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Academic Center for Dentistry (ACTA), University of Amsterdam, The NetherlandsDepartment of Oral and Maxillofacial Surgery, Amsterdam UMC, University of Amsterdam, The Netherlands
Corresponding author at: Department of Oral and Maxillofacial Surgery, Amsterdam University Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam ZO, The Netherlands.
Management of zygomaticomaxillary complex (ZMC) fractures can be challenging. Consequently, there is a difference in treatment amongst clinicians. In the literature it remains unclear if the number of fixation points affects the quality of the anatomical reduction, stability through time, and potential complications. Therefore, the objective of this study was to assess the outcome of no fixation, one-point fixation and multiple-point fixation of ZMC fractures. MEDLINE, EMBASE and The Cochrane Central Register of Controlled Trials were searched to identify eligible studies. After screening 925 articles, 17 studies fulfilled the inclusion criteria. Based on this systematic review no clear conclusions can be drawn on how stability, repositioning, and postoperative complications are affected by the number of fixation points. Nevertheless, it can be concluded that the advantage of multiple approaches is direct visualisation, and the downside is potentially approach-related complications. This review suggests that intraoperatively assisted cone-beam computed tomography (CBCT) can help improve the quality of the repositioning and by minimising the number of fixation points, the number of postoperative complications could be further reduced.
The zygomaticomaxillary complex (ZMC) is an integral part of the facial structure and plays an important functional, structural, and aesthetic role in the mid-facial contour and in protecting the orbital contents.
Although ZMC fractures predominate in young adult males, there is geographic and sociodemographic variation in the incidence and aetiology of ZMC fractures, due to socioeconomic, cultural, and environmental factors.
Clinical decision making in the treatment of ZMC fractures can be challenging. Various treatment algorithms have been introduced; however, uniform consensus is still lacking.
Theoretically, three treatment options are possible for ZMC fractures: an expectative policy, closed reduction without fixation, and open reduction with fixation at one or more buttresses.
The primary goals when treating ZMC fractures surgically are anatomical reduction and a stable position to ensure the optimal postoperative aesthetic and functional results.
Reduction of the fracture can be realised through closed (stab-incision) and open reduction.
Closed reduction is a common treatment option for ZMC fractures. The stability of reduction relies on interfragmentary bone support, combined with the assumption that there is no muscle traction on the ZMC. The limited visualisation of the fracture site has been implicated as a disadvantage, but the introduction of intraoperative cone-beam computed tomography (CBCT) gives a new perspective to this discussion.
Tomographic osteometry of the zygomatic bone applied to traumatology of facial bones: preliminary retrospective study of zygomatic summit in 28 patients.
Tomographic osteometry of the zygomatic bone applied to traumatology of facial bones: preliminary retrospective study of zygomatic summit in 28 patients.
Proponents suggest that open reduction without fixation allows reduction under direct visualisation, since the periosteum is incised and elevated to expose all lines of fracture.
It needs to be noted that multiple approaches are necessary to make it possible to expose all fracture lines. However, exposure of the fractured segments and complete overview is not considered a part of management in all types of fractures. If open reduction is chosen, the standard treatment mostly involves internal fixation with titanium plates and screws to achieve stability.
Several authors have suggested that the number of fixation points should be based on several factors: the displacement of the fracture segment, the type of fracture, and the stability of the ZMC after reduction.
It remains unclear whether successful and predictable outcomes can be achieved with more fixation points on ZMC fractures, and if the number of fixation points affects the quality of the anatomical reduction, stability through time, and the potential complications. We carried out a systematic review of the literature to gain more insight into clinical decision making in the surgical treatment of ZMC fractures. We also wanted to assess what affects the quality of reposition that is needed to achieve adequate stability and reduce the number of complications. Therefore, we assessed the outcome of no fixation, one-point fixation, and multiple-point fixation in the management of ZMC fractures.
Material and methods
Protocol development
A protocol was developed a priori to answer the following question: What are the outcomes of no fixation, one-point fixation, and multiple point fixation when managing ZMC fractures, especially regarding malar symmetry and stability? This systematic review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.
The search strategy was developed with the help of a biomedical information specialist according to the syntax rules of each database (Table 1). A literature search of the following electronic databases was conducted: MEDLINE (1964-2021), EMBASE (1947-2021) and the Cochrane Central Register of Controlled Trials (CENTRAL; inception to 2021). The automated search was supplemented by manually searching the references of relevant review articles and eligible studies for additional useful publications.
Table 1Search strategy.
Database
Strategy
Medline
(“Zygomatic Fractures”[Mesh] OR zygoma*[tiab]) AND (“Fracture Fixation, Internal”[Mesh] OR fixat*[tiab] OR osteosynthes*[tiab] OR plate*[tiab]) AND (1 point[tiab] OR one point[tiab] OR 2 point*[tiab] OR two point*[tiab] OR 3 point*[tiab] OR three point*[tiab] OR 4 point*[tiab] OR four point*[tiab] OR fixation point*[tiab] OR point fixation*[tiab] OR stability[tiab] OR malar[tiab] OR symmetr*[tiab] OR asymmetr*[tiab] OR form[tiab] OR singl*[tiab] OR multi[tiab])
Embase
('zygoma arch fracture'/exp OR zygoma*:ti,ab) AND ('osteosynthesis'/exp OR fixat*:ti,ab OR osteosynthes*:ti,ab OR plate*:ti,ab) AND (“1 point”:ti,ab OR “one point”:ti,ab OR “2 point*”:ti,ab OR “two point*”:ti,ab OR “3 point*”:ti,ab OR “three point*”:ti,ab OR “4 point*”:ti,ab OR “four point*”:ti,ab OR “fixation point*”:ti,ab OR “point fixation*”:ti,ab OR stability:ti,ab OR malar:ti,ab OR symmetr*:ti,ab OR asymmetr*:ti,ab OR form:ti,ab OR singl*:ti,ab OR multi:ti,ab)
Cochrane
([mh “Zygomatic Fractures”] OR zygoma*:ti,ab) AND ([mh “Fracture Fixation, Internal”] OR fixat*:ti,ab OR osteosynthes*:ti,ab OR plate*:ti,ab) AND (“1 point”:ti,ab OR “one point”:ti,ab OR “2 point*”:ti,ab OR “two point*”:ti,ab OR “3 point*”:ti,ab OR “three point*”:ti,ab OR “4 point*”:ti,ab OR “four point*”:ti,ab OR “fixation point*”:ti,ab OR “point fixation*”:ti,ab OR stability:ti,ab OR malar:ti,ab OR symmetr*:ti,ab OR asymmetr*:ti,ab OR form:ti,ab OR singl*:ti,ab OR multi:ti,ab)
To be eligible, the studies had to meet the following criteria:
1.
Type of patients or population: adult patients with zygomatic fractures requiring closed reduction without fixation, or a surgical fixation treatment method with titanium plates and screws.
2.
Type of intervention: three-point fixation (zygomaticomaxillary buttress fixation method with infraorbital rim and frontozygomatic sutures).
3.
Comparison or control group: closed reduction without fixation or, one-point fixation or two-point fixation (zygomaticomaxillary buttress and/or infraorbital rim or frontozygomatic).
4.
Principal outcomes: the form and/or function of the ZMC complex.
5.
Outcomes: facial symmetry, malar eminence (Grade I, II, III), vertical dystopia, malar height, malar projection, displacement (horizontal and vertical), enophthalmos, diplopia, muscle traction (temporalis and masseter), stability, infection, infraorbital paraesthesia, sensory disturbance, repair operation, pain, periorbital swelling, limited mouth opening, scarring, operation time, haematoma, patient satisfaction, and cost of the plate.
6.
Study design: randomised clinical trials (RCT), prospective controlled clinical trials (CCT), cohort studies and case series.
7.
Study language: English.
Exclusion criteria
1.
Studies with <15 patients.
2.
Use of biodegradable or other material such as titanium as a fixation plate.
3.
Panfacial fractures.
4.
Experts’ opinions, conference abstracts, letters to the editor, animal studies, reviews, and systematic reviews.
Screening methods
One reviewer (IR) initially screened the abstracts. Full-text documents were obtained of all the articles meeting the inclusion criteria. Full text analysis was performed independently by two reviewers (IR and LD).
Data extraction
The following data were extracted from the studies that met the above-mentioned criteria: author(s), year of publication, study design, country, number of patients, males/females, mean age, age range, follow-up (months), radiographic assessment/imaging technique, clinical assessment/symptoms, fracture site, number of fixation points (in combination with number of patients), site of fixation, description of ‘stability’, type of mini plate (material), and the variables mentioned in ‘Outcomes’.
Evaluation of study quality and risk of bias
The methodological quality of the included studies was assessed independently by two reviewers (IR and LD). The risk of bias of the randomised studies was assessed using the seven domains of the Cochrane Collaboration tool for RCT’s:
random sequence generation, allocation concealment, blinding of the participants and researchers, blinding of the outcome, incomplete outcome data, selective outcome reporting, and ‘other sources of bias’. These seven domains were graded as: low risk, unclear risk, or high risk of bias. The Methodological Index for Non-Randomised Studies (MINORS) was used to assess the methodological quality of the non-randomised studies.
This tool consists of 12 domains: a clearly stated aim, inclusion of patients, collection of data, appropriate endpoints, unbiassed assessment, follow-up period, loss to follow-up, calculation of the sample size, adequate control group, contemporary groups, baseline equivalence, and statistical analysis. The twelve domains were scored as: not reported (0), reported but inadequate (1), reported and adequate (2).
Statistical analysis
Data were extracted from all the included studies to investigate the management of ZMC fractures and their focus on stability and predictability in restoring malar symmetry. The postoperative evaluation results of no fixation, one-point fixation, two-point fixation, and three-point fixation were evaluated using descriptive statistics.
Results
Study selection
The primary search of the period until February 1, 2021, resulted in 427 hits with the MEDLINE search, 461 with the EMBASE search, and 37 with the Cochrane search (Fig. 1). A total of 373 duplicates was removed, leaving 555 studies. After screening the titles and abstracts, 481 studies were excluded because they did not justify the exclusion or inclusion criteria. Checking the reference lists of the relevant reviews and scanning the eligible studies manually revealed three additional articles. This selection procedure resulted in seventy-six eligible studies for full-text analysis.
The analysis resulted in 15 studies being excluded because the predefined principal outcomes were not described. Another 16 studies were excluded because they used a material for internal fixation other than titanium plates and screws. Fourteen articles were excluded because there was no information about the number of fixation points, or detailed information could not be extracted. Nine articles were excluded because they were a part of a conference abstract. Two studies were excluded because they were reported in other language. And finally, three articles were excluded because the full text was not yet available. A total of 17 articles fulfilled the inclusion criteria.
Characteristics of the studies
The studies’ characteristics used for qualitative syntheses are depicted in Table 2. The number of patients varied from 15 patients
Of these eight articles, three described the outcome of open reduction with internal fixation (ORIF) using two-point fixation, three articles compared the outcome of ORIF using two-point fixation and three-point fixation, one article described the outcome of ORIF using one-point fixation, and one article described the outcome of ORIF using three-point fixation (Table 3). Five were retrospective studies with the mean follow up varying from 3.4 months
Of these five articles, one described the outcomes of no fixation, one described the outcome of ORIF using one-point fixation, two-point fixation, and three-point fixation, one compared the outcome of ORIF using two-point and three-point fixation, one described the outcome of ORIF using one-point fixation, and one article described the outcome of ORIF using two-point fixation. Four RCT studies compared the ORIF outcomes on applying two-point fixation and three-point fixation, with the mean follow-up varying from six weeks
ZMB: 2.0-mm mini plate and screws ZMB, FZB: 2.0-mm mini plate and screw+ 0.6-mm miniplate ZMB, FZB, IOR: 2.0-mm mini plate and screw+ 0.6-mm mini plate + 1.6-mm plate
Orbital height and bilateral orbital width
CT (preoperatively), 3D CBCT (immediately postoperatively and at least 3 months postoperatively)
3D CT-scan, PNS X- ray (preoperatively and postoperatively)
FZB: lateral eyebrow approach IOR: infra orbital approach
Rana, 2012
2-point: ZMB, FZB 3-point: ZMB, FZB, IOR
ZMB, FZB: 1.5 mm mini plates ZMB, FZB, IOR: 1.5 mm mini plates (ZMB, FZB), 0.9mm microplates (IOR)
Malar height and vertical dystopia
Waters' view, Caldwell's posterior-anterior view (preoperatively and 6 weeks postoperatively)
ZMB: intraoral buccal sulcus incision FZB: lateral eyebrow incision or upper lid blepharoplasty incision IOR: subciliary incision or transconjunctival approach
Chakranarayan, 2009
2-point: ZMB, FZB
ZMB: ‘L’ shaped titanium mini bone plate with two screws on each side of the fracture line FZB: 4- or 5-hole straight titanium mini bone plate with two screws on each side of the fracture line
NM
Paranasal sinus view and submentovertex (preoperatively and 6 weeks postoperatively)
The five retrospective and eight prospective studies also differed in follow-up time and outcome measurements. The risks of bias of the ‘random sequence generation’, ‘selective reporting’ and ‘other bias’ domains were low (Table 4). ‘Blinding of the participants and researchers’ and ‘blinding of the outcome assessment’ were found to have high risks of bias, since the participants and surgeons were informed and aware of the number of fixation points. Only one included RCT scored a high risk of bias in the domain ‘incomplete outcome data’, due to the fact that patients were lost to follow up.
Subgroup analyses could not be performed because none of the RCTs scored a low risk of bias.
Table 4Risk of bias assessment of RCT, prospective studies and retrospective studies. Cochrane Collaboration tool for assessing risk of bias of the includes RCT, MINORS (Methodological Index for Non-randomised studies) for assessing risk of bias of the prospective cohort studies and retrospective cohort studies.
Cochrane Collaboration tool for assessing risk of bias
MINORS
Study name (year)
Random sequence generation (selection bias)
Allocation concealment (selection bias)
Blinding of participants and researchers (performance bias)
Blinding of outcome assessment (detection bias)
Incomplete outcome data (attrition bias)
Selective reporting (reporting bias)
Other bias
A clearly stated aim
Inclusion of consecutive patients
Prospective collection of data
Endpoints appropriate to the aim of the study
Unbiased assessment of the study
Follow up-period appropriate to the aim of the study
Loss to follow up less than 5%
Prospective calculation of the study size
An adequate control group
Contemporary groups
Baseline equivalence of the groups
Adequate statistical analysis
Randomised controlled trials
Nasr et al (2018)
Low
Unclear
High
High
Low
Low
Low
Latif et al (2017)
Low
Low
High
High
Low
Low
Low
Rana et al (2012)
Low
Low
High
High
High
Low
Low
Parashar et al (2007)
Low
Unclear
High
High
Low
Low
Low
Retrospective studies
Shokri et al (2020)
2
2
0
2
0
1
0
0
0
0
0
0
Kim et al (2018)
2
1
0
2
0
2
2
0
1
2
0
2
Starch-Jensen et al (2018)
2
1
0
2
0
2
0
0
1
2
0
0
Balakrishnan et al (2015)
0
1
0
0
0
0
2
0
1
0
0
0
Jo et al (2014)
2
1
0
2
0
2
2
0
0
0
0
2
Prospective studies
Degala et al (2021)
2
2
2
2
0
2
2
0
1
0
0
0
Mahmood et al (2019)
2
2
2
2
0
2
2
2
1
2
0
2
Mittal et al (2019)
2
2
2
2
0
2
2
0
0
0
0
2
Dutt (2018)
2
1
2
2
0
2
2
0
1
2
0
2
Kumar Punjabi et al (2016)
2
2
2
2
0
1
2
0
0
0
0
0
Abu Dakir et al (2015)
1
1
2
1
0
2
2
0
0
0
0
0
Ebenezer et al (2014)
2
2
2
2
0
2
2
0
0
0
0
0
Chakranarayan (2009)
2
2
2
2
0
2
2
0
0
0
0
0
High: high risk of bias, Low: low risk of bias, Unclear: unclear risk of bias, 0: not reported, 1: reported but inadequate, 2: reported and adequate.
Furthermore, all prospective and retrospective studies failed to use an unbiased assessment of the study endpoints and to report a baseline equivalence of groups (Table 4). Three prospective and three retrospective studies compared the difference in outcome between the number of fixation points and a control group. The other prospective and retrospective studies highlighted the outcome of a specific number of fixation points but did not have a control group.
Eleven of the 17 included articles reported explicitly that they did not receive any funding or have any conflicts of interest.
Evaluation of postoperative stability after open reduction and internal fixation of zygomaticomaxillary complex fractures using cone beam computed tomography analysis.
Outcome measures of the included randomised controlled trials
The RCTs included in this systematic review generally did not describe the same outcome variables and differed in follow-up time. Because of the high heterogeneity between the four included, the outcome measures could not be meaningfully pooled.
All four RCTs compared two-point with three-point fixation. None of the outcome variables listed above was assessed by them and vertical dystopia was the only parameter described by three of them.
The results of their outcome measures are depicted in Table 5, Table 6. The overall outcomes of the three-point fixation was favourable compared to the two-point fixation of comparable ZMC fractures. This finding was based on the results of descriptive variables extracted directly from the RCTs. Only the cost of the plate was significantly favourable for two-point fixation, however patient satisfaction and operation time did not reveal significant differences between two-point or three-point fixation.
The postoperative muscle traction of the masseter and temporalis variable was not significantly favourable for either three-point or two-point fixation.
It has been implied that multiple point fixation leads to more stability, this was also seen in the results of this systematic review. Latif et al (2017) and Rana et al (2012) reported, respectively, that 76% and 80% of the patients with three-point fixation had stable fractures postoperatively, while only 28% and 32% of the two-point fixation patients had stable fractures postoperatively (Table 5).
Both of these studies reported a significant postoperative difference in malar height, vertical dystopia, and fracture stability between three-point and two-point fixation and concluded that three-point fixation is a favourable treatment modality for the management of ZMC fractures.
Outcome measures of prospective and retrospective studies
Malar symmetry
The outcome measures from the included prospective and retrospective studies were divided into four categories: malar symmetry, stability, complications, and clinical outcome. Facial asymmetry after surgery was reported in 13% of cases in the no fixation group by Starch-Jensen et al (2018), while facial asymmetry was reported by Shokri et al (2020) in none of the patients who had received one-point fixation (Table 7).
Ebenezer et al (2014), Balakrishnan et al (2015) and Degala et al (2021), respectively, reported facial asymmetry in 0%, 4%, and 50% of the patients who had received two-point point fixation.
Facial asymmetry was reported by Kumar Punjabi et al (2016) in 30% of the patients who had received three-point fixation and Degala et al (2021) reported facial asymmetry in 8% of three-point fixation.
It should be noted that multiple point fixation is associated with more postoperative complications, such as scarring, which could also lead to facial asymmetry.
There was almost no noticeable difference between two-point and three-point fixation in terms of malar eminence (Grades I, II, and III), however the difference between three-point and two-point fixation for the variable Grade III was reported as significant by Dutt et al (2018).
Evaluation of postoperative stability after open reduction and internal fixation of zygomaticomaxillary complex fractures using cone beam computed tomography analysis.
On the contrary, Dutt et al (2018) reported a significantly lower vertical dystopia score in the three-point fixation group than in the two-point fixation group.
Mahmood et al (2019) reported that mean malar height reduced in the two-point and three-point fixation group, but that malar height was significantly lower in the three-point fixation group.
Dutt et al (2018) and Mittal et al (2019) described the mean vertical dystopia (mean ±SD; in mm, total population) and Kim et al. (2018) described the mean changes of orbital height (mean±SD; in mm, total population).
Malar height (mean ± SD; in mm, total population/ mean vertical difference: VD ratio)
Mittal et al (2019) and Mahmood et al (2019) describe mean malar height) mean ±SD; in mm, total population) and Jo et al (2014) described mean vertical difference (mean horizontal difference: VD ratio).
Malar projection (mean horizontal difference: HD ratio)
No fixation
Starch-Jensen (2018) 3/23; 13%
-
-
-
-
-
-
1-point fixation
Shokri (2020) 0/162; 0%
-
-
-
Kim (2018) 0.50 ± 0.10 (14)
-
-
2-point fixation
Balakrishnan (2015) 6/164; 4%
Dutt (2018) 5/20; 25%
Dutt (2018) 8/20; 40%
Dutt (2018) 7/20; 35%
Kim (2018) 0.47 ± 0.13(14)
Mittal (2019) 69.10 ± 4.35 (20)
Jo (2014) 0.989
Ebenezer (2014) 0/20; 0%
Dutt (2018) 2.10 (20)
Mahmood (2019) 58.07±4.61 (30)
Degala (2021) 6/12; 50%
Mittal (2019) 0.28 ± 0.55 (20)
Jo (2014) 1.019
3-point fixation
Kumar Punjabi (2016) 6/20; 30%
Dutt (2018) 6/20; 30
Dutt (2018) 9/20; 45
Dutt (2018) 5/20; 25%
Kim (2018) 0.47 ± 0.09(13)
Mahmood (2019) 57.20±3.96 (30)
-
Degala (2021) 1/12; 8%
Dutt (2018) 0,94 (20)
1 Malar eminence: Grade I: Excellent cosmetic result, no malar asymmetry. Grade II: Good cosmetic result, malar asymmetry on careful inspection. Grade III: Poor cosmetic result, noticeable malar asymmetry.
2 Dutt et al (2018) and Mittal et al (2019) described the mean vertical dystopia (mean ± SD; in mm, total population) and Kim et al. (2018) described the mean changes of orbital height (mean± SD; in mm, total population).
3 Mittal et al (2019) and Mahmood et al (2019) describe mean malar height) mean ± SD; in mm, total population) and Jo et al (2014) described mean vertical difference (mean horizontal difference: VD ratio).
Data for the stability parameters regarding horizontal and vertical displacement could be extracted from only one study and they found no significance difference between the number of fixation points and postoperative horizontal and vertical displacement.
Evaluation of postoperative stability after open reduction and internal fixation of zygomaticomaxillary complex fractures using cone beam computed tomography analysis.
Evaluation of postoperative stability after open reduction and internal fixation of zygomaticomaxillary complex fractures using cone beam computed tomography analysis.
Only two of the included studies reported on the variable infection; Shokri et al (2020) and Ebenezer et al (2014) both reported an infection rate of 5% (Table 9).
Infraorbital paraesthesia was reported in 17% of the cases in the two-point fixation group by Chakranarayan et al (2009) and in 4% of the cases in the three-point fixation group by Balakrishnan et al (2015).
However, no significant difference was found. Both Starch-Jensen et al (2018) and Shokri et al (2020) reported that no patient required revision surgery after open reduction with internal fixation.
If one-point and two-point fixation are compared with each other on postoperative pain; one-point fixation scores better than two-point fixation (Table 10). Dakir et al (2017) reported that none of the one-point fixation patients experienced pain.
Mean mouth opening was reported by Mahmood et al (2019) and a significant improvement in the three-point fixation group was observed compared to the two-point fixation group.
Dakir et al (2017) reported no scarring after one-point fixation, Ebenezer et al (2014) observed a scarring rate of 10% in the two-point fixation group and Balakrishnan et al (2015) reported a rate of 4% in the three-point fixation group.
This systematic review assessed the outcome of no fixation, one-point fixation, and multiple-point fixation in the management of ZMC fractures. The primary goal of treating ZMC fractures surgically is to achieve stable anatomical reduction, resulting in optimal postoperative aesthetic and functional conditions, and minimal postoperative complications.
When considering adequate anatomical reduction, visualisation is a key factor. In this analogy, more surgical access allows the surgeon to inspect more of the fractured sites and, consequently, leads also to adequate anatomical reduction.
Although multiple approaches enable direct visualisation, the downside is the potential of inducing approach-related complications. Relatively high risks of postoperative complications are especially associated with approaches to the infraorbital rim and/or orbital floor (such as subciliary or transconjunctival approaches).
Thus, it is important to implement a treatment strategy that focuses on a predictable outcome and patient satisfaction, and not only on maximum exposure.
Tomographic osteometry of the zygomatic bone applied to traumatology of facial bones: preliminary retrospective study of zygomatic summit in 28 patients.
Stability can be assessed by comparing the intraoperative scan with the postoperative images through time. Intraoperative CBCT will not help with the long-term stability but is necessary to assess stability through time. Several publications have shown that adequacy of reduction has been improved significantly when an intraoperative (CB)CT scan is used.
A prospective multicenter study to compare the precision of posttraumatic internal orbital reconstruction with standard preformed and individualized orbital implants.
Scanning costs extra operation time, but can also result in a reduction of operation time when additional surgical approaches can be avoided. Interestingly, in this review, 12 studies verified the reduction postoperatively, but none intraoperatively. Only seven of the studies used 3D imaging preoperatively and postoperatively and seven of the included studies used a plain radiograph for preoperative and postoperative assessments. The difference in imaging techniques between the studies needs to be taken into consideration. Since none of the included studies applied intraoperative imaging, stability could only be assessed by comparing postoperative images through time.
A second important aspect in the predictable treatment of ZMC fractures is stability (through time). Stability after ZMC fracture treatment can be defined as ‘a reduced ZMC fracture, which remains in a stable anatomical position over time’. Stability is assessed through time in this systematic review because we wanted to establish information about the demands of the osteosynthesis materials. Two requirements need to be mentioned with respect to this. Regarding a closed reduction, the interfragmentary bone support, with or without ORIF, must be stable enough to maintain the position and capable of withdrawing the forces applied to the ZMC. In this context, it is remarkable that most of the literature does not address the effect of the masticatory muscles on the stability of the ZMC in the presence of a fracture. From an anatomical perspective, the masseter muscle originates from the zygomatic bone and zygomatic arch, and the temporalis muscle passes medially to the zygomatic bone prior to entering the coronoid process and anterior ramus of the mandible.
The forces generated by muscle activity can act directly on the ZMC fracture and can therefore, potentially, cause malar asymmetry and vertical dystopia.
When evaluating treatment quality, most authors focus on stability as one of the main variables. However, none of the studies in this systematic review reported on the quality of the reduction. Inevitably, plate and screw fixation are often required to align fractures properly after high energy injuries characterised by comminution, injured periosteum, and severe displacement.
A comminuted fracture of the zygoma has less interfragmentary support than a comminuted fracture of the mandibula, due to the muscle traction and force on the mandibula. In most cases, these comminuted fractures cannot be repositioned adequately by means of interfragmentary support, and therefore need fixation. Most of the included studies erroneously misinterpreted this requirement of fixation, in our opinion, as ‘lack of stability’. Of the included 17 studies, 12 reported on stability, but based on different definitions. Two studies assessed the stability through time, by comparing immediate postoperative images with those obtained several months later.
Evaluation of postoperative stability after open reduction and internal fixation of zygomaticomaxillary complex fractures using cone beam computed tomography analysis.
Kim et al (2018) described stability in terms of orbital height, bilateral orbital width, and horizontal and vertical changes of the screw. Stability was assessed by comparing immediate postoperative CBCT images with CBCT images obtained three months later. The one aforementioned study concluded that there was no significant difference in postoperative stability between one-point, two-point, and three-point fixation.
Evaluation of postoperative stability after open reduction and internal fixation of zygomaticomaxillary complex fractures using cone beam computed tomography analysis.
It was stated that one-point fixation at the zygomatic buttress through upper vestibular incision is sufficiently rigid, as long as accurate anatomical reduction is achieved.
Evaluation of postoperative stability after open reduction and internal fixation of zygomaticomaxillary complex fractures using cone beam computed tomography analysis.
The second study that assessed stability through time was by Abu Dakir et al (2017) who compared an immediate postoperative 2D radiograph with a six month postoperative radiograph, but they did not provide a definition of stability.
The third, and probably most important, aspect in the treatment of ZMC fractures is related to predictability of clinical outcome and complications. Multiple point fixation is expected to be associated with more complications than single point or closed reduction in relation to repositioning and fixation, or to the approach.
Enophthalmos and infraorbital paraesthesia are present more in patients who have had two- or three-point fixation than patients who have had single point fixation or closed reduction (Table 5, Table 6, Table 8, Table 9).
This outcome could be explained by the more severe primary injury requiring more extensive fixation and not the result of the fixation method itself. The stability rate of 100% after two-point fixation reported by Ebenezer et al (2014) was not in line with our expectations, since Latif et al (2017) and Rana et al (2012) reported respectively that 8% and 32% of the two-point fixation patients had stable fractures postoperatively.
An explanation for this may be that the definition of stability differs in each study and/or the relatively small patient group. It needs to be mentioned that patient satisfaction is an important aspect of treatment success and yet only one study investigated and mentioned this variable.
makes it difficult to compare the results with each other. Ideally, all included studies would have used an intraoperative or immediate postoperative image to compare with those obtained later (long-term follow up). However, in this systematic review, only two studies assessed the stability through time.
Evaluation of postoperative stability after open reduction and internal fixation of zygomaticomaxillary complex fractures using cone beam computed tomography analysis.
Another limitation is the heterogeneity among the studies in radiographic assessment, but also in the amount of displacement and comminution of the ZMC fractures. The considerable difference in displacement and comminution between patients from the same study means they could not be stratified in this systematic review. Also, the days from trauma to surgery were not weighed as a success factor. The studies stated that anatomical reduction is best accomplished in the early phase of bone healing. Bone healing and resorption starts three weeks after the trauma, resulting in less interfragmentary support, which means one should aim to operate within 21 days post-injury.
Special attention should be paid to two systematic reviews; Gadkari et al (2019) compared malar asymmetry and stability after two-point versus three-point fixation and Jazayeri et al (2019) examined the patients’ outcomes (complication rates and patient-reported satisfaction) of one-point, two-point, three-point, and four-point fixation.
Unfortunately, both reviews did not define stability further, and also assessed biodegradable material, which is confusing because the material characteristics differ from titanium and can also cause late tissue responses.
Evaluation of soft tissue asymmetry using cone-beam computed tomography after open reduction and internal fixation of zygomaticomaxillary complex fracture.
J Korean Assoc Oral Maxillofac Surg.2014; 40: 103-110
which can affect stability. Hence, some caution needs to be exercised regarding the conclusions of both reviews.
It is, unfortunately, not possible to draw reliable conclusions and to generalise the results about no fixation, one-point fixation, and multiple fixation. Despite the fact that the definitions of stability differ greatly in each study, they support the same principles in terms of outcome measures. The three predictable treatment aspects of ZMC fractures are: adequate anatomical reposition, stability, and to be as least invasive as possible. To comply with these principles, the literature suggests that using a (CB)CT scan operatively has the potential to improve the reposition quality, stability through time, and postoperative complications can be reduced by minimising the number of fixation points.
Then the debate will shift to the amount of stability required to keep the ZMC in a proper position and how to reach this with a minimal approach. We speculate that new technological developments, such as using 3D technology to produce and insert plates, may achieve this goal, even for comminuted fractures.
Funding
No funding was received for this study.
Conflict of interest
We have no conflicts of interest.
Ethics statement/confirmation of patients’ permission
The study was approved by the internal review board of ACTA (# 2020279). Patients’ consent was not required.
References
Starch-Jensen T.
Linnebjerg L.B.
Jensen J.D.
Treatment of zygomatic complex fractures with surgical or nonsurgical intervention: a retrospective study.
Tomographic osteometry of the zygomatic bone applied to traumatology of facial bones: preliminary retrospective study of zygomatic summit in 28 patients.
Evaluation of postoperative stability after open reduction and internal fixation of zygomaticomaxillary complex fractures using cone beam computed tomography analysis.
A prospective multicenter study to compare the precision of posttraumatic internal orbital reconstruction with standard preformed and individualized orbital implants.
Evaluation of soft tissue asymmetry using cone-beam computed tomography after open reduction and internal fixation of zygomaticomaxillary complex fracture.
J Korean Assoc Oral Maxillofac Surg.2014; 40: 103-110
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