Jamie Isenstein - Arm Chair, 2006

While not activated as a relational prosthetic, since it exists as a performance/sculpture rather than as an interaction between artist/chair and audience/potential-participant, Arm Chair nevertheless could be one and is therefore worth considering.

From the artist's gallery portfolio:

An Intimate Transaction, Between Two People With No History and No Future

Sarah Zarr in her short essay, "Something for the Pain," about her trip to the physiotherapist's office:

"The claustrophobic space, and us so close in it, made me want to giggle or crack a joke.  But I remained dignified and managed to act like people ask to touch my hips every day."

and

David Cross - Bounce, 2006

All images, video and text from the artist's website:

Bounce is a one day performance/installation that explores the relationship between pleasure, danger and the uncanny.  Over a seven-hour period the audience are invited to engage/interact with a large inflatable children’s play structure.  The leisurely ambience of the work is recast however by the unforeseen presence of the artist.  Two small eyeholes on the top of the structure reveal a body inside watching the audience from within.  The relational enjoyment of the work is recast by this uncanny moment of uncertainty when play is interrupted by a fragmentary live presence.  Bounce is a performance/intallation that renegotiates the artist/audience relationship mixing conviviality and recreation with violence and phobia.  it navigates a space between the real and fantasy linking the visceral transgression of body art with languages of everyday gratification.

David Cross - Re-Tard, 2007

All images and text from the artist's website:

3 Photographs, Assorted Sculptural Objects, Performance.

Re-tard examines the relationship between, [sic] abstraction, children’s recreational structures and the grotesque.. Utilising commercially manufactured canvas props set up as a tableaux in the gallery space, the work consists of two modes, an opening performance and a subsequent interactive installation.  Three large coloured panels are positioned diametrically across the gallery space.  The panels have slots where my body and the bodies of the performers penetrate the surface.  Each panel has two air holes where an assortment of attachable components can be fitted or removed.  As in a children’s fun house, the audience are encouraged to manipulate the pieces by attaching or removing individual components.  As well as the tableaux of objects, three large-scale photographs of the panels with my body positioned inside them are located on the gallery walls..Re-tard picks at the blurry edges of abstraction where formal concerns intercede with the popular languages of infantile play structures.