The purpose of this cross-sectional prospective observational study is to determine the efficacy of high-resolution ultrasonography in identifying and characterizing nasal bone fractures in adult patients with recent facial trauma. The primary questions it aims to answer are:

• Can high-resolution ultrasonography effectively detect nasal bone fractures?
• Is high-resolution ultrasonography capable of indirectly detecting septal fractures?
• What are the specificity and sensitivity of high-resolution ultrasonography in comparison to computed tomography scan?

Participants will undergo examination and treatment in accordance with current standards for nasal fracture management. Additionally, high-resolution ultrasonography will be performed during the initial physical examination, preceding any therapeutic interventions.

BACKGROUND

The bony and cartilaginous skeleton of the external nose is exceptionally prone to injury, due to its fragile structure and protruding, tent-like shape. As the cartilages are able to bend under pressure, the impact of trauma is usually transferred to the thinnest, distal parts of nasal bones, where they overlap the lateral cartilages forming a junction called the keystone region. This location plays a major role in supporting the cartilaginous skeleton and, at the same time, is most likely to be fractured. Similarly, the cartilaginous nasal septum is able to bend, which is the reason why trauma to the distal nasal bones frequently continues along anterior borders of the perpendicular plate of the ethmoid and vomer, creating a complex, C-shaped septal fracture. These pathomechanisms of nasal fracture explain its possible significant negative influence on the function and aesthetics of the nose. Early nasal fracture detection and treatment is critical for avoiding complications. Clinical examination is considered a gold standard for the diagnosis. Imaging tests are of secondary importance, as their clinical application in this condition has many disadvantages. A commonly applied plain radiograph of the nose was proven not to be cost efficient due to high percentage of false results. A computed tomography scan (CT) has a satisfactory sensitivity and specificity, but is relatively expensive, causes radiation exposure and provides images of limited resolution, which may fail to reveal subtle fracture lines.

Several studies have shown high-resolution ultrasonography (HRUS) to be a safe and efficient method for nasal fracture diagnosis. However, the use of this modality in a clinical setup has not become common, despite over 20-year history of publications supporting its efficacy. Potential factors contributing to this circumstance include a lack of a standardized examination protocol, a difficult ultrasonography image acquisition and a clinician's reluctance to use a full-sized device in an otolaryngology medical office.

The aim of this study is to assess the efficacy of a standardized 10-step point-of-care ultrasonography in the diagnosis of nasal fractures.

STUDY DESIGN

This cross-sectional prospective study will be conducted between December 1, 2023, and December 1, 2024, at the University Clinical Centre in Gdańsk, in accordance with the Helsinki Declaration and with approval from the institutional bioethics committee for scientific research (No: KB/625/2023).

Patients who have presented to the emergency department with nasal trauma sustained within the 14 days preceding their consultation will be enrolled in the study. Exclusion criteria will include extensive facial trauma, a history of nasal fracture, surgical interventions (e.g. rhinoplasty, frontal/ethmoid sinus surgery), or minor invasive procedures (e.g. hyaluronic acid filler, thread lifting) in the examined area.

A CT scan of the face and HRUS protocol will be performed before any interventions are undertaken.

A total of 50 patients is anticipated.

The collected data will include medical history, physical examination, CT scan of the face and HRUS of the nose.

Ultrasonography of the external nose will be performed with the use of a high-resolution transducer (Clarius L20HD3 8-20 MHz) and a 3mm-thick disposable gel pad, according to the 10-step protocol. At each location, the transducer position will be adjusted with rocking and tilting movements until it is held perpendicular to the bone surface, which provides optimal image quality, and a single image will be saved for further assessment. Images obtained at each location will be assessed for five different findings.

A standard computed tomography scan of the face will be performed. Each of 7 specific areas will be assessed by an experienced radiologist for a diclocated or non-dislocated nasal fracture.

DATA ANALYSIS

Statistical analysis of the data will be performed using the R language. A variable marked as a "final diagnosis established by the consulting clinician" will be considered a reference point for calculating the sensitivity and specificity of methods. For this purpose, a McNeymar chi-square test and Cohen's Kappa will be used.

Records lacking the final diagnosis or any part of the HRUS protocol will be excluded from the study.

The database will be anonymised.

The source data and the database verification will be performed collectively by the authors following the addition of every 10 new records.

Inclusion Criteria:

• nasal trauma during the 14 days preceding examination

Exclusion Criteria:

• extensive facial injuries
• history of surgical or non-surgical interventions in the examined area
• history of nasal fracture
• refusal to participate, inability to give consent

Adult patients with a history of recent facial trauma involving external nose. Patients with no history of surgical or non-surgical interventions in the examined area eg. rhinoplasty, hyaluronic acid filler, external approach frontal/ethmoid sinus surgery as well as no history of nasal fracture.

Study Protocol and Statistical Analysis Plan will be shared upon request, including individual participant data that underlie the results reported in this article, after deidentification (text, tables, figures, and appendices).

Proposals should be directed to "g.smigielski@gumed.edu.pl". To gain access, data requestors will need to sign a data access agreement.

Beginning 6 months and ending 36 months following article publication.

For individual participant data meta-analysis. Proposed use of the data should have been approved by an independent review committee.