Virtual trial reduction system for hip arthroplasty and coordinate systems therefor

• US 8,078,254 B2
• Filed: 06/01/2004
• Issued: 12/13/2011
• Est. Priority Date: 06/02/2003
• Status: Active Grant

• Current Assignee: M.D. Stephen B. Murphy
• Original Assignee: M.D. Stephen B. Murphy
• Inventors: Murphy, Stephen B.
• Primary Examiner(s): Hindenburg, Max
• Assistant Examiner(s): DANEGA, RENEE A
• Application Number:
  US10/565,921
• Publication Number:
  US 20060264731A1
• Time in Patent Office: 2,751 Days
• Field of Search: 600/407, 600/587, 600/424
• US Class Current: 600/407
• CPC Class Codes: A61B 17/1659 Surgical rasps, files, planes, or scrapers
• CPC Class Codes: A61B 2034/102 Modelling of surgical devices, implants or prosthesis
• CPC Class Codes: A61B 2034/105 Modelling of the patient, e.g. for ligaments or bones
• CPC Class Codes: A61B 2034/108 Computer aided selection or customisation of medical implants or cutting guides
• CPC Class Codes: A61B 2034/2055 Optical tracking systems
• CPC Class Codes: A61B 2034/2072 Reference field transducer attached to an instrument or patient
• CPC Class Codes: A61B 2034/256 having a database of accessory information, e.g. including context sensitive help or scientific articles
• CPC Class Codes: A61B 34/10 Computer-aided planning, simulation or modelling of surgical operations
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 90/36 Image-producing devices or illumination devices not otherwise provided for
• CPC Class Codes: A61F 2/36 Femoral heads ; Femoral endoprostheses
• CPC Class Codes: A61F 2/4607 of hip femoral endoprostheses
• CPC Class Codes: A61F 2/4609 of acetabular cups
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• CPC Class Codes: A61F 2/4684 Trial or dummy prostheses
• CPC Class Codes: A61F 2002/30616 Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/3611 Heads or epiphyseal parts of femur
• CPC Class Codes: A61F 2002/3625 Necks
• CPC Class Codes: A61F 2002/4632 using computer-controlled surgery, e.g. robotic surgery
• CPC Class Codes: A61F 2002/4658 for measuring dimensions, e.g. length
• CPC Class Codes: A61F 2002/4668 : for measuring angles

Abstract

A patient-specific pelvic coordinate system is produced from a single near AP intra-operative image of the patient, obviating the need for use of a patient tracker.

Claims

1. A method for providing, without using a patient tracker, a patient-specific pelvic coordinate system from a single near AP intra-operative image of the patient, said method comprising:

forming a single intra-operative fluoroscopic image of the patient'"'"'s pelvis in the near AP direction using an x-ray source;

defining first and second landmarks on anatomically separated regions of said pelvis on said image, said landmarks being separated from each other in at least an anterior-posterior direction;

determining the transaxial displacement of said landmarks on said image;

determining the axial displacement of said landmarks on said image;

calculating by a processor the axial rotation of the pelvis using the transaxial displacement as a measure of the axial rotation of said pelvis with respect to the plane of said image, and

calculating by a processor the transaxial rotation of the pelvis using said axial displacement as a measure of the transaxial rotation of said pelvis with the respect to the plane of said image.

2. The method of claim 1 in which the axial rotation of the pelvis is calculated as a function of the transaxial displacement and the distance between the x-ray source and the image plane.

3. The method according to claim 1 wherein said first landmark comprises the image point of the public symphysis.

4. The method according to claim 1 wherein the second landmark comprises the midpoint of a line between corresponding points on said image of the left and right sacroiliac joints.

5. The method according to claim 1 wherein said displacements are normalized with respect to the separation between a further pair of landmarks on the pelvis.

6. The method according to claim 5 wherein said further pair of landmarks comprises the left and right teardrops.