Initial survival of the Isis® total trapeziometacarpal prosthesis with conical trunk threaded cups

The treatment of trapeziometacarpal osteoarthritis through the implantation of total trapeziometacarpal prostheses is in continuous expansion. The Isis® prosthesis is a trunk-conical threaded anchorage prosthesis. Our objective was to assess the functional results and survival of this implant for at least one year of follow-up.

Prospective study on 53 Isis® prosthesis, implanted from april 2014 to january 2019. The Van Cappelle functional test, pain, strength, mobility, return to previous activity, radiological variables and placement of the trapezial component were evaluated. The surgical technique was performed with a guide wirefocused on the trapezius and control of the scopia. Observed complications were recorded and statistical analysis was performed.

Fifty-one implants (49 patients) were reviewed. Mean follow-up was 2.1 years (1-5.7). Van Cappelle's test, pain, mobility, and grip and clamp strength improved significantly, as did the distance between the metacarpal head and the trapezius base; 96% of the patients returned in less than 6 months to their activities. Minor complications, 3 De Quervain's tendinopathy and 2 intra-operative metacarpal and 2 trapezium fractures were recorded, and one carpal tunnel syndrome. There was no dislocation, mobilization, or implant infection.

The functional results of the Isis® prosthesis are excellent in the short term, far exceeding the first year of 100% of survival. The complications that arose were minor and few. The anchorage and placement of the trapezial component guided by scopia seem to be crucial for the good result.