A comparison of one point versus two point fixation in the management of zygomatico-maxillary complex fractures

Introduction

The zygomatic bone articulates with the frontal, sphenoid, temporal, and maxillary bones, defining the anterior and lateral projection of the face. The mid-facial contour and the contents of the orbits are safeguarded by the zygomatic complex. One of the most frequent facial injuries in maxillofacial trauma is zygomatic complex fracture, which primarily affects young adult males.1 The distinctive tetrapod configuration of the ZMC, which articulates with several bones, defines the cheek prominence, the inferior and lateral orbital boundaries, and the anterolateral aspect of the face.2, 3

If these fractures are not attended to, they may lead to functional and aesthetic deficits such as;

Variable surgical techniques have been performed to achieve satisfactory outcomes e.g. the Gillies’ temporal approach, upper eyelid, lateral eyebrow, sub-ciliary, transconjunctival, and intraoral approaches.4, 5, 6

Achieving anatomic reduction and stable fixation is the major objective of the treatment in order to avoid functional or cosmetic impairments following surgery.

Hence, the current study compares the stability and aesthetic outcome of one- point versus two-point fixation of tripodal zygomatic fractures by using miniplates, through assessment of clinical and radiological outcomes.

Aim

To analyze and compare the stability, aesthetic appearance in zygomatic complex fractures after open reduction with single point and two-point fixation.

Objectives

Materials and Methods

The procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional or regional) and with the Helsinki Declaration of 1975, as revised in 2000. The study was conducted on subjects reporting to the Department of Faciomaxillary Surgery, XXX. Randomization was carried out using sequentially numbered, opaque, sealed envelopes as the allocation concealment scheme (simple random technique). Each envelope contained the names of either group one or group two to which the patients will be allotted. A prospective study segregating the patients into one point fixation group and two-point fixation group will be done before the proposed procedure. All patients with tripod fractures of the zygoma will undergo computed tomography (CT) scans before and after ORIF. Group 1 consisting of 17 patients will undergo open reduction with 1-point (zygomatico-maxillary buttress region) internal fixation through a buccogingival incision, and group 2 composed of another 17 patients will undergo open reduction with 2-point (zygomatico-maxillary buttress and fronto-zygomatic regions) internal fixation through buccogingival and lateral eyebrow incisions. Clinically all the patients will be assessed as a part of follow-up protocol at one week, 3 weeks, 6 weeks after the procedure for the following factors:

In patients under group 2 (Two point fixation group), lateral eyebrow incision e.g. unsightly scar or keloid formation, and complications of the miniplates e.g. infection and palpability of the plate will also be assessed. (FIGURE 2, 2a, 3, 3a, 4, 4a, 5, 5a, 5b, 5c)

Figure 1

A): Frontal view of the patient; B): Pre-operative 3D CT scan depicting fracture of right zygomatico-maxillary complex

Figure 2

A): Intra operative view of right zygomatico-maxillary buttress showing the fracture line; B): Depicting reduction and fixation with titanium miniplates and screws of right zygomatico-maxillary buttress

Figure 3

A): Frontal view of the patient for two point fixation; B): Pre-operative 3D CT scan depicting fracture of left zygomatico-maxillary complex

Figure 4

A): Intraoperative view of left zygomatico-maxillary buttress showing the fracture line; B): Depicting reduction and fixation with titanium miniplates and screws of left zygomatico-maxillary buttress; C): Intra operative view of fractured left fronto-zygomatic suture/ lateral orbital rim; D): Depicting reduction and fixation with titanium miniplates and screws of fronto-zygomatic screws

Armamentarium (Figure 5)

1. Titanium mini plates- 2mm straight ‘L’ plates

2. Titanium miniplates- 1.5mm 4-holed straight plates

3. Titanium screws 6 mm, 8 mm

4. Surgical screw holder, Screw driver and

5. Basic surgical Instruments

6. Plate bender

Figure 5

Basic armamentarium for open reduction and internal fixation

Results

When compared to the one-point fixation group, only 14 patients had substantial stability with a P-value of <0.05 being statistically significant. In contrast, nearly all patients in the two-point fixation group had higher stability. In the two-point fixation group, nearly all patients had a post-operative scar; in the one-point fixation group, however, only two patients had the same scar, and the mouth opening was also improved. In two-point fixation, paresthesia was observed in nearly seven patients, while in one-point fixation, it was present in only two patients. (Table 1, Table 2, Table 3, Table 4, Table 5, Table 6)

Table 1 shows the stability among one point and two-point fixation. The stability was present in almost all the patients in two-point fixation whereas only 14 individuals had stability in one point fixation. P-value <0.05 is considered to be statistically significant. The comparison for stability clearly shows that statistically significant difference was seen among one- and two-point fixation. In stability, two-point fixation stands ahead superior than one point fixation.

Table 2 shows the scar among one point and two-point fixation. The scar was present in almost all the patients in two-point fixation whereas only 2 individuals had scar in one point fixation. P-value <0.05 is considered to be statistically significant. The comparison for scar clearly shows that statistically significant difference was seen among one- and two-point fixation. In scar, one-point fixation stands ahead superior than two-point fixation.

Table 3 shows the comparison of mouth opening among one point and two-point fixation. The mean of mouth opening was higher in one point fixation (41.17) than two-point fixation (38.94). Statistically significant difference for mouth opening was seen.

Table 4 shows the complication among one point and two-point fixation. The complication was present in 2 patients in two-point fixation whereas only no individuals had complication in one point fixation. P-value <0.05 is considered to be statistically significant. The comparison for complication clearly shows that statistically significant difference was seen among one- and two-point fixation. In complication, two-point fixation stands ahead superior than one-point fixation.

Table 5 shows the paraesthesia among one point and two-point fixation. The paraesthesia was present in almost 7 patients in two-point fixation whereas only 2 individuals had paraesthesia in one point fixation. P-value <0.05 is considered to be statistically significant. The comparison for paraesthesia clearly shows that statistically significant difference was seen among one- and two-point fixation. In paraesthesia, two-point fixation stands ahead superior than one-point fixation.

Table 6 shows the comparison of satisfactory score among one point and two-point fixation. The mean of score was higher in two-point fixation (9.17) than one-point fixation (8.70). Statistically significant difference for satisfactory score was seen.

Discussion

One crucial component of the facial structure is the zygomaticomaxillary complex. The orbit, maxilla, and temporal fossa are all related to the zygoma, a diamond-shaped bone in the centre part of the face. Its faces are temporal, orbital, and lateral. The frontozygomatic suture (FZS), infraorbital rim, zygomaticomaxillary buttress, and zygomaticotemporal suture are the four articulations of the zygoma. With the exception of the nose, it sustains injuries more frequently than any other facial feature due to its placement.7, 8

While occasional traumas may result in a fracture of the antral wall or orbital rim alone, the majority of injuries involve the zygomatic bone, hence the term "zygomaticomaxillary." the mandibular mobility implications. Most midface fractures are caused by trauma to the zygomatic complex, and for these fractures, early intervention is usually seen to be the best course of action.9, 10, 11

However, 1-point fixation in the FZ area through a lateral eyebrow incision usually leaves ex-ternal scars, palpability of plates, and swelling resulting from severed muscle and soft tissue. Because the soft tissue overlying the FZ area is very thin, thin plates must be used to prevent visibility, sensibility, and palpability. One-point fixation in the ZM area does not leave external scars or palpability of plates or screws. In addition, when plates or screws are removed, a buccogingival incision leaves no external scars. Repeated lateral eyebrow incisions may give more chances to leave external scars.12, 13

In ZMC fractures, maintaining reduction is the goal of bone repair for both practical and aesthetic reasons. Studies on biomechanics have tried to identify the forces operating on the ZMC and how they can impact fixation methods. Although the masseter is the primary muscle responsible for ZMC displacement, its actual impact on the result of surgery remains a matter of controversy. When a ZMC fracture lasts four to six weeks, Dal Santo et al. showed a substantial reduction in ipsilateral masseteric force. Furthermore, elevating masseteric attachments from the zygoma using an intraoral method to exposure may potentially have an impact on muscle performance. Asymmetry following reduction is found to be between 10 and 13%. Fracture instability is not as likely to be the cause of this malar asymmetry as it is imprecise reduction.12, 13, 14

Tarabichi noted that in vitro studies are deceptive due to the lack of serration along the orbital rim and the disregard of the roles of the superficial musculoaponeurotic system, uninterrupted periosteum, and skin in stabilising a fractured zygoma. reported successful results with trans-sinus reduction through the comminuted anterior wall of the sinus and 1-point fixation of malar fractures. Fujioka et al. proposed that in their in vivo analysis, when the fracture was not comminuted and 3-point alignment was obtained, 1-point fixation at the zygomaticomaxillary compartment was adequately robust.14, 15

Thus, 1-point fixation at the ZMB area should be sufficiently stable for tripod fractures if it is not difficult to reduce displacement of the F-Z process and a comminuted fracture of the infraorbital rim and zygomatic arch using ultrasonography. Two-point fixation should be done in the ZMB as well as the F-Z compartment additional lateral canthal incision if the lateral orbital rim is comminuted.

Conclusion

According to our research, the zygomatico-maxillary complex can be sufficiently stabilised by 1-point fixation at the ZMB without suffering from comminuted fractures of the lateral orbital rim. Additionally, in certain patients with zygomatic tripod fractures, one-point fixation in the zygomatico-maxillary buttress region can prevent ugly scars and provide excellent surgical outcomes.

When there is a small preoperative bone gap in the F-Z area, single point fixation in the ZM area is preferable; however, when there is a large bony gap in the FZ area, two-point fixation is preferable. However, the scar in the FZ area and the palpability of the prosthesis there make the two-point fixation patients unhappy.

In the FZ area, absorbable plates or microplates could be employed to prevent the prosthesis from being palpable. It is an excellent fixation by intraoral maxillary vestibular technique (Balasubramanian’s or Keen’s Intra oral approach) to prevent multiple surgical incision, probable infection, additional scar, and nerve palsy. For ZMC minimally displaced fractures with little post-operative problems, ZM buttress fixation is considerably superior.

Study Limitations

Since each author's assessment of the parameters was different, it was impossible to standardise them for comparison. In one study, Kim et al. (2017) observed no statistically significant differences between the two groups (three-point fixation and two-point fixation) in terms of post-operative stability.

The authors of two studies, Hasse et al. (2011) and Ji et al. (2016), did not state which type of fixation was better in their investigation; nonetheless, they came to the conclusion that since there are numerous fixation techniques accessible, the best method to treat ZMC fractures is to use a safe, facilitated procedure.

Source of Funding

None.

Conflict of Interest

None.