title: Long-Term Symptoms Onset and Heterotopic Bone Formation around a Total Temporomandibular Joint Prosthesis: a Case Report.
abstract: BACKGROUND
  The literature on total alloplastic temporomandibular joint (TMJ) reconstructions is encouraging, and studies on total alloplastic TMJ replacements outcomes showed acceptable improvements in terms of both pain levels and jaw function. Nevertheless, some adverse events, such as heterotopic bone formation around the implanted prosthesis, may occur. In consideration of that, the present manuscript describes a case of heterotopic bone formation around a total temporomandibular joint prosthesis, which occurred several years after the implant.
  
  
  METHODS
  The present manuscript describes a case of heterotopic bone formation around a total TMJ prosthesis, which occurred several years after the implant in patients, who previously underwent multiple failed TMJ surgeries.
  
  
  RESULTS
  Ten years after the surgical TMJ replacement to solve an ankylotic bone block, the patient came to our attention again referring a progressive limitation in mouth opening. A computerized tomography showed evidence of marked heterotopic bone formation in the medial aspects of the joint, where a new-born ankylotic block occupied most part of the gap created by resecting the coronoid process at the time of the TMJ prosthesis insertion.
  
  
  CONCLUSIONS
  Despite this adverse event has been sometimes described in the literature, this is the first case in which its occurrence happened several years after the temporomandibular joint replacement. It can be suggested that an accurate assessment of pre-operative risk factors for re-ankylosis (e.g., patients with multiple failed temporomandibular joint surgeries) and within-intervention prevention (e.g., strategies to keep the bone interfaces around the implant separated) should be better standardized and define in future studies.
authors.affiliation: Department of Maxillofacial Surgery, University of Padova Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Guarda-Nardini
authors.affiliation: Department of Maxillofacial Surgery, University of Padova Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Manfredini
authors.affiliation: Department of Maxillofacial Surgery, University of Padova Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Olivo
authors.affiliation: Department of Maxillofacial Surgery, University of Padova Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ferronato
keywords: ankylosis; heterotopic ossification; temporomandibular joint; temporomandibular joint disc; temporomandibular joint disorders.