Transcutaneous Implant for Skeletal Attachment of External Prosthetic Devices

Abstract

Provided herein are devices and methods for connecting a transcutaneous external prosthetic device to a bone, such as a bone of an amputee. The device is a two-piece transcutaneous implant device to provide reversible connection for ease of implantation, reliability, and relatively easy access for removal, while maximizing tissue ingrowth to reduce risk of infection and attendant adverse outcomes. The devices provided herein comprise a prosthetic interface and a bone anchor. A through-hole that traverses a longitudinal length of the prosthetic interface and at least a longitudinal portion of the bone anchor receives a fastener to reversibly connect the prosthetic interface to the bone anchor implanted in bone. A connector may connect to a failsafe element which, in turn, connects to an external prosthetic device.

1 . A transcutaneous device to anchor an external prosthetic device to a bone, the transcutaneous device comprising:
 a bone anchor configured for implantation into bone;   a prosthetic interface for connecting an external prosthetic device to the bone anchor, wherein the prosthetic interface comprises a shaped tissue ingrowth surface configured to maximize available surface area for soft tissue ingrowth and vascularization; and   a through-hole that traverses a longitudinal length of the prosthetic interface and at least a longitudinal portion of the bone anchor for receiving a fastener to reversibly connect the prosthetic interface to the bone anchor implanted in bone;   wherein the prosthetic interface is configured for implantation external to bone and for soft tissue ingrowth and vascularization after implantation.   
     
     
         2 . The transcutaneous device of  claim 1 , further comprising:
 a fastener that is a bolt to secure the prosthetic interface to the bone anchor.   
     
     
         3 . The transcutaneous device of  claim 2 , wherein the bolt is reversibly connected to the bone anchor, so that the prosthetic interface can be removed from the bone anchor by removing the bolt from the bone anchor. 
     
     
         4 . (canceled) 
     
     
         5 . The transcutaneous device of  claim 1 , wherein the prosthetic interface comprises a connector to mate the transcutaneous device to an external prosthetic device. 
     
     
         6 . The transcutaneous device of  claim 1 , having an external prosthetic device-prosthetic interface failure load that is less than a bone anchor-bone failure load or an implant failure load, thereby minimizing or avoiding damage to the bone or the implant by a force exerted on an external prosthetic device that in the absence of the external prosthetic device-prosthetic interface failure load results in bone damage or catastrophic implant failure; and optionally the external prosthetic device-prosthetic interface failure load is provided by a failsafe. 
     
     
         7 . (canceled) 
     
     
         8 . The transcutaneous device of  claim 1 , wherein the shaped tissue ingrowth surface has a geometry that is bulbous. 
     
     
         9 . The transcutaneous device of  claim 1 , wherein the shaped tissue ingrowth surface comprises:
 an apex region concentrically positioned on a distal portion of a central body outer surface,   a rounded radial edge portion; and   a convex outer-facing surface extending between the apex region and rounded radial edge portion;   thereby maximizing surface area available for soft-tissue ingrowth and vascularization.   
     
     
         10 . (canceled) 
     
     
         11 . The transcutaneous device of  claim 1 , wherein the prosthetic interface further comprises a solid ring to mechanically stabilize the shaped tissue ingrowth surface to the central body. 
     
     
         12 . The transcutaneous device of  claim 1 , wherein the prosthetic interface further comprises a suture ring positioned at the apex region of the tissue ingrowth surface to provide an anchoring point for skin upon implantation. 
     
     
         13 . The transcutaneous device of  claim 1 , wherein a distal portion of the bone anchor and a proximal portion of the prosthetic interface is formed from or coated with a highly porous material to facilitate ingrowth of target tissue, wherein optionally the highly porous material comprises tantalum with dodecahedral interconnecting pores, having a porosity selected from a range that is greater than 70% and less than 90%, and an average pore diameter that is selected from a range that is greater than 100 μm and less than 700 μm. 
     
     
         14 . The transcutaneous device of  claim 13 , wherein the pore size is selected to the target tissue surrounding the bone anchor and prosthetic interface, with target tissue that is bone having a pore size that is smaller than for target tissue that is soft tissue. 
     
     
         15 . The transcutaneous device of  claim 13 , wherein the highly porous material further comprises antibiotics, anti-infectious chemicals, and/or morphogenic proteins. 
     
     
         16 . The transcutaneous device of  claim 13 , wherein the proximal portion of the prosthetic interface connects to the distal portion of the bone anchor at a step-off region, wherein the proximal portion and distal portions each have an outer dimension, and the proximal portion outer diameter is greater than the distal portion outer parameter to provide a stable base to seat the prosthetic interface against a surface of the bone in which the bone anchor is implanted. 
     
     
         17 . The transcutaneous device of  claim 16 , wherein the bone anchor has a tip end, and the distal portion of the bone anchor coated with a highly porous material extends:
 substantially to the tip end; or   part way to the tip end, and a solid stem extends from the distal portion of the bone anchor coated with a highly porous material to the tip end.   
     
     
         18 . (canceled) 
     
     
         19 . (canceled) 
     
     
         20 . (canceled) 
     
     
         21 . (canceled) 
     
     
         22 . The transcutaneous device of  claim 17 , wherein a portion of the solid stem receives the through-hole, and the through-hole of the solid stem is threaded for receiving the fastener that connects the prosthetic interface with the bone anchor. 
     
     
         23 . The transcutaneous device of  claim 1 , further comprising a failsafe connected to the prosthetic interface. 
     
     
         24 . A method for implanting a transcutaneous device for connecting an external prosthetic device to a bone, said method comprising the steps of:
 inserting a bone anchor into an intramedullary canal of the bone;   providing a prosthetic interface;   passing a fastener through a through-hole of the prosthetic interface and a through-hole of the bone anchor; and   fastening the fastener to the bone anchor, thereby connecting the prosthetic interface to the bone anchor and arranging the prosthetic interface for receipt of an external prosthetic device.   
     
     
         25 . The method of  claim 24 , further comprising connecting the external prosthetic device to a distal portion of the prosthetic interface. 
     
     
         26 . The method of  claim 24 , wherein the prosthetic interface is positioned outside the bone and skin overlaying the bone is attached to the prosthetic interface. 
     
     
         27 . The method of  claim 24 , wherein the fastener is configured to be removed to facilitate extraction of the prosthetic interface or the prosthetic interface and the bone anchor. 
     
     
         28 . (canceled) 
     
     
         29 . (canceled) 
     
     
         30 . (canceled) 
     
     
         31 . (canceled) 
     
     
         32 . (canceled) 
     
     
         33 . (canceled)