## 3 Discussion
There is no standardized protocol for the management of TMJ ankylosis, and even less so in pediatric patients. Thanks to scientific advances in materials since 1990s, alloplastic temporomandibular joint replacement has begun to represent a viable option for multiple-operated patients with distorted TMJ anatomy or severe anatomical discrepancies involving the TMJ and recurrent ankylosis. The application of alloplastic TMJ prosthesis has been extensively reported in the adults, but their use in skeletally immature patients is controversial. The main concern regards the interference with the physiological mandible growth process, resulting in an impaired functionality and abnormal shape due to the presence of screws tightened on the mandibular angle which oppose resistance on the downward growth of the mandible ramus [33]. However, reestablishing a correct functionality of the stomatognathic system is essential to drive the correct growth of the maxilla and prevent abnormalities in the occlusal plane. It is well acknowledged that hypoplasia of the affected mandibular side might also result in an asymmetrical growth pattern of the corresponding half of the maxilla. Moreover, the affected side also negatively conditions the development of musculature, resulting in the atrophy of the masseter and the internal pterygoid muscles, which are less stretchable and more fibrotic. Therefore, in the absence of a correct restoration of symmetry and function, the subsequent surgery would bear a substantially higher risk of failure owing to the tendency of muscles to relapse and midface asymmetry which would likely require orthognathic surgery as well, not to mention the psychosocial and emotional implications that the missed restoration of facial harmony and function would have on the child patient [34]. In order to minimize the risk of re-ankylosis, an ipsilateral coronoidectomy was planned at the same time as the alloplastic TMJ replacement, as described by [PERSON] et al. [35]. Prostheses are designed based on the final occlusion of the patient, which is virtually determined, therefore virtual surgical planning allows the tailoring of the shape and position of implants on the correct occlusal relationship. Surgical guides are a useful tool to replicate the desired position of prostheses in the real patient, thanks to their strict adherence to the patient's anatomy and their ability to provide predrilled holes and an \"installation socket\", which further enhances accuracy of placement [35]. Naturally, the major concern regards the need to ensure the patient is a viable candidate for at least one further surgery, considering both the physiological growth of the patient and the potential lifespan of these devices. [PERSON] et al. suggested three potential solutions for the future surgical revision: (1) Replace the whole prosthesis, or just one of its components, with one of adequate dimensions; (2) A ramus orthognathic procedure, considering that the ramus component of the TMJ total joint replacement device, especially those which are patient-fitted, are fixed posterior to the mandibular foramen; (3) Osteodistraction using the ramus component as one of the legs of the distraction device [36; 37]. Adequate physiotherapy and regular follow-up play a leading role in patient follow-up and allow for the detection of any complications related to the first intervention. Furthermore, a careful follow-up of the patient allows the establishment of the correct timing for the second surgery, and the evaluation of when the patient is ready.