Changes in carpal ligament length in throwing motion of the wrist

Abstract

Objective To investigate changes in wrist ligament length when the wrist is in different throwing positions.Methods Six wrists of 6 volunteers were enrolled in the experiment to obtain CT scans at 5 throwing positions of the wrist:20 degrees of radial deviation with 60 degrees of extension,10 degrees of radial deviation with 30 degrees of extension,neutral,20 degrees of ulnar deviation with 30 degrees of flexion,and 40 degrees of ulnar deviation with 60 degree of flexion.The carpal and distal radioulnar joint structures were reconstructed 3-dimensionally with customized software.Changes in length of the palmar and dorsal wrist ligaments in throwing motion were computed with the software. Results From wrist radial deviation with extension to ulnar deviation with flexion,the lengths of the radioscaphocapitate(RSC)ligament.the long radiolunate ligament(LRL),the ulnoceapitate ligament(UC)and the ulnotriquetral ligament (UT)decreased significantly(P<0.05),but the lengths of dorsal radiocarpal ligament(DRC)and the dorsal interearpal ligament(DIC)inserting on the trapezoid increased significantly(P<0.05).The lengths of ulnolunate ligament(UL)and the dorsal interearpal ligament inserting on the seaphoid were the shortest when the wrist was in the neutral position. Conclusions At wrist ulnar deviation with flexion,the RSC,LRL.UC and UT ligaments are slack.At wrist radial deviation with extension.the DRC ligament and the dorsal intercaroal ligament inserrting on the trapezoid are slack.The UL ligament and the dorsal intercarpal ligament inserting on the seaphoid are the slackest in the neutral position.These positions may be favorable to the healing of these ligaments. Key words: Carpal joints; Ligaments; Movement; In vivo study