Accurate reconstructions of pelvic defects and discontinuities using statistical shape models

Meynen, Alexander; Matthews, Harold; Nauwelaers, Nele; Claes, Peter; Mulier, Michiel; Scheys, Lennart

doi:10.1080/10255842.2020.1784404

Cited by 12 publications

(5 citation statements)

References 35 publications

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“…The possibility to create a statistically sound set of bones is a mandatory issue when, for instance, a prosthesis needs to be designed to cover the need of a whole population [23]. In addition, it can provide key information for the design of parametric [24] and modular [25] models.…”

Section: Discussionmentioning

confidence: 99%

Stochastic PCA-Based Bone Models from Inverse Transform Sampling: Proof of Concept for Mandibles and Proximal Femurs

et al. 2021

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Principal components analysis is a powerful technique which can be used to reduce data dimensionality. With reference to three-dimensional bone shape models, it can be used to generate an unlimited number of models, defined by thousands of nodes, from a limited (less than twenty) number of scalars. The full procedure has been here described in detail and tested. Two databases were used as input data: the first database comprised 40 mandibles, while the second one comprised 98 proximal femurs. The “average shape” and principal components that were required to cover at least 90% of the whole variance were identified for both bones, as well as the statistical distributions of the respective principal components weights. Fifteen principal components sufficed to describe the mandibular shape, while nine components sufficed to describe the proximal femur morphology. A routine has been set up to generate any number of mandible or proximal femur geometries, according to the actual statistical shape distributions. The set-up procedure can be generalized to any bone shape given a sufficiently large database of the respective 3D shapes.

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Section: Discussionmentioning

confidence: 99%

Stochastic PCA-Based Bone Models from Inverse Transform Sampling: Proof of Concept for Mandibles and Proximal Femurs

et al. 2021

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“…In addition, a virtually reduced pelvis or the contralateral mirrored hemipelvis can be 3D printed for pre-contouring the implant, because the shape of the left and right hemipelvis are almost identical [ 29 ]. One could virtually reduce the fracture [ 23 ], using a statistical shape model as a template [ 30 , 31 ], when encountering contralateral acetabular fractures or associate pelvic ring injuries. Although 3D virtual surgical planning can be time-consuming, and it is not widely available yet, surgical guides should be considered as an adjunct to conventional implants, thus making it potentially widely applicable in other hospitals.…”

Section: Discussionmentioning

confidence: 99%

Accuracy of Patient-Specific Drilling Guides in Acetabular Fracture Surgery: A Human Cadaver Study

Meesters

Assink

Duis

et al. 2021

JPM

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Due to the complex anatomical shape of the pelvis, screw placement can be challenging in acetabular fracture surgery. This study aims to assess the accuracy of screw placement using patient-specific surgical drilling guides applied to pre-contoured conventional implants in acetabular fracture surgery. CT scans were made of four human cadavers to create 3D models of each (unfractured) pelvis. Implants were pre-contoured on 3D printed pelvic models and optically scanned. Following virtual preoperative planning, surgical drilling guides were designed to fit on top of the implant and were 3D printed. The differences between the pre-planned and actual screw directions (degrees) and screw entry points (mm) were assessed from the pre- and postoperative CT-scans. The median difference between the planned and actual screw direction was 5.9° (IQR: 4–8°) for the in-plate screws and 7.6° (IQR: 6–10°) for the infra-acetabular and column screws. The median entry point differences were 3.6 (IQR: 2–5) mm for the in-plate screws and 2.6 (IQR: 2–3) mm for the infra-acetabular and column screws. No screws penetrated into the hip joint or caused soft tissue injuries. Three-dimensional preoperative planning in combination with surgical guides that envelope pre-contoured conventional implants result in accurate screw placement during acetabular fracture surgery.

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“…The healthy shape model construction was unchanged from a previous study in which it was validated. 19 In short, the CT scans of these patients were checked for bony abnormalities by an experienced hip surgeon (M. M.). Watertight 3D shapes were constructed after the segmentation of the pelvises from the CT scans models using Mimics Innovation Suite (v22.0, Materialise).…”

Section: Healthy Shape Model Creation and Reconstruction Methodsmentioning

confidence: 99%

“…The paired principal component score plots of the first six components can be found in Figure S1. Validation of this shape model was performed using a leaveone-out cross-validation study as described in Meynen et al 19 The reconstruction of the pre-diseased morphology itself was synthesized from the remaining healthy parts of pathologic pelvises.…”

Section: Healthy Shape Model Creation and Reconstruction Methodsmentioning

confidence: 99%

The morphological variation of acetabular defects in revision total hip arthroplasty—A statistical shape modeling approach

Meynen

Vles

Zadpoor

et al. 2021

Journal Orthopaedic Research

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Classification and evaluation of acetabular defects remain challenging and are primarily based on qualitative classification methods. That is because quantitative techniques describing variations of acetabular defects and accompanying bone loss volume are not available. This study introduces a new method based on statistical shape models (SSMs) to quantitively describe acetabular defects. This method is then applied to 87 acetabular defects to objectively describe the variations in acetabular defects typically encountered during revision total hip arthroplasty. The absolute bone loss volume, relative bone loss volume, and relative bone loss surface area with respect to the SSM-based pre-diseased anatomy were used to quantify the acetabular bone defects in different segments of the acetabular surface. The absolute bone loss volume of the average defect shape was equal to 37.0 cm 3 . The first three principal modes, accounting for 62% of the total shape variation, were found to represent variations in acetabular defect morphology. The first, second, and third principal modes described, respectively, the size of the bone defects, the difference between superomedially and superolaterally migrated defects, and the degree of involvement of the posterior or anterior column. The developed SSM and the introduced approach could be used to create automated and unbiased classification methods based on quantitative data. Moreover, the proposed model and the underlying data provide the basis for a quantitative design approach where the shape and size of new acetabular implants are determined according to clinical variation present in acetabular defects.

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Accurate reconstructions of pelvic defects and discontinuities using statistical shape models

Cited by 12 publications

References 35 publications

Stochastic PCA-Based Bone Models from Inverse Transform Sampling: Proof of Concept for Mandibles and Proximal Femurs

Stochastic PCA-Based Bone Models from Inverse Transform Sampling: Proof of Concept for Mandibles and Proximal Femurs

Accuracy of Patient-Specific Drilling Guides in Acetabular Fracture Surgery: A Human Cadaver Study

The morphological variation of acetabular defects in revision total hip arthroplasty—A statistical shape modeling approach

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