University of Twente Student Theses
What if the Lower Limb Knee’ds to be Realigned? A Standardised Protocol for Semi-Automatic Lower Limb Alignment in Preoperative Planning of Corrective Surgery: A Collaborative Research With MST, UMCG, and UMCU
Rhebergen, A. (2025) What if the Lower Limb Knee’ds to be Realigned? A Standardised Protocol for Semi-Automatic Lower Limb Alignment in Preoperative Planning of Corrective Surgery: A Collaborative Research With MST, UMCG, and UMCU.
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| Abstract: | Introduction – Proper lower limb function relies on balanced force distribution across the hip, knee, and ankle joints. Femoral or tibial malalignment disrupts this balance, causing mechanical impairments. Corrective surgery aims to restore alignment, but conventional 2D/3D planning methods can cause unintended corrections. In collaboration with MST, UMCG, and UMCU, this thesis presents a standardised, clinically implementable protocol for semi-automatic lower limb alignment in frontal, sagittal, and axial directions to improve preoperative planning. Method – A 3D semi-automated alignment protocol is developed by reviewing literature, internal protocols, and reaching consensus among MST, UMCG, and UMCU. The protocol, scripted in Python 3.8, requires minimal user input. Reproducibility is assessed through intra- and interrater variability. Accuracy is evaluated by comparing 2D and 3D angle measurements across AP/lateral radiographs, non-weightbearing CT, and weightbearing-adjusted CT. Implementation in HTO planning assesses the impact of coordinate systems on virtual postoperative results and patient-specific guide design. Results – The protocol is developed with partial consensus, lacking agreement on the femoral condyle centre. Intra- and interobserver variability analysis demonstrates high robustness (ICC > 0.90), with low maximal angle discrepancies except for a few measures of moderate reliability. Accuracy analysis reveals significant differences between 2D and 3D measurements, indicating these are not interchangeable. Clinical implementation improves surgical planning by ensuring accurate coordinate system usage and enhancing guide design. Discussion – The initial UMCG mechanical approach proves most robust. Key limitations include a small, heterogeneous sample, variability in joint surface marking, inconsistencies in 3D segmentation, and inaccuracies in manual 2D-3D matching. The long-term clinical benefits of patient-specific guides remain unproven. Future research should focus on clinical outcomes and integrating 3D musculoskeletal models with gait analysis to determine optimal alignment before heavily investing in technical protocol improvements. Conclusion – This 3D protocol enables precise, multi-planar adjustments, minimising unintended corrections and enhancing preoperative planning and surgical guide development. It may ultimately improve personalised surgical planning and patient outcomes in corrective surgery. |
| Item Type: | Essay (Master) |
| Clients: | MST, Enschede, the Netherlands MST, Enschede, the Netherlands UMCG, Groningen, the Netherlands UMCU, Utrecht, the Netherlands |
| Faculty: | TNW: Science and Technology |
| Subject: | 44 medicine |
| Programme: | Technical Medicine MSc (60033) |
| Link to this item: | https://purl.utwente.nl/essays/106046 |
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