ASSESSMENT OF THUMB POSITIONING IN THE TREATMENT OF ULNAR COLLATERAL LIGAMENT INJURIES - A LABORATORY STUDY

In the treatment of ulnar collateral ligament injuries in the metacarp ophalangeal joint of the thumb, a cast or splint is often molded with the thumb and hand positioned so the patient can return quickly to a p articular sport or activity. However, it is unknown whether a given po sition of immobilization or whether an early rehabilitation program wi ll compromise ligament healing by causing undue tension in the ligamen t. To better define acceptable positions for thumb immobilization and a safe range of motion, this laboratory study measured strain in the u lnar collateral ligament at different degrees of metacarpophalangeal j oint flexion. Ligament strain was found to increase with increasing jo int flexion; the most significant increases in strain occurred as the joint moved from 0 degrees to 25 degrees of flexion, with the dorsal p ortion of the ligament demonstrating greater strain than the palmar po rtion. Based on these results, immobilization of the metacarpophalange al joint in excessive flexion and unrestricted early rehabilitation ex ercises should be done with caution and guided by the grade of injury or the quality of repair.