How is tendon rupture differentiated from other sequelae of rheumatoid arthritis (RA)?

Updated: Jun 11, 2021
  • Author: Michael Neumeister, MD, FRCSC, FACS; Chief Editor: Joseph A Molnar, MD, PhD, FACS  more...
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When diagnosing extensor tendon ruptures secondary to RA, 3 other sequelae of RA that mimic this problem should be considered. First, MP joint dislocation produces a fixed deformity with a flexed and ulnarly deviated finger. Second, volar and ulnar subluxation of the extensor tendons into the gutters between the phalanges limits extensor function as the extensors essentially become flexors in this position. In this condition, the patient can sometimes maintain MP extension actively after the finger is passively extended. Finally, paralysis due to posterior interosseous nerve compression can also cause symptoms similar to extensor tendon rupture when it affects the common extensor muscle. Differentiation between tendon rupture and paralysis can be difficult, and the most reliable diagnostic maneuver is to test for the presence of MP joint extension while flexing the wrist (tenodesis effect). Because the tendon is not in continuity when it is ruptured, wrist flexion does not restore MP joint extension.

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