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Chin J Traumatol
Chin J Traumatol
Chinese Journal of Traumatology
1008-1275
1008-1275
Elsevier

S1008-1275(24)00077-4
10.1016/j.cjtee.2024.07.005
Short Communication
A serial case study of the combined use of intraoperative CT and surgical navigation system for the removal of small foreign bodies in the maxillofacial region
Ma Dong-Yang doctormdy@hotmail.com
ab⁎
Zhang Shu-Meng b
Pang Chao-Yuan a
Zhang Wen-Kai a
Wang Bing-Wu a
a Department of Oral and Maxillofacial Surgery, The 940th Hospital of Joint Logistics Support Force of PLA, Lanzhou, 730050, China
b Department of Oral and Maxillofacial Surgery, School of Stomatology, Lanzhou University, Lanzhou, 730000, China
⁎ Corresponding author. Department of Oral and Maxillofacial Surgery, The 940th Hospital of Joint Logistics Support Force of PLA, Lanzhou, 730050, China. doctormdy@hotmail.com
05 7 2024
9 2024
05 7 2024
27 5 279283
18 1 2024
30 4 2024
6 6 2024
© 2024 Chinese Medical Association. Production and hosting by Elsevier B.V.
2024
Chinese Medical Association
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Purpose

The removal of small foreign bodies embedded within the deep soft tissues of the maxillofacial region is a complex and challenging task for maxillofacial surgeons. The purpose of this study was to explore the efficacy of the combination of intraoperative CT and surgical navigation for the removal of small foreign objects in the maxillofacial region.

Methods

A serial case study was conducted involving all consecutive patients who underwent surgical removal of small foreign bodies in the maxillofacial region. The combination of intraoperative CT and a surgical navigation system was used at a single medical institution from January 2018 to December 2022. Comprehensive data, including patient demographics, characteristics of the foreign bodies, previous surgical interventions, duration of the surgical procedure, and removal success rate were collected for this study. Relevant data were recorded into Microsoft Excel sheet and analyzed using SPSS version 22.0.

Results

Nine patients (6 males and 3 females) were included in this study, with an average age of 37 years. Each patient had previously undergone an unsuccessful removal attempt utilizing conventional surgical methods based on preoperative CT imaging or C-arm guidance at a local healthcare facility. Four patients also experienced unsuccessful attempts with preoperative CT image-based navigation systems. However, by employing the combined approach of intraoperative CT and surgical navigation, the foreign bodies were successfully removed in all 9 patients. The mean duration of the surgical procedure was 59 min, and the average size of the foreign bodies was approximately 26 mm³. Postoperative follow-up exceeding 6 months revealed no complications.

Conclusion

The combined use of a surgical navigation system and intraoperative CT represents a potent and effective strategy for the precise localization and subsequent removal of small foreign bodies from the soft tissue structures of the maxillofacial region. This integrative approach appears to increase the success rate of surgical interventions in such cases.

Keywords

Maxillofacial trauma
Intraoperation
Computed tomography
Navigation system
Foreign body
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pmc1 Introduction

The craniomaxillofacial region, which is frequently exposed to the external environment, is inherently prone to trauma.1 Such exposure often results in the penetration and subsequent retention of foreign bodies within maxillofacial structures, leading to a spectrum of acute and potential complications, including bleeding, airway compromise, and neurovascular damage.1 While some foreign bodies may remain clinically asymptomatic for years, their long-term consequences, such as persistent pain, impaired wound healing, infection, fistulation, dysphagia, and restricted mouth opening, are not uncommon.1 Consequently, the removal of foreign bodies in the maxillofacial region is generally advocated.1,2

Traditional methodologies for addressing this issue typically include the localization of foreign bodies via preoperative 2-dimensional (2D) or 3D radiographic imaging.1 The removal process, often being reliant on the surgeon's expertise, involves exposing and extracting the foreign body through the existing wound, a localized incision, or, in some cases, a coronal incision.1,2 However, without accurate identification of the appropriate surgical plane, these procedures risk damaging surrounding anatomical structures, extending the operation time, or even failing altogether.2,3 Recent advancements in digital technology, particularly the development of surgical navigation system, have regenerated this process. This system, designed to align preoperative image data with the intraoperative anatomical context using optical sensors, offers a new paradigm for foreign body removal.2,4,5 Preoperative CT scanning is typically employed for diagnostic purposes and surgical planning, with the navigation system subsequently guiding the surgeon to the precise location of the foreign body for removal.4 However, challenges arise due to potential discrepancies between the preoperative imaging and the intraoperative anatomical state caused by soft tissue deformation and changes in head position during surgery.2,5 These discrepancies can complicate the removal of small foreign bodies in deep soft tissue structures, particularly when considering the possibility of movement of the object from the time of injury to surgery.6

In regard to these challenges, the purpose of our research is to propose the combined use of intraoperative CT and surgical navigation for precise removal of small foreign bodies in the maxillofacial region. The aim of this approach, which leverages real-time intraoperative CT, is to ensure an accurate correlation between CT image data and the intraoperative anatomical structure, thereby reducing the incidence of aforementioned errors and enhancing surgical precision. Using this method, our team successfully treated 9 patients suffering from the retention of small foreign bodies in maxillofacial soft tissue.

2 Methods

2.1 Patient selection

This study included 9 patients with maxillofacial foreign bodies, as detailed in Table 1. The cohort comprised 6 males and 3 females, with an average age of 37 years (ranging from 21 to 58 years). The duration of foreign body retention varied from 3 days to 32 years, with a median of 20 days. The mean follow-up duration was 1.1 years. This study included a comprehensive collection of all sequential cases involving small foreign bodies (defined as those less than 30 mm³ in size) located in the maxillofacial region. These data were collected from January 2019 to December 2022. Each foreign body was definitively identified through CT scanning (Fig. 1A – C). These foreign objects were removed using a synergistic approach in which intraoperative CT was combined with a surgical navigation system. An array of the data, including demographic information, previous treatment history, characteristics of the foreign body, and some surgical factors were meticulously recorded for each patient. Additionally, the intraoperative procedures and the outcomes of these procedures were subjected to detailed analyses. The study protocol was approved by the Committee for Medical Ethics of the authors’ Hospital (2020kyll099). Prior to undergoing surgery, all patients or their legally authorized representatives provided informed consent, specifically for the use of intraoperative CT and the navigation system during their procedures.Table 1 Demographic, foreign body characteristics, and surgical factors in 9 cases.

Table 1Patient	Age (year)	Gender	Location	Duration	Reason for removal	Material	Size (mm3)	Operating time (min)	Approach	Incision length (cm)	
1	42	F	Parapharyngeal	32 years	Interference with MRI	Metal stitch	30 × 1 × 1	61	Intraoral + extraoral	3.0	
2	58	M	Infratemporal fossa	20 days	Skin fistula	Metal fragment	6 × 5 × 1	52	Intraoral + extraoral	2.5	
3	41	M	Floor of mouth	1 years	Pain	Bone fragment	7 × 4 × 1	36	Extraoral	2.0	
4	23	F	Cheek	3 months	Skin fistula	Tooth fragment	3 × 2 × 2	49	Intraoral + extraoral	1.5	
5	21	F	Pterygomandibular space	3 days	Infection	Metal fragment	4 × 2 × 1	83	Intraoral	2.0	
6	30	M	Orbital	8 days	Pain	Glass fragment	4 × 3 × 2	56	Extraoral	1.5	
7	54	M	Masseter muscle	2 years	Religious reasons	Metal screw	5 × 2 × 2	110	Intraoral + extraoral	2.0	
8	28	M	Cheek	14 days	Pain	Stone fragment	4 × 3 × 2	30	Extraoral	1.5	
9	35	M	Parotid	8 days	Infection	Shrapnel	5 × 3 × 1	35	Extraoral	1.0	

Fig. 1 Preoperative and intraoperative CT image of a metal foreign body in the right side of infratemporal fossa. (A) Preoperative 3-dimensional reconstruction image; (B) Preoperative axial view; (C) Preoperative sagittal view; (D) Intraoperative 3-dimensional reconstruction image with the patient's mouth open; (E) Intraoperative axial view; (F) Intraoperative sagittal view.

Fig. 1

2.2 Patient preparation

Patients were positioned supine, with their heads securely immobilized using a carbon-fiber bracket. Following the induction of general anesthesia accompanied by endotracheal intubation, the surgical region was thoroughly disinfected. To facilitate precise navigation, several self-tapping screws were strategically implanted in both the nasal bone and the maxillary alveolar bone to serve as fiducial markers. A supine position (with the head tilted to one side and/or the mouth open wide if required), which is conducive to exposing foreign bodies and surgical access, was adopted. Then, an individualized incision was made according to the specific location of the foreign body and the characteristics of the original wound. Surgical exploration through the incision was performed using forceps to reach the vicinity of the foreign body.

2.3 Intraoperative CT examination

The arrangement of the anesthesia apparatus, ventilation conduit, and surgical instrument table was modified to facilitate the unobstructed passage of the scanning equipment. While maintaining the patient's surgical position, the surgical field was wrapped with a sterile plastic sheath. The CT scanner (SOMATOM Sensation Definition AS, Siemens, Germany) was then maneuvered into position to verify comprehensive coverage of the maxillofacial region. In anticipation of radiation exposure, the medical staff retreated to a designated radiation protection chamber. The patient underwent CT imaging with specific parameters, including a slice thickness of 1.0 mm, a voltage of 100 kV, an electric current of 140 mA, and a pitch of 0.98, which were specifically calibrated for bone window scanning to detect metal foreign bodies (Fig. 1D – F). Following the completion of the scan, both the CT and operating tables were repositioned to their initial locations. A second intraoperative scan was taken if a foreign body was not found within 60 min.

2.4 Intraoperative navigation and surgical procedures

The intraoperative imaging data were exported in DICOM format and subsequently imported into Brainlab iPlan CMF 3.0 software (Brainlab, Heimstetten, Germany) to facilitate 3D model reconstruction. During the surgical process, the foreign body was distinctly marked with color for enhanced visibility. A reference frame was securely affixed to the patient's skull using a screw. The KICK® Navigation System (Brainlab AG, Munich, Germany), an infrared-based navigation technology, was used. According to the reference points being setted on the skull bone surface and the alveolar bone, point registration was performed with a navigation probe, ensuring a precise match between the virtual and physical environments. Additionally, forceps were registered and the patient's images were viewed in real time (Fig. 2A). The spatial correlation between the probe tip and the foreign body was continuously monitored (Fig. 2B). Subsequently, the object was meticulously clamped and extracted using forceps (Fig. 2C & D). Comprehensive details of the intraoperative navigation were recorded via screenshots.Fig. 2 Intraoperative navigation, location, and removement of the mental foreign body. (A) Intraoperative navigation using a guidance probe tip; (B) The foreign body in multiple views; (C) Side view of the foreign body; (D) Positive view of the foreign body.

Fig. 2

2.5 Patient follow-up

All patients were followed up for at least 6 months. Postoperative complications were observed and recorded.

3 Results

This study included 9 patients with maxillofacial foreign bodies, as detailed in Table 1. The cohort comprised 6 males and 3 females, with an average age of 37 years (ranging from 21 to 58 years). The duration of foreign body retention varied from 3 days to 32 years, with a median of 20 days. The distribution of foreign bodies included 2 in the parapharyngeal space, 2 in the cheek, 1 in the orbital cavity, 1 in the masseter muscle, 1 in the pterygomandibular space, 1 in the floor of the mouth, and 1 in the parotid gland. These foreign bodies consisted of 5 metallic objects (1 broken metal instrument, 2 shrapnel, 1 needle, and 1 micro screw), 1 glass fragment, 1 tooth fragment, 1 bone fragment, and 1 stone fragment (Fig. 3).Fig. 3 General view of removed from the other 8 patients. (A) Case 1; (B) Case 2; (C) Case 3; (D) Case 4; (E) Case 6; (F) Case 7; (G) Case 8; (H) Case 9.

Fig. 3

All patients had undergone at least 1 unsuccessful removal attempt using conventional surgical methods guided by preoperative CT imaging or C-arm fluoroscopy at local hospitals. Notably, removal failed in 4 patients (Patients 2, 3, 5, and 7) even with the assistance of preoperative CT image-based navigation systems (1 in a local hospital and 3 in our department). In contrast, retrieval was successful in all 9 patients through a combined approach of intraoperative CT and surgical navigation, yielding a 100 % success rate. These foreign bodies were removed via existing wounds, fistula tracts, or additional minor incisions. Small intraoral incisions were utilized in 5 patients, where CT scans were performed with a bite block in place to maintain mouth opening. No nerve or vascular injuries were observed intraoperatively. The average surgical duration (including the intraoperative CT scanning time, registration time, and the time of foreign body retrieval) was 59 min, and the average size of the foreign bodies was approximately 26 mm³. Throughout the follow-up period, no postoperative complications were noted, and no residual foreign bodies were detected on postoperative CT. The detailed patient clinical data are presented in Table 1.

4 Discussion

In this study, 9 patients with small foreign bodies in the maxillofacial region were successfully treated without major complications using a combination of a navigation system and intraoperative CT. This novel combined approach proved both effective and safe.

Foreign bodies in the maxillofacial area necessitate removal for various reasons and are common challenges for oral and maxillofacial surgeons.7 In the cases presented, the primary motivations for foreign body removal included pain, infection, and fistula formation. Additionally, removal was warranted in 2 asymptomatic patients due to interference with magnetic resonance imaging (MRI) and for religious reasons. Notably, in Patient 1, a foreign body had remained undetected for 32 years. The patient, who was advised to undergo MRI for sporadic headaches, was alerted to a suspected metallic object during the MRI. Subsequent CT imaging confirmed the presence of a metal needle in the maxillofacial region, which was removed successfully using the described technique. While the removal of most foreign bodies was advisable, it was crucial to weigh the benefits against potential surgical risks.7

Effective detection and precise localization are essential prerequisites for the surgical removal of foreign bodies.1,7 The complexity of this process varies based on several factors, including the nature, size, and location of the foreign body, as well as its proximity to adjacent anatomical structures. Removal becomes more challenging when the foreign body is small and situated in deep bodily structures.7,8 Various techniques, such as plain radiographs, ultrasound, CT, MRI, and electromagnetic metal detectors are employed for localization.1,9 Our case series demonstrated that all foreign bodies, composed of materials such as metal, glass, teeth, and bone, were detectable by thin-slice CT scanning. However, for organic materials not visible on CT, MRI has proven to be a useful alternative.1

Intraoperative imaging offers real-time insights into the location of foreign bodies, aiding surgeons in precise localization and removal.3 This approach is particularly beneficial in cases where previous surgical explorations have failed.3,8 For instance, Majumdar et al.3 reported a case where a bomb splinter, entering below the right infraorbital rim and lodging in the infratemporal fossa, was retrieved using a preauricular incision approach and intraoperative C-arm fluoroscopy. Despite its effectiveness, this method required repositioning across different planes, increasing both radiation exposure and operative duration. In contrast, 3D localization systems, especially surgical navigation, offered superior technical support for the minimally invasive and accurate removal of maxillofacial foreign bodies.4 Resembling a Global Positioning System, these navigation tools assisted surgeons in pinpointing and extracting foreign objects efficiently, minimizing the need for repeated explorations and reducing surgery time.4,5,8

Retrieving small foreign bodies in the deep maxillofacial region can be challenging3,8, as their position may shift due to factors such as gravity, swallowing, mouth opening, and body movement. Klimczak et al.6 reported that a metal foreign body was retained in the skull base after a blunt trauma incident. However, it disappeared from the original site at the time of intraoperative examination and was identified at the level of the gastroesophageal junction by chest X-ray.6 This case report illustrated that static preoperative images can sometimes be insufficient for successful retrieval. Lehmann et al.5 suggested using intraoperative CT scanning when a foreign body is not found within a reasonable operation time. In our study, the operation time in 1 patient reached 110 min (Patient 7), which was significantly longer than that in other patients. In this case, the metal screw (5 × 2 × 2 mm³) was lodged in the masseter muscle. After 60 min of removal attempts with the aid of intraoperative CT and the navigation system, the screw remained undiscovered through the intraoral approach. The patient was then scheduled to undergo a second intraoperative CT scan, and the position change of the foreign body was revealed. It was ultimately removed after the second attempt through the combination of intraoral and extraoral incisions. The use of a registered probe or forceps can also induce soft tissue deformation and thus cause deviation from the static image. Although this combination technique is effective in guiding surgeons to reach the vicinity of a foreign body, some degree of surgical exploration, negative pressure suction, and endoscopic technology may still be helpful.1,5

To simulate the maxillofacial position during surgery, Holmes et al.8 reported a patient who, with the aid of an intraoral bite block for mouth opening, underwent CT scanning immediately before surgery. Similarly, in our study, the use of an intraoral bite block or mouth gag was instrumental in minimizing positioning errors for 5 patients with intraoral incisions. Fig. 1, Fig. 2 demonstrated, through a comparison of preoperative and intraoperative CT images, that the location of the foreign body shifted following mouth opening. To enhance the accuracy before intraoperative CT scanning, the placement of multiple metal markers along the maxillofacial region was proposed to decrease registration errors and shorten the operative duration.8 As a part of this strategy, 4 self-tapping mini-screws, which served as registration markers, were preoperatively implanted in the skull, nasal bone, and maxillary alveolar bone. This approach effectively streamlined the landmark selection process and enhanced registration precision.

Intraoperative CT image-based navigation exemplified advancements in modern precision medicine, leading to the development of more sophisticated surgical techniques and improving outcomes.4,10 Habib et al.10 conducted a review of the clinical data of 67 patients who underwent posterior cervicothoracic fixation with various intraoperative imaging modalities. Their findings revealed that the integration of intraoperative CT and a navigation system significantly reduced the incidence of misplaced screws, from 9% to 2.4%, compared to both 2D fluoroscopic guidance and O-arm navigation. This underscores the considerable improvement in screw placement accuracy in the cervicothoracic region offered by this technique.10 Furthermore, Lehmann et al.5 described a transoral approach incorporating preoperative CT (just before surgery), an image guidance probe, and endoscopic tools for extracting foreign bodies from the infratemporal fossa, providing a less invasive and more efficient removal method. In summary, the effective management of patients with facial injuries necessitated a sequential, multidisciplinary approach, accurate diagnostic procedures, and thorough clinical examinations.

The current study has several limitations. First, the small sample size and the absence of a control group, which would involve the use of either intraoperative CT or a surgical navigation system, preclude a comparative analysis of these interventions. Second, the use of CT is associated with an increased risk of ionizing radiation exposure, which might be an established risk factor for malignant tumors, especially in children.11, 12, 13 A careful balance between the maximum benefit and minimum risk is needed when applying CT examinations, especially in pregnant women and the pediatric population.12 The use of bone window settings or cone-beam CT scanning has been shown to significantly reduce radiation exposure.11,12 However, these methods have disadvantages, such as diminished detection of low-density foreign bodies and soft tissues.12 Third, the application of both intraoperative CT scanners and navigation systems can increase the burden on patients. Furthermore, because of the cost of medical equipment as well as the necessary installation conditions, the technology may be inaccessible in primary health care facilities.12

In conclusion, intraoperative CT image-based navigation technology is an alternative approach for the anatomical localization and surgical removal of foreign bodies. Consequently, we advocate for the application of intraoperative CT in conjunction with a navigation system, particularly in complex scenarios involving the removal of small foreign bodies from the maxillofacial region. This combination can be especially beneficial in cases where traditional methods may prove challenging.

Funding

This work was funded by the Technological Innovation Plan and Innovation Team Project of PLA (2023YXKY005 ).

Ethical statement

This study was approved by the Committee for Medical Ethics of the authors’ Hospital (2020kyll099).

Declaration of competing interest

The authors declare that they have no conflict of interest.

Author contributions

Study conception and design: Dong-Yang Ma, Shu-Meng Zhang, and Chao-Yuan Pang; Material preparation, data collection, and analysis: Dong-Yang Ma, Shu-Meng Zhang, Chao-Yuan Pang, Wen-Kai Zhang, Bing-Wu Wang; First draft writing: Dong-Yang Ma.

All authors commented on the previous versions of the manuscript, and read and approved the final manuscript.

Peer review under responsibility of Chinese Medical Association.
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