The CapFlex-PIP© implant is a modular gliding surface proximal interphalangeal (PIP) joint prosthesis. For implantation, there are two approaches available: The dorsal central split approach according to Swanson and the volar approach described by Simmen.~Our experiences and data from our prospective registry indicate, that the active extension of the PIP joint is better after the dorsal approach, but sometimes related with hyperextension of the PIP joint and secondary swan-neck deformity. Extension is supposed to be better after the volar approach, but associated with active and passive extension lag. Evidence of theses experiences will assist the surgeon in the preoperative planning to select the appropriate approach according to the patient's needs.~The primary objective is to investigate the active extension six months after implantation of the CapFlex-PIP© arthroplasty, comparing the dorsal with the volar approach.~This is a randomized controlled trial.
The primary objective is to investigate the active extension six months after implantation of the CapFlex-PIP© arthroplasty, comparing the dorsal with the volar approach.~This is a randomized controlled trial including 70 patients with PIP OA indicated for CapFlex arthroplasty.