The role of the traumatic factor and isomorphic reaction in the early diagnosis of psoriatic arthritis
Authors: Koreshkova Ksenia M. , Khismatullina Zarema R. 
Published: November 2022

Rationale: Evaluation of the role of the deep Koebner's phenomenon and traumatization seems to be a promising direction in the search of the solution for the delayed diagnosis of psoriatic arthritis (PsA) in patients with psoriasis. We have put forward the question if joint and ligament abnormalities induced by a trauma or persistent physical activity could be an analogue of the skin isomorphic reaction in psoriasis.
Aim: To identify joint and ligament abnormalities in patients with psoriasis caused by mechanical stress and their association with the deep Koebner's phenomenon and PsA.
Materials and methods: This was an open-label, non-randomized, comparative study in parallel groups in 80 in-patients with psoriasis (recruited in the Dermatovenereological clinic № 1, Ufa); the control group included 80 in-patients with PsA. All patients were assessed by a dermatovenereologist, including past history, severity of psoriasis, degree of PsA activity, special questionnaires and the presence of an isomorphic reaction in the skin and periarticular tissues. The joints with maximal physical activity were assessed by X-ray. PsA was diagnosed by a rheumatologist.
Results: The patients from both groups were matched in terms of age, gender, and duration of psoriasis. Pain, joint stiffness and limitation of mobility were present not only in the PsA group, but also in the patients with psoriasis (35%, 27.5% and 26.2% of the patients, respectively). Despite most of the patients in the psoriasis group had no active complaints (65.0% vs. 0% in the control group, p 0.001), clinical signs of inflammation of the tendons and entheses and relevant history were found in 47.5% (68.7% in the control group, p = 0.007). Hand tendinitis was most prevalent symptom in both groups: 40.0% (32/80) in the psoriasis group and 63.7% (51/80) in the PsA group (p = 0.003). Achilles tendon lesions were found in 17.5% (14/80) and 52.5% (42/80) (p 0.001) and periarticular edema in 27.5% (22/80) and 63.7% (51/80), respectively (p 0.001). The combination of these signs with psoriatic plaques in this area was observed in 32.5% (26/80) and 92.5% (74/80) of the patients, respectively (p 0.001). The comparison of the clinical and X-ray data showed that 38 patients with psoriasis and newly diagnosed PsA had had an increased physical load on the affected joints, as well as signs of a deep isomorphic reaction (tendinitis, periarticular edema, or enthesitis near the involved joints). In both groups, the most common form of PsA was distal one (63.2% [24/38] of the patients with newly diagnosed PsA and 58.7% [47/80] of the patients with previously diagnosed PsA, p = 0.648).
Conclusion: Involvement of the periarticular tissues, as well as early, including preclinical, X-ray abnormalities in the joints of patients with psoriasis can be associated with increased physical activity and the deep Koebner's phenomenon. Therefore, even if patients with psoriasis do not have any clinical manifestations of PsA and no complaints when seen by a dermatovenereologist, it is recommended to perform a detailed collection of past history data with clarification of the type of physical activity and past trauma, as well as to examine both by inspection and palpation the periarticular tissues (tendons and entheses), for the timely use of X-ray examination, consultation of a rheumatologist aimed at diagnosis of psoriatic arthritis.