The “Keystone” technique for metacarpophalangeal joint exam
Welcome to the March edition of #ChatJRheum
When examining a patient in clinic, do you question the accuracy of our physical exam; how well does the exam correlate with what would be found on imaging? Is the joint active and therefore at risk of disease progression and damage? This month’s article for discussion validates a new technique for metacarpophalangeal joint exam in rheumatoid arthritis. The dorsal four-finger technique (DFFT) proved to be a more sensitive technique to detect joint swelling with better ultrasound (US) correlation than the traditional two-finger technique (TFT).
The agreement between ballottement or spongy joint exam and US grey-scale and power-doppler findings of synovitis was greater with DFFT compared to TFT. As might be expected, a ballotable and tender joint correlated best with positive doppler on US. Of additional benefit, DFFT detected more non-tender joints with active synovitis on ultrasound, therefore in the absence of tenderness, DFFT might be a more accurate assessment of disease activity. “Sponginess” or soft tissue swelling over the joint that was not ballottable correlated less with ultrasound findings. There was similar intraobserver and interobserver reliability between the two exam techniques.
A weakness of the study is that patients had established rheumatoid arthritis, with mean disease duration of 21.8 years. More studies are needed in other populations, including in the early arthritis cohort, and in other institutions with less familiarity with the four-finger or “Keystone” technique
For now, the authors provide easy to follow pictures and description of this exam technique.
I encourage you to try the technique this month while examining a patient with rheumatoid arthritis and respond back about your experience. Will you use the DFFT exam in your clinic instead of the TFT?
I hope you will return to the forum this month for ongoing reflection, discussion or feedback on this topic.
- Sarah Troster, forum moderator