Distraction rate and latency: factors in the outcome of paediatric maxillary distraction

Summary 

Background/purpose

Over 50 years ago, current tenets of distraction osteogenesis were developed through work on the lower extremity; however, the application of these tenets in the paediatric craniofacial skeleton remains questionable.

Prompted by recent concern that traditional aspects of distraction may be either outdated or wholly inapplicable to the paediatric maxilla, we retrospectively evaluated maxillary distraction protocol using a 24-h latency period in conjunction with a distraction rate of 2mm/day.

Methods

Following maxillary advancement via a distraction protocol consisting of a 24-h latency period and a distraction rate of 2mm/day, seven consecutive paediatric cases were evaluated. Standard profile photos and cephalometric films taken preoperatively, at device removal and at 1-year follow-up were compared. With the sella as the point of registration, pre- and post-distraction films were superimposed on the sella–nasion plane. Sella–nasion–subspinale, the angle of convexity, the distance from incisal edges to the y-axis, and angulation of the upper incisor to the sella–nasion plane were analysed to evaluate hard-tissue changes.

Results

Patient age ranged from 3 to 14 years (mean=7.43 years). Maxillary distraction length averaged 11mm (range=10–12mm). Interval from device application to removal averaged 98 days (range=75–180 days). The interval of the active distraction ranged from 11 to 65 days (mean=24 days). From distraction completion to device removal averaged 85 days (range=60–150). Follow-up intervals ranged from 52 to 24 months (mean=34 months). All patients demonstrated substantial clinical advancement of the maxilla with correction of midfacial deficiencies. A single patient developed mild cellulitis at one skin–device interface; no other complications were noted. Cephalometric and clinical evaluations at 1 year post-distraction demonstrated stable results, and parental satisfaction was qualitatively high.

Conclusions

The surgical dogma of lower-extremity distraction osteogenesis is not absolute and may not be optimal for use in the paediatric maxilla. Our results demonstrate effective maxillary correction following application of a 24-h latency period coupled with rapid distraction at 2mm/day. Our success with a short latency period and more rapid device expanse may be a product of the significant vascularity and improved healing potential of the paediatric maxilla.

Keywords: Distraction, Rate, Latency, Maxillary distraction