Patients and methods
In 147consecutive patients with osteoarthritis of the trapeziometacarpal joint 151 (14 bilateral case) thumbs were surgically treated at Hospital Virgen de la Salud (Toledo, Spain) between 2013 and 2014. The indication for surgery was failure of conservative treatment in patients with TMC. 137 patients were seen for follow-up, 2 patients had died, and 18 patients were lost to follow -up.
Patients included in the study had undergone TMC joint arthroplasty for primary osteoarthritis, and conservative treatment fails, including steroid injections and physical therapy for a minimum of 6 to 12 weeks.
The ARPE TMC joint arthroplastyconsists of an unconstrained uncemented arthroplasty with a cup inserted into the trapezium and a stemmed component inserted into the thumb metacarpal.
At follow-up patients were asked to complete a visual linearanalogue scale (VAS) for satisfaction with the result of the operation and persisting pain from the thumb, the Spanish validated Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire was used to evaluate function of the affected hand (9). The radiological examination consisted of posterior-anterior and oblique radiographs. In preoperative radiographs Eaton-Little was used, and in postoperative radiographs were assessed with regard to implant loosening and alignment.

Surgical technique
A lateral approach was used in all cases, with the incision centred over the TMC joint, the extensor pollicis brevis was reflect dorsally and the abductor pollicis longus was reflected ventrally. The capsule of the TMC joint was opened longitudinally, and saw was used to cut off 6-8 mm of the proximal surface of the first metacarpal perpendicular to the metacarpal axis.
And awl was used to open the intramedullary canal of the first metacarpal bone and enlarged with rasps until satisfactory cortical contact was obtained. The trial stem was implanted, and the back of the stem was aligned with the nail of the thumb.
The fist metacarpal was then subluxate ventrally to provide access to the trapezium, a thin bone cut was made to remove a little bone as possible. The osteophytes were removed.
The centre of the trapezium in distal surface was identified and a hole was drilled with surgical awl, this hole was enlarged with curettes and trapezium reamer.
A trial head was inserted, and a trial reduction undertaken, the trail was assessed for stability and impingement. The definitive head was inserted and the joint reduced. The capsule and the skin were closed (Figure 1).
Figure 1.  Exemple of trapeziometacarpal prosthesis A short plaster of Paris arm cast in functional position for 3 weeks was used in all patients. After 3 weeks the cast was removed, and an exercise programme was undertaken.
The Kaplan-Meier method was used to estimate survival probability over time.
All surgeries were performed by the same experienced and fully qualified orthopaedic had surgeon, and at follow-up the patients were evaluated by Italian independent researchers.