Chapter 8 Summary and Conclusion
8.4 Limitations of Thesis and Suggestions for the Future Work
This thesis has focused on improving the precision of 3D printing orthopaedic application in multiple ways across the production line from 3D modelling to 3D printing and surface modification. Prominent results have been obtained in each area. However, a number of limitations below can be used for directing the future research.
1. The limited access to the commercially available image processing software for 3D modelling and implant fabrication has prevented the comparison of our designs and fixation plates with the orthopaedic industry. In this thesis, open sourced Drishti software commonly used in museum is applied to the medical field.
2. A lack exists in the quantification analysis of the time consumption in the CT image converting process; hence it’s impossible to optimize the parameters of Drishti conversion for an optimal outcome. Secondary development of Drishti has the potential to solve the problem by measuring the conversion time by inserting two bookmarks at the beginning and the end of a conversion
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task. A collaboration between software developers, bioengineers and surgeons can provide with a way to standardise the conversion process to an optimal outcome.
3. Threshold process is not standardised. The differences between CT scanning machines, parameters of scan tasks, and operations by surgeons may largely influence the image quality of a CT scan. Thus, a repeatable threshold protocol can hardly be achieved via the current global thresholding technique. A standardised thresholding protocol collaboratively formulated by surgeons and medical image technicians would be essential.
4. Lacking in the protocol to eliminate spikes and small noise components of a 3D bone models generated from noisy of CT images. A further investigation to understand the geometrical difference before and after applying the automatic cleaning process in identifying and removing the 3D model’s spikes and small noise components may be necessary.
5. Lack of understanding the reliability of the manually removed disinterested regions such as the sacrum and the femur head. These areas are connected to the pelvis model in the whole surface. In a future study, finding a replicable method of determining a distinguishable borderline of segmenting these components may be necessary.
6. Lacking a validated protocol in designing and numerically simulating of the metal implant. The fixation plate models designed in this study are based on the suggestion and guidance of surgeons without concrete validation before 3D printing. Even though the design complies with basic rules such as that the fixation screw was at least 3 mm away from the fracture line, the formulation of a tailored protocol of designing a customised implant is desirable and may lead to the development of an automatic implant design
168 method.
7. Lacking a clinical trial to verify the geometry of the 3D printed metal implant to the fractured pelvis. This research analysed the geometrical fitness using a 3D CAD model and a metal 3D printed fixation implant. However, the geometrical fit of the end-user fixation plate to the actual patient are unknown. 8. Requiring real case studies in applying functional FDM fabricated surgical
guide that is post treated by laser scan. This thesis has verified the mechanical and biological reliability of CO2 laser polished PLA object
fabricated by the FDM method. The method has proved valid in fabricating high precision surgical guide. The next stage would be to clinically test the feasibility of the method in real cases.
9. Requiring a comprehensive comparison between post surface treatments. There are various post surface modification methods on the market. Even though this thesis demonstrates that the laser polishing has the potential to be the best choice due to its contactless and highly controllable nature, its comparison with other post processing methods is necessary to rationalize decision making in selecting a proper post treatment method.
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