The concept of first metacarpal M1-M2 arch. New interest in trapeziometacarpal prostheses.

Analysis of the M1-M2 arch, otherwise known as the M1-M2 metacarpal hanger, objectively helps all surgeons treating basal thumb osteoarthritis to fit a trapeziometacarpal prosthesis that respects the physiological length of the thumb column and thus the physiological tensions of the APL, EPL, and EPB tendons as well as the interossei and thenar muscles. Kapandji X-ray views are a gold-standard in the radiological study of basal thumb osteoarthritis, to classify progression, measure trapezium height, and assess the deformity. Ledoux's M1/M2 ratio is the only method for assessing the normal length of the thumb column but cannot be easily used during surgery.

[Retinaculum flexors: clinical and experimental anatomic bases in favor of reconstruction in carpal tunnel surgery].

The goal of this anatomical study is to prove that reconstruction of the flexor retinaculum in carpal tunnel syndrome surgery is a reliable procedure and can improve the results of this procedure. In the first static study, we noted that when left to heal spontaneously, after 3 months the gap between the two edges of the cut retinaculum remained equal to or even larger than the gap created at the time of the surgery. A special Canaletto implant was created to achieve this reconstruction.