow) was found with no difference between the two patient groups. These results support that inflammation is an important pathological feature in OA.

Acknowledgement: the study was supported by an unrestricted grant from Pfizer, Cambridge Weight Plan and the Oak Foundation.

	OA (n=99) Median [IQ] mean (SD)	RA (n=18) Median [IQ] mean (SD)	p-value (t-test)	p-value (Wilcoxon)
Synovial hypertrophy (mm)	21.8 [17.1;27] 24.54(11.91)	14.35 (14.12;6.0) [11.6; 20.2]	<0.0001	<0.0001
Baker`s cyst (0-12)	0 [0; 5] 2.19(2.52)	0 [0; 0] 0.24(0.66)	<0.0001	0.0044
Doppler (0-7)	0 [0;1] 0,69(1,18)	0 [0;1] 0.67(0.97)	0.94	0.80

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/knee-joint-pathology-in-patients-with-rheumatoid-arthritis-and-osteoarthritis-using-a-validated-ultrasound-scoring-system-a-cross-sectional-study/