Is Zygomatic Osteotomy a Viable� Option to Achieve Symmetry and� Stability in Post-traumatic Residual� Deformity of the Zygomaticomaxillary� Complex?

Is Zygomatic Osteotomy a Viable� Option to Achieve Symmetry and� Stability in Post-traumatic Residual� Deformity of the Zygomaticomaxillary� Complex?

1. Is Zygomatic Osteotomy a Viable Option to Achieve Symmetry and Stability in Post-traumatic Residual Deformity of the Zygomaticomaxillary Complex? Prem Kumar Rathod, MDS, Rahul Yadav, MDS, Ongkila Bhutia, MDS, Ajoy Roychoudhury , MDS, Krushna Bhatt, MDS, and Kamalpreet Kaur, MDS

2. J Oral Maxillofac Surg DOI : https://doi.org/10.1016/j.joms.2021.01.017 Received: November 16 2020 Accepted: January 16 2021

3. Post traumatic residual deformity of ZMC often present with esthetic and functional deformity t/t plan: zygomatic osteotomy Dissatisfactory outcome?  difficulty to understand the original position of zygoma intraoperatively  loss of the landmarks and the fracture edges (secondary to bone remodeling)  d espite achieving perfect hard tissue symmetry  instability d/t incomplete contact at the osteotomy sites, scar tissue, muscle pull on hardware.

4. No zygoma analysis fulfills the criteria of quantification and stability assessment

5. AIM to prospectively evaluate the symmetry and stability after zygomatic osteotomy and miniplate fixation in patients with unilateral post traumatic residual deformity of ZMC using zygoma analysis. Specific aims: to measure the ZMC ocular motility infraorbital paraesthesia diplopia evaluate the orbital volume (preoperatively, post operatively, and 6 months postoperatively)

6. Study Design Prospective study IECPG540/20.12.2017, RT– 2/31.01.2018 NCT05830747 Ethical approval no. Study design CTR no .

7. Inclusion criteria >18 years of age unilateral residual deformity of ZMC fractures, presenting at least 10 weeks after trauma with deformity of at least 3 mm in 1 or more dimensions causing concern to aesthetics and/or function to the patient giving consent for surgery, and follow-up exclusion criteria craniofacial anomalies pathology of ZMC bilateral ZMC posttraumatic deformities metabolic disorders of bone ZMC asymmetry due to causes other than trauma pregnant women

8. Sample calculation and randomization Formal sample not calculated 10 patients (male: female = 9:1)

9. Primary outcome: to evaluate the symmetry and stability of ZMC Secondary outcome: orbital volume changes (in cm3) correction of diplopia (number of gazes), increase in mouth opening (whether >/< 35 mm: yes/no), ocular motility (number of gazes) infraorbital paresthesia

10. Procedure

11. Anteroposterior displacement- maxillozygion and suprajugale Superoinferior displacement- frontozygomatic and orbitale points Mediolateral displacement- Jugale and Zygion

12. zygoma plane (a plane created by joining 3 points: suprajugale , maxillozygion , and zygion ) coronal plane (plane connecting porion on either side) zygoma plane coronal plane in 3D bilateral zygoma planes frankfurt plane (visible in the nasal region and it connects porion to orbitale )

13. Post-traumatic residual deformity of the left side was analyzed with respect to the uninjured right ZMC for a study patient.

14. Digital pre surgical planning was done virtual osteotomy and repositioning in relation to the mirrored half of the normal side the discrepancy in position between the injured and the uninjured ZMC the length of gaps created, the need for bone grafts (if gap >5 mm), and areas of bone removal areas of bone removal were estimated for surgical planning standard zygomatic osteotomy procedure was performed

15. Surgical approaches used: coronal, periorbital, intraoral vestibular, or preexisting scar if any. Osteotomy cuts Fracture lines or Sequence: frontozygomatic region, zygomatic arch, and infraorbital rim. The cut at the infraorbital rim was extended to meet the zygomatic buttress and the final osteotomy is made at the sphenozygomatic region

16. Steps in repositioning intraoperatively Excess bone removed from the frontozygomatic region . And temporarily fixed either with transosseous wiring or using a miniplate and just 2 screws on either side of the osteotomy to allow for minor movements discrepancy at the zygion point on the zygomatic arch is used for mediolateral alignment bone is removed at the infraorbital rim region to allow for mediolateral movement at the central portion of ZMC the amount of gaping in the zygomaticosphenoid is estimated at a particular point. zygomatic arch is reduced and fixed . The ZMC buttress is fixed. Orbital reconstruction was done by adapting the orbital mesh

17. ZMC was analyzed on MIMICS software where pre operative, immediate postoperative, and 6 months postoperative data were assessed

18. Results 10 patients male-to-female ratio of 9:1

19. Six months postoperatively , the changes were not statistically significant as all measurements had p > .05, indicating stability suggesting no/ minimal relapse

20. DISCUSSION Owing to post fracture malunion and subsequent remodeling, many of the landmarks and most notably the fracture edges are lost, such ZMC deformities make an intraoperative assessment of reduction or symmetry difficult. Hence, residual deformity cases require virtual surgical planning and quantification of the amount of deformity. There’s lack of standardisation in evaluation of ZMC

21. The ZMC analysis protocol as used in the present study measured the difference between width, height, and projection bilaterally, which also helped in the estimation of rotation of ZMC Estimation and replication of angular displacement (rotations) in ZMC are difficult. Zygoma plane helped to analyze this.

22. Why virtual planning? d/t post-traumatic disarticulation of the ZMC at the frontozygomatic region, followed by distraction osteogenesis due to the continuous pull from the masseter  excess bone deposition in the FZ region Makes it difficult to achieve postsurgical symmetry The results of this study confirm the stability after zygomatic osteotomy and fixation with miniplates in patients with post-traumatic residual deformity of the ZMC.

23. The statistically significant change between preoperative and post operative zygoma position was at landmarks where there was greater preoperative deformation. This change was highest in the mediolateral projection from the mid-sagittal plane when measured at whitnall’s tubercle and zygion point on the arch, and an anteroposterior projection at maxillozygion , and suprajugale .

24. Literature has described the plane of zygoma as rotation around the horizontal plane or vertical plane. However, any object has a possibility of movement in the 3 planes. This third plane correction is often important to obtain symmetry of the lateral wall of the orbit and the palpebral aperture. The study patients had significant improvement in orbital volume and mouth opening postoperatively. There was an improvement in ocular motility and diplopia as well, although these were insignificant statistically.

25. Bite et al found enophthalmos in several patients despite the near-normal orbital volume and concluded that this could be because of cicatricial contracture. Similar to this study, there was some enophthalmos in this study. The factors that were implicated in the instability after zygomatic osteotomy were minor gaping while repositioning, surrounding scar tissue, masseter pull while performing mouth opening, gradually re gain of the activity of masseter, inefficient hardware. The present hardware could compensate for the aforementioned factors. This also correlates with other studies. This masseteric force might be insignificant to cause instability, even at 6 months postoperatively after fixation with miniplates.

26. conclusion Zygomatic osteotomy and fixation were stable at 6 months postoperatively in this study, a long with significant improvement in mouth opening and orbital volume. Zygoma analysis method would help to quantify, understand, and communicate the symmetrical position of the zygoma and to plan perizygomatic surgeries. Help in more accurate treatment planning in treating unilateral as well as bilateral residual/congenital deformity cases and could stand as a foundation for esthetic and reconstructive surgery of ZMC if this could be applied to surgical navigation.

27. Critical evaluation

28. Positives Clear research objectives Detailed description of the surgical technique Clinically relevant

29. Negatives Small sample size Lacks a control group or a comparison to other surgical techniques Narrow demographic Doesn’t provide long-term data on the stability Does not sufficiently explore the risks associated with zygomatic osteotomy, such as infection, nerve damage, or relapse of deformity

30. Thank you!