Nager syndrome, also known as
Nager acrofacial dysostosis, was first described by Nager and de Reynier in 1948. The patients commonly present with
micrognathia, and a preventive
tracheostomy is necessary when there are symptoms of upper
airway obstruction. Mandibular
distraction osteogenesis is considered as an effective procedure, which not only improves
micrognathia but also minimizes the chances of
tracheostomy. However, mandibular
distraction osteogenesis has some complications such as relapse,
teeth injury,
infection, and injury of the temporomandibular joints (TMJs). In this study, the author reported two patients with
Nager syndrome who suffered from
ankylosis of TMJs after mandibular
distraction osteogenesis. In addition, a comprehensive literature review of post-distraction
ankylosis of TMJs in patients with
Nager syndrome was performed. Few studies demonstrated the condition of TMJs after mandibular
distraction osteogenesis, and three studies were identified from the review. One study reported
ankylosis of bilateral coronoid processes, in which coronoidectomies were necessary. Another study reported the use of
prostheses to replace the ankylosed joints in a patient who had undergone many surgeries of the joints, such as gap
arthroplasties, reconstructions with costochondral grafts, etc. One other study raised the concept of unloading the condyles during the mandibular distraction to prevent subsequent
ankylosis. It seems that multiple factors are related to the
ankylosis of TMJs after mandibular
distraction osteogenesis in patients with
Nager syndrome. Prevention of post-distraction
ankylosis of the joints is important because the treatment is difficult and not always effective. We should conduct more studies about protection of the joints during mandibular distraction in the future.