Ultrasound in Evaluation of Subclinical Enthesitis of Extensor Digitorum Tendon and Nail Unit Changes in Psoriasis

Abstract

Abstract Background Subclinical inflammation at entheseal level has been detected in patients with psoriasis without previous history of arthropathy or Psoriatic arthritis (PsA). Ultrasound (US) is a valid and sensitive tool for the assessment of inflammatory involvement at entheseal level in PsA patients. Objective To detect subclinical arthritis or enthesitis at distal interphalangeal (DIP) fingers and nail unit changes in psoriatic patient for early detection of PsA Patients and Methods This study included 30 adult psoriatic patients and 30 healthy matched controls. All underwent history, clinical examination, Psoriasis Area and Severity Index (PASI), Nail Psoriasis Severity Index (NAPSI) score calculation and musculoskeletal US both grey and power Doppler (PD) assessed at enthesis of extensor digitorum tendon insertion at distal phalanx, DIP joints from 2nd to 5th finger bilaterally examined for detection of synovitis and over the nail for morpho-structural evaluation. Results Patient’s ages ranged from 18-65 years and controls 20-60 years (mean ±SD 45.07 ± 13.52, 38.37 ± 11.96 respectively), male to female ratio 1:2. DIP joint affection in the form of synovial hypertrophy and effusion with PD was found in 13.3% of cases. Enthesophyte with PD in 56.7% of cases. On comparison between NAPSI score by clinical examination versus US examination, the sensitivity of US was 100%, all cases clinically positive by NAPSI were positively affected by US (20 cases). Also 30% of cases were negative by NAPSI and were positive by US (7cases). Three cases were negative by both NAPSI and US. A significant positive correlation was observed between disease duration and NAPSI Score (r = 0.429, pvalue<0.05), similarly between presence of enthesophyte with PD and PASI Score (r = 0.547, pvalue<0.02). Conclusion Detection of subclinical enthesopathy at DIP joint by ultrasound is not infrequent, so it is an important tool for examining enthesis in psoriatic patients. The presence of a high PASI score and long disease duration could be considered as predictive parameters for the presence of psoriatic enthesitis ongoing to arthritis.