Does Freehand, Patient-specific Instrumentation or Surgical Navigation Perform Better for Allograft Reconstruction After Tumor Resection? A Preclinical Synthetic Bone Study

BACKGROUND

Joint-sparing resection of periarticular bone tumors can be challenging because of complex geometry. Successful reconstruction of periarticular bone defects after tumor resection is often performed with structural allografts to allow for joint preservation. However, achieving a size-matched allograft to fill the defect can be challenging because allograft sizes vary, they do not always match a patient's anatomy, and cutting the allograft to perfectly fit the defect is demanding.

QUESTIONS/PURPOSES

(1) Is there a difference in mental workload among the freehand, patient-specific instrumentation, and surgical navigation approaches? (2) Is there a difference in conformance (quantitative measure of deviation from the ideal bone graft), elapsed time during reconstruction, and qualitative assessment of goodness-of-fit of the allograft reconstruction among the approaches?

METHODS

Seven surgeons used three modalities in the same order (freehand, patient-specific instrumentation, and surgical navigation) to fashion synthetic bone to reconstruct a standardized bone defect. National Aeronautics and Space Administration (NASA) mental task load index questionnaires and procedure time were captured. Cone-beam CT images of the shaped allografts were used to measure conformance (quantitative measure of deviation from the ideal bone graft) to a computer-generated ideal bone graft model. Six additional (senior) surgeons blinded to modality scored the quality of fit of the allografts into the standardized tumor defect using a 10-point Likert scale. We measured conformance using the root-mean-square metric in mm and used ANOVA for multipaired comparisons (p < 0.05 was significant).

RESULTS

There was no difference in mental NASA total task load scores among the freehand, patient-specific instrumentation, and surgical navigation techniques. We found no difference in conformance root-mean-square values (mean ± SD) between surgical navigation (2 ± 0 mm; mean values have been rounded to whole numbers) and patient-specific instrumentation (2 ± 1 mm), but both showed a small improvement compared with the freehand approach (3 ± 1 mm). For freehand versus surgical navigation, the mean difference was 1 mm (95% confidence interval [CI] 0.5 to 1.1; p = 0.01). For freehand versus patient-specific instrumentation, the mean difference was 1 mm (95% CI -0.1 to 0.9; p = 0.02). For patient-specific instrumentation versus surgical navigation, the mean difference was 0 mm (95% CI -0.5 to 0.2; p = 0.82). In evaluating the goodness of fit of the shaped grafts, we found no clinically important difference between surgical navigation (median [IQR] 7 [6 to 8]) and patient-specific instrumentation (median 6 [5 to 7.8]), although both techniques had higher scores than the freehand technique did (median 3 [2 to 4]). For freehand versus surgical navigation, the difference of medians was 4 (p < 0.001). For freehand versus patient-specific instrumentation, the difference of medians was 3 (p < 0.001). For patient-specific instrumentation versus surgical navigation, the difference of medians was 1 (p = 0.03). The mean ± procedural times for freehand was 16 ± 10 minutes, patient-specific instrumentation was 14 ± 9 minutes, and surgical navigation techniques was 24 ± 8 minutes. We found no differences in procedure times across three shaping modalities (freehand versus patient-specific instrumentation: mean difference 2 minutes [95% CI 0 to 7]; p = 0.92; freehand versus surgical navigation: mean difference 8 minutes [95% CI 0 to 20]; p = 0.23; patient-specific instrumentation versus surgical navigation: mean difference 10 minutes [95% CI 1 to 19]; p = 0.12).

CONCLUSION

Based on surgical simulation to reconstruct a standardized periarticular bone defect after tumor resection, we found a possible small advantage to surgical navigation over patient-specific instrumentation based on qualitative fit, but both techniques provided slightly better conformance of the shaped graft for fit into the standardized post-tumor resection bone defect than the freehand technique did. To determine whether these differences are clinically meaningful requires further study. The surgical navigation system presented here is a product of laboratory research development, and although not ready to be widely deployed for clinical practice, it is currently being used in a research operating room setting for patient care. This new technology is associated with a learning curve, capital costs, and potential risk. The reported preliminary results are based on a preclinical synthetic bone tumor study, which is not as realistic as actual surgical scenarios.

CLINICAL RELEVANCE

Surgical navigation systems are an emerging technology in orthopaedic and reconstruction surgery, and understanding their capabilities and limitations is paramount for clinical practice. Given our preliminary findings in a small cohort study with one scenario of standardized synthetic periarticular bone tumor defects, future investigations should include different surgical scenarios using allograft and cadaveric specimens in a more realistic surgical setting.

Navigational exploration of bony defect mimicking a solid lesion of the mandible compared to conventional surgery by young professionals

INTRODUCTION

The aim of the current study was to evaluate the accuracy of resection a solid lesion in an acrylic lower jaw by young professionals using a dynamic computer-assisted surgical system comparted to conventional surgery technique.

MATERIAL AND METHODS

Twenty students performed the removal of the lesion conventionally and twenty students did the operation with a dynamic computer-assisted surgical system. Both groups were compared regarding the defect size, operation time, and surgical complications.

RESULTS

The defect size in the jaw was significant smaller with the navigated surgery (p < 0.001). Operation time was shorter without navigation system, but no significance was found (p = 0.137). Without navigation system three young professionals perforated the lingual cortex.

DISCUSSION

Navigated surgery can immediately be used by young professionals and support young surgeons in everyday clinical practice, especially in operations with difficult anatomic situations.

Intraoral Condylectomy with 3D-Printed Cutting Guide versus with Surgical Navigation: An Accuracy and Effectiveness Comparison

This study compares the accuracy and effectiveness of our novel 3D-printed titanium cutting guides with intraoperative surgical navigation for performing intraoral condylectomy in patients with mandibular condylar osteochondroma (OC). A total of 21 patients with mandibular condylar OC underwent intraoral condylectomy with either 3D-printed cutting guides (cutting guide group) or with surgical navigation (navigation group). The condylectomy accuracy in the cutting guide group and navigation group was determined by analyzing the three-dimensional (3D) discrepancies between the postoperative computed tomography (CT) images and the preoperative virtual surgical plan (VSP). Moreover, the improvement of the mandibular symmetry in both groups was determined by evaluating the chin deviation, chin rotation and mandibular asymmetry index (AI). The superimposition of the condylar osteotomy area showed that the postoperative results were very close to the VSP in both groups. The mean 3D deviation and maximum 3D deviation between the planned condylectomy and the actual result were 1.20 ± 0.60 mm and 2.36 ± 0.51 mm in the cutting guide group, and 1.33 ± 0.76 mm and 4.27 ± 1.99 mm in the navigation group. Moreover, the facial symmetry was greatly improved in both groups, indicated by significantly decreased chin deviation, chin rotation and AI. In conclusion, our results show that both 3D-printed cutting-guide-assisted and surgical-navigation-assisted methods of intraoral condylectomy have high accuracy and efficiency, while using a cutting guide can generate a relatively higher surgical accuracy. Moreover, our cutting guides exhibit user-friendly features and simplicity, which represents a promising prospect in everyday clinical practice.

Using augmented reality to guide bone conduction device implantation

Exact placement of bone conduction implants requires avoidance of critical structures. Existing guidance technologies for intraoperative placement have lacked widespread adoption given accessibility challenges and significant cognitive loading. The purpose of this study is to examine the application of augmented reality (AR) guided surgery on accuracy, duration, and ease on bone conduction implantation. Five surgeons surgically implanted two different types of conduction implants on cadaveric specimens with and without AR projection. Pre- and postoperative computer tomography scans were superimposed to calculate centre-to-centre distances and angular accuracies. Wilcoxon signed-rank testing was used to compare centre-to-centre (C-C) and angular accuracies between the control and experimental arms. Additionally, projection accuracy was derived from the distance between the bony fiducials and the projected fiducials using image guidance coordinates. Both operative time (4.3 ± 1.2 min. vs. 6.6 ± 3.5 min., p = 0.030) and centre-to-centre distances surgery (1.9 ± 1.6 mm vs. 9.0 ± 5.3 mm, p < 0.001) were significantly less in augmented reality guided surgery. The difference in angular accuracy, however, was not significantly different. The overall average distance between the bony fiducial markings and the AR projected fiducials was 1.7 ± 0.6 mm. With direct intraoperative reference, AR-guided surgery enhances bone conduction implant placement while reduces operative time when compared to conventional surgical planning.

Skull-Base Surgery-A Narrative Review on Current Approaches and Future Developments in Surgical Navigation

Surgical navigation technology combines patient imaging studies with intraoperative real-time data to improve surgical precision and patient outcomes. The navigation workflow can also include preoperative planning, which can reliably simulate the intended resection and reconstruction. The advantage of this approach in skull-base surgery is that it guides access into a complex three-dimensional area and orients tumors intraoperatively with regard to critical structures, such as the orbit, carotid artery and brain. This enhances a surgeon's capabilities to preserve normal anatomy while resecting tumors with adequate margins. The aim of this narrative review is to outline the state of the art and the future directions of surgical navigation in the skull base, focusing on the advantages and pitfalls of this technique. We will also present our group experience in this field, within the frame of the current research trends.

Clinical application and accuracy assessment of imaging-based surgical navigation guided 125I interstitial brachytherapy in deep head and neck regions

Brachytherapy has the advantages of being minimally invasive and highly conformal, and it achieves good results in head and neck tumors. To precisely implant the radioactive seeds according to the preplan in deep head and neck regions, the surgical navigation is applied. This study aims to explore the clinical application and accuracy of imaging-based surgical navigation-guided 125I interstitial brachytherapy in terms of seed position. We included 41 patients with tumors in deep head and neck regions. The brachytherapy treatment plan was designed, and the preplanned data were transferred to the navigation system. Needle implantation and seed delivery were performed under surgical navigation system guidance with or without the combination of individual template. The treatment accuracy was evaluated by comparing seed cluster locations between the preoperative treatment plan and the postoperative treatment outcome. A total of 2879 seeds were delivered. The range, mean and median distances between the geometric centers of the preoperative seed point clusters and the postoperative seed point clusters were 0.8-10.5 mm, 4.5 ± 2.3 mm and 4.1 mm, respectively. The differences between preoperative and postoperative volumes of the minimum bounding box of seed point clusters were nonsignificant. In conclusion, the imaging-based surgical navigation system is a promising clinical tool to provide the preplanned data for interstitial brachytherapy intraoperatively, and it is feasible and accurate for the real-time guidance of needle implantation and seed delivery in deep head and neck regions.

Surgical Navigation, Augmented Reality, and 3D Printing for Hard Palate Adenoid Cystic Carcinoma En-Bloc Resection: Case Report and Literature Review

Adenoid Cystic Carcinoma is a rare and aggressive tumor representing less than 1% of head and neck cancers. This malignancy often arises from the minor salivary glands, being the palate its most common location. Surgical en-bloc resection with clear margins is the primary treatment. However, this location presents a limited line of sight and a high risk of injuries, making the surgical procedure challenging. In this context, technologies such as intraoperative navigation can become an effective tool, reducing morbidity and improving the safety and accuracy of the procedure. Although their use is extended in fields such as neurosurgery, their application in maxillofacial surgery has not been widely evidenced. One reason is the need to rigidly fixate a navigation reference to the patient, which often entails an invasive setup. In this work, we studied three alternative and less invasive setups using optical tracking, 3D printing and augmented reality. We evaluated their precision in a patient-specific phantom, obtaining errors below 1 mm. The optimum setup was finally applied in a clinical case, where the navigation software was used to guide the tumor resection. Points were collected along the surgical margins after resection and compared with the real ones identified in the postoperative CT. Distances of less than 2 mm were obtained in 90% of the samples. Moreover, the navigation provided confidence to the surgeons, who could then undertake a less invasive and more conservative approach. The postoperative CT scans showed adequate resection margins and confirmed that the patient is free of disease after two years of follow-up.

Automatic Registration and Error Color Maps to Improve Accuracy for Navigated Bone Tumor Surgery Using Intraoperative Cone-Beam CT

Computer-assisted surgery (CAS) can improve surgical precision in orthopaedic oncology. Accurate alignment of the patient’s imaging coordinates with the anatomy, known as registration, is one of the most challenging aspects of CAS and can be associated with substantial error. Using intraoperative, on-the-table, cone-beam computed tomography (CBCT), we performed a pilot clinical study to validate a method for automatic intraoperative registration.

Development of a cadaveric head and neck cancer model and three-dimensional analysis of margins in surgical navigation-aided ablations

INTRODUCTION

The adequacy of the surgical resection is the main controllable variable that is in the hands of the surgical team. There exists an unmet need to increase the rate of negative margins, particularly in cancers invading the craniofacial area. The study aimed 1) at developing a gross tumor model to be utilized for research, educational, and training purposes and 2) establishing the 3-dimensional relationship between the outer surface of the surgical specimen and tumor surface and test the effect of guiding ablations on cadavers with surgical navigation (SN).

MATERIAL AND METHODS

Seven cadaver heads were employed to create 24 craniofacial tumor models. Simulation of tumor resections was performed by 8 surgeons. Fourteen and 10 resections were performed with and without SN-guidance, respectively. Gross specimens underwent computed tomography and 3-dimensional analysis through dedicated software. Task load was assessed through a validated questionnaire. Tumor model reliability was studied based on visual analogue scale rate by surgeons and radiologists.

RESULTS

SN reduced the rate of margin involvement, particularly by decreasing the percentage of the gross specimen outer surface involvement in areas uncovered by normal bony structures. The workload of SN-aided ablations was found to be medium-to-somewhat-high. Tumor model reliability was deemed satisfactory except for the extension to bony structures.

CONCLUSIONS

A gross tumor model for head and neck cancers involving the craniofacial area was developed and resulted satisfactorily reliable from both a surgical and radiologic standpoint. SN reduced the rate of margin involvement, particularly by improving delineation of bone-uncovered areas.

Navigation-Guided Transnasal Endoscopic Delineation of the Posterior Margin for Maxillary Sinus Cancers: A Preclinical Study

Background

The resection of advanced maxillary sinus cancers can be challenging due to the anatomical proximity to surrounding critical anatomical structures. Transnasal endoscopy can effectively aid the delineation of the posterior margin of resection. Implementation with 3D-rendered surgical navigation with virtual endoscopy (3D-SNVE) may represent a step forward. This study aimed to demonstrate and quantify the benefits of this technology.

Material and Method

Four maxillary tumor models with critical posterior extension were created in four artificial skulls (Sawbones^®). Images were acquired with cone-beam computed tomography and the tumor and carotid were contoured. Eight head and neck surgeons were recruited for the simulations. Surgeons delineated the posterior margin of resection through a transnasal approach and avoided the carotid while establishing an adequate resection margin with respect to tumor extirpation. Three simulations were performed: 1) unguided: based on a pre-simulation study of cross-sectional imaging; 2) tumor-guided: guided by real-time tool tracking with 3D tumor and carotid rendering; 3) carotid-guided: tumor-guided with a 2-mm alert cloud surrounding the carotid. Distances of the planes from the carotid and tumor were classified as follows and the points of the plane were classified accordingly: “red”: through the carotid artery; “orange”: <2 mm from the carotid; “yellow”: >2 mm from the carotid and within the tumor or <5 mm from the tumor; “green”: >2 mm from the carotid and 5–10 mm from the tumor; and “blue”: >2 mm from the carotid and >10 mm from the tumor. The three techniques (unguided, tumor-guided, and carotid-guided) were compared.

Results

3D-SNVE for the transnasal delineation of the posterior margin in maxillary tumor models significantly improved the rate of margin-negative clearance around the tumor and reduced damage to the carotid artery. “Green” cuts occurred in 52.4% in the unguided setting versus 62.1% and 64.9% in the tumor- and carotid-guided settings, respectively (p < 0.0001). “Red” cuts occurred 6.7% of the time in the unguided setting versus 0.9% and 1.0% in the tumor- and carotid-guided settings, respectively (p < 0.0001).

Conclusions

This preclinical study has demonstrated that 3D-SNVE provides a substantial improvement of the posterior margin delineation in terms of safety and oncological adequacy. Translation into the clinical setting, with a meticulous assessment of the oncological outcomes, will be the proposed next step.

Augmented Reality and Intraoperative Navigation in Sinonasal Malignancies: A Preclinical Study

Objective

To report the first use of a novel projected augmented reality (AR) system in open sinonasal tumor resections in preclinical models and to compare the AR approach with an advanced intraoperative navigation (IN) system.

Methods

Four tumor models were created. Five head and neck surgeons participated in the study performing virtual osteotomies. Unguided, AR, IN, and AR + IN simulations were performed. Statistical comparisons between approaches were obtained. Intratumoral cut rate was the main outcome. The groups were also compared in terms of percentage of intratumoral, close, adequate, and excessive distances from the tumor. Information on a wearable gaze tracker headset and NASA Task Load Index questionnaire results were analyzed as well.

Results

A total of 335 cuts were simulated. Intratumoral cuts were observed in 20.7%, 9.4%, 1.2,% and 0% of the unguided, AR, IN, and AR + IN simulations, respectively (p < 0.0001). The AR was superior than the unguided approach in univariate and multivariate models. The percentage of time looking at the screen during the procedures was 55.5% for the unguided approaches and 0%, 78.5%, and 61.8% in AR, IN, and AR + IN, respectively (p < 0.001). The combined approach significantly reduced the screen time compared with the IN procedure alone.

Conclusion

We reported the use of a novel AR system for oncological resections in open sinonasal approaches, with improved margin delineation compared with unguided techniques. AR improved the gaze-toggling drawback of IN. Further refinements of the AR system are needed before translating our experience to clinical practice.

Imaging-based navigation technologies in head and neck surgery

PURPOSE OF REVIEW

Image guided navigation has had significant impact in head and neck surgery, and has been most prolific in endonasal surgeries. Although conventional image guidance involves static computed tomography (CT) images attained in the preoperative setting, the continual evolution of surgical navigation technologies is fast expanding to incorporate both real-time data and bioinformation that allows for improved precision in surgical guidance. With the rapid advances in technologies, this article allows for a timely review of the current and developing techniques in surgical navigation for head and neck surgery.

RECENT FINDINGS

Current advances for cross-sectional-based image-guided surgery include fusion of CT with other imaging modalities (e.g., magnetic resonance imaging and positron emission tomography) as well as the uptake in intraoperative real-time 'on the table' imaging (e.g., cone-beam CT). These advances, together with the integration of virtual/augmented reality, enable potential enhancements in surgical navigation. In addition to the advances in radiological imaging, the development of optical modalities such as fluorescence and spectroscopy techniques further allows the assimilation of biological data to improve navigation particularly for head and neck surgery.

SUMMARY

The steady development of radiological and optical imaging techniques shows great promise in changing the paradigm of head and neck surgery.

Electromagnetic surgical navigation in patients undergoing mandibular surgery

The purpose of this study was to evaluate the feasibility of electromagnetic (EM) navigation for guidance on osteotomies in patients undergoing oncologic mandibular surgery. Preoperatively, a 3D rendered model of the mandible was constructed from diagnostic computed tomography (CT) images. Cutting guides and patient specific reconstruction plates were designed and printed for intraoperative use. Intraoperative patient registration was performed using a cone beam CT scan (CBCT). The location of the mandible was tracked with an EM sensor fixated to the mandible. The real-time location of both the mandible and a pointer were displayed on the navigation system. Accuracy measurements were performed by pinpointing four anatomical landmarks and four landmarks on the cutting guide using the pointer on the patient and comparing these locations to the corresponding locations on the CBCT. Differences between actual and virtual locations were expressed as target registration error (TRE). The procedure was performed in eleven patients. TREs were 3.2 ± 1.1 mm and 2.6 ± 1.5 mm using anatomical landmarks and landmarks on the cutting guide, respectively. The navigation procedure added on average half an hour to the duration of the surgery. This is the first study that reports on the accuracy of EM navigation in patients undergoing mandibular surgery.

Assessment of a liposomal CT/optical contrast agent for image-guided head and neck surgery

This study evaluates a long-acting liposomal fluorescence / CT dual-modality contrast agent (CF800) in head and neck cancer to enhance intraoperative tumor demarcation with fluorescence imaging and cone-beam computed tomography (CBCT). CF800 was administered to 12 buccal cancer-bearing rabbits. Imaging was acquired at regular time points to quantify time-dependent contrast enhancement. Surgery was performed 5-7 days after, with intraoperative near-infrared fluorescence endoscopy and CBCT, followed by histological and ex-vivo fluorescence assessment. Tumor enhancement on CT was significant at 24, 96 and 120 hours. Volumetric analysis of tumor segmentation showed high correlation between CBCT and micro-CT. Fluorescence signal was apparent in both ex-vivo and in-vivo imaging. Histological correlation showed [100%] specificity for primary tumor. Sensitivity and specificity of CF800 in detecting nodal involvement require further investigation.CF800 is long acting and has dual function for CT and fluorescence contrast, making it an excellent candidate for image-guided surgery.

Navigation-guided osteotomies improve margin delineation in tumors involving the sinonasal area: A preclinical study

OBJECTIVES

To demonstrate and quantify, in a preclinical setting, the benefit of three-dimensional (3D) navigation guidance for margin delineation during ablative open surgery for advanced sinonasal cancer.

MATERIALS AND METHODS

Seven tumor models were created. 3D images were acquired with cone beam computed tomography, and 3D tumor segmentations were contoured. Eight surgeons with variable experience were recruited for the simulation of osteotomies. Three simulations were performed: 1) Unguided, 2) Guided using real-time tool tracking with 3D tumor segmentation (tumor-guided), and 3) Guided by 3D visualization of both the tumor and 1-cm margin segmentations (margin-guided). Analysis of cutting planes was performed and distance from the tumor surface was classified as follows: "intratumoral" when 0 mm or negative, "close" when greater than 0 mm and less than or equal to 5 mm, "adequate" when greater than 5 mm and less than or equal to 15 mm, and "excessive" over 15 mm. The three techniques (unguided, tumor-guided, margin-guided) were statistically compared.

RESULTS

The use of 3D navigation for margin delineation significantly improved control of margins: unguided cuts had 18.1% intratumoral cuts compared to 0% intratumoral cuts with 3D navigation (p < 0.0001).

CONCLUSION

This preclinical study has demonstrated the significant benefit of navigation-guided osteotomies for sinonasal tumors. Translation into the clinical setting - with rigorous assessment of oncological outcomes - would be the proposed next step.