Introduction: The surgical gold standart treatment of the thumb osteoarthritis is the trapeziectomy with tendon interposition and ligament reconstruction. The trapeziometacarpal prosthesis is an option badly estimated in the literature.
Between 1994 and 2001, 43 non-cimented trapeziometacarpal prosthesis ARPE® (Biomet™) was implanted by the same operator for isolated trapezio-metacarpal degenerative osteoarthritis. The minimal follow-up is 5 years.
The aim of this study is to evaluate the fonction of the thumb with a 5 year-old or more trapeziometacarpal prosthesis. The technique is described and the revisions are analysed.
Material and methods: 33 women and 2 men, mean age 59,4-years, were operated after failure of the conservative treatment. There are 7 lost sight (9 prosthesis) and 2 deaths (2 prosthesis). 27 other patients (32 prostheses) were examined by the author with an original revision questionnary associated to the score of DASH. The average follow up for the 25 prosthesis always implanted is 86 months.
7 revisions (16%) were necessary on average after 34 months (1 month in 10 years) : 5 for loosenning, 1 for premature dismantling and 1 for recurrent partial dislocation. 6 were treated by trapeziectomy with tendinous interposition of palmaris longus according to the technique of F.E. Jones.
Results: The mobility is perfect for all patients but one. There is no tendancy for the cup or steem to sink into the bone but there is often some medial calcifications around the trapezium. Average DASH score is 27.4/100. There is no infection and only one dislocation at 1 months (reduction by closed procedure). The survival of the prosthesis is 85% in 5 years.
In the first 13 months, 4 revisions is necessary. The ablation of the cup is easy but the extraction of de metacarpal still is often difficult. The scaphometacarpal height is constantly lowered (34,5 % on average). Aesthetically, 2 patients are disappointed and preferred their thumb with prosthesis.
Discussion and conclusion: The prosthesis ARPE ® is an effective option in this series for the treatment of the degenerative trapeziometacarpal osteoarthritis but its radioclinic control is necessary for the first year.
