0
Research Papers

Shaping Patient Specific Surgical Guides for Arthroplasty to Obtain High Docking Robustness

[+] Author and Article Information
Joost Mattheijer

Leiden University Medical Center,
Biomechanics and Imaging Group,
Department of Orthopaedics,
Albinusdreef 2,
Leiden 2333 ZA, The Netherlands;
Department of BioMechanical Engineering,
Delft University of Technology,
Mekelweg 2,
Delft 2628 CD, The Netherlands
e-mail: J.Mattheijer@lumc.nl

Just L. Herder

Department of Precision and Microsystems Engineering,
Delft University of Technology,
Mekelweg 2,
Delft 2628 CD, The Netherlands
e-mail: J.L.Herder@tudelft.nl

Gabriëlle J. M. Tuijthof

Department of BioMechanical Engineering,
Delft University of Technology,
Mekelweg 2,
Delft 2628 CD, The Netherlands;
Academic Medical Centre,
Department of Orthopaedic Surgery,
Meibergdreef 9,
Amsterdam 1105 AZ, The Netherlands
e-mail: G.J.Tuijthof@amc.uva.nl

Rob G. H. H. Nelissen

Leiden University Medical Center,
Biomechanics and Imaging Group,
Department of Orthopaedics,
Albinusdreef 2,
Leiden 2333 ZA, The Netherlands
e-mail: R.G.H.H.Nelissen@lumc.nl

Jenny Dankelman

Department of BioMechanical Engineering,
Delft University of Technology,
Mekelweg 2,
Delft 2628 CD, The Netherlands
e-mail: J.Dankelman@tudelft.nl

Edward R. Valstar

Leiden University Medical Center,
Biomechanics and Imaging Group,
Department of Orthopaedics,
Albinusdreef 2,
Leiden 2333 ZA, The Netherlands
Delft University of Technology,
Department of BioMechanical Engineering,
Mekelweg 2,
Delft 2628 CD, The Netherlands
e-mail: E.R.Valstar@lumc.nl

1Corresponding author.

Contributed by the Design Automation Committee of ASME for publication in the Journal of Mechanical Design. Manuscript received June 25, 2012; final manuscript received April 2, 2013; published online May 10, 2013. Assoc. Editor: Matthew B Parkinson.

J. Mech. Des 135(7), 071001 (May 10, 2013) (13 pages) Paper No: MD-12-1323; doi: 10.1115/1.4024231 History: Received June 25, 2012; Revised April 02, 2013

Patient specific surgical guides (PSSGs) are used in joint replacement surgery to simplify the surgical process and to increase the accuracy in alignment of implant components with respect to the bone. Each PSSG is fabricated patient specifically and fits only in the planned position on the joint surface by the matching shape. During surgery, the surgeon holds the PSSG in the planned position and the incorporated guidance is used in making the essential cuts to fit the implant components. The shape of the PSSG determines its docking robustness (i.e., the range of forces that the surgeon may apply without losing the planned position). Minimal contact between the PSSG and the joint surface is desired, as this decreases the likelihood of interposition with undetected tissues. No analytical method is known from literature where the PSSG shape can be optimized to have high docking robustness and minimal bone-guide contact. Our objective is to develop and validate such an analytical method. The methods of motion restraint, moment labeling and wrench space—applied in robotic grasping and workpart fixturing—are employed in the creation of this new method. The theoretic approach is utilized in an example by optimizing the PSSG shape for one joint surface step-by-step. The PSSGs that arise from these optimization steps are validated with physical experiments. The following design tools for the analytical method are introduced. The optimal location for bone-guide contact and the application surface where the surgeon may push can be found graphically, respectively, by the use of the wrench space map and the application angle map. A quantitative analysis can be conducted using the complementary wrench space metrics and the robustness metric R. Utilization of the analytical method with an example joint surface shows that the PSSG's shape can be optimized. Experimental validation shows that the standard deviation of the error between the measured and calculated angular limits in the docking force is only 0.7 deg. The analytical method provides valid results and thus can be used for the design of PSSGs.

FIGURES IN THIS ARTICLE
<>
Copyright © 2013 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

(a) The surgical guide is held into its planned position by an application force of the surgeon. The location of the bone-guide contact and application surface bound what forces may be applied. Pushing at a different location might result in a different range in the application force. (b) A guide with different contact and application surface might result in different range in forces that may be applied.

Grahic Jump Location
Fig. 4

Range of wrenches that is allowed for three example application points. The wrench limits shown in physical space (a) correspond to the wrench limits shown in wrench space (b). (a) Force closure may be attained when pushing at point pa1 and pa2. Force closure may not be attained when pushing at pa3, as all forces will result in movement of the guide. (b) The negated contact wrenches span subspace Ac. All the wrenches going through one point in physical space are located on a curve in the wrench space. The intersection of the curve with subspace Ac determines the wrench limits where between an application wrench will result in force closure.

Grahic Jump Location
Fig. 3

Surgical guide having, respectively, (a) two and (b) three bone-guide contact points. Guide (a) remains its position when the contact normals and the line of action of the application force, all intersect in one point. For every other application point, the angle of application must be different to maintain static equilibrium, e.g., fa1 and fa2. Every deviation in the line of action will cause motion and thus this guide cannot be docked. Guide (b) can be docked onto the bony geometry. For each application point, there is a range in which the angle of application may be varied (gray areas), e.g., fa1 and fa2. This range may vary for every other application point. Force fa2 has a broader range then fa1.

Grahic Jump Location
Fig. 6

Guide 2 the contact is changed to four logical contact points which are selected from the positive basis contact. (a) The guide in position on the bony geometry. Contact is indicated white on the bone line. In the background is the application angle map which shows for a certain application point: the mean direction to push (arrow field); and the range in which the application angle may be varied (grayscale color). The robustness metric R is given to show the docking quality of the actual guide. (b) The wrench space for the guide. Each of the adjacent wrench space curves corresponds to a point on the application surface and shows the wrenches that are possible through these points. Area A0 shows the wrench space covered when the guide has full contact or positive basis contact (without consideration of the application surface); area Ac shows the wrench space covered when the guide has the indicated white contact (also without consideration of the application surface); and area Aa shows the wrench space of wrenches that can actually be subjected onto the application surface. The wrench space metrics ηc, ηa,c, and ηg show how well wrench space is covered.

Grahic Jump Location
Fig. 7

Guide 3 the contact is changed to six logical contact points which are selected from the positive basis contact. (a) The guide in position on the bony geometry. Contact is indicated white on the bone line. In the background is the application angle map which shows for a certain application point: the mean direction to push (arrow field); and the range in which the application angle may be varied (grayscale color). The robustness metric R is given to show the docking quality of the actual guide. (b) The wrench space for the guide. Each of the adjacent wrench space curves corresponds to a point on the application surface and shows the wrenches that are possible through these points. Area A0 shows the wrench space covered when the guide has full contact or positive basis contact (without consideration of the application surface); area Ac shows the wrench space covered when the guide has the indicated white contact (also without consideration of the application surface); and area Aa shows the wrench space of wrenches that can actually be subjected onto the application surface. The wrench space metrics ηc, ηa,c, and ηg show how well wrench space is covered.

Grahic Jump Location
Fig. 5

Guide 1 three random contact points with the application surface at a random height. (a) The guide in position on the bony geometry. Contact is indicated white on the bone line. In the background is the application angle map which shows for a certain application point: the mean direction to push (arrow field); and the range in which the application angle may be varied (grayscale color). The robustness metric R is given to show the docking quality of the actual guide. (b) The wrench space for the guide. Each of the adjacent wrench space curves corresponds to a point on the application surface and shows the wrenches that are possible through these points. Area A0 shows the wrench space covered when the guide has full contact or positive basis contact (without consideration of the application surface); area Ac shows the wrench space covered when the guide has the indicated white contact (also without consideration of the application surface); and area Aa shows the wrench space of wrenches that can actually be subjected onto the application surface. The wrench space metrics ηc, ηa,c, and ηg show how well wrench space is covered.

Grahic Jump Location
Fig. 2

Motion restraint and moment labeling. (a) An arbitrary shaped object X is making contact with another object. The normal nc at the point of contact divides the plane into two areas of motion restraint: an area left to the normal wherein every point only allows positive rotation of object X; and an area right to the normal wherein every point only allows negative rotation of object X. (b) Two example rotations that the motion restraint still allows. Positive rotation of object X about the point in the positive area will rotate p0 belonging to the object to p+. Negative rotation of object X about the point in the negative area will rotate p0 to p. The division of planar space into a positive and negative area can also be used to define the normal nc itself in a technique called moment labeling. The normal produces a positive moment about all points in the positive area and a negative moment about all points in the negative area.

Grahic Jump Location
Fig. 8

Guide 4 the contact is changed to the positive basis contact. (a) The guide in position on the bony geometry. Contact is indicated white on the bone line. In the background is the application angle map which shows for a certain application point: the mean direction to push (arrow field); and the range in which the application angle may be varied (grayscale color). The robustness metric R is given to show the docking quality of the actual guide. (b) The wrench space for the guide. Each of the adjacent wrench space curves corresponds to a point on the application surface and shows the wrenches that are possible through these points. Area A0 shows the wrench space covered when the guide has full contact or positive basis contact (without consideration of the application surface); area Ac shows the wrench space covered when the guide has the indicated white contact (also without consideration of the application surface); and area Aa shows the wrench space of wrenches that can actually be subjected onto the application surface. The wrench space metrics ηc, ηa,c, and ηg show how well wrench space is covered.

Grahic Jump Location
Fig. 9

Guide 5 the application surface is made narrower so that it falls within the white part of the grayscale map. (a) The guide in position on the bony geometry. Contact is indicated white on the bone line. In the background is the application angle map which shows for a certain application point: the mean direction to push (arrow field); and the range in which the application angle may be varied (grayscale color). The robustness metric R is given to show the docking quality of the actual guide. (b) The wrench space for the guide. Each of the adjacent wrench space curves corresponds to a point on the application surface and shows the wrenches that are possible through these points. Area A0 shows the wrench space covered when the guide has full contact or positive basis contact (without consideration of the application surface); area Ac shows the wrench space covered when the guide has the indicated white contact (also without consideration of the application surface); and area Aa shows the wrench space of wrenches that can actually be subjected onto the application surface. The wrench space metrics ηc, ηa,c, and ηg show how well wrench space is covered.

Grahic Jump Location
Fig. 10

Guide 6 the application surface is made as wide as possible within the white part of the grayscale map. (a) The guide in position on the bony geometry. Contact is indicated white on the bone line. In the background is the application angle map which shows for a certain application point: the mean direction to push (arrow field); and the range in which the application angle may be varied (grayscale color). The robustness metric R is given to show the docking quality of the actual guide. (b) The wrench space for the guide. Each of the adjacent wrench space curves corresponds to a point on the application surface and shows the wrenches that are possible through these points. Area A0 shows the wrench space covered when the guide has full contact or positive basis contact (without consideration of the application surface); area Ac shows the wrench space covered when the guide has the indicated white contact (also without consideration of the application surface); and area Aa shows the wrench space of wrenches that can actually be subjected onto the application surface. The wrench space metrics ηc, ηa,c, and ηg show how well wrench space is covered.

Grahic Jump Location
Fig. 11

Experimental setup for testing the limits of the range of the application angle. A digital angle measuring device is used to create an inclination table. One leg of the measuring device is clamped to a vertical panel while the other leg can move freely. The bony geometry is fixed onto the inclination table (the free leg). For an experiment, the guide is placed onto the bony geometry in the planned position. Weight is hung in one of the grooves of the application surface, representing an application force.

Grahic Jump Location
Fig. 12

Comparison between the measured limits of the application angle (indicated with +) and the calculated limits of the application angle (indicated with ○) for guides 1–6. Every individual measurement is displayed in the graph. Application points are at 25%, 50% and 75% of the length of the application surface. Application point 3 is excluded from the experiment for the symmetrical guides (i.e., guides 2–6) because the limits of the application angle are expected to be identical to those of point 1.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In