Background/Purpose: very little is known about the differences in joint and periarticular structure involvement in rheumatoid or psoriatic arthritis (PsA). The main pathological features detected by US in rheumatoid arthritis (RA) are synovitis and bone erosion while, in spondyloarthropathies, entheseal inflammation is the common feature. Tendon involvement is particularly frequent and dactylitis is a typical PsA manifestation. Aim of the study was to find possible differences in ultrasound (US) involvement of wrist and hand in PsA and RA.

Methods: bilateral US examination of the wrist and hand was performed, by the same physician blinded to the diagnosis, in a consecutive, unselected, group of subjects affected by RA and PsA, using a Logiq 9 (General Electrics Medical Systems, Milwaukee, WI) with a linear probe (14 MHz). Radiocarpal, intercarpal, metacarpophalangeal, proximal interphalangeal and distal interphalangeal joints and flexor and extensor tendons (in wrist and hand) were examined bilaterally. Bone erosion and tenosynovitis were diagnosed according to the OMERACT definitions [1], while synovitis was considered when a synovial hypertrophy (with or without power Doppler signal) was present. The patients were recruited on a time-criteria (the last who came for an outpatient visit). The RA and PsA diagnosis was given by other rheumatologists, according to the 1987 ACR and Caspar criteria, respectively.

Results: mean age and disease duration were comparable for both groups, while male/female ratio was different (as expected) (Table I). US findings are reported in Table I. The number of hand joints involved was higher in RA than in PsA (182 vs 150). Given the results, it is interesting that the total number of proliferative tenosynovitis was significantly greater in RA (49/68 vs 7/34 in PsA at the wrist level and 58/98 vs 13/63 in PsA at the hand level).

Table I

	RA (N=55)	PsA (N=55)
F/M	48/7	28/27
Mean age (yrs)	60.7±12.7	57.4±12.5
Disease duration (months)	113.3±97.7	100.6±95.6
Wrist synovitis (N of pts; %)	38;69	24;44
Hand synovitis (N of pts; %)	28;51	37;67
Wrist tenosynovitis (N of pts; %)	23;43	16;29
Hand tenosynovitis (N of pts; %)	22;40	25;45
Hand erosions	30;54	26;47

Conclusion: wrist synovitis occurred significantly more frequently in RA patients than PsA subjects, while no significant differences were observed in hand synovitis between the groups. There was no difference in tendon involvement for frequency between RA and PsA groups considering the number of patients with tenosynovitis but it became significantly different when considering the total amount of tenosynovitis (as well as the number of proliferative tenosynovitis). The latter aspect could be determined by a more aggressive inflammation of the tendons in those patients that present tendon involvement and are affected by RA (only 10 RA patients had hand proliferative tenosynovitis, compared to 7 in the PsA group, indicating a lower frequency of synovial proliferation in the second group). There were no other significant differences in the results of the two groups.

References

1 – WAKEFIELD RJ, BALINT PV, SZKUDLAREK M et al.: Musculoskeletal ultrasound including definitions for ultrasonographic pathology. J Rheumatol 2005; 32: 2485-7.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/us-examination-of-wrists-and-hands-a-comparison-between-rheumatoid-arthritis-and-psoriatic-arthritis/