Clinical evaluation of an automated virtual surgical planning platform for mandibular reconstruction

Evaluating the benefit of virtual surgical planning on bony union rates in head and neck reconstructive surgery

OBJECTIVES

Virtual surgical planning (VSP) has gained acceptance because of its benefits in obtaining adequate resection, achieving cephalometric accuracy, and reducing operative time. The aim of this study is to compare the rate of union between VSP and free-hand surgery (FHS), identify predictors of non-union and evaluate the difference in operative time.

METHODS

Post-operative CT were retrospectively reviewed for 123 patients who underwent maxillary or mandibular reconstruction between 2014 and 2021 using either VSP or FHS. Each apposition was graded as complete, partial or non-union. The rate of union, risk difference and inter-rater reliability were calculated. The difference in operative time was assessed. Predictors of non-union were identified using logistic regression.

RESULTS

A total of 326 appositions were graded (VSP n = 150; FHS n = 176). The rates of complete and partial union were higher with VSP than FHS (74.7% vs. 65.3%; 18% vs. 15.9%, respectively, p = 0.01). Non-union was found at a higher rate with FHS than with VSP (18.7% vs. 7.3%). The non-union risk difference was 11.4. FHS, major complications and apposition at the native bone were predictors of non-union (OR 2.9, p = 0.02; OR 3.4, p = 0.01; OR 2.5, p = 0.05, respectively). The mean surgical time was shorter with VSP than with FHS (265.3 vs. 381.5 min, p < 0.001). The inter-rater agreement was high (k = 0.85; ICC = 0.86).

CONCLUSION

VSP demonstrated significantly higher bony union rates and shorter operative time. FHS, development of major complications and apposition with native bone correlated with non-union.

Bone reconstruction using CAD/CAM technology in head and neck surgical oncology. A narrative review of state of the art and aesthetic-functional outcomes

Bone defects following resections for head and neck tumours can cause significant functional and aesthetic defects. The choice of the optimal reconstructive method depends on several factors such as the size of the defect, location of the tumour, patient’s health and surgeon’s experience. The reconstructive gold standard is today represented by revascularised osteo-myocutaneous or osteomuscular flaps with osteosynthesis using titanium plates. Commonly used donor sites are the fibula, iliac crest, and lateral scapula/scapular angle. In recent years, computer-aided design (CAD)/computer assisted manufacturing (CAM) systems have revolutionised the reconstructive field, with the introduction of stereolithographic models, followed by virtual planning software and 3D printing of plates and prostheses. This technology has demonstrated excellent reliability in terms of accuracy, precision and predictability, leading to better operative outcomes, reduced surgical times and decreased complication rates. Among the disadvantages are high costs, implementation times and poor planning adaptability. These problems are finding a partial solution in the development of “in house” laboratories for planning and 3D printing. Strong indications for the use of CAD/CAM technologies today are the reconstruction of total or subtotal mandibular or maxillary defects and secondary bone reconstructions.

Cost-effective Solution for Maxillofacial Reconstruction Surgery with Virtual Surgical Planning and 3D Printed Cutting Guides Reduces Operative Time

Background: This study aimed to explore a low-cost solution for virtual surgical planning/3D printed surgical guides in a training hospital, assessing the impact on intraoperative time and bleeding. Material and Methods: We included a total of 13 patients. 8 who underwent maxillofacial reconstruction surgery with fibula-free flap utilizing virtual surgical planning/3D printed guides (VP/SG), and 5 using conventional surgery (CS) from 2017 to 2020. The surgical time, bleeding, length of hospital stay, and comorbidities were collected and compared in two groups. We recorded the average cost for the complete surgical planning and 3D printed guides. We applied a qualitative survey to the surgeons involved in the surgical procedures. Results The mean surgical time in the VP/SG group was 8.16 ± 2.7, compared to the CS group 12.5 ± 3.8, showing a 4.34 hours difference with statistical significance (p = 0.033). Patients from the CS group had a higher bleeding volume of 921 ± 467.6 mL VS 760 ± 633.8 mL in the VP/SG group. The average cost for the complete surgical planning and 3D printed guides was 914.44 ± 46.39 USD. All the surgeons who answered the survey preferred to perform the procedure utilizing the virtual planning/3D printed guides. Conclusions Virtual planning and 3D printed surgical guides have the potential to reduce operation time in maxillofacial reconstruction.

Development and validation of a novel craniofacial statistical shape model for the virtual reconstruction of bilateral maxillary defects

Bilateral maxillary defects are a challenge for fibula free flap reconstruction (FFFR) surgery due to limitations in virtual surgical planning (VSP) workflows. While meshes of unilateral defects can be mirrored to virtually reconstruct missing anatomy, Brown class c and d defects lack a contralateral reference and associated anatomical landmarks. This often results in poor placement of osteotomized fibula segments. This study was performed to improve the VSP workflow for FFFR using statistical shape modeling (SSM) - a form of unsupervised machine learning - to virtually reconstruct premorbid anatomy in an automated, reproducible, and patient-specific manner. A training set of 112 computed tomography scans was sourced from an imaging database by stratified random sampling. The craniofacial skeletons were segmented, aligned, and processed via principal component analysis. Reconstruction performance was validated on a set of 45 unseen skulls containing various digitally generated defects (Brown class IIa-d). Validation metrics demonstrated promising accuracy: mean 95th percentile Hausdorff distance of 5.47 ± 2.39 mm, mean volumetric Dice coefficient of 48.8 ± 14.5%, compactness of 7.28 × 105 mm2, specificity of 1.18 mm, and generality of 8.12 × 10-6 mm. SSM-guided VSP will allow surgeons to create patient-centric treatment plans, increasing FFFR accuracy, reducing complications, and improving postoperative outcomes.

Applications of three-dimensional imaging techniques in craniomaxillofacial surgery: A literature review

Three-dimensional (3D) imaging technologies are increasingly used in craniomaxillofacial (CMF) surgery, especially to enable clinicians to get an effective approach and obtain better treatment results during different preoperative and postoperative phases, namely during image acquisition and diagnosis, virtual surgical planning (VSP), actual surgery, and treatment outcome assessment. The article presents an overview of 3D imaging technologies used in the aforementioned phases of the most common CMF surgery. We searched for relevant studies on 3D imaging applications in CMF surgery published over the past 10 years in the PubMed, ProQuest (Medline), Web of Science, Science Direct, Clinical Key, and Embase databases. A total of 2094 articles were found, of which 712 were relevant. An additional 26 manually searched articles were included in the analysis. The findings of the review demonstrated that 3D imaging technology is becoming increasingly popular in clinical practice and an essential tool for plastic surgeons. This review provides information that will help researchers and clinicians consider the use of 3D imaging techniques in CMF surgery to improve the quality of surgical procedures and achieve satisfactory treatment outcomes.

Virtual surgical planning for maxillary reconstruction with the scapular free flap: An evaluation of a simple cutting guide design

BACKGROUND

The study's objective is to assess the feasibility and utility of VSP for maxillary reconstruction with the scapular free flap.

METHODS

An open-source VSP platform was used to create the reconstruction models and simple guides. Clinical, operative, and postoperative data were collected.

RESULTS

Ten patients in the VSP cohort and 18 in the non-VSP control cohort were included in the study. There was a significant reduction in operative time (256.0 ± 69.4 vs. 448.1 ± 108.2 min, p < 0.01), tracheotomy rate (20% vs. 72%, p < 0.01), increased two-team utilization rate (80% vs. 0%, p < 0.01) and better reconstructive accuracy (7.5 ± 3.4 vs. 11.7 ± 7.6 mm, p = 0.048) for the VSP cohort.

CONCLUSIONS

Maxillary reconstruction planned with an in-house open-source VSP platform and accompanied simple guides can facilitate a two-team approach, reduce operative time, and improve structural accuracy. This open-source technology has great potential to be readily applied in other institutions to improve efficiency and outcomes.

Virtual planning and 3D-printed guides for mandibular reconstruction: Factors impacting accuracy

Objectives

Examine accuracy and factors impacting accuracy for mandibular reconstruction with virtual surgical planning, 3D printed osteotomy guides and preoperatively bent mandibular reconstruction plate (VSP/3Dprinted-guide/plate).

Method

Retrospective review of osseous-free-flap mandibular reconstructions with VSP/3Dprinted-guide/plate between January 2015 and July 2020 at a single academic medical center.Patient demographics, disease, and treatment variables were extracted. Accuracy was assessed by 3D-model-overlay with cephalometric and donor-bone segment length measurements. Multivariate analyses were performed to determine factors impacting cephalometric accuracy.

Results

60 cases met criteria: 41 (68%) cancer, 14 (23%) osteoradionecrosis (ORN), 5 (8%) secondary mandibular reconstruction. Thirteen cases (22%) were Brown class III or IV. Thirty-nine cases (65%) had ≥2 flap bone segments. Average donor-bone length was 82 mm (SD: 28). 3D-model-overlay accuracy demonstrated minimal deviation between planned and actual reconstruction: intercondylar distance = 2.10 mm (SD: 2.2); intergonial distance = 2.23 mm (SD: 1.9); anterior-posterior distance (APD) = 1.76 mm (SD: 1.5); gonial angle (GA) = 3.11 degrees (SD: 2.4). Mean change in donor-bone segment length inferiorly was 2.67 mm (SD: 2.6) and superiorly 3.27 mm (SD: 3.2). Higher number of donor-bone segments was associated with decreased accuracy in GA (p = .023) and longer donor-bone length was associated with decreased accuracy in APD (p = .031).

Conclusion

To our knowledge this is the largest series assessing surgical accuracy of VSP/3Dprinted-guide/plate for osseous-free-flap mandibular reconstruction. We demonstrate highly accurate results, with increased number of donor-bone segments and donor-bone length associated with decreased accuracy. Our findings further support VSP/3Dprinted-guide/plate as a reliable and accurate tool for mandibular reconstruction.

Level of Evidence

Level 4.

The comprehensive on-demand 3D bio-printing for composite reconstruction of mandibular defects

Background

The mandible is a functional bio-organ that supports facial structures and helps mastication and speaking. Large mandible defects, generally greater than 6-cm segment loss, may require composite tissue reconstruction such as osteocutaneous-vascularized free flap which has a limitation of additional surgery and a functional morbidity at the donor site. A 3D bio-printing technology is recently developed to overcome the limitation in the composite reconstruction of the mandible using osteocutaneous-vascularized free flap.

Review

Scaffold, cells, and bioactive molecules are essential for a 3D bio-printing. For mandibular reconstruction, materials in a 3D bio-printing require mechanical strength, resilience, and biocompatibility. Recently, an integrated tissue and organ printing system with multiple cartridges are designed and it is capable of printing polymers to reinforce the printed structure, such as hydrogel.

Conclusion

For successful composite tissue reconstruction of the mandible, biologic considerations and components should be presented with a comprehensive on-demand online platform model of customized approaches.

Benefits of Patient-Specific Reconstruction Plates in Mandibular Reconstruction Surgical Simulation and Resident Education

Poorly contoured mandibular reconstruction plates are associated with postoperative complications. Recently, a technique emerged whereby preoperative patient-specific reconstructive plates (PSRP) are developed in the hopes of eliminating errors in the plate-bending process. This study’s objective is to determine if reconstructions performed with PSRP are more accurate than manually contoured plates. Ten Otolaryngology residents each performed two ex vivo mandibular reconstructions, first using a PSRP followed by a manually contoured plate. Reconstruction time, CT scans, and accuracy measurements were collected. Paired Student’s t-test was performed. There was a significant difference between reconstructions with PSRP and manually contoured plates in: plate-mandible distance (0.39 ± 0.21 vs. 0.75 ± 0.31 mm, p = 0.0128), inter-fibular segment gap (0.90 ± 0.32 vs. 2.24 ± 1.03 mm, p = 0.0095), mandible-fibula gap (1.02 ± 0.39 vs. 2.87 ± 2.38 mm, p = 0.0260), average reconstruction deviation (1.11 ± 0.32 vs. 1.67 ± 0.47 mm, p = 0.0228), mandibular angle width difference (5.13 ± 4.32 vs. 11.79 ± 4.27 mm, p = 0.0221), and reconstruction time (16.67 ± 4.18 vs. 33.78 ± 8.45 min, p = 0.0006). Lower plate-mandible distance has been demonstrated to correlate with decreased plate extrusion rates. Similarly, improved bony apposition promotes bony union. PSRP appears to provide a more accurate scaffold to guide the surgeons in assembling donor bone segments, which could potentially improve patient outcome and reduce surgical time. Additionally, in-house PSRP can serve as a low-cost surgical simulation tool for resident education.

The role of computer aided design/computer assisted manufacturing (CAD/CAM) and 3- dimensional printing in head and neck oncologic surgery: A review and future directions

Microvascular free flap reconstruction has remained the standard of care in reconstruction of large tissue defects following ablative head and neck oncologic surgery, especially for bony structures. Computer aided design/computer assisted manufacturing (CAD/CAM) and 3-dimensionally (3D) printed models and devices offer novel solutions for reconstruction of bony defects. Conventional free hand techniques have been enhanced using 3D printed anatomic models for reference and pre-bending of titanium reconstructive plates, which has dramatically improved intraoperative and microvascular ischemia times. Improvements led to current state of the art uses which include full virtual planning (VP), 3D printed osteotomy guides, and patient specific reconstructive plates, with advanced options incorporating dental rehabilitation and titanium bone replacements into the primary surgical plan through use of these tools. Limitations such as high costs and delays in device manufacturing may be mitigated with in house software and workflows. Future innovations still in development include printing custom prosthetics, 'bioprinting' of tissue engineered scaffolds, integration of therapeutic implants, and other possibilities as this technology continues to rapidly advance. This review summarizes the literature and serves as a summary guide to the historic, current, advanced, and future possibilities of 3D printing within head and neck oncologic surgery and bony reconstruction. This review serves as a summary guide to the historic, current, advanced, and future roles of CAD/CAM and 3D printing within the field of head and neck oncologic surgery and bony reconstruction.

Crescent-shaped skin paddle for a fibular flap: Avoiding skin grafting at the donor site

A fibular osteocutaneous flap is the mainstay of oromandibular reconstruction. This report aimed to present a crescent-shaped skin paddle, a novel fibular skin paddle designed to achieve both sufficient intraoral lining and primary closure of the donor site. A 3-5-cm-wide crescent-shaped skin paddle was harvested according to the locations of the distal septocutaneous perforators on preoperative color Doppler sonography. This narrow skin paddle fits well morphologically into the mucosal defect, enabling a reliable intraoral lining. This advantage becomes more evident when the mandibular defect crosses the midline or extends posteriorly to the maxillary tuberosity as the shape of the mucosal defect becomes arcuate. Primary closure of the donor site is easier to achieve because the required width of the crescent-shaped skin paddle is minimized. This method reduces donor-site morbidity associated with skin grafting while ensuring safe intraoral closure with a fibular osteocutaneous flap.

Institutional-based and commercial virtual surgical planning in maxillomandibular reconstruction - Comparing the digital plan and postoperative scan

BACKGROUND

Virtual surgical planning (VSP) is increasingly used in maxillomandibular osseous free flap reconstruction. Non-commercial ('in-house') VSP may offer the same level of accuracy and other benefits, without the inflated costs and time delays inherent in using commercial providers. Comparisons between commercial and in-house methods are lacking. This study aims to determine the accuracy of VSP, compare in-house and commercially planned cases, and explore predictors of the reconstruction error.

METHODS

Seventy-six patients who had a virtually planned maxillomandibular reconstruction between January 2012 and July 2020 were retrospectively identified. The preoperative digital plan was compared to the postoperative CT scan in terms of length of bone segments, angle between adjacent segments and intercondylar, and intergonial angle distances (mandibular reconstructions only).

RESULTS

Forty-four patients fulfilled the inclusion criteria. The mean intergonial and intercondylar distances error was 1.7 ± 1.01 mm, mean segment length error was 1.3 ± 1.40 mm, and mean angles error was 1.9 ± 2.32°. The difference in error of in-house VSP compared to commercial VSP was not statistically significant for intercondylar and intergonial distance (p = 0.76), segment length (p = 0.15), or angle between segments (p = 0.92). The increased error was associated with osteoradionecrosis as the indication for surgery, greater number of segments, and secondary reconstructions.

CONCLUSION

VSP is an accurate method of maxillary and mandibular reconstruction. In-house VSP may be similar in accuracy to commercial VSP options. Higher levels of inaccuracy are likely to occur in more complex reconstructions, particularly secondary reconstructions, and in the setting of osteoradionecrosis.

Maxillectomy defects: Virtually comparing fibular and scapular free flap reconstructions

BACKGROUND

This study virtually compares patient-specific fibular and scapular reconstructions for maxillectomies.

METHODS

Nine maxillectomy defects were created on 10 maxillas and virtually reconstructed with patient-specific fibulas and scapulas. Reconstructions were compared for restoring midface cephalometrics, dental implantability, and pedicle length.

RESULTS

Of 90 maxillectomy defects, the vertically oriented scapula provided improved orbital floor and maxillary height reconstructions (p < 0.001), albeit at the cost of dental implantability compared to the fibula (p < 0.001). In two defects crossing the midline, the fibula, allowing for more osteotomies, provided improved maxillary projection. In the remaining three defects crossing the midline, the horizontally oriented scapula was comparable to the fibula. Fibular and scapular reconstructions were amenable for dental implantation and had similar pedicle lengths, although favoring scapula in extensive defects.

CONCLUSION

Fibular and scapular reconstructions of maxillectomy defects provide unique strengths. This virtual analysis can guide a goal-oriented reconstruction based on defect type and patient-specific goals.

Multicentre evaluation of the interest in planned surgery for mandibular reconstruction with fibula free flap: a retrospective cohort study

PURPOSE

The aim of this study was to determine the impact and cost-effectiveness of virtual surgical planning during fibula free flap mandibular reconstruction on peri- and postoperative data.

METHODS

We conducted a retrospective cohort study from January 2012 to December 2016 in four French university centres.

RESULTS

Three hundred fibula free flaps for mandibular reconstruction were performed in 294 patients. Surgeries were planned in 29.7% of cases (n = 89). There was no significant difference in the rate of negative-margins excision, median length of hospital stay, operative time, and early complications between planned and non-planned surgeries. Morphological analysis revealed a higher rate of centred occlusion in planned patients (satisfactory alignment of interincisal points: Planned 65.5% vs Non-Planned 33.3%, p = 0.006).

CONCLUSION

In mandibular reconstruction by fibula free flap, the additional cost generated by virtual surgical planning does not seem to be balanced by savings resulting from a shorter operative course, a reduced hospital stay, or a reduction in postoperative complications. However, virtual surgical planning may provide a higher rate of centred occlusion. Long-term benefits should be assessed by further studies.