Skeletal Radiology

, Volume 36, Issue 11, pp 1061–1066

Sensitivity and specificity of plain radiographic features of peripheral enthesopathy at major sites in psoriatic arthritis

Scientific Article



It has been proposed that the defining difference between rheumatoid arthritis and spondyloarthropathy (including psoriatic arthritis) is the initial pathological lesion where the emphasis in psoriatic arthritis is on the enthesis and in rheumatoid arthritis on the synovium. Classical radiological descriptions of seronegative spondyloarthropathy include enthesopathy at major entheseal insertions characterised by erosions and exuberant new bone formation. In this study, the plain radiographic features of spondyloarthropathy are compared between psoriatic arthritis, other spondyloarthropathies and rheumatoid arthritis.


The CASPAR study collected clinical, radiological and laboratory data on 588 patients with physician diagnosed psoriatic arthritis and 525 controls with other inflammatory arthritis, 70% of which had rheumatoid arthritis. Plain radiographs of the pelvis and heels were part of the study protocol, although radiographs of other potential entheseal sites such as the knee, elbow and shoulder, were interpreted if available. All radiographs were read blind by two observers working in tandem.


Significant differences in entheseal erosion and entheseal new bone formation were found between psoriatic arthritis, ankylosing spondylitis, undifferentiated spondyloarthropathy, rheumatoid arthritis and other diagnoses (entheseal erosion, chi-squared 20.8, p = 0.008; entheseal new bone formation, chi-squared 24.5, p = 0.001). These differences were mainly due to a higher proportion of these features in ankylosing spondylitis. No differences in the plain radiographic features of enthesopathy were found between psoriatic arthritis and rheumatoid arthritis except in the case of entheseal new bone formation at sites of attachment of inguinal ligament, sartorius and rectus femoris muscles to the ilium (OR 3.01, 95% CI 1.13–8.02). Very few subjects with symptomatic heel involvement had radiographic changes and minimal differences were found between those with and without symptoms in terms of new bone formation and erosion at either calcaneal site.


New bone formation and erosion at major entheseal sites is most commonly seen in ankylosing spondylitis. Plain radiographic features of major enthesopathy are poor discriminators between psoriatic arthritis and rheumatoid arthritis.


Psoriatic arthritis Rheumatoid arthritis Ankylosing spondylitis Undifferentiated spondyloarthropathy Enthesopathy Radiography 


  1. 1.
    Wright V Psoriasis and arthritis. Ann Rheum Dis 1956; 15: 348–356.PubMedCrossRefGoogle Scholar
  2. 2.
    Baker H, Golding DN, Thompson M. Psoriasis and arthritis. Ann Intern Med 1963; 58: 909–925.PubMedGoogle Scholar
  3. 3.
    McGonagle D, Conaghan P, Emery P. Psoriatic arthritis: a unified concept 20 years on. Arthr Rheum 1999; 42(6): 1080–1086.CrossRefGoogle Scholar
  4. 4.
    Resnick D, Niwayama G. Diagnosis of bone and joint disorders. 1st edn. Saunders, Philadelphia, PA, USA, 1981.Google Scholar
  5. 5.
    Taylor WJ, Gladman DD, Helliwell PS, et al. Classification criteria for psoriatic arthritis: development of new criteria from a large international study. Arthr Rheum 2006; 54(8): 2665–2673.CrossRefGoogle Scholar
  6. 6.
    Taylor WJ, Porter GG, Helliwell PS. Operational definitions and observer reliability of the plain radiographic features of psoriatic arthritis. J Rheumatol 2003; 30(12): 2645–2658.PubMedGoogle Scholar
  7. 7.
    Secundini R, Scheines EJ, Gusis SE, Riopedre AM, Citera G, Maldonado Cocco JA. Clinico-radiological correlation of enthesitis in seronegative spondyloarthropathies (SNSA). Clin Rheum 1997; 16(2): 129–132.CrossRefGoogle Scholar
  8. 8.
    McGonagle D, Marzo-Ortega H, O’Connor P, et al. The role of biomechanical factors and HLA-B27 in magnetic resonance imaging-determined bone changes in plantar fascia enthesopathy. Arthr Rheum 2002; 46(2): 489–493.CrossRefGoogle Scholar
  9. 9.
    Falsetti P, Frediani B, Fioravanti A, et al. Sonographic study of calcaneal entheses in erosive osteoarthritis, nodal osteoarthritis, rheumatoid arthritis and psoriatic arthritis. Scand J Rheum 2003; 32: 229–234.PubMedCrossRefGoogle Scholar
  10. 10.
    Falsetti P, Frediani B, Filippou G, et al. Enthesitis of proximal insertion of the deltoid in the course of seronegative spondyloarthritis: an atypical enthesitis that can mime impingement syndrome. Scand J Rheum 2002; 31: 158–162.PubMedCrossRefGoogle Scholar
  11. 11.
    Lambert RGW, Dhillon SS, Jhangri GS, et al. High prevalence of symptomatic enthesopathy of the shoulder in ankylosing spondylitis: deltoid origin involvement constitutes a hallmark of disease. Arthr Rheum (Arthr Care Res) 2004; 51(5): 681–690.CrossRefGoogle Scholar
  12. 12.
    Gorter S, van der Heijde DMFM, vander Linden S, et al. Psoriatic arthritis: performance of rheumatologists in daily practice. Ann Rheum Dis 2002; 61: 219–224.PubMedCrossRefGoogle Scholar
  13. 13.
    Symmons DP, Lunt M, Watkins G, et al. Developing classification criteria for peripheral joint psoriatic arthritis: step I, establishing whether the rheumatologists opinion on the diagnosis can be used as the "gold standard". J Rheum 2006; 33: 552–557.PubMedGoogle Scholar
  14. 14.
    Palazzi C, Olivieri I, Petricca A, Salvarani C. Rheumatoid arthritis or psoriatic arthritic symmetrical polyarthritis? A difficult differential diagnosis. Clin Exp Rheum 2002; 20(1): 3–4.Google Scholar

Copyright information

© ISS 2007

Authors and Affiliations

  1. 1.Academic Unit of Musculoskeletal and Rehabilitation MedicineUniversity of LeedsLeedsUK
  2. 2.Airedale Hospital NHS TrustKeighleyUK

Personalised recommendations