Various developmental disorders of the human skull result in craniofacial abnormalities in which certain bones fail to grow in proper proportion to other bones, or in which certain bones fuse prematurely, causing malformation of the mid-face or mandible. For example, one disorder, Pierre Robin Sequence (PRS) is a complex condition in which infants are born with a micrognathic and/or retrognathic mandible that causes glossoptosis, resulting in respiratory distress. Mandibular distraction is a treatment option, in which the mandible is advanced anteriorly, thereby pulling the tongue forward and opening up the airway.
A chief complaint among surgeons who use internal mandible distractors to treat infants with certain disorders such as PRS is that some distractors require a second surgical procedure for removal. The removal procedure is difficult for several reasons: (1) the locations of the footplates change during the course of treatment making them difficult to access through the same incision that was used for distractor implementation, and (2) soft and hard tissue grows over the bone screws during treatment making it difficult to engage the screwdriver blade into the screw recess for removal.
Distractors that use resorbable footplates have been used to avoid the second surgical procedure, however, there have been complaints with the current distractors that are used. For example, one distractor consists of a metallic drive screw with a metallic activation extension that engages two resorbable footplates, and can be detached by externally reversing the metallic drive screw at the end of the consolidation phase and removing it through the percutaneous activation port. Such a distractor has reportedly had problems with strength and bone segment stability.
USPTO Backgrounds
USPTO Backgrounds