The accuracy of computer-assisted primary mandibular reconstruction with vascularized bone flaps: iliac crest bone flap versus osteomyocutaneous fibula flap

Abstract

Background: The intention of mandibular reconstruction is to restore the complex anatomy with maximum possible functionality and high accuracy. The aim of this study was to evaluate the accuracy of computer-assisted surgery in primary mandibular reconstruction with an iliac crest bone flap compared with an osteomyocutaneous fibula flap.

Materials and methods: Preoperative computed tomography data of the mandible and the iliac crest or fibula donor site were imported into a specific surgical planning software program. Surgical guides were manufactured using a rapid prototyping technique for translating the virtual plan, including information on the transplant dimensions and shape, into real-time surgery. Using postoperative computed tomography scans and an automatic surface-comparison algorithm, the actual postoperative situation was compared with the preoperative virtual simulation.

Results: The actual flap position showed a mean difference from the virtual plan of 2.43 mm (standard deviation [SD] ±1.26) and a surface deviation of 39% <2 mm and 15% <1 mm for the iliac crest bone flap, and a mean difference of 2.18 mm (SD ±1.93) and a surface deviation of 60% <2 mm and 37% <1 mm for the osteomyocutaneous fibula flap. The position of the neomandible reconstructed with an osteomyocutaneous fibula flap indicated a mean difference from the virtual plan of 1.25 mm (SD ±1.31) and a surface deviation of 82% <2 mm and 57% <1 mm, in contrast to a mean difference of 1.68 mm (SD ±1.25) and a surface deviation of 63% <2 mm and 38% <1 mm for the neomandible after reconstruction with an iliac crest bone flap. For shape analysis, a similarly high accuracy could be calculated for both flaps.

Conclusion: Virtual surgical planning is an effective method for mandibular reconstruction with vascularized bone flaps, and can help to restore the anatomy of the mandible with high accuracy in position and shape. It seems that primary mandibular reconstruction with the osteomyocutaneous fibula flap is more accurate compared with the vascularized iliac crest bone flap.

Keywords: computer-assisted surgery; primary mandibular reconstruction; surgical guide; vascularized bone flaps; virtual planning.

Figure 1

Virtual mandibular reconstruction. Notes: The best-fitting part of the right iliac crest in terms of shape and interface with the affected right mandible and the distal part of the right fibula were selected virtually prior to surgery (A); three-dimensional virtual reconstruction of the right mandible, with the right iliac flap and the right fibula fitted perfectly into the defect (B). Materials and methods

Figure 2

Mandibular resection guides. Notes: Fixed mandibular resection guides on the right mandible using mini screws (A, C); resected portion of the right mandible with resection guides (B, D).

Figure 3

Transplant cutting guide. Notes: Transplant cutting guides temporarily fixed on the donor site (A, C); still-pedicled transplant, precision-cut with cutting guides (B, D).

Figure 4

Superimposition of the actual postoperative situation on its preoperative virtual plan for the neomandible, segmented flap, and left and right mandible with color gradient. Notes: Iliac crest bone flap (A); osteomyocutaneous fibula flap (B).

Figure 5

Primary mandibular reconstruction. Notes: Using the stereolithographic model to prebent miniplates on the still-pedicled, osteotomized transplant (A, C), reconstructed right mandible with the iliac crest bone flap (B); and osteomyocutaneous fibula flap (D).

Figure 6

Surface-deviation analysis for the position of the mandible reconstruction with the iliac crest bone flap and osteomyocutaneous fibula flap. Notes: Iiliac crest bone flap: Iliac flap position (A), right mandible position (B), left mandible position (C), and neomandible position (D). Osteomyocutaneous fibula flap: fibula flap position (E), right mandible position (F), left mandible position (G), and neomandible position (H). The calculation showed a surface deviation <1 mm (blue line) and <2 mm (red line). Abbreviation: ED, element distribution.

Figure 7

Surface-deviation analysis for the shape of the mandible reconstruction with the iliac crest bone flap and osteomyocutaneous fibula flap. Notes: Iiliac crest bone flap: Iliac flap shape (A), right mandible shape (B) and left mandible shape (C). Osteomyocutaneous fibula flap: fibula flap shape (D), right mandible shape (E) and left mandible shape (F). The calculation showed a surface deviation <1 mm (blue line) and <2 mm (red line). Abbreviation: ED, element distribution.