Post Market Clinical Follow-Up KeriFlex®

Inclusion Criteria: * Adult patients (age ≥ 18 years) * Patients who are going to undergo arthroplasty of the metacarpophalangeal or proximal interphalangeal joint using a KeriFlex® implant in accordance with the instructions for use and the labelling in force. * Patients with rheumatoid arthritis, osteoarthritis or post-traumatic osteoarthritis Exclusion Criteria: * Pregnant or breastfeeding women * Patients with an intellectual disability who cannot follow their surgeon's instructions * Patients with general surgery contraindications and particularly to the implantation of a KeriFlex® implant * Patients with acute or chronic, local or systemic infections * Metacarpal or phalanx destruction or poor bone quality preventing adequate fixation * Muscle loss, alteration or vascular deficiency in the affected finger * Patients with significant physical activity involving treated joint * Children, young growing patients with open epiphyses