Navigation-Guided Harvesting of Autologous Iliac Crest Graft for Mandibular Reconstruction

Accuracy of virtual surgical planning in mandibular reconstruction: application of a standard and reliable postoperative evaluation methodology

OBJECTIVE

The purpose of this study was to determine the accuracy of virtual surgical planning for mandibular reconstruction, along with the implementation of a postoperative evaluation methodology.

MATERIALS AND METHODS

The study is a prospective case series for computer-assisted mandibular reconstruction surgery. Analysis of the degree of agreement between virtual measurements and postoperative actual outcomes was performed. The reliability of the proposed evaluation methodology was assessed and analyzed using the Inter-Class Coefficient (ICC) test. Statistical significance was set at the 5% level.

RESULTS

Nine consecutive patients were selected. The analysis of all angular and linear parameters reported a highly statistically significant degree of agreement between the preoperative and postoperative measurements (P < 0.001). Furthermore, an extreme degree of reliability was reported when the evaluation methodology was scrutinized (ICC = 0.9).

CONCLUSION

The excellent degree of agreement between the virtual plan and the actual outcome reported in this study validated the surgical accuracy of virtually assisted mandibular reconstruction. This study pointed out the reliability and reproducibility of the standardized evaluation protocol in an attempt to obtain a tolerable value for the acceptable postoperative results regarding the accuracy of computer-assisted surgery.

Accurate Reconstruction of Mandibular Defects With Vascularized Bone Flaps Through Utilization of Mandible Space-Retention Guides

PURPOSE

Comprehensive evaluation of the effects of using computer-aided design and space retention guide technology to reconstruct mandibular defects using vascularized autogenous bone flaps.

METHOD

This study included 8 patients who received autogenous bone flaps (2 cases of vascularized fibula flaps and 6 cases of vascularized iliac flaps) for mandibular defect reconstruction at Peking University School and Hospital of Stomatology, from July 2018 to May 2021. All patients received digital surgery planning, CAD/CAM, surgical guide technique for the removal of diseased bone segments, as well as vascularized fibular flap/iliac flap reconstruction. Three-dimensional deviations were analyzed after the operation.

RESULT

The mandibular defects of all 8 patients were successfully reconstructed using the vascularized fibular flap/iliac bone flap. There were no serious complications at either the donor site or recipient site during our follow-up. The average three-dimensional deviation of all 8 patients was 1.92 mm, based on comparisons of preoperative design and actual postoperative computed tomography.

CONCLUSION

Utilizing CAD/CAM, we designed a new mandibular space-retention guide, which can accurately translate the preoperative digital design plan to real-time surgery with satisfactory accuracy and efficacy.

Comparison of augmented reality and cutting guide technology in assisted harvesting of iliac crest grafts - A cadaver study

BACKGROUND

Harvesting vascularized bone grafts with computer-assisted surgery represents the gold standard for mandibular reconstruction. However, current augmented reality (AR) approaches are limited to invasive marker fixation. This trial compared a markerless AR-guided real-time navigation with virtually planned and 3D printed cutting guides for harvesting iliac crest grafts.

MATERIAL AND METHODS

Two commonly used iliac crest transplant configurations were virtually planned on 10 cadaver hips. Transplant harvest was performed with AR guidance and cutting guide technology. The harvested transplants were digitalized using cone beam CT. Deviations of angulation, distance and volume between the executed and planned osteotomies were measured.

RESULTS

Both AR and cutting guides accurately rendered the virtually planned transplant volume. However, the cumulative osteotomy plane angulation differed significantly (p = 0.018) between AR (14.99 ± 11.69°) and the cutting guides (8.49 ± 5.42°). The cumulative osteotomy plane distance showed that AR-guided navigation had lower accuracy (2.65 ± 3.32 mm) than the cutting guides (1.47 ± 1.36 mm), although without significant difference.

CONCLUSION

This study demonstrated the clinical usability of markerless AR-guided navigation for harvesting iliac crest grafts. Further improvement of accuracy rates might bring clinical implementation closer to reality.

Review of surgical resection and reconstruction in head and neck cancer. Traditional versus current concepts

This review summarizes the development of head and neck cancer resection and reconstruction. The developments in the treatment of cancer patients are reflected in their surgical outcomes, in addition to functional and aesthetic improvements. New technologies, such as surgical simulation and planning, minimally invasive surgery, and microsurgery have been added to the field to improve surgical resection of the tumor and reconstruction. The field is still growing to optimize the management of head and neck cancer.

Introduction of an algorithm for planning of autologous fibular transfer in mandibular reconstruction based on individual bone curvatures

BACKGROUND

Reconstruction of the mandible with autologous transplants is a challenging task and current computer-aided surgical planning remains cumbersome. Thus, the aim of the present study was to create an automated computational approach for this procedure.

METHODS

The developed algorithm is based on curves following characteristic anatomical features. Geometrical data from a physiological mandible and a fibula were used to generate six different defects, and geometrical accordance was investigated to demonstrate the applicability of the method with different reconstruction parameters (n = 309).

RESULTS

The method proved to be applicable, it recognized given clinical constraints and the values of accordance could be used to quantify the success of reconstructions.

CONCLUSIONS

With the present approach, the complex three-dimensional task of mandibular reconstruction was simplified, and thus it allows implementation in clinical routine. The computational planning that is proposed may be used to design cutting guides or as geometrical input data for real-time navigated surgery.

Translating Computer-Aided Design and Surgical Planning Into Successful Mandibular Reconstruction Using a Vascularized Iliac-Crest Flap

PURPOSE

This study evaluated the computer-aided approach to the reconstruction of mandibular defects using a vascularized iliac-crest flap.

MATERIALS AND METHODS

From December 2015 to October 2016, 14 patients (8 men and 6 women) 18 to 64 years old (median age, 29 yr) were treated at the Peking University School and Stomatology Hospital (Beijing, China). Biopsy specimens from all patients were subjected to histologic examination before segmental mandibulectomy. Computer-based surgical techniques, including virtual surgical planning, computer-aided design and manufacturing, rapid prototyping, and intraoperative navigation, were used to restore the anatomic continuity and configuration of the mandible using a vascularized iliac-crest flap. Two transverse dimensions and 1 anteroposterior (A-P) dimension were evaluated based on the virtual plan and postoperative computed tomogram. Lines from condylar head to condylar head and from gonial angle to gonial angle were defined as the transverse dimensions. A perpendicular line drawn from the mandibular midline to the center point on the condylar head to condylar head measurement was defined as the A-P dimension. Complications were evaluated during follow-up.

RESULTS

The flap success rate was 92.9% (13 of 14), with 1 flap failure. After the operation, there were no other serious complications in 13 of the 14 patients, who exhibited a good mandibular configuration with good occlusion. Furthermore, the height of bone graft was sufficient for implants. Healing of the recipient and donor sites with no serious complication was uneventful. The average surgical errors in the A-P dimension and transverse dimensions were 1.8 ± 1.0 mm (range, 0.2 to 3.7 mm), 2.2 ± 1.1 mm (range, 0.9 to 5.0 mm), and 2.6 ± 1.6 mm (range, 0.3 to 7.2 mm), respectively.

CONCLUSIONS

The use of these digital techniques was found to be a viable option for reconstruction of mandibular defects, but the results should be interpreted cautiously because of the small number of patients and the relatively short follow-up.

Planning of mandibular reconstructions based on statistical shape models

PURPOSE

The reconstruction of large continuity defects of the mandible is a challenging task, especially when the shape of the missing part is not known prior to operation. Today, the surgical planning is based mainly on visual judgment and the individual skills and experience of the surgeons. The objective of the current study was to develop a computer-based method that is capable of proposing a reconstruction shape from a known residual mandible part.

METHODS

The volumetric data derived from 60 CT scans of mandibles were used as the basis for the novel numerical procedure. To find a standardized representation of the mandible shapes, a mesh was elaborated that follows the course of anatomical structures with a specially developed topology of quadrilaterals. These standard meshes were transformed with defined mesh modifications toward each individual mandible surface to allow for further statistical evaluations. The data were used to capture the inter-individual shape variations that were considered as random field variations and mathematically evaluated with principal component analysis. With this information of the mandibular shape variations, an algorithm was developed that proposes shapes for reconstruction planning based on given residual mandible geometry parts.

RESULTS

The accuracy of the novel method was evaluated on six different virtually defined continuity defects that were each created on three mandibles that were not part of the initial database. Virtual reconstructions showed sufficient accuracy of the algorithm for the planning of surgical reconstructions, with average deviations toward the actual geometry of [Formula: see text] mm for small missing parts and 5 mm for large hemi-lateral defects.

CONCLUSIONS

The presented algorithm may be a valuable tool for the planning of mandibular reconstructions. The proposed shapes can be used as templates for computer-aided manufacturing, e.g., with 3D printing devices that use biocompatible materials.

Developments in image-guided deep circumflex iliac artery flap harvest: a step-by-step guide and literature review

PURPOSE

The deep circumflex iliac artery (DCIA) flap has evolved significantly over time in the intricacies of flap design and breadth of surgical application. This has been facilitated by advances in preoperative imaging and planning, in particular, computed tomographic angiography. Studies have highlighted that advanced imaging modalities and other technologies such as image-guided stereolithographic biomodeling can substantially improve flap planning, flap harvest, and operative outcomes.

PATIENTS AND METHODS

The present report comprises a combined literature review and clinical cohort study of 20 consecutive patients to assess the modern technologies applied to DCIA flap planning and harvest. We have also described a step-by-step guide for the implementation of these techniques into clinical practice.

RESULTS

The protocol for a single, standardized technique of computed tomographic angiography scanning is presented and was applied to a range of techniques in the preoperative planning of DCIA flaps. These include 1) bony and vascular imaging analysis of both donor and recipient sites, 2) stereolithographic "biomodeling" of both donor and recipient bony and vascular anatomy, and 3) the use of preoperative "virtual surgery" with image-guided stereotactic navigation. The application and role of each technique was explored.

CONCLUSIONS

Modern imaging and stereolithographic techniques are innovations that can substantially improve surgical outcomes in DCIA flap surgery, such as has been highlighted in our clinical experience and in published studies. Notably, few outcome studies have been reported, and the need for larger case series and comparative studies is apparent.