The role of the Frankfurt Plane in treatment planning and prognosis for patients with unilateral temporomandibular joint ankylosis developed in early childhood

Relevance. The treatment of unilateral temporomandibular joint (TMJ) ankylosis remains a significant challenge. Children who develop unilateral ankylosis in early childhood frequently exhibit pronounced craniofacial asymmetry. Accordingly, assessing the extent of asymmetry between the left and right sides of the skull, the positional discrepancy of the auditory canals, and the inclination of the Frankfurt plane is crucial for planning future analyses and reconstructing the TMJ fossa during total joint replacement.

Objective. To determine the difference in the Frankfurt plane inclination angle in patients with unilateral TMJ ankylosis that developed in early childhood.

Materials and methods. The study included 38 patients (18 boys and 20 girls) aged 13 to 19 years with unilateral TMJ ankylosis diagnosed between the ages of 1 and 6. All patients underwent head computed tomography (CT), followed by cranial rotation analysis using specialized software to align with the natural head posture. Measurements of cephalometric landmarks Porion (Por) and Orbitale (Or) on both sides of the skull were performed, and the inclination of the Frankfurt plane was assessed using Jacobson 3D digital analysis tools.

Results. CT analysis of 38 patients with unilateral TMJ ankylosis, diagnosed between the ages of 1 and 6, revealed a consistent pattern in the position of the auditory canal and adjacent structures. The Porion on the ankylosed side was, on average, 5.74 mm lower than on the contralateral side. Furthermore, the mean inclination angle of the Frankfurt plane on the ankylosed side exceeded the normal range, averaging 5.48°, while the angle on the contralateral side remained within normal limits (0–3°).

Conclusion. The difference in Frankfurt plane inclination observed in 87% of patients with unilateral TMJ ankylosis developed in early childhood should be taken into account when planning treatment, designing total TMJ prostheses, and forecasting clinical outcomes for this patient population.

1. Kaban LB, Perrott DH, Fisher K. A protocol for management of temporomandibular joint ankylosis. J Oral Maxillofac Surg. 1990;48(11):1145-51; discussion 1152. doi: 10.1016/0278-2391(90)90529-b

2. el-Sheikh MM. Temporomandibular joint ankylosis: the Egyptian experience. Ann R Coll Surg Engl. 1999;81(1):12-18. Available from: https://pubmed.ncbi.nlm.nih.gov/10325678/

3. McFadden LR, Rishiraj B. Treatment of temporomandibular joint ankylosis: a case report. J Can Dent Assoc. 2001;67(11):659-63. Available from: https://pubmed.ncbi.nlm.nih.gov/11841743/

4. Epifanov SA, Shtempel MS, Zangieva OT, Fedotov RN, Vyselceva UV, Shomin EA. Total temporomandibular joint replacement in TMJ ankylosis. Bulletin of Pirogov National Medical & Surgical Center. 2022;17(1):9-15 (In Russ.). doi: 10.25881/20728255_2022_17_1_9

5. Zangieva OT, Fedotov PH, Stamp MS, Shomin EA, Topolnitsky OZ, Epifanov SA. Characteristics of rehabilitation for patients with severe asymmetric jaw deformities resulting from temporomandibular joint pathology. Pediatric dentistry and dental prophylaxis. 2024; 24(2):125–132 (In Russ.). doi: 10.33925/1683-3031-2024-768

6. Ahmad M, Hollender L, Anderson Q, Kartha K, Ohrbach R, Truelove EL, et al. Research diagnostic criteria for temporomandibular disorders (RDC/TMD): development of image analysis criteria and examiner reliability for image analysis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009;107(6):844-60. doi: 10.1016/j.tripleo.2009.02.023

7. Wojczyńska A, Gallo LM, Bredell M, Leiggener CS. Alterations of mandibular movement patterns after total joint replacement: a case series of long-term outcomes in patients with total alloplastic temporomandibular joint reconstructions. Int J Oral Maxillofac Surg. 2019;48(2):225-232. doi: 10.1016/j.ijom.2018.06.005

8. van Loon JP, Otten E, Falkenström CH, de Bont LG, Verkerke GJ. Loading of a unilateral temporomandibular joint prosthesis: a three-dimensional mathematical study. J. Dent. Res. 1998; 77(11):1939–1947. doi: 10.1177/00220345980770111201.

9. Brown ZL, Sarrami S, Perez DE. Will they fit? Determinants of the adaptability of stock TMJ prostheses where custom TMJ prostheses were utilized. Int J Oral Maxillofac Surg. 2021;50(2):220-226. doi: 10.1016/j.ijom.2020.05.009

10. Wojczyńska A, Leiggener CS, Bredell M, Ettlin DA, Erni S, Gallo LM, et al. Alloplastic total temporomandibular joint replacements: Do they perform like natural joints? Prospective cohort study with a historical control. Int. J. Oral Maxillofac. Surg. 2016;45(10):1213–1221. doi: 10.1016/j.ijom.2016.04.022

11. Chen X. The instantaneous center of rotation during human jaw opening and its significance in interpreting the functional meaning of condylar translation. Am. J. Phys. Anthropol. 1998;106(1):35–46. doi: 10.1002/(SICI)1096-8644(199805)106:1<35::AID-AJPA3>3.0.CO;2-C

12. Leader JK, Boston JR, Debski RE, Rudy TE. Mandibular kinematics represented by a non-orthogonal floating axis joint coordinate system. J. Biomech. 2003;36(2):275–281. doi: 10.1016/S0021-9290(02)00337-8

13. Leiggener CS, Erni S, Gallo LM. Novel approach to the study of jaw kinematics in an alloplastic TMJ reconstruction. Int. J. Oral Maxillofac. Surg. 2012;41(9):1041–1045. doi: 10.1016/j.ijom.2012.06.014

14. Chen CC, Lin CC, Hsieh HP, Fu YC, Chen YJ, Lu TW. In vivo three-dimensional mandibular kinematics and functional point trajectories during temporomandibular activities using 3d fluoroscopy. Dentomaxillofac. Radiol. 2021;50(2):20190464. doi: 10.1259/dmfr.20190464

15. Merema BBJ, Witjes MJH, Van Bakelen NB, Kraeima J, Spijkervet FKL. Four-Dimensional Determination of the Patient-Specific Centre of Rotation for Total Temporomandibular Joint Replacements: Following the Groningen Principle. J Pers Med. 2022;12(9):1439. doi: 10.3390/jpm12091439