Method for producing undercut micro recesses in a surface, a surgical implant made thereby, and method for fixing an implant to bone

A method for producing a multiplicity of undercut micro recesses in a surface of an article in a selected pattern which can be repeated in any selected number of surfaces, the method comprising:

• applying a maskant layer to substantially an entirety of a selected surface of the article;
• removing portions of the maskant layer by computer-directed laser ablation in programmed loci to expose underlying portions of the surface of the article in a programmed pattern;
• applying an etchant to the exposed underlying surface portions for a time sufficient to etch the exposed surface portions and to enable the etchant to etch beneath remaining portions of the maskant layer and produce the multiplicity of undercut recesses;
• and
• removing the remaining maskant layer portions to provide the selected surface in exposed condition with the multiplicity of undercut recesses therein.

A method for producing a surgical implant having facility for stimulating ingrowth of bone upon attachment of the implant to a bone, the method comprising:

• providing a rigid article;
• applying a maskant layer to substantially an entirety of a datum surface of the article;
• removing portions of the maskant layer in selected loci to expose underlying portions of the datum surface of the article;
• applying an etchant to the exposed underlying datum surface portions for a time sufficient to enable the etchant to undercut remaining portions of the maskant layer and produce a multiplicity of undercut recesses having sharp edges at their intersections with the datum surface;
• and
• removing the remaining portions of the maskant layer to provide the datum surface in exposed condition with the sharp edges for shaving particulate matter from the bone, and with the recesses for receiving and retaining the bone particulate matter for stimulating ingrowth of bone.

A method for producing a textured surface in a surgical implant, the method comprising:

• applying a maskant layer to substantially an entirety of a datum surface of the implant;
• removing portions of the maskant layer in selected loci to expose underlying portions of the datum surface of the implant;
• applying an etchant to the exposed underlying datum surface portions for a time sufficient to etch the exposed surface portions and to enable the etchant to etch beneath remaining portions of the maskant layer and produce a multiplicity of undercut recesses having sharp edges at their intersections with the datum surface;
• and
• removing the remaining portions of the maskant layer to provide the datum surface in exposed condition with the sharp edges for shaving particulate matter from the bone, and with the recesses for receiving and retaining the bone particulate matter for stimulating ingrowth of bone.

A method for attaching a surgical implant to a bone, the method comprising:

• providing a surgical implant having a datum surface and a multiplicity of undercut micro recesses in the datum surface, such that the implant exhibits a greater fractal area at a level below the datum surface than is exhibited at the datum surface, intersections of the datum surface and the recesses defining sharp edges;
• pressing the datum surface against a surface of the bone;
• and
• urging the implant along the bone surface, to cause the sharp edges to shave particulate bone matter from the bone;
• wherein the recesses receive and retain the particulate bone matter which stimulates ingrowth of the bone.

A method for attaching a surgical implant to a bone, the method comprising:

• providing a surgical implant having a datum surface, a multiplicity of micro recesses in the datum surface, and bone milling structure on the datum surface;
• pressing the datum surface against a surface of the bone;
• and
• urging the implant along the bone surface to mill particulate bone matter from the bone;
• wherein the recesses are adapted to receive and retain the particulate bone matter which stimulates ingrowth of the bone.

A method for making a surgical implant having generally opposed datum surfaces spaced from each other by a predetermined distance, each of the datum surfaces being adapted to interlock with a bone surface, the method comprising the steps of:

• providing an article having first and second datum surface portions adapted to respectively engage first and second bone surfaces, the datum surface portions being spaced from each other by the predetermined distance which is substantially equal to a distance between the first and second bone surfaces;
• applying a maskant layer to substantially an entirety of each of the datum surfaces;
• removing the maskant layers in selected loci to expose underlying portions of the datum surfaces in selected patterns;
• applying an etchant to the exposed underlying datum surface portions for a time sufficient to etch the exposed portions of the datum surfaces and to enable the etchant to etch beneath the remaining maskant layers and produce undercut recesses;
• and
• removing the remaining maskant to provide the opposed datum surfaces in exposed condition with the multiplicity of undercut recesses;
• wherein the datum surfaces are devoid of structure protruding therefrom.

A surgical implant comprising:

• an article having a datum surface for abutting engagement with a bone;
• a multiplicity of undercut micro recesses in the datum surface, such that said article exhibits a greater fractal area at a level below the surface than is exhibited at the datum surface;
• intersections of said recesses and the datum surface defining sharp edges adapted to cut the bone and produce bone particulates;
• said recesses being adapted to receive and retain the bone particulates cut from the bone by the edges, to stimulate ingrowth of the bone into said recesses.