How is flexor tendon rupture in rheumatoid arthritis (RA) diagnosed?

Updated: Jun 11, 2021
  • Author: Michael Neumeister, MD, FRCSC, FACS; Chief Editor: Joseph A Molnar, MD, PhD, FACS  more...
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The diagnosis of flexor tendon rupture is more straightforward. The flexor pollicis longus is the most common flexor tendon to be affected by RA. Patients with this condition are not able to actively flex the thumb IP joint. The diagnosis can be slightly complicated if chronic stiffness or hyperextension is present in this joint. Similarly, loss of function in the proximal IP (PIP) joint or the distal IP (DIP) joint suggests rupture of the flexor digitorum superficialis (FDS) or profundus (FDP), respectively. Rheumatoid nodules can limit FDP function and produce symptoms similar to FDP tendon rupture; therefore, this diagnosis should be considered. A palpable nodule can aid in differentiating between these conditions. Furthermore, when the flexor tendon is ruptured, the affected finger also has a more extended posture in the resting position.

To make the diagnosis of concomitant FDP and FDS tendon rupture, passive motion of the finger must be present in the absence of active motion at the DIP and PIP joints. The flexor tendons can rupture at multiple sites in the hand, including the wrist, palm, and fingers. Surgical exploration is usually required to determine the exact location of the rupture.

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