Digital planning and individual implants for secondary reconstruction of midfacial deformities: A pilot study

Abstract

Objective: To evaluate the feasibility and accuracy of implementing three-dimensional virtual surgical planning (VSP) and subsequent transfer by additive manufactured tools in the secondary reconstruction of residual post-traumatic deformities in the midface.

Methods: Patients after secondary reconstruction of post-traumatic midfacial deformities were included in this case series. The metrical deviation between the virtually planned and postoperative position of patient-specific implants (PSI) and bone segments was measured at corresponding reference points. Further information collected included demographic data, post-traumatic symptoms, and type of transfer tools.

Results: Eight consecutive patients were enrolled in the study. In five patients, VSP with subsequent manufacturing of combined predrilling/osteotomy guides and PSI was performed. In three patients, osteotomy guides, repositioning guides, and individually prebent plates were used following VSP. The median distances between the virtually planned and the postoperative position of the PSI were 2.01 mm (n = 18) compared to a median distance concerning the bone segments of 3.05 mm (n = 12). In patients where PSI were used, the median displacement of the bone segments was lower (n = 7, median 2.77 mm) than in the group with prebent plates (n = 5, 3.28 mm).

Conclusion: This study demonstrated the feasibility of VSP and transfer by additive manufactured tools for the secondary reconstruction of complex residual post-traumatic deformities in the midface. However, the median deviations observed in this case series were unexpectedly high. The use of navigational systems may further improve the level of accuracy.

Keywords: CAD/CAM; computer‐assisted surgery; craniomaxillofacial trauma; patient‐specific implants; virtual surgical planning.

FIGURE 1

Computer‐assisted workflow. (A) Virtual surgical planning with repositioning of bone segments, (B) CAD of combined predrilling/osteotomy guides, (C) CAD of PSI, (D) CAD/CAM‐manufactured predrilling/osteotomy guides and (E) PSI, (F) intra‐operative image showing the predrilling/osteotomy guides and (G) PSI in place

FIGURE 2

Color‐coded difference images (heat maps) visualize the degree of geometric deviations for the bone segments and the PSI

FIGURE 3

Median distance between the virtually planned and the postoperative position of the PSI themselves (left; n = 18, median 2.01 mm, range 0.92–5.61 mm) and median distance of the bone segments (right; n = 12, median 3.05 mm (n = 12, range 1.68–6.06 mm)

FIGURE 4

Median distances between the virtually planned and the postoperative position of all bone segments in the group where PSI were applied (left; n = 7, median 2.77 mm, range 1.68–3.74 mm) and in the group without using PSI (right; n = 5, median 3.28 mm, range 2.87–6.06 mm)

FIGURE 5

Median distances between the virtually planned and the postoperative position of the lateral midface segments (left: n = 6, median 2.90 mm, range 1.68–6.06 mm) and the central midface segments (right: n = 6, median 3.22 mm, range 2.35–3.74 mm)