Amputees may be able to hear and feel through their prostheses, study finds
A team of Swedish researchers have found that people with prostheses attached directly to their bones can detect sound using the implants, demonstrating the flexible boundaries of human perception.
‘Osseoperception’, which was first observed in patients with dental implants, is a special sensory ability; the awareness of surroundings provided by a prosthesis. It has been described as a “feeling” arising from vibrations which travel from the implant and through the skeleton.
However, researchers were uncertain as to whether vibrations could travel through bones other than the skull, and still be heard, rather than simply felt.
“Until now, the consensus was that the sense of touch played the primary role in osseoperception for patients with artificial limbs fixated into their skeletons,” says Dr Max Ortiz Calatan, who supervised the research.
Scientists from the University of Gothenburg, Chalmers University of Technology and Sahlgrensky University Hospital collaborated on the study, which appears in the current issue of the journal Nature Scientific Reports.
The researchers applied different vibrations to patients with prosthetic limbs made from titanium and connected to their bone. They found that patients could hear and feel the vibrations, expanding their sensory awareness. Even subtle sensory stimuli were found to travel through the body through an artificial limb, and be perceived as sound.
The study demonstrated that attaching artificial limbs directly to the bone – osseointegration – improves patients’ function, comfort, and sharpens their ability to perceive their surroundings.
Their findings open up new possibilities for developing improved prostheses which could, for instance, help amputees regain natural feeling while holding an object, or walking over an uneven surface.
“In practice, the stimuli received by the patients are perceived more strongly and carry more information because they are composed of two modalities; touch and hearing,” says Dr Ortiz Catalan. “This is an important step forward in understanding the osseoperception phenomenon and, more generally, the tactile and auditory perception of humans. This discovery may offer a new starting point for implementing novel prostheses that provide enriched sensory feedback to the user.”