Detecting partial tears of the finger extensor tendons in rheumatoid arthritis patients by physical examination alone can be difficult. But without an alternative method of diagnosis, patients may undergo unnecessary surgery. Dutch researchers hoped that two different imaging modalities would hold the answer, but found that both fell short of expectations.
Researchers from several institutions in the Netherlands, including the University Medical Centre Utrecht, tested the diagnostic value of sonography and MRI to visualize partial tendon tears. Tenosynovitis of finger flexor and extensor tendons occurs in as many as 64% of RA patients. Ruptures are most common in the extensor pollicis longus (Rheumatology 2000, Vol.39, pp.55-62).
The Dutch team studied 21 patients from March 1994 to 1997. Sonography and MRI of the most severely damaged finger extensor tendons was done six weeks before surgery. Altogether, 252 finger extensor tendons were analyzed. Sonography was done with a 10-MHz linear-array transducer. The sensitivity of sonography was 33%, the specificity was 89%, and the accuracy was 75%, the authors reported.
MRI was performed with a 1-tesla system with a dedicated wrist surface coil as a receiver. The sensitivity for MRI was 27%, the specificity was 83%, and the accuracy was 69%.
During surgical synovectomy, an orthopedic surgeon inspected all tendons. Partial tears were found in 81% of the patients.
"For clinical practice, these results are disappointing," the authors concluded. "Sonography is not sensitive enough as a screening method to detect partial tears in finger extensor tendons...further developments of MRI, such as three-dimensional acquisition techniques and a higher tesla rate, might better define the course and integrity of tendons."
By Shalmali Pal
AuntMinnie.com staff writer
March 15, 2000
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