Minimally Invasive Oral and Maxillofacial Surgery by Oded Nahlieli

Author:Oded Nahlieli
Language: eng
Format: epub
Publisher: Springer Berlin Heidelberg, Berlin, Heidelberg

Fig. 6.4The Rigid External Distractor (RED II System, KLS Martin, Tuttlingen, Germany) is anchored by pins to the parietal bone for midface and maxillary distraction

Following 4 days of latency period, bone elongation is initiated by turning the distraction rods at a rate of 1 mm a day as desired. Following a 3–4-month period of retention, the devices are removed, in case of external devices by simple unscrewing of the device screws and in case of internal devices by an additional operation under general anesthesia.

The external device RED system is uncomfortable to the child to wear for long periods is exposed to external trauma forces during that period, and there is a risk of parietal bone penetration. The RED system offers greater distraction length, permits to perform the osteotomy in a hypoplastic deficient bone, offers a control over the vector of lengthening, and is easily removed by unscrewing the pins. Internal distraction devices are fixated directly to the bone. They are safer to wear for long periods, do not create social discomfort, and therefore permit longer retention periods which may contribute to better stability than external devices. Their major disadvantage is the need for a second operation under general anesthesia for device removal [11].

The hypoplastic maxilla in cleft patients is usually associated with moderate to severe retrusion and is better treated by distraction osteogenesis than by conventional orthognathic surgery as are moderate to severe cases of midface deficiency. Maxillary orthognatic surgery has the major advantage of a single, one stage operation and is indicated in mild adult maxillary or midface deficiency when craniofacial growth has ceased. However, in moderate or severe hypoplasia or in growing patients, distraction osteogenesis has a great advantage over conventional orthognatic surgery.

Distraction osteogenesis as a treatment modality in craniofacial surgery revolutionized the treatment of midface hypoplasia characteristic of craniofacial synostotic syndromes such as Apert and Crouzon. New bone is generated in the osteotomy sites as elongation is applied. As in mandibular distraction osteogenesis, the gradual elongation and newly bone formation minimizes the resistance observed in extreme advancement and the relapse prevalence encountered in orthognatic advancement techniques. One of the main objectives of the distraction osteogenesis advancement in these patients is to establish normal size and position of the bony orbits. Timing of midface advancement is debatable, yet previous observations [32] revealed orbit growth forward between ages 8.5 and 15.5 was <4 mm thus making this procedure feasible already in childhood.

The surgical procedure includes the following steps. A coronal flap is elevated. An Osteotomy at the Le Fort III level is created and the distal fragment is downfractured. Both external and internal devices can be used. The internal distraction devices are fitted to the zygoma bilateral and then fixated. The activating pin is passed through a percutaneous cannula. After a latency period, elongation is initiated at a rate of 1 mm/day. After achieving the desired elongation, the cannula and activating pin are detached and the distraction device is left for a consolidation period. The device is then removed, in case of internal devices by a second operation [32].

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