Evaluation of computer-assisted mandibular reconstruction with vascularized iliac crest bone graft compared to conventional surgery: a randomized prospective clinical trial

Abstract

Background: Computer-assisted surgery plays an increasingly important role in mandibular reconstruction, ensuring the best possible masticatory function and aesthetic outcome.

Methods: Twenty patients were randomly assigned to computer-assisted or conventional mandibular reconstruction with vascularized iliac crest bone graft in a prospective study design.Virtual surgical planning was based on preoperative CT-data using specific surgical planning software. A rapid prototyping guide transferred the virtual surgery plan to the operation site. During surgery the transplant ischemic time, reconstruction time, time for shaping the transplant and amount of bone removed were measured. Additionally, the difference in the intercondylar distance before and after surgery was calculated.

Results: Computer-assisted surgery shortened the time of transplant ischemia (P < 0.005) and defect reconstruction (P < 0.001) compared to conventional surgery. The time to saw and shape the transplant at the donor site was shorter using conventional surgery (P < 0.005); therefore, the overall time for surgery didn't change (P = 0.527). In the computer-assisted group, the amount of bone harvested equaled the defect size, whereas the transplant size in the conventional group exceeded the defect site by 16.8 ± 5.6 mm (P < 0.001) on average. The intercondylar distance before compared to after surgery was less affected in the computer-assisted than in the conventional group (P < 0.001).

Conclusions: The presented study shows that computer-assisted surgery can help reduce the time for mandibular defect reconstruction and consequently the transplant ischemic time. In the computer-assisted group, the iliac crest donor site defect was downsized and the postoperative condyle position was less altered, reducing possible risks of postoperative complications and donor site morbidity.

Trial registration: DRKS00005181.

Figure 1

The absolute deviation in the pre- and postoperative intercondylar distance was measured by superimposition of the preoperative with the postoperative three-dimensional model of the mandible. Grey indicates the iliac crest transplant and the altered postoperative position of the mandible with the condyle. The preoperative position of the condyle is marked in red.

Figure 2

Preoperative three-dimensional model of the facial skeleton.

Figure 3

Virtual resection of the right mandible in a case of primary reconstruction.

Figure 4

Preoperative virtual planning. (A) Iliac crest is moved into the defect site of the left mandible. (B) Transplant cutting guide placed on the left iliac crest. (C) Virtually-cut iliac crest graft placed at the defect site of the mandible. (D) Whole facial skeleton with the final iliac crest graft in position.

Figure 5

Primary reconstruction of the mandible. (A) For primary reconstruction the resected part of the right mandible (blue) acted as reference for the left iliac crest graft (red). (B) Iliac crest graft (red) marked on the pelvis.

Figure 6

Guides and models. The transplant cutting guide (A) and resection guide of the mandible (B) are manufactured via a rapid prototyping selective laser sintering method. Stereolithographic model of the virtually-created transplant of the iliac crest (C) and the mandible after resection (D).

Figure 7

Resection of the mandible. (A) Fixed resection guide on the mandible using mini screws. (B) Resected portion of the mandible with resection guide.

Figure 8

Harvest of the iliac crest transplant. (A) Transplant cutting guide temporarily fixed on the iliac crest. (B) Still-pedicled transplant with cutting guide. The arrow marks the pedicle.

Figure 9

Using the stereolithographic model to pre-bend mini plates on the still-pedicled iliac crest graft.

Figure 10

Primary and secondary reconstruction of the mandible. (A) Iliac crest transplant fixed at the right mandible in a case of primary reconstruction. Arrow indicates the anastomosis. (B) Iliac crest transplant in a case of secondary reconstruction placed at the defect site of the left mandible.

Figure 11

Time (minutes ± standard deviation) was measured during surgery. The time needed for shaping the transplant at the donor site was significantly shorter in the computer-assisted group, whereas the time for shaping the transplant at the defect site, osteosynthesis and reconstruction was reduced using computer-assisted surgery.

Figure 12

Ischemic time (minutes ± standard deviation) of the iliac crest bone graft. In the computer-assisted group the ischemia of the transplant was significantly less compared to conventional surgery.

Figure 13

Operation time (minutes ± standard deviation) comparing both groups. No change in overall operation time was observed.

Figure 14

Measured size (mm ± standard deviation) of the defect and of the bone harvested using conventional surgery. In the conventional group, the amount of bone harvested was significantly higher compared to the defect size.

Figure 15

Absolute preoperative to postoperative intercondylar deviation (mm ± standard deviation). Using computer-assisted surgery the absolute intercondylar deviation comparing pre- and postoperative condyle position was significantly lower in contrast to conventional surgery.