Recent TV coverage of the use of prostheses in animals1, 2 have brought to the attention the novel invention of the Intraosseus Transcutaneous Amputation Prosthesis (ITAP).3
Traditional prostheses are attached to limb stumps by straps or other attachment methods. Therefore the stump, covered in soft tissue and skin, presses on the prosthesis. This can lead to a number of complications, such as pressure sores. These prosthetics can also be quite inefficient if the muscles that move the prosthesis are active far away from the prosthesis.
The ITAP was developed by researchers at University College London to address these issues. The ITAP prevents trauma to soft tissues by redistributing stress to the bone. However, the ITAP creates a breach in the skin's protective barrier to infection - therefore a method was required to prevent infection from occurring around the entry point of the prosthesis. The ITAP was therefore modelled on deer antlers, as antlers represent bone that grows out of a skin base, without infection occurring (Fig. 1).
The research group developed a pin that could be inserted into bone, and which had an external peg to which a prosthetic limb could be attached (Fig. 2).
The surface of the pin is shaped with grooves to prevent rotation in the bone (Fig.2: 1), and also treated with a substance such as hydroxy apatite (a form of calcium phosphate), to encourage integration into the bone. The middle section of the pin consists of a flange (Fig.2: 4) that which forms a link between the bone and the epithelial surface of the soft tissue surrounding it. This flange has a porous coating (Fig.2: 6) to encourage soft tissue growth. This can further be promoted by treating the surfaces with adhesion-promoting proteins, such as fibronectin or laminin. The implant attaches directly to the skin at this point - something that has never been done before. A successful seal between the implant and the skin prevents infections. The exterior peg (Fig.2: 5) is treated with a diamond-like carbon layer that prevents the adhesion of micro-organisms, further reducing the risk of infection.
The ITAP was first used in a clinical trial in 2005 in a woman who had lost a thumb due to a bite from a horse.4 ITAP products have been used for the prosthetic replacement of 12 fingers and thumbs, 1 arm, 2 legs, and 5 craniofacial bones in humans, and for the replacement of thoracic and pelvic limbs in a number of cats and dogs (see a photo5 of Coal, an American Bulldog who received an ITAP at Fitzpatrick Referrals).
1 http://www.bbc.co.uk/programmes/b00syxlx
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2 http://www.fitzpatrickreferrals.co.uk/
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3 Blun G et al. Transcutaneous prosthesis. US patent 7014661
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4 http://www.ukti.gov.uk/investintheuk/sectoropportunities/lifesciences/localisation/110831.html (2010)
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5 Fitzpatrick N. Intraosseous Transcutaneous Amputation Prosthesis. The SPVS Review pp43-52 (2009)
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Traditional prostheses are attached to limb stumps by straps or other attachment methods. Therefore the stump, covered in soft tissue and skin, presses on the prosthesis. This can lead to a number of complications, such as pressure sores. These prosthetics can also be quite inefficient if the muscles that move the prosthesis are active far away from the prosthesis.
The ITAP was developed by researchers at University College London to address these issues. The ITAP prevents trauma to soft tissues by redistributing stress to the bone. However, the ITAP creates a breach in the skin's protective barrier to infection - therefore a method was required to prevent infection from occurring around the entry point of the prosthesis. The ITAP was therefore modelled on deer antlers, as antlers represent bone that grows out of a skin base, without infection occurring (Fig. 1).The research group developed a pin that could be inserted into bone, and which had an external peg to which a prosthetic limb could be attached (Fig. 2).
The surface of the pin is shaped with grooves to prevent rotation in the bone (Fig.2: 1), and also treated with a substance such as hydroxy apatite (a form of calcium phosphate), to encourage integration into the bone. The middle section of the pin consists of a flange (Fig.2: 4) that which forms a link between the bone and the epithelial surface of the soft tissue surrounding it. This flange has a porous coating (Fig.2: 6) to encourage soft tissue growth. This can further be promoted by treating the surfaces with adhesion-promoting proteins, such as fibronectin or laminin. The implant attaches directly to the skin at this point - something that has never been done before. A successful seal between the implant and the skin prevents infections. The exterior peg (Fig.2: 5) is treated with a diamond-like carbon layer that prevents the adhesion of micro-organisms, further reducing the risk of infection.
The ITAP was first used in a clinical trial in 2005 in a woman who had lost a thumb due to a bite from a horse.4 ITAP products have been used for the prosthetic replacement of 12 fingers and thumbs, 1 arm, 2 legs, and 5 craniofacial bones in humans, and for the replacement of thoracic and pelvic limbs in a number of cats and dogs (see a photo5 of Coal, an American Bulldog who received an ITAP at Fitzpatrick Referrals).1 http://www.bbc.co.uk/programmes/b00syxlx
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2 http://www.fitzpatrickreferrals.co.uk/
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3 Blun G et al. Transcutaneous prosthesis. US patent 7014661
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4 http://www.ukti.gov.uk/investintheuk/sectoropportunities/lifesciences/localisation/110831.html (2010)
Source
5 Fitzpatrick N. Intraosseous Transcutaneous Amputation Prosthesis. The SPVS Review pp43-52 (2009)
Source
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