# US 2015/0105830 A1 · Bone screw with self-constrained flexibility > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2015/0105830 A1 - Document ID: US20150105830A1 - Status: Published application - Kind: A1 - Application number: 14/511,123 - Filed: 2014-10-09 - Published: 2015-04-16 - Earliest claimed: 2013-10-11 - Assignees: Biedermann Technologies GmbH & Co. KG - Inventors: Lutz Biedermann; Wilfried Matthis; Bernd Fischer - Web page: https://patentgrep.com/patent/US20150105830A1 ## CPC - A61B 17/8625: {Shanks, i.e. parts contacting bone tissue} - A61B 17/8605: {Heads, i.e. proximal ends projecting from bone} - A61B 17/8685: {comprising multiple separate parts} - A61B 17/869: {characterised by an open form, e.g. wire helix} - A61B 17/686: {Plugs, i.e. elements forming interface between bone hole and implant or fastener, e.g. screw} - A61B 17/7001: {Screws or hooks combined with longitudinal elements which do not contact vertebrae (A61B17/7058 takes precedence)} - Y10T 29/49963: Threaded fastener - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A bone screw is provided including a longitudinal core member having a longitudinal axis defining a longitudinal direction and having an outer surface and a helical groove in the outer surface, the groove being defined by opposed sidewalls; and a helical thread body configured to be accommodated in the groove. When the thread body is assembled in the groove of the core member and when the core member is straight, the thread body is configured to abut one opposed sidewall without abutting the other opposed sidewall along a full turn of the thread body, the thread body is configured to slide in the groove between the opposed sidewalls of the helical groove parallel to the longitudinal axis, and a first portion of the thread body that is outside the helical groove has a height greater than a second portion of the thread body that is in the helical groove. ## Claims ### Claim 1 A bone screw comprising: a longitudinal core member defining a longitudinal axis and having an outer surface and, a helical groove in the outer surface, the helical groove being defined by opposed sidewalls and a bottom surface between the opposed sidewalls; and a helical thread body configured to be accommodated in the helical groove, wherein, when the thread body is assembled in the helical groove of the core member and when the core member is straight along the longitudinal axis, the thread body is configured to abut one opposed sidewall without abutting the other opposed sidewall along a full turn of the thread body, and wherein, when the thread body and the core member are assembled, a first potion of the thread body that is outside the helical groove has a height greater than a second portion of the thread body that is in the helical groove, and wherein the thread body is configured to slide in the groove between the opposed sidewalls of the helical groove in a direction parallel to the longitudinal axis. ### Claim 2 (depends on 1) The bone screw of claim 1, wherein the longitudinal core member is a solid body. ### Claim 3 (depends on 1) The bone screw of claim 1, wherein the helical groove has a first end and a second end, and comprises a first engagement portion at the second end, and wherein the thread body comprises a second engagement portion that is configured to engage the first engagement portion to hold the thread body in the groove. ### Claim 4 (depends on 1) The bone screw of claim 1, wherein the opposed sidewalls of the groove comprise a first sidewall and an opposite second sidewall as a first stop and a second stop, respectively, to limit the sliding of the thread body along the longitudinal axis. ### Claim 5 (depends on 4) The bone screw of claim 4, wherein the thread body is configured to abuts the first sidewall when no transverse load is applied to the core member. ### Claim 6 (depends on 4) The bone screw of claim 4, wherein, when a transverse load is applied to the core member, the thread body is configured to slide in the groove in the direction parallel to the longitudinal axis until portions of the thread body abut the second sidewall. ### Claim 7 (depends on 1) The bone screw of claim 1, wherein the helical groove has a first pitch and the thread body has a second pitch, and wherein the first pitch and the second pitch are the same as each other. ### Claim 8 (depends on 1) The bone screw of claim 1, wherein the helical groove has a first pitch and the thread body has a second pitch, and wherein the first pitch and the second pitch are different from each other. ### Claim 9 (depends on 1) The bone screw of claim 1, wherein the core member has a first end and a second end, and comprises a tip portion at the first end, and wherein an end of the thread body has a smaller outer diameter than adjacent portions of the thread body, and the smaller outer diameter matches an outer diameter of the tip portion. ### Claim 10 (depends on 1) The bone screw of claim 1, wherein the core member has a first end and a second end, and comprises a head at the second end. ### Claim 11 (depends on 10) The bone screw of claim 10, wherein the core member further comprises a shank, wherein the head and the shank are separable, and wherein the head is configured to be connected to the shank. ### Claim 12 (depends on 11) The bone screw of claim 11, wherein the shank comprises a threaded portion having an outer thread, and wherein the head has a threaded bore that is configured to engage the threaded portion of the head. ### Claim 13 (depends on 3) The bone screw of claim 3, wherein the first end of the groove is open. ### Claim 14 A method of assembling a bone screw, the method comprising: selecting a longitudinal core member defining a longitudinal axis and that comprises having an outer surface and a helical groove in the outer surface, the helical groove being defined by opposed sidewalls and a bottom surface between the opposed sidewalls; selecting a helical thread body configured to be accommodated in the helical groove; and screwing the helical thread body onto the core member, wherein, when the thread body is assembled in the helical groove of the core member and when the core member is straight along the longitudinal axis, the thread body is configured to abut one opposed sidewall without abutting the other opposed sidewall along a full turn of the thread body, wherein, when the thread body and the core member are assembled, a first portion of the thread body that is outside the helical groove has a height greater than a second portion of the thread body that is in the helical groove, and wherein the thread body is configured to slide in the groove between the opposed sidewalls of the helical groove in a direction parallel to the longitudinal axis. ### Claim 15 (depends on 14) The method of claim 14, wherein the helical groove has a first pitch and the thread body has a second pitch, and wherein the first pitch and the second pitch are the same as each other. ### Claim 16 (depends on 14) The method of claim 14, wherein the helical groove has a first pitch and the thread body has a second pitch, and wherein the first pitch and the second pitch are different from each other. ### Claim 17 A method of inserting a bone screw into a bond, the bone screw comprising a longitudinal core member defining a longitudinal axis and having an outer surface and a helical groove in the outer surface, the helical groove being defined by opposed sidewalls and a bottom surface between the opposed sidewalls; and a helical thread body configured to be accommodated in the helical groove, wherein , when the thread body is assembled in the helical groove of the core member and when the core member is straight along the longitudinal axis, the thread body is configured to abut one opposed sidewall without abutting the other opposed sidewall along a full turn of the thread body, and wherein, when the thread body and the core member are assembled, a first portion of the thread body that is outside the helical groove has a height greater than a second portion of the thread body that is in the helical groove, and wherein the thread body is configured to slide in the groove between the opposed sidewalls of the helical groove in a direction parallel to a longitudinal axis, the method comprising: preparing a core hole in the bone; and inserting the longitudinal core member with the thread body assembled in the helical groove of the core member into the core hole. ### Claim 18 (depends on 17) The method of claim 17, further comprising: attaching a head onto the core member before the inserting the longitudinal core member; and after the inserting the longitudinal core member, retracting the core member into the head.