Ultrasound imaging of normal displacement of the extensor carpi ulnaris tendon within the ulnar groove in 12 forearm-wrist positions

AJR Am J Roentgenol. 2009 Sep;193(3):651-5. doi: 10.2214/AJR.08.1725.


Objective: Instability of the extensor carpi ulnaris (ECU) tendon can be a difficult clinical diagnosis because of normal changes in tendon position during wrist motion. Our goal was to determine the normal variation of ECU tendon displacement in 12 forearm-wrist positions.

Subjects and methods: Ultrasound imaging of the ECU tendons of 40 symptom-free wrists of healthy volunteers (13 women, seven men; mean age, 22.3 years; range, 20-25 years) was performed. Each ECU tendon was examined in 12 positions: four wrist positions (ulnar deviation, radial deviation, flexion, and extension) in each of three forearm positions (pronation, supination, and neutral).

Results: ECU tendon displacement in the right hand was not significantly different from that in the left, and displacement in men did not differ significantly from that in women. There was a small but significant difference between displacement in the dominant and that in the nondominant hand (p < 0.02). Mean ECU tendon displacement was greatest in the supinated forearm position (p < 0.001) followed by the neutral position (p < 0.001) and was least in the pronated position (p < 0.001). Both ulnar deviation (p < 0.001) and flexion (p < 0.002) were associated with greater ECU tendon displacement than were radial deviation (p < 0.001) and extension (p < 0.002). Maximum percentage displacement volar to the ulnar border of the groove was 50% in flexed supination and ulnar deviation. The maximum displaced distance volar to the ulnar border of the groove was 5 mm.

Conclusion: Sonographic evaluation of the ECU tendon is simple and practical. Knowledge of normal ECU displacement relative to the ulnar groove may help in evaluation of ulnar-sided wrist pain.

MeSH terms

  • Female
  • Forearm / diagnostic imaging*
  • Humans
  • Image Processing, Computer-Assisted
  • Male
  • Posture
  • Reference Values
  • Tendons / diagnostic imaging*
  • Ulna / diagnostic imaging*
  • Ultrasonography
  • Wrist Joint / diagnostic imaging*
  • Young Adult