What is the Accuracy of Radiographic Measurements of MCP Ulnar Deviation in RA?

HealthDay News – Significant discordance was found between radiographic and goniometric metacarpophalangeal (MCP) joint ulnar deviation (UD) measurements in patients with rheumatoid arthritis (RA), a study published in the Journal of Medical Imaging and Radiation Oncology reported.

Regina M. Taylor-Gjevre, MD, from the University of Saskatchewan in Saskatoon, Canada, and colleagues enrolled 15 RA patients with clinically apparent UD and 11 without UD who underwent rheumatological examination before recruitment. An occupational therapist (OT) performed goniometric measurements for UD at the metacarpophalangeal joints. 

Standardized hand radiographs and magnetic resonance imaging (MRI) studies of the dominant hand were assessed. Two experienced musculoskeletal radiologists independently performed angulation measurements for radiographs and MRI.

The researchers found that for both radiographic and MRI measurements, inter-observer correlation between radiologists was >0.97. The correlation between OT goniometric measurements and imaging-based measurements was 0.496 and 0.317 for radiographs and MRI, respectively. The correlation between imaging modalities was 0.513. Radiographic and MRI study measurements significantly underestimated the angulation in RA patients with UD, compared with OT measurements (P < .001).

Summary and Clinical Applicability

Radiographic assessments of UD angulation in MCP joints may not accurately represent degree of joint malalignment in RA.

“Although imaging plays a key role in understanding structural damage and disease activity in RA, it should be emphasized that radiological measurements underrate joint malalignment,” the authors write.

Limitations and Disclosures

This study was primarily limited by the small sample size.  No conflicts of interest were reported by study authors.

Reference

Taylor-gjevre RM, Mitchell A, Street M, L eswick DA, Stewart SA, Obaid H. The role of radiology in the quantification of digital ulnar deviation in rheumatoid arthritis patients. J Med Imaging Radiat Oncol. 2016; [Epub ahead of print] April 6, 2016. DOI: 10.1111/1754-9485.12454