Trapeziometacarpal osteoarthrosis: clinical results and sonographic evaluation of the interposed tissue after trapeziectomy and first metacarpal suspension by external minifixation at a minimal two-year follow-up.

Among the surgical options to treat trapeziometacarpal osteoarthrosis, trapeziectomy has been criticized as unable to prevent postoperative collapse of the thumb, causing painful scapho-metacarpal impingement. The implantation of an external minifixator between the first and the second metacarpals for sufficient time has been proposed to maintain the postoperative space created by the bone resection to allow the development of a resistant interposed fibrous tissue. Nineteen patients (16 women, 3 men, mean age 64.5 years) were evaluated at 3.3 years of follow-up after an unilateral trapeziectomy and first metacarpal suspension by external minifixation. Eighty-four percent of the patients were very satisfied with the operation. The mean DASH score was 27.7%, the pain 1.7/10 (Visual Analogue Scale), the opening angle of the first web 58.3° and the Kapandji opposition score 9.5/10. Sonography demonstrated the existence of a strong fibrotic interposed tissue, preventing scapho-metacarpal impingement. The mean height of the trapeziectomy space (8.4mm) was maintained upon active pinch and maximal traction on the thumb. A significant atrophy of thenar muscles was also demonstrated, except for the Abductor pollicis brevis. In conclusion, total trapeziectomy with external minifixation provides acceptable clinical results, stabilizes the base of the thumb and prevents scapho-metacarpal impingement. The study brings also important new information about the nature of the interposed tissue in the trapezial space and about the state of the thenar muscles after trapeziectomy.