Patient-specific 3D-printed mini-versus reconstruction plates for free flap fixation at the mandible: Retrospective study of clinical outcomes and complication rates

Customized Surgical Plates for Computer-Assisted Maxillary and Mandibular Reconstruction

Jaw reconstruction after ablative surgeries poses significant challenges for maxillofacial reconstructive surgeons. Offering maximum functional rehabilitation, osseous free flaps have become the standard of care. The conventional approach involves shaping donor bone segments into the jaw configuration in a free-hand fashion, which can lead to unpredictable and suboptimal outcomes. Recent advancements in computer-assisted surgery, virtual surgical planning (VSP), and 3-dimensional printing technologies offer promising solutions to these challenges, enabling the fabrication of patient-specific surgical guides and patient-specific surgical plates. This article outlines the workflow of VSP and the clinical application of patient-specific devices in jaw reconstruction.

Fibula free flap reconstruction: improving the accuracy of virtual surgical planning using titanium inserts

Although advancements in three-dimensional (3D) modelling techniques have significantly reduced deviations between planned and actual clinical outcomes in fibula free flap reconstructions, discrepancies between the virtual surgical plan (VSP) and postoperative results persist. In this study, three head and neck surgeons performed 10 fibula osteotomies using conventional cutting templates and 10 osteotomies using more rigid cutting templates with titanium inserts. Differences in 3D angles and segment lengths between the planned and achieved osteotomy planes were calculated. The use of the titanium inserts resulted in a decrease in 3D angular deviation by 0.5° and a reduction in fibula segment length deviation by 0.2 mm for both the short and long sides. The use of the inserts enhanced guidance of the saw and diminished the risk of creating a false route, resulting in a better alignment with the VSP. This may lead to better reconstructive results, decreased operation times, and a potential reduction in complications in a cost-effective manner.

A novel algorithm for streamlined surgeon-dominated patient-specific implant design in computer-assisted jaw reconstruction

BACKGROUND

Computer-assisted surgery has transformed the approach to jaw resection and reconstruction in recent years. However, the extensive time and technical expertise needed for the planning and creation of patient-specific implants and guides have posed significant challenges for many surgeons in the field. This study introduces a novel algorithm designed to streamline the traditionally intricate and time-consuming Computer-Aided Design (CAD) process for developing patient-specific implants (PSIs).

METHODS

The algorithm requires a three-dimensional (3D) model of the reconstructed part. A set of points is selected along the planned location of the plate by the surgeon, defining both the geometry and the positions of the screw holes. These points are then connected to create trace lines, followed by smoothing using cubic-spline data interpolation. Subsequently, a rectangle is swept along the trace line to form the skeleton of the PSI's surface model. Screw holes are incorporated into the surface model, which is then converted into 3D printable file format. Finite element analysis is conducted to evaluate the functionality of the designed PSI.

RESULTS

Implant design time exhibits significant reductions with the proposed algorithm, which optimizes the model files for printing. Finite Element Analysis is successfully applied to demonstrate the stress levels in the implant plate, which are within safe limits for titanium 3D-printed implants.

CONCLUSIONS

This algorithm offers a faster, more efficient, and accurate alternative to traditional CAD methods, with the potential to revolutionize the field of patient-specific implant design. Furthermore, the study demonstrates the utility of a mechanistic model for correlating patient bite force with muscle forces in the literature.

Complications following miniplate insertion in maxillofacial fractures: a systematic review

Background

Maxillofacial fractures, frequently arising from road traffic incidents, falls, and acts of interpersonal aggression, are a considerable public health issue, exhibiting diverse epidemiological patterns according to demographic factors. The application of miniplates for fracture stabilization is a recognized technique, with innovative methods such as 3D plate systems emerging. Nonetheless, consequences including infections and hardware malfunctions persist. This systematic review seeks to present current evidence regarding the complications linked to miniplate placement in maxillofacial fractures over the last ten years.

Methods

A systematic review was performed in accordance with PRISMA principles. Databases such as the Cochrane Library, PubMed, and Scopus were examined from September 2014 to September 2024. Studies documenting problems related to miniplate placement were included, without language constraints. The ROBINS-I tool was utilized for non-randomized studies, whereas the Cochrane risk of bias tool was applied to randomized controlled trials.

Results

From 2,289 initially found studies, 56 satisfied the inclusion criteria. Among these, 28 employed interventional designs, whilst the remaining 28 were observational research. The predominant problems documented in several investigations encompassed infection, wound dehiscence, malocclusion, paraesthesia, malunion/non-union, segment movement, hardware failure, and palpable hardware. Advanced methodologies such as 3D plate systems and locking mechanisms were linked to diminished complication rates.

Conclusion

This systematic analysis presents a decade of updated research about problems associated with miniplate placement in maxillofacial fractures. Novel methodologies such as 3D plate systems and locking mechanisms demonstrate promise in mitigating problems relative to conventional techniques. These findings can facilitate informed decision-making in clinical practice. Additional study utilizing standardized outcomes and prospective designs is essential to enhance comprehension of the long-term effects of miniplate utilization.

Towards improved functionality of mandibular reconstruction plates enabled by additively manufactured triply periodic minimal surface structures

Additive manufacturing for fabrication of patient-specific oral and maxillofacial implants enables optimal fitting, significantly reducing surgery time and subsequent costs. However, it is still common to encounter hardware- or biological-related complications, specifically when radiation treatment is involved. For mandibular reconstruction plates, irradiated patients often experience plate loosening and subsequent plate exposure due to a decrease in the vascularity of the irradiated tissues. We hypothesize that an acceleration of the bone ingrowth prior to radiation treatment can increase the survival of such plates. In this work, a new design of a mandibular reconstruction plate is proposed to promote osseointegration, while providing the necessary mechanical support during healing. In this regard, six different Triply Periodic Minimal Surface (TPMS) structures were manufactured using laser-powder bed fusion. Three-point bending and in-vitro cell viability tests were performed. Mechanical testing demonstrated the ability for all structures to safely withstand documented biting forces, with favorable applicability for the Gyroid structure due its lower flexural modulus. Finally, cell viability tests confirmed high cell proliferation rate and good cell adhesion to the surface for all TPMS structures. Overall, the new design concept shows potential as a viable option for plates with improved functionality and higher survival rate.

Osteoradionecrosis in osseous free flaps after maxillofacial reconstruction: a single-center experience

Objective

In the multimodal treatment of advanced head and neck malignancies, primary free flap reconstruction in a one stage procedure with tumor resection is frequently combined with adjuvant radiotherapy. Radiotherapy is known to exhibit side effects on transplanted free flaps, including osteoradionecrosis (ORN) of native and transplanted bone. This study aims to evaluate the therapeutic outcomes and potential predictors of free flap ORN within osseous free flaps based on a large-scale, single-center database.

Methods

A retrospective analysis was conducted on patients who underwent osseous free flap reconstruction of maxilla or mandible in a one stage procedure followed by adjuvant radiotherapy due to an advanced head and neck malignancy between April 2017 and July 2023. After case matching, patients with and without free flap ORN were assessed for potential predictors using univariate and multivariate analysis.

Results

112 patients met the inclusion criteria. 21 patients (19%) developed ORN within the free flap. Following case matching, 42 patients (10 females, mean age 61.5 ± 9.1 years) were included in the final analysis. The mean time to ORN diagnosis was 19 (7-56) months after surgery. Total flap loss occurred in 7 patients (33%) following flap ORN. Smoking (76% vs. 38%; OR 5.78; p=0.03) and prior plate exposure (67% vs. 24%; OR 5.61; p=0.03) emerged as robust predictors of flap ORN in uni- and multivariate analysis.

Conclusion

Osseous free flap ORN is a severe radiooncologic complication, often resulting in total flap loss and subsequently increased morbidity. Smoking and prior plate exposure were identified as key predictors of flap ORN development. Individual risk assessment and careful evaluation of osseous free flap irradiation must be evaluated in future radiooncological concepts.

Comparative study of CAD/CAM reconstruction and miniplates for patient-specific fixation in LCL-type mandibular reconstruction

Objective

Miniplates offer superior clinical handling and facilitate postoperative removal after mandibular reconstruction but unfavorable load distribution under high stress has been shown. This study aimed to compare the clinical outcome of patient-specific 3D-printed (PS-3D) titanium miniplate with reconstruction plate fixation in three-segmental LCL-type reconstructions for the first time.

Methods

Patients undergoing three-segmental LCL-type mandibular reconstruction after malignant tumor resection between April 2017 and July 2023 were analyzed in a retrospective single-center study. Inclusion criteria were primary reconstruction using a fibula free flap and PS-3D titanium mini- or reconstruction plate fixation. Complication rates were recorded and analyzed within 6 months after surgery using the N - 1 Chi2- and unequal variance t-test.

Results

38 patients (10 females, 28 males; mean age 61.4 ± 7.6 years) met the inclusion criteria. In 14 patients (36.8%) miniplates were used in the anterior region. Rates of fixation failure, plate exposure, incomplete osseous union, wound infection, soft tissue, and overall complications did not differ significantly between the two plate systems.

Conclusion

Complication rates did not differ significantly between PS-3D mini- and reconstruction plates in three-segmental LCL-type mandibular reconstructions. Given their advantages in clinical handling and postoperative removal, PS-3D miniplates can be a viable alternative also in larger mandibular reconstructions.

Biomechanical evaluation of CAD/CAM magnesium miniplates as a fixation strategy for the treatment of segmental mandibular reconstruction with a fibula free flap

Titanium patient-specific (CAD/CAM) plates are frequently used in mandibular reconstruction. However, titanium is a very stiff, non-degradable material which also induces artifacts in the imaging. Although magnesium has been proposed as a potential material alternative, the biomechanical conditions in the reconstructed mandible under magnesium CAD/CAM plate fixation are unknown. This study aimed to evaluate the primary fixation stability and potential of magnesium CAD/CAM miniplates. The biomechanical environment in a one segmental mandibular reconstruction with fibula free flap induced by a combination of a short posterior titanium CAD/CAM reconstruction plate and two anterior CAD/CAM miniplates of titanium and/or magnesium was evaluated, using computer modeling approaches. Output parameters were the strains in the healing regions and the stresses in the plates. Mechanical strains increased locally under magnesium fixation. Two plate-protective constellations for magnesium plates were identified: (1) pairing one magnesium miniplate with a parallel titanium miniplate and (2) pairing anterior magnesium miniplates with a posterior titanium reconstruction plate. Due to their degradability and reduced stiffness in comparison to titanium, magnesium plates could be beneficial for bone healing. Magnesium miniplates can be paired with titanium plates to ensure a non-occurrence of plate failure.