An investigation of dynamic ulnar impingement after the Darrach procedure with ultrasonography

Dynamic ulnar impingement is a common and painful symptom after the Darrach procedure. However, the current detection method with static radiographs often falls short of examining the dynamically symptomatic wrists. We, therefore, investigate the utility of ultrasonography to assess dynamic ulnar impingement. In this cross-sectional study, 20 patients, with 22 wrists, who had undergone the Darrach procedure were evaluated at a mean of 55 months (range, 25-171) from the index procedure. Real-time ultrasonographic imaging in the axial plane of the bone and soft tissue was performed during three different dynamic testing methods, including weight-stressed (WS), pronation-supination (PS), and forceful fist clenching (FC), to investigate ulnar impingement. Dynamic radiographs were obtained for comparison. Clinical outcomes were evaluated with grip strength and patient-reported outcomes including pain in daily activities on a numeric rating scale (NRS), the Patient-Rated Wrist Evaluation (PRWE), and the Quick Disability of the Arm, Shoulder and Hand (QDASH). Ultrasonographic ulnar impingement found during PS method was associated with worse pain and function, yet impingement diagnosed with dynamic radiographs or ultrasonography with WS and FC method was not associated with worse outcomes. While radiographic impingement was found in a total of 12 wrists (55%), ultrasonography with the WS and PS method revealed true bone contact in only 2 (9%) and 4 (18%) of the wrists, respectively. The addition of ultrasonography may be valuable in follow-up evaluations after the Darrach procedure.