Reverse engineering vs conceptual design principles in the making of artificial knee models.
Abstract: The process of reverse engineering involves, disassembling and disclosing the method in which it works. It often shows an effective way for learning to construct a product/technology or improvise it. In medical devices design, reverse engineering principles are more often used in implants designing and specifically in orthopedic implants designing. This paper discusses the efficacy of using reverse engineering and combining the same with conceptual design principles to meet the objectives. The design is tested on using a reverse engineered artificial knee and the same improvised using conceptual design principles. The results prove that the combination of reverse engineering and conceptual design opens up a greater scope for the product design in the field of medical devices design.
Subject: Implants, Artificial
Prosthesis
Authors: Sivarasu, Sudesh
Prasanna, Sam
Mathew, Lazar
Pub Date: 04/01/2011
Publication: Name: Trends in Biomaterials and Artificial Organs Publisher: Society for Biomaterials and Artificial Organs Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2011 Society for Biomaterials and Artificial Organs ISSN: 0971-1198
Issue: Date: April, 2011 Source Volume: 25 Source Issue: 2
Product: SIC Code: 3842 Surgical appliances and supplies
Accession Number: 308434330
Full Text: Introduction

The objective of this work was to remodel a fixed bearing standard artificial knee implant using the reverse engineering principles. The obtained model was simulated in MSC ADAMSView software for kinematic analysis. The results were taken and compared with the High flexion artificial knee which was taken from conceptual design (1).

Principles of reverse engineering

Reverse engineering is defined as the systematic process of acquiring the important design factors and information regarding engineering aspects from an existing product. It is a process which analyzes a product/technology specially to find out the design aspects and its functions. This is a kind of analysis which engages an individual in a process of constructive learning of the design and its functionality of systems and products. Reverse engineering method plays a significant role in the development of science and technology innovations. The process of reverse engineering involves, disassembling and disclosing the method in which it works. It often shows an effective way for learning to construct a product/technology or improvise it.

Goals and Uses of Reverse Engineering

* Recreating the design, making the design decision, and the information which is developed by the original design team.

* Learning the working principle.

* Justifications of design decisions of the original design team

* Redesigning the product to improvise, modify to suit the modern circumstances etc.

* Understanding the functionality of product in depth.

* Evaluating a product to understand its limitations and comparison with other products using simulation technology.

Materials and Methods

Reconstruction of standard artificial knee model using the reverse engineering principles

Reconstruction of a 3D model of the standard artificial knee could be done using the commercial CAD/CAM packages like SolidWorks, CATIA, PRO-E, and AUTOCAD etc. For this study SolidWorks 2008 was used for modeling for its various advantages over the other packages. SolidWorks is design automation software. The SolidWorks software enables to design models more quickly and precisely. The sketch ideas and different experimental designs could be created in 3D models using SolidWorks. Its designs are defined by 3 dimensions and based on the components which are parts and assemblies. Using the measurements obtained from the real standard artificial knee implant, the model was constructed in SolidWorks. The fixed bearing standard artificial knee implant has 3 components namely the femoral component, tibial component and the polyethylene insert.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

Results and Discussion

3D model of the fixed bearing artificial knee implant

The fixed bearing artificial knee model consists of 3 components namely the femoral component, tibial component and tibial polyethylene insert. A 3D model was developed from the existing the real implant. The measurements of the individual components were measured using the vernier caliper. Using those measurements and a solid model was created using SolidWorks 2008. Once all the three components were modeled, each component were taken into the assembly module of the SolidWorks and it was assembled to get a complete assembly of the fixed bearing standard artificial knee implant.

3D model of the novel mobile bearing high flexion artificial knee

The novel mobile bearing high flexion artificial knee implant was taken from the conceptual design from S Sivarasu & L Mathew (1). They have aimed to design an artificial high-flexion knee, which emphasizes the high-flexion extension range of over 125 degree that would provide the comfort of squatting even after total knee replacement. The performance of the joint after the surgical procedure is dependent on the implant design. The emphasize for customized joint design for the eastern world has be in the discussion for a while now, mainly owing to the economic growth surrounding the eastern countries like China and India. The requirement of eastern world for their lifestyles is the provision to sit on the lower platform. This means that the flexion-extension requirement of the implant is over 120 degrees. More over the activities like squatting would require mild inner rotation in the implant, so a Rotating platform design is considered for the knee design. A multi radii design with an extended condylar portion is considered for the femoral component design. The inner profile is maintained such that it can be used with standard zigs that are used in TKS. The inner structures are of the component are design such that it enhances bone growth even after the implantation.

Degree of Freedom comparison

Degree of Freedom comparison for the normal knee and the reverse engineered and conceptually designed knee implants in Table.1

Conclusion

The performance of the conceptually design knee is better than the reverse engineered knee joint. Hence it is concluded that the best combination is that of reverse engineering over which conceptual design has to be applied for making the ideal artificial knee

References and further reading

(1.) S. Sivarasu, L. Mathew, 3D CAD Conceptual Design of an Artificial Knee; Journal of Long Term Effects of Medical Implants. 2007, 17, 313-320

(2.) S. Sivarasu, L. Mathew, Finite Element Based Design Optimization of a Novel High Flexion Knee used in Total Knee Arthroplasty; Applied Bionics & Biomechanics, 2008, 5, 77-87.

(3.) S. Sivarasu, L. Mathew, Kinematic Analysis and Three-Dimensional Finite Element Analysis of a Mobile Bearing Artificial High Flexion Knee, Biomedical Engineering: Applications, Basis and Communications, 2009, 21, 279-286

(4.) S. Sivarasu, L. Mathew, Artificial Knee Implant Design Parameters Affecting the Range of Motion Improvement after the Total Knee Arthroplasty; Journal of Long Term Effects of Medical Implants, 2008, 18, 259-265

(5.) S. Sivarasu, L. Mathew, Artificial Knee for Eastern Lifestyles. The Patent Office Journal, Issue: 09/2009. Date: 27-02-2009. p. 5732

(6.) S. Sivarasu, L. Mathew, Techniques in Development of a Low Weight Medical Implants and its strength validation using Finite Element Methods; Journal of Long Term Effects of Medical Implants, 2009, 19, 51-57.

(7.) S. Prasanna, S. Sivarasu, L. Mathew, Comparative Kinematic Analysis of the Range of Movement of a Normal Human Knee Joint, Standard Artificial Knee and Artificial High Flexion Knee; Biomedical Engineering: Applications, Basis and Communications, 2010, 22, 41-45.

Sudesh Sivarasu *, Sam Prasanna, Lazar Mathew

Centre for Biomedical Research, VIT University, Vellore 632 014

* corresponding author--Dr. Sudesh Sivarasu, e-mail: sudeshsivarasu@gmail.com

Received 31 July 2010; Accepted 3 August 2010; Available online 4 May 2011
Table 1: Degree of Freedom Comparison

Planes/Models                 Normal   Reverse       Conceptually
                              Knee     Engineering   Designed
                                       Knee          Knee

Sagittal        Translation   1        1(F/E)        1(F/E)
                Rotation      1        1(F/E)        1(F/E)
Transverse      Translation   1        -             -
                Rotation      1        -             1(AR)
Total                         4        2             3
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