A Novel Screening Technique for Ulnar-Sided Carpometacarpal Dislocations.

Area of Science:

• Orthopedics
• Radiology
• Hand Surgery

Background:

• Ulnar-sided carpometacarpal joint dislocations are frequently missed during initial patient evaluations.
• Accurate diagnosis is crucial for effective treatment and preventing long-term complications.

Purpose of the Study:

• To evaluate the utility of the capitate-metacarpal angle as a diagnostic tool for ulnar-sided carpometacarpal joint dislocations.
• To establish a simple and reliable radiographic measurement for identifying these injuries.

Main Methods:

• Retrospective review of patients with surgically treated ulnar-sided carpometacarpal dislocations and a control group with no carpal pathology.
• Measurement of the capitate-metacarpal angle on plain radiographs using specialized software.
• Utilized 3D models from CT scans to obtain a true lateral view for accurate angle measurement.

Main Results:

• The average capitate-metacarpal angle was 10° in the control group and 19° in the study group.
• A screening threshold of 15° demonstrated a sensitivity of 0.85 and specificity of 0.79.
• Both 2D and 3D measurements confirmed the angle's reliability in detecting dislocations.

Conclusions:

• The capitate-metacarpal angle is a reliable screening tool for diagnosing ulnar-sided carpometacarpal dislocations.
• An increased angle on plain radiographs may warrant advanced imaging for suspected injuries.
• This measurement aids in the early detection of difficult-to-diagnose carpometacarpal joint injuries.