This systematic review assessed the diagnostic value of ultrasonography in maxillofacial fractures. A computerized literature search of MEDLINE, PubMed and GoogleMed databases was conducted for publications on diagnostic ultrasound and maxillofacial fractures in English. Search phrases were ‘maxillofacial fractures’ or ‘midfacial fractures’ or ‘zygomatic complex fractures’ or ‘nasal bone fractures’ or ‘orbital fractures’ or ‘mandibular fractures’ combined with ‘ultrasound’ or ‘ultrasonography’. The Boolean operator ‘AND’ was used to narrow the searches. 17 articles published between 1992 and 2009 were reviewed: two on midfacial fractures, nine on orbital fractures, three on nasal fractures, and two on mandibular fractures. One article described case series of ultrasonographic diagnosis of mandibular and midfacial fractures. The sensitivity and specificity of ultrasound in detecting orbital fractures were 56–100% and 85–100%, respectively, whilst that of nasal fractures were 90–100% and 98–100%, respectively. Sensitivity and specificity of ultrasonography in detecting zygomatic fractures were >90%. For mandibular fractures, the sensitivity and specificity was 66–100% and 52–100%, respectively. Much evidence justifies the use of diagnostic ultrasonography in maxillofacial fractures, especially fractures involving the nasal bone, orbital walls, anterior maxillary wall and zygomatic complex. The sensitivity and specificity of ultrasonography is generally comparable with CT.
Conventional plain radiography and computed tomography (CT) scans are the traditional diagnostic tools for maxillofacial injuries ; CT being the gold standard . Both are associated with disadvantages and limitations. In conventional radiography, the superimposition of images of the overlying structures sometimes makes definite radiological interpretation difficult . Another disadvantage is that real-time image visualization is impracticable without digital technology, hence, only a hard copy image of two-dimensional plain films is available for evaluation. These limitations have largely been overcome by CT, but the disadvantages of CT imaging include limited access to facilities, high cost, and high radiation exposure . In addition, in patients with metallic implants there can be blurring of the image due to artefacts generated by the metal . Also, CT requires special patient positioning, which may not be possible in uncooperative patients and in those who may have suffered cervical spine injuries .
Rapid developments in computing hardware and microelectronic technology have facilitated technological advancement in ultrasonography in the last three decades, making it applicable not only to soft tissues but also to bony lesions of the head and neck . This has increased interest in evaluating ultrasound imaging as an alternative to conventional radiography and CT in the diagnostic evaluation of maxillofacial fractures . Most literature reports are very promising, but whether ultrasonography can replace conventional radiography and CT in the diagnosis of maxillofacial fractures has still to be established.
If evidence in support of the utility of ultrasonography in maxillofacial trauma imaging is established, a new level of evidence-based practice, leading to cost-effectiveness and optimal risk control in maxillofacial trauma care may have been revealed. Evidence-based practice involves integrating individual clinical expertise with the best available external clinical evidence from systematic research . The systematic review of evidence on new diagnostic, prognostic, therapeutic, rehabilitative or preventive regimens is desirable. In this systematic review, a pioneering effort, based on best available research, is made to evaluate and appraise the current role of diagnostic ultrasonography in maxillofacial fractures. The objectives are to ascertain the level of evidence available, to highlight the specific indications and to identify any current limitations to the use of ultrasonography as an alternative to radiation imaging techniques in the diagnostic evaluation of maxillofacial fractures.
Materials and methods
In a multi-staged approach, a rigorous search for articles on ultrasonography in maxillofacial fractures was conducted. The first step involved a search for existing systematic reviews and/or meta-analyses on the subject via the following gateways: Cochrane reviews; ADA. EBD systematic reviews (American Dental Association. Evidence-based Dentistry); HINARI library (Health InterNetwork Access to Research Intiatives); PubMed and Essential Evidence plus ( www.essentialevidenceplus.com ). In the second stage, a computerized literature search of MEDLINE, PubMed and GoogleMed databases was conducted for publications on ultrasound and maxillofacial fractures. Mesh phrases used for the search were ‘maxillofacial fractures’ or ‘midfacial fractures’ or ‘zygomatic complex fractures’ or nasal bone fractures’ or ‘orbital fractures’ or ‘mandibular fractures’ combined with ‘ultrasound’ or ‘ultrasonography’.
The Boolean operator ‘AND’ was used to combine and narrow the searches. The search was limited to articles originally published in English or for which a full text English translation was available. During this round of searching, abstracts were reviewed and the relevant full text articles were selected. The third step involved a manual search of the reference lists of all the selected articles to identify other relevant articles for final selection. Articles were selected if the following inclusion criteria were fulfilled: availability of full text article in English; studies were performed on humans; CT or conventional radiography or intraoperative findings were the reference methods used to compare ultrasonography; site of fracture evaluated was unambiguously stated; type and resolution (frequency) of the transducer used was clearly specified; outcomes were measured in terms of sensitivity and specificity or comparison of absolute number of fractures detected by the specific imaging techniques. Full texts of all selected articles were critically appraised for methodology (including adequate description of ultrasound evaluation technique, and the reference method to which the diagnostic value of ultrasound was compared), validity of results, and inferences made.
The initial search for previously published systematic review on the use of ultrasonography in maxillofacial fractures yielded nothing. Subsequent searches for studies relevant to the subject produced 17 articles that satisfied the inclusion criteria. These articles were published between 1992 and 2009. They consist of two articles that considered midfacial fractures as a group (S8 and S15), nine articles dedicated to the study of orbital fractures (S1, S2, S5, S6, S9–13), three articles specific to nasal fractures (S14, S16, and S17), and two articles on mandibular fractures (S4 and S7). One of the articles described case series of ultrasonographic diagnosis of mandibular and midfacial fractures (S3) ( Table 1 ). All the articles were descriptive and comparative in nature. With the exception of the single case series, all were either prospective or cross-sectional in design. Investigator blinding was performed in five studies whilst a control group was introduced in four studies. The sample size ranged from 10 to 171 subjects in the experimental studies whilst five cases were involved in the case series. CT was the commonest imaging modality to which ultrasonography was compared. Some investigators used either conventional plain radiographs, or intraoperative observations or combinations of these reference methods ( Table 1 ). Transducers with frequency ranging between 7.5 MHz and 30 MHz were employed in the studies. Curved probes and small probe designs were used in most cases, whilst a few investigators employed linear probes. The closed eye technique was preferred for all orbital ultrasonographic imaging.
|Study no.||Article||Design||Controlled or not||Sample size||Type of fracture||Reference methods||Transducer type||Outcome|
|S1||F orrest et al. (1993)||Prospective||Controlled||18||Orbital walls||CT||10 MHz curvilinear||Se—92%,|
|Single blind||Closed eye technique||Sp—100%|
|S2||L ata et al. (1993)||Prospective||Controlled||19||Orbital walls||CT||10 MHz, small probe||Se—92%|
|Closed eye technique||Sp—100%|
|S3||H irai et al. (1996)||Case series||Not controlled||5||Nasal bone (1)||Intraoperative findings, plain radiograph||15 MHz, 30 MHz small probe||Good correlation in all cases|
|Orbital rim (1)|
|Anterior wall maxilla (1)|
|Angle of mandible (1)|
|Mandibular symphysis (1)|
|S4||K leinheinz et al. (1997)||Cross-sectional||Not controlled||30||Subcondylar fractures||Plain radiograph (orthopantomographs)||7.5 MHz, linear||Se—100%|
|S5||J enkins and T hau (1997)||Prospective||Not controlled||20||Orbital floor||CT and intraoperative findings||7.5 MHz, curvilinear||Se—85%|
|Close eye technique||Sp—88%|
|S6||M cCann et al. (2000)||Prospective, single blind||Not controlled||22||Zygomatico-orbital complex||Plain radiograph and intraoperative findings||7.5 MHz, convex||For orbital floor; Se—100%, Sp—95%, zygomatico-maxillary; Se—94%, Sp—100%.|
|S7||F riedrich et al. (2001)||Prospective||Not controlled and ramus||32||Mandibular condyle||Plain radiograph (orthopantomograph and PA view)||7.5 MHz, small probe||Se—66%|
|S8||F riedrich et al. (2003)||Prospective||Controlled||81||Midfacial fractures||CT||Small part applicator||Good correlation for depressed zygomatic arch, multiple fractures of zygomatic complex ± anterior orbital floor nasal bridge, anterior wall of maxillary sinus|
|Poor correlation for non dislocated fractures, complex fractures, and lateral extension of fracture lines|
|S9||J ank et al. (2004)||Prospective, single blind||Not controlled||58||Orbital floor||Intraoperative finding and comparison with CT||7.5 MHz, curvilinear||Se—94%|
|Closed eye technique||Sp—57%|
|S10||J ank et al. (2004)||Prospective||Not controlled||40||Medial and lateral||CT||7.5 MHz, curved||Ac—96%|
|Orbital walls||Closed eye technique||NPV—57%|
|Medial wall; Se—56%, Sp—95%, Ac—90%, PPV—71%, NPV—91%|
|Lateral wall; Se—92%, Sp—88%, Ac—90%, PPV—92%, NPV—88%|
|S11||J ank et al. (2004)||Prospective||Not controlled||60||Infraorbital rims||CT||7.5 MHz, curved closed eye technique||Infraorbital rim; Se—94%, Sp—92%, Ac—92%, PPV—91%, NPV—92%|
|Orbital floor; Se—95%, Sp—100%, Ac—98%, PPV—100%, NPV—77%|
|S12||J ank et al. (2006)||Prospective||Not controlled||28||Orbital fractures||CT||7.5 MHz, curved closed eye technique||Inferior orbital margin; Se—86%, Sp—94%, Ac—90%, PPV—92%, NPV—89%|
|Orbital floor; Se—90%, Sp—100%, Ac—94%, PPV—100%, NPV—60%|
|Medial wall; Se—89%, Sp—91%, Ac—90%, PPV—80%, NPV—95%|
|Lateral wall; Se—93%, Sp—87%, Ac—90%, PPV—88%, NPV—93%|
|S13||J ank et al. (2006)||Prospective,||Not controlled double blind||13||Medial and lateral||CT||7.5 MHz, curved closed eye technique||Medial wall; Se—100%, Sp—90%, Ac—92%, PPV—75%, NPV—100%|
|Orbital walls||Lateral wall; Se—88%, Sp—94%, Ac—92%, PPV—88%, NPV—94%|
|S14||H ong et al. (2007)||Cross-sectional||Not controlled||26||Nasal bone||CT, conventional X-ray||7–15 MHz hockey stick||Ac—100%|
|S15||B lessmann et al. (2007)||Cross-sectional, single blind||Controlled||10||Midfacial fractures||CT||8 MHz for orbital||Poor correlation for isolated orbit floor and undisplaced zygomatic arch|
|12 MHz for others|
|Linear||Good correlation for medial and lateral orbital walls, anterior wall of maxilla and displaced zygomatic arch|
|S16||M uhammadi et al. (2009)||Cross-sectional double blind||Not controlled||171||Nasal bone||Convention X-ray||10 MHz, linear||Se—90%, Sp—98%, PPV—98%, NPV—87%|
|S17||L ee et al. (2009)||Cross-sectional double blind||Not controlled||138||Nasal bone||Conventional X-ray CT||High resolution US||Se—100%|
|10–15 MHz hockey stick||Sp—100%|