# US 12,004,755 B2 · Surgical power drill including a measuring unit suitable for bone screw length determination > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,004,755 B2 - Document ID: US12004755B2 - Status: Granted - Kind: B2 - Application number: 18/048,806 - Filed: 2022-10-21 - Published: 2023-04-13 - Granted: 2024-06-11 - Earliest claimed: 2020-07-01 - Assignees: Synthes GmbH - Applicants: Synthes GmbH - Inventors: Markus Windolf; Michael Schuetz - Web page: https://patentgrep.com/patent/US12004755B2 ## CPC - A61B 17/1626: {Control means; Display units} - A61B 17/1615: {Drill bits, i.e. rotating tools extending from a handpiece to contact the worked material} - A61B 17/1622: {Drill handpieces (A61B17/1626, A61B17/1628 take precedence)} - A61B 17/1633: {Sleeves, i.e. non-rotating parts surrounding the bit shaft, e.g. the sleeve forming a single unit with the bit shaft (A61B17/1644 takes precedence)} - A61B 2090/061: {for measuring dimensions, e.g. length} - A61B 2090/062: {penetration depth} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract A device (25) for drilling holes in bone and configured to determine bone screw length, the device (25) including a surgical power drill (2) comprising: a) a housing (12) and; b) a measuring device (1) releasably attached or fixed to the housing (12), wherein the measuring device (1) is configured to measure the distance (x) covered by the housing (12) in the direction of the longitudinal axis (7) and relative to a surface of an implant (26) or a bone during a drilling process, wherein the measuring device (1) comprises a processing unit (14) to record the distance (x) covered with respect to time; the processing unit (14) comprises one or more differentiators to determine at least the first and second derivatives of the distance (x) covered with respect to time; and the processing unit (14) further comprises a peak detector to analyze one or more peaks occurring in the graph of the highest derivative with respect to time, and wherein the measuring device (1) comprises a laser device or an ultrasound position sensor for displacement assessment. ## Claims ### Claim 1 A device for drilling holes in bone and determining a length of a bone screw, the device comprising: a surgical power drill comprising a housing and a drill bit that is configured to drill into the bone, wherein the drill bit extends along a longitudinal axis; a measuring device releasably attached to or non-releasably fixed to the housing, wherein the measuring device is configured to measure a distance traveled by a cutting tip of the drill bit in a drilling direction along the longitudinal axis and relative to a surface of an implant, an instrument, or the bone during a drilling process, wherein the measuring device comprises a processing unit configured to measure the distance traveled by the cutting tip in the drilling direction relative to the surface of the implant, the instrument, or the bone with respect to time; wherein the processing unit comprises one or more differentiators configured to determine at least first and second derivatives of the distance traveled with respect to time; and wherein the processing unit further comprises a peak detector configured to analyze one or more peaks of the second derivative or a highest one of the derivatives with respect to time so as to determine that the cutting tip has exited a cortex of the bone. ### Claim 2 (depends on 1) The device of claim 1, further including: a motor and a spindle driven by the motor within the housing, wherein the spindle has a longitudinal axis. ### Claim 3 (depends on 1) The device of claim 1, wherein the measuring device is configured to measure the distance traveled by the cutting tip the drilling direction relative to the surface of the implant or the bone during the drilling process. ### Claim 4 (depends on 1) The device of claim 1, wherein the one or more differentiators are configured to determine at least first and second derivatives of the distance traveled with respect to time at any instant and to record at least a graph of a highest derivative with respect to time. ### Claim 5 (depends on 1) The device of claim 1, wherein the processing unit further comprises a peak detector configured to analyze one or more peaks of the highest derivative with respect to time. ### Claim 6 (depends on 1) The device of claim 1, wherein the measuring device comprises a laser device or an ultrasound position sensor for displacement assessment. ### Claim 7 (depends on 1) The device according to claim 1, wherein the peak detector is configured to identify an acceleration peak when a maximum value of determined acceleration exceeds a pre-defined threshold value. ### Claim 8 (depends on 1) The device according to claim 1, wherein the peak detector is configured to identify a jerk peak when a maximum value of a determined jerk exceeds a predefined threshold value. ### Claim 9 (depends on 1) The device according to claim 1, wherein the processing unit comprises a microprocessor or a central processing unit having a processor register configured to record the distance traveled by the cutting tip of the drill bit in the drilling direction along the longitudinal axis and relative to the surface of the implant or the bone with respect to time during the drilling process, wherein the microprocessor or central processing unit is programmed to compute the at least first and second derivatives of the distance traveled by the cutting tip of the drill bit in the direction of the longitudinal axis and relative to the surface of the implant or the bone with respect to time and thus forms at least a first and a second differentiator and wherein the microprocessor or central processing unit is programmed to form the peak detector. ### Claim 10 A method for analyzing a bone drilling operation, the method comprising steps of: advancing a drill bit of a surgical power drill into a bone along a drilling direction so as to drill a hole in the bone and; during the advancing step, measuring a position of a cutting tip of the drill bit along the drilling direction with respect to time, the position of the cutting tip being measured relative to one of 1) a surface of the bone, 2) a surface of an implant, and 3) a surface of an instrument; determining at least first and second derivatives of the position versus time, so as to determine at least one of velocity and acceleration, respectively, versus time; and identifying one or more peaks of the second derivative or a highest one of the derivatives with respect to time so as to determine that the cutting tip has exited a cortex of the bone. ### Claim 11 (depends on 10) The method of claim 10, wherein determining at least the first and second derivatives comprises determining a third derivative of the position versus time, such that the velocity, the acceleration, and a jerk, respectively, versus time are determined. ### Claim 12 (depends on 10) The method of claim 10, wherein the measuring step is a contactless measuring step. ### Claim 13 (depends on 12) The method of claim 12, wherein the measuring step comprises actuating one of a laser device and an ultrasound position sensor so as to measure the position of the cutting tip. ### Claim 14 (depends on 12) The method of claim 12, further comprising the step of performing laser triangulation so as to perform the measuring step. ### Claim 15 (depends on 10) The method of claim 10, wherein the step of determining at least the first and second derivatives is performed in real time. ### Claim 16 (depends on 10) The method of claim 10, further comprising the step of determining a relative position between a first member that is fixed to a housing of the surgical power drill that includes the drill bit, and a second member which is displaceable along a longitudinal direction that includes the drilling direction when it has been determined that the cutting tip has exited the cortex of the bone. ### Claim 17 (depends on 16) The method of claim 16, further comprising the step of selecting a bone screw having a length corresponding to the relative position between the second member and the first member. ### Claim 18 (depends on 16) The method of claim 16, further comprising the step of frictionally fitting a clamping portion of the second member to the drill bit. ### Claim 19 (depends on 16) The method of claim 16, further comprising: positioning the surgical power drill relative to the bone so that a front end of the second member and the cutting tip of the drill bit abut the surface of the bone; and storing a relative position from the positioning step as a starting point for measurement of a position of the cutting tip relative to the surface of the bone in the drilling direction with respect to time. ### Claim 20 (depends on 10) The method of claim 10, further comprising the step of identifying an acceleration peak when a maximum value of determined acceleration exceeds a predefined threshold value.