Palmar midcarpal instability: the results of treatment with 4-corner arthrodesis

Palmar midcarpal instability (PMCI) is one type of nondissociative carpal instability. The optimal treatment for PMCI is uncertain. The purpose of this investigation was to evaluate the results of capitate-lunate-triquetrum-hamate (4-corner) arthrodesis for PMCI.

Over a 10-year period 8 patients were treated with 4-corner arthrodesis for PMCI. The instability was diagnosed clinically and confirmed with cineradiography. The symptomatic instability began in all patients after a notable trauma; 6 of the patients were injured at work and 2 were injured in a motor vehicle accident. Patients were evaluated at an average of 34 months after surgery.

Seven of the 8 patients were satisfied with the surgery and 6 of 8 patients had no pain or mild pain. Both patients injured in motor vehicle accidents returned to all preinjury activities. Four of the 6 workers' compensation patients returned to work, 3 at full duty and 1 in a restricted position. Two patients, both with workers' compensation, did not return to their pre-injury jobs. One had occasional moderate pain and the other had chronic pain. The average wrist flexion/extension arc of motion decreased with surgery from 135 degrees to 75 degrees. The average grip strength increased significantly with surgery from 20 kg to 32 kg; however, grip strength remained significantly lower than the opposite side strength of 54 kg.

Four-corner arthrodesis is a reasonable option for PMCI. Compared with previous reports of soft tissue reconstruction 4-corner arthrodesis may provide a more reliable solution for this difficult problem.