Abstract
Segmental mandibular defects require reconstruction. The fibula flap serves as a versatile flap in restoring mandibular contour and bony height. With the advances in computer-aided design and additive manufacturing technology, an innovative “one-piece” patient-specific reconstruction plate to facilitate double-barrel fibula flap shaping and bone securing was developed; the plate is described in this study. The “one-piece” plate is fabricated with individualized specifications and is mainly composed of three components: the long-bar reconstruction plate, a short-bar plate, and connecting bars. Our initial experiences showed that mandibular reconstructive surgery was greatly facilitated by the “one-piece” reconstruction plate for double-barrel fibula flap reconstruction and achieved satisfactory outcomes. A well-designed clinical trial is required to confirm the superiority of the “one-piece” reconstruction plate in the future. ClinicalTrials.gov registration: NCT03057223.
The mandibular defect after tumour resection should be repaired to prevent violating aesthetics and physiological function. The vascularized free fibula flap is the workhorse in mandibular reconstruction, with a good blood supply and flexibility . However, the thickness of the fibula is not sufficient to fully restore the normal height of the mandible. To address the problem of bone height, the distal fibula segment can be folded back onto the proximal portion to form a double-barrel complex . As the lower fibula is aligned to restore the lower jaw line, the upper fibula is fine-tuned to approximate the normal dentition. In the double-barrel fibula-based mandibular reconstruction, multiple sections of surgical plate are generally used for the fixation of bone segments; these are difficult to manipulate and this will depend on surgeon experience . In addition, it is difficult to determine the optimal position of multiple bone segments and plates simultaneously, thereby rendering the reconstruction outcomes unpredictable .
In recent years, additive manufacturing technology has been used widely to develop patient-specific medical devices. A large number of medical implants have emerged for the repair of skull, zygoma, vertebra, finger, and pelvic bone defects . Meanwhile, patient-specific surgical plates have been developed to facilitate head and neck reconstruction . The patient-specific plate can precisely fit the bone without the need for bending, and can guide the alignment and fixation of bone segments . In an effort to enhance double-barrel fibula-based mandibular reconstruction, we developed a “one-piece” patient-specific reconstruction plate that greatly simplifies the surgical procedure and improves reconstruction outcomes. This article describes the basic features of the “one-piece” reconstruction plate and its advantages in the double-barrel mandibular reconstruction.
Patients and methods
The study was approved by the Institutional Review Board of the University of Hong Kong (UW 16-315). Detailed procedures for computer-assisted mandibular reconstruction and additive manufacturing have been described previously . A total of 24 patients underwent mandibular reconstruction using patient-specific surgical plates in our unit, and five of them received the “one-piece” reconstruction plate for double-barrel fibula-based mandibular reconstruction (Supplementary Material Table S1). The accuracy of reconstruction and clinical outcomes have been reported in previous articles , while the current article focuses on the features and benefits of the “one-piece” reconstruction plate.
Results
The “one-piece” reconstruction plate comprises a lower long-bar reconstruction plate, an upper short-bar plate, and two vertical connecting rods, which are designed in a double-layer structure. Each “one-piece” reconstruction plate was developed based upon the patient’s computed tomography (CT) imaging data and adapted to the reconstructed mandible accurately ( Fig. 1 ). The plate was designed with customized dimensions, and the screw hole spacing varied in each case. In the case shown, the thickness and width of the load-sharing long-bar reconstruction plate were 1.8 mm and 4 mm, respectively, whereas for the non-load-sharing short-bar plate, the thickness and width were 1.5 mm and 3.6 mm, respectively ( Fig. 1 ). The screw hole positions were defined individually to prevent interrupting key anatomical structures or dental implants. Screw holes were also excluded from the positions that bridged the osteotomies, where stress concentration occurs and enhanced fatigue strength is needed. In connecting the two horizontal long-bar and short-bar plates, two vertical rods were designed to ensure the stability of the fibula segments, which assured the vertical height of the reconstructed mandible for both aesthetic and functional considerations. There was no flap failure in this case series. No plate or screw exposure was observed during follow-up.
