Nassim Ayoub

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

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.

Computer-Aided Mandibular Reconstruction With Vascularized Iliac Crest Bone Flap and Simultaneous Implant Surgery

The intention of oral rehabilitation in patients with mandibular defects is an early prosthetic treatment with maximum possible functionality and high accuracy. The present study describes a new computer-aided technique for mandibular reconstruction using a free vascularized iliac flap and simultaneous insertion of dental implants into the flap while it is still pedicled at the donor site. Based on preoperative computerized tomography data of the facial skeleton and the iliac crest donor site, a surgical guide transferred the virtual plan including information on the transplant dimensions and shape as well as the position of the dental implants into real-time surgery. Using postoperative computerized tomography scans, the actual situation were compared with the preoperative simulation. A mean difference of 0.75 mm (SD ± 0.72) for the flap shape and 0.70 mm (SD ± 0.44) for the implant position analysis was determined. A calculation of the closest point distance showed a surface deviation of <2 mm for the shape analysis in 93.3% of the values and <1 mm for implant position in 75.2% of the values. The mean angular deviation was 3.65°. Virtual surgical planning is a suitable method for mandibular reconstruction with vascularized iliac crest flaps and simultaneous implant surgery. It can be used to restore the anatomy of the mandible with a high accuracy and can help to shorten subsequent dental rehabilitation.

Computer-assisted zygoma reconstruction with vascularized iliac crest bone graft.

The reconstruction of zygoma is a challenge with regard to aesthetic and reconstructive demands.

Three-dimensional evaluation of the different donor sites of the mandible for autologous bone grafts

ObjectivesFor effective placement of endosseous implants, a sufficient volume of bone is required at the recipient site. The aim of this study is to evaluate the density and maximum amount of harvestable bone graft required from the mandible symphysis, coronoid process, and ascending ramus, depending on dentition.Materials and methodsCT data from 42 patients (13 females and 29 males) in DICOM format were read using special planning software. Three different virtual bone grafts were created, and the dimension outcomes, surface, volume, and density were measured in a dentate group (n = 22) and a total edentulous group (n = 20).ResultsComparisons between corresponding bone grafts showed no difference for the symphysis and coronoid process in relation to dentition, and no difference in bone density was observed. However, significant changes between the average values of the ramus were found between the two groups (p < 0.0001).ConclusionsAppropriate software and CT data can deliver more accurate examinations of the mandible in relation to potential donor sites. Atrophy primarily affects the ascending ramus; the symphysis and coronoid process are only slightly influenced.Clinical relevanceUsing appropriate software in conjunction with implant planning, it is possible to analyze potential donor areas within the jaw and create virtual bone grafts

Medial approach for minimally-invasive harvesting of a deep circumflex iliac artery flap for reconstruction of the jaw using virtual surgical planning and CAD/CAM technology

Donor site morbidity is the most common limitation of the deep circumflex iliac artery (DCIA) flap, so the purpose of this paper is to describe a new, minimally-invasive, approach to its harvest using virtual surgical planning and CAD/CAM technology to reduce functional and aesthetic morbidity at the donor site. Virtual surgical planning was based on preoperative computed tomographic data. A newly-designed surgical guide made using CAD/CAM technology was used to transfer the virtual surgical plan to the site of operation. This enabled us to raise a bicortical flap from the pelvis with preservation of the anterior superior iliac crest from the medial side with minimal muscular stripping. The guide, designed at slightly less than 90° to the lateral cortex, allowed the cut segment of bone to be raised medially. The new virtual surgical planning guide allowed a medial approach with reduced stripping of muscle and lower morbidity. No complications were encountered during the operation or the healing phase. Patients treated in this way had a shorter recovery period, with minimal complaints about walking or loss of profile of the hip. We conclude that virtual surgical planning can aid a minimally-invasive approach with predictable results. This allows a medial approach to the harvest of DCIA with preservation of important anatomical structures, and a reduction in donor site morbidity.

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

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.

Three-dimensional evaluation of the posterior airway space: differences in computed tomography and cone beam computed tomography

ObjectivesObstructive sleep apnea syndrome (OSAS) becomes increasingly important. For diagnosis and surgery, computed tomography (CT), and cone beam computed tomography (CB-CT) are used equally, although in most of cases, patient positioning differs between supine positioning (CT) and upright seating positioning (CB-CT). We measured volumetric and anatomical changes in the posterior airway space (PAS) between upright and supine positioning in a three-dimensional set up.Materials and methodsCoherent CT and CB-CT scans of 55 patients were included in the study. Using Brainlab ENT 3.0, image data was superimposed, and three-dimensional models were segmented. PAS height, cross-sectional area, vertical and horizontal position of the mandible and hyoid, and volumetric analyses of the three-dimensional models were measured.ResultsPAS height and cross-sectional area were significantly higher in CB-CT compared to CT scans (p < 0.001). In the vertical dimension, the mandible and hyoid were localized more caudally in CB-CT in contrast to CT scans (p < 0.04; p < 0.001). Three-dimensional evaluation showed a greater volume of the PAS in CB-CT (p < 0.0001). Pearson correlation coefficient showed a correlation between vertical positioning of the mandible and hyoid compared to the positioning of the patient.ConclusionsPatient positioning during CT and CB-CT has an effect on the location of anatomical structures like the mandible and hyoid and changes the dimensions and volume of the posterior airway space significantly.Clinical relevanceThe radiological technique used and the positioning of the patient should be taken into account when considering further surgical therapy.