Construction of restored model of fractured femurs based on anatomic features

Figures & data

Figure 1. Flow diagram of constructing restored model based on anatomic features.

Figure 2. Feature definition of femur anatomy.

Figure 3. Extracting feature points of femur shaft.

Figure 4. Definition of vertex height.

Figure 5. Steps of reference model construction.

Figure 6. Construction of individual intact restored fracture model.

Figure 7. Experimental platform of constructing individual reference model.

Figure 8. Reconstruction results of Sample A.

Table 1. Average time consumption of stages.

ID	Stage	Time/s
1	Feature extraction of individual fracture model	3.411
2	Construction of reference model and feature extraction	26.582
3	Rigid registration of feature points	0.417
4	Restoration of major fracture segments	1.957
5	Reconstruction of comminuted part, grouping and smoothing	24.813

Figure 9. Shape comparisons between reconstructed and reference model.

Figure 10. Shape comparisons between reconstructed and original model.

Table 2. Average error of sample model reconstruction (mm).

Anatomic region	Comparison with reference model	Comparison with original model
Head	0.937	0.276
Neck	0.531	0.204
Trochanter	0.876	0.197
Shaft	0.728	0.154
Condyle	1.040	0.213

Table 3. Comparison of existing methods of restoring fractured bones.

Several methods	Feature representation	Referential model	Reduction method	Modeling efficiency	Construction accuracy	Fracture curves
Ren et al. [15]	–	None	Manual	Low	Not sure	+
Shen et al. [16]	–	None	Manual	Low	Not sure	+
Hu et al. [18]	–	Bilateral	ICP algorithm	High	High	–
Buschbaum et al. [19]	–	None	Parameter change	High	High	+
This method	+	Reconstructed	Improved ICP algorithm	High	Higher	+

+ means SUPPORT, – means NOT SUPPORT.

Table

Ps	Name	Definition	Ps	Name	Definition
Ps1	Head center	Hemisphere center fitted of the vertices of head.	Ps3 – Ps9	Proximal feature points	Centers of proximal cross section.
Ps1	Neck center	Isthmus center fitted of the vertices of neck.	Ps10	Shaft center	Centers of minimum cross section of shaft.
Ps3	Neck-shaft intersection	Intersection of neck axis and shaft axis.	Ps11 – Ps18	Distal feature points	Centers of distal cross section.

Table

Ps	Name	Definition	Ps	Name	Definition
Pa1	Top point	Highest point of trochanter.	Pa8	Anterior internal condyle point	Most anterior point of the internal condyle.
Pa2	Greater trochanter point	Most lateral point of trochanter.	Pa9	Bottom lateral point	Lowest point of lateral condyle.
Pa3	Lesser trochanter point	Proximal point with maximum curvature.	Pa10	Trochlear trench point	Points with maximum intercondylar curvature
Pa4	Condyle upper point	Point with maximum curvature in distal coronal plane.	Pa11	Bottom internal point	Lowest point of internal condyle.
Pa5	Lateral condyle point	Most lateral point of the condyle.	Pa12	Posterior lateral condyle point	Most posterior point of the lateral condyle.
Pa6	Internal condyle point	Most internal point of the condyle.	Pa13	Posterior internal condyle point	Most posterior point of the internal condyle.
Pa7	Anterior lateral condyle point	Most anterior point of the lateral condyle.