Trans-mastoid anchorage as a novelty in glenoid fossa reconstruction for hemifacial microsomia with agenesis of zygomatic arch and external acoustic meatus-Technical note with a case illustration.

Total joint reconstruction (TJR) has become the most preferred method of reconstruction in recent years for hemifacial microsomia (HFM). This requires meticulous planning for the glenoid fossa and ramus prosthesis along with the arch in certain indications. TJR in a type V HFM is extremely challenging due to agenesis/hypolasia of the zygoma and arch which compromises anchorage of the glenoid prosthesis. Conventional options used for such indications incorporate extended designs for the fossa. However, the two designs used commonly are associated with limitations; (i) the temporal extension is overtly large and cannot be anchored in patients with thin temporal bone and (ii) the glenoid fossa incorporated into the arch prosthesis, where the fossa is not positioned on stable bone and occlusal loading is non-physiological; transmitted onto the arch prosthesis rather than the skull base. The authors propose the use of the mastoid process as an alternative for anchorage of fossa prosthesis. This technique offers stable anchorage while facilitating ideal positioning on the skull base for optimal masticatory load transmission. The case illustration depicts reconstruction of the TMJ, zygoma and the zygomatic arch in a 31-year-old man with type V HFM, with a three-year follow-up, with good clinical outcomes sans complications.