The Ascension PyroCarbon proximal interphalangeal (PIP) total joint is used in osteoarthritis of the PIP finger joint. No systematic study of the positioning of this prosthesis and its relation to proximal and middle phalanx morphology has yet been reported.
Positioning of the proximal and distal components of the Ascension PyroCarbon PIP total joint was radiographically analysed in 152 human cadaver fingers.
Ideal implant position in the axis of the phalanx and with contact of the implant head with bone in both the frontal and sagittal planes was seen in only 33 % of the phalanges. Implant malposition was observed in the remaining 67 % of phalanges.
The current design of the Ascension PyroCarbon PIP total joint can lead to malpositioning that we attribute to its incomplete accommodation of the morphology of the proximal and middle phalanx, the surgical challenges the design poses, or both acting together.