Single-Double-Single Barrel (1-2-1) Fibula Free Flap Design for Functional and Aesthetic Brown Class III Mandibular Reconstruction

Summary:

This novel hybrid single-double-single barrel (1-2-1) design for fibula free flap reconstruction addresses the unique challenges presented by Brown class III mandibular defects, which involve long-span defects at both bodies of the mandible and the chin. The importance of this design lies in its ability to overcome the limitations of traditional approaches in terms of mandible height and pedicle length, while optimizing both functional and aesthetic outcomes.

The technique uses a combination of single-double-single barrel fibula segments to achieve ideal aesthetics and support for dental prosthesis across different areas of the mandible. At the chin, a double-barrel design provides proper chin and lower lip projection and supports dental prosthesis at the alveolus, and single-barrel segments are used for the mandibular bodies to allow adequate restorative space for dental rehabilitation and save the pedicle length. Favorable outcomes were demonstrated in terms of flap survival, dental implant osseointegration, bony healing, facial aesthetics, and occlusal rehabilitation. By addressing both functional and aesthetic requirements, this technique represents an important advancement in mandibular reconstruction for complex Brown class III defects. The approach showcases the potential of computer-assisted surgery and innovative flap designs to improve patient outcomes in challenging reconstructive scenarios.

Brown class III mandibular defects present unique challenges for functional and aesthetic reconstruction of the mandible.¹ The aims of the reconstruction are to maintain airway, rebuild lower third face contour, reconstruct chin projection and lip competence, restore facial symmetry, and provide alveolar height and bone stock for dental rehabilitation. With this long-span defect, the fibula free flap is still the treatment of choice in most parts of the world.² However, the positioning of fibula segments is challenging. At the chin area, a double-barrel fibula design is required for good chin and lower third face contour, lip support, and dental rehabilitation. Although at the body of the mandible, a double-barrel design will create a neomandible that is too high, encroaching into the space for dental rehabilitation. A double barrel for long-span reconstruction is also not always possible because of the limitation of fibula bone and pedicle length. Here, we present a novel single-double-single (1-2-1) hybrid design for functional and aesthetic class III mandibular reconstruction.

For a predictable and efficient operation, virtual surgical planning was performed before surgery. The standard workflow of computer-assisted jaw reconstruction was previously described by our team.^3–5 Computed tomographic scans of both skull and fibula were required to build the virtual models in ProPlan CMF 2.0 software (Materialise, Leuven, Belgium). Virtual surgical planning was performed by the chief surgeon and the prosthodontic-driven reconstruction was planned. Tooth positions of future implant-supported fixed dental prosthesis were determined by the prosthodontists in the team, considering such factors as span width, arch shape, occlusion, loading conditions, prosthesis type, cleansability, and other factors. Based on the location of future teeth, simultaneous dental implant positions were virtually planned.

The design of 1-2-1 fibula flap included 3 steps. (See Video [online], which demonstrates the design of the 1-2-1 fibula flap.) First, to house the planned positions of dental implants, the 3-segment fibula, including bilateral body segments and the upper chin segment, was positioned at the alveolar level, leaving at least 15 mm of clearance from the superior edge of fibula to maxillary arch for future dental prosthesis (Fig. 1). Second, the lower chin segment was designed at the distal end of the fibula, preserving 7 cm of fibula bone from the lateral malleolus. To allow this segment to be folded, surpassing mandibular body position and then reaching the lower border of chin, an additional bone segment needed to be spared and then removed between the lower chin segment and the body segment. The length of the spare segment should equal the length of the body segment (segment 3) plus 1 to 1.5 cm. Thus, the whole fibula flap would be osteotomized into 5 segments, with the second to last segment being removed to form the 1-2-1 design (Fig. 1). Third, to allow bone contact between the chin double-barrel segments and the bilateral body segments, the positions of the single-barrel segments were adjusted inferiorly, contacting both upper and lower chin segments at the same time. However, the vertical step between 3 alveolus segments should not be too large, to avoid the difficulty of dental prosthesis positioning. The fibula vessel pedicle was located at the proximal side of the body segment that was opposite to the double-barrel fibula folding side.

Fig. 1.

Virtual surgical plan of the single-double-single barrel (1-2-1) fibula free flap design, with 4 immediate dental implants and planned dental prosthesis. The sequence of the segments from proximal to distal end of the fibula was marked as 1 to 5. Segment 4 was dissected from the pedicle and discarded to allow turning of segment 5 to the double-barrel chin position. Green and purple arrows indicate the translational movement of the body segments (segments 1 and 3) to increase bone contact with the double-barrel chin segment (segment 5). However, the vertical steps between segments 1, 2, and 3 need to be minimized to facilitate future dental prosthesis fabrication.

Video. This video demonstrates the design of the 1-2-1 fibula flap.

Download video file ^{(10.9MB, mp4)}

Patient-specific fibula harvesting and positioning guides were designed using 3-Matic 13.0 (Materialise). Surgical guides were 3-dimensionally printed with ISO-certified biocompatible autoclavable MED610 resin (Stratasys Ltd.) or NextDent SG (Vertex Dental, the Netherlands). (See Figure, Supplemental Digital Content 1, which shows ossifying fibroma at the mandible. Patient-specific 3-dimensionally printed osteotomy guide was fixed into position with 3 screws on each side. Brown class III mandibular defect after guided osteotomies [patient 2], https://links.lww.com/PRS/H924.) As part of an ongoing clinical trial entitled “3D-Printed Patient-Specific Surgical Plates versus Conventional Surgical Plates in Jaw Reconstruction,” 3 patients were randomly assigned to 3-dimensionally printed patient-specific titanium plates group, and the other 3 to a commercial plates group.

During the surgery, the dental implants were inserted, and the fibula was osteotomized into 5 segments according to the 3-dimensionally printed fibula guide. (See Figure, Supplemental Digital Content 2, which shows patient-specific 3-dimensionally printed fibula guide for fibula harvest, segmentation, and immediate dental implant insertion. The sequence of the segments from the proximal to the distal end of the fibula was marked as 1 to 5. Segment 4 was dissected from the pedicle and discarded to allow turning of segment 5 to the double-barrel chin position [patient 2], https://links.lww.com/PRS/H925.) Before osteotomy, careful subperiosteal elevation at the medial surface of osteotomy sites was performed to protect the pedicle. As mentioned above, to allow the most distal fibula segment to be folded and positioned at lower border of chin, the second to last segment was divided from the pedicle in a subperiosteal fashion and then discarded. (See Figure, Supplemental Digital Content 3, which shows the spare segment [segment 4] has been removed to allow turning of the pedicle for segment 5 to reach the double-barrel chin position [patient 6], https://links.lww.com/PRS/H926. See Figure, Supplemental Digital Content 4, which shows segment 5 has been turned to the double-barrel chin position and plated [patient 6], https://links.lww.com/PRS/H927.) The periosteum at the junction between the alveolar segments was mobilized to allow the positioning with a step between the upper chin and body segments. The fibula segments, together with the dental implants, were fixed using either the 3-dimensionally printed titanium plates or transfer guide (Fig. 2) and transferred to repair the mandibular defect. The skin paddle inset, microvascular anastomosis, and wound closure were performed as usual.

Fig. 2.

Intraoperative photograph of the 1-2-1 fibula design fixed with the 3-dimensionally printed patient-specific plate.

Six patients have been operated on using this technique. (See Table, Supplemental Digital Content 5, which shows clinical data. Plating time is the the time spent for the plating of fibula segments to the remaining mandible. M, male; F, female; PSI, patient-specific implants; NonPSI, commercial miniplate, https://links.lww.com/PRS/H928.) The average length of fibula was 35.3 cm (range, 31.0 to 43.0 cm), and the average length of segments used for reconstruction was 3.2 cm (range, 2.0 to 6.5 cm). Although difficult anastomosis was encountered in 1 of the cases because of compromised quality of the blood vessel, leading to prolonged operation time, the flap survival rate was 100%. The anastomosis was performed at the upper neck below the angle of the mandible, where the pedicle came off from segment 1, before the flap inset (Fig. 1). No vein graft was required in any of the 6 cases. All 6 patients resumed complete oral feeding and intelligible speech within 1 to 2 weeks after surgery. A total of 31 immediate dental implants were inserted, averaging 5.2 for each patient. The average time spent to plate the fibula segments to the remaining mandible was 18.3 minutes and 87 minutes using the 3-dimensionally printed plates and commercial plates, respectively. All dental implants achieved successful osseointegration. Postoperative radiography showed good bony union (Fig. 3). After the delivery of dental prosthesis, facial aesthetics and occlusion were satisfactorily rehabilitated (Fig. 4). (See Figure, Supplemental Digital Content 6, which shows frontal view at 4 years postoperatively in patient 2, https://links.lww.com/PRS/H929. See Figure, Supplemental Digital Content 7, which shows the profile view at 4 years postoperatively for patient 2 and lateral cephalometric radiograph showing the restoration of chin contour with the double-barrel fibula design for patient 4, https://links.lww.com/PRS/H930.)

Fig. 3.

After dental rehabilitation of the mandibular teeth. Note the single-barrel segments at the body of the mandible provided sufficient bone height and restorative space for dental rehabilitation of the posterior teeth. However, the double-barrel segments at the chin provided good facial projection.

Fig. 4.

Frontal view of teeth at 4 years postoperatively.

DISCUSSION

The novel 1-2-1 design offers a reliable and ideal solution for functional and aesthetic reconstruction of Brown class III mandibular defects using a free fibula flap with immediate dental implants. It addresses the requirements of both the facial contour at the chin with the double-barrel fibula and the appropriate positioning of fibula segments at the mandible body for dental rehabilitation, while saving as much pedicle length for anastomosis as possible. Our experience showed favorable clinical outcomes.

Since the popularization of free fibula flap for mandible reconstruction, multiple attempts have been made to solve the height difference between fibula and mandible. Chang et al. described the technique of the double-barrel fibula with immediate dental implants for both functional and aesthetic reconstruction of mandible.⁶ However, the double-barrel fibula design usually creates a neomandible that is too high at the body of the mandible. Ch’ng et al. described the technique of rotating the lower segment to reduce the height.⁷ However, in extensive defects, such as Brown class III, a double-barrel design over the whole defect is not always possible considering the length of fibula bone and remaining pedicle for anastomosis. The current design offers a solution for these issues at the same time.

One challenge lies in the complexity of the design. Four fibula segments were positioned in a 1-2-1 barrel fashion for the mandible reconstruction, and 1 extra bone segment was discarded to allow folding of the double barrel at the chin position (see Figure, Supplemental Digital Content 3, https://links.lww.com/PRS/H926; see Figure, Supplemental Digital Content 4, https://links.lww.com/PRS/H927). With immediate dental implants, high precision is required for the cutting and positioning of multiple fibula segments. Computer-assisted surgery with prefabricated surgical guides offers a practical solution with both accuracy and efficiency for such a complicated fibula design.^2,8,9

Another challenge is the remaining pedicle length, especially in the Asian population, with only 35 cm of fibula length for men and 31 to 32 cm for women on average.¹⁰ A potential solution is to use nonvascular fibula bone graft for the contour of lower border of mandible, which has risk of resorption and infection and thus is not suitable for infection patients and cancer patients who need postoperative radiotherapy. In the current design, all 4 segments of fibula were vascularized. In some cases, with a short fibula, the remaining pedicle length for anastomosis was minimal. Nonetheless, the operation was successfully performed in all 6 cases without the need for vein graft. However, for patients with multiple previous operations or radiotherapy and no available recipient vessels in the upper neck, we shall avoid this design; otherwise a vein graft will be needed. Our 1-2-1 fibula design could achieve different goals of Brown class III mandibular reconstruction, including chin projection, lip competence, lower third face contour, and dental rehabilitation; therefore, we recommend it as an ideal reconstruction solution for such defects.

This technical report has its limitations because of the small sample size. A prospective study with comparison to standard technique will reveal the objective aesthetic and functional outcomes and also the complications. However, because of the relatively limited number of class III defects, a multicenter study will be needed to answer these questions in the future.

DISCLOSURE

The authors have no financial or personal conflict of interests to disclose.

PATIENT CONSENT

Patients provided written informed consent for the use of their information and images.

ACKNOWLEDGEMENTS

The study was supported by Health and Medical Research Fund (project no. 08192096), and the Food and Health Bureau, Hong Kong.

Supplementary Material

prs-156-407e-s002.pdf ^{(1.2MB, pdf)}

prs-156-407e-s003.pdf ^{(755.8KB, pdf)}

prs-156-407e-s004.pdf ^{(2.5MB, pdf)}

prs-156-407e-s005.pdf ^{(1.9MB, pdf)}

prs-156-407e-s006.pdf ^{(32.2KB, pdf)}

prs-156-407e-s007.pdf ^{(297.9KB, pdf)}

prs-156-407e-s008.pdf ^{(641KB, pdf)}