The radial and ulnar collateral ligaments of the wrist are true ligaments.

PURPOSE Our hypothesis in this study is that the radial and ulnar collateral ligaments of the wrist exist and are true ligaments which can be visualized by high resolution ultrasound. METHODS High-resolution ultrasound examination of the radial and ulnar collateral ligaments of the wrist was performed on 56 fresh cadaveric wrists. The visibility of these ligaments was assessed by four observers who classified the ligaments in consensus as well seen, adequately seen or not seen. Surgical dissections of 12 radial collateral ligaments and 12 ulnar collateral ligaments were then performed and the ligaments were classified as present or absent. The ultrasound and dissection results were then compared. To confirm that the dissected structures represent true ligaments a histologic examination of the ligaments was performed. RESULTS All examined radial and ulnar collateral ligaments were seen on the ultrasound examination. The radial collateral ligament was seen between the radial styloid and radial aspect of the scaphoid. The ulnar collateral ligament was seen between ulnar styloid process and the triquetrum. On all surgical dissections, the radial collateral ligament was present at the floor of the first extensor compartment and the ulnar collateral ligament was at the floor of the sixth extensor compartment. Both ligaments were proven to be true capsular ligaments on both dissection and histological examinations. CONCLUSION The radial and ulnar collateral ligaments of the wrist are true ligaments and can be seen at the floor of the first and the sixth extensor compartments, respectively, using a high-resolution ultrasound. Based on their anatomic location, they most likely provide static stability to the wrist joint.