Craniofacial Anomalies, Part 2 - Plastic Surgery Internal

inconvenience to the patient and the cutaneous scars.
The intraoral device was more socially acceptable
and left no visible scars, but there was loss of vector
control and a second procedure was required to
remove the device.
Polley 484 reported on an external halo-mounted
device for midfacial monobloc DO in a newborn.
Chin and Toth 464 and Cohen 486 developed internal
devices for midface advancement (Fig 30), citing
the advantage of patient convenience;
Cohen’s 486,487 device was resorbable to eliminate
the need for a removal procedure. Motor-driven
distraction devices have also been reported. 488
External devices are most commonly used in the
midface. 489
Fig 30. Patient with repaired cleft lip and severe midfacial
hypoplasia. A, B, before distraction. Middle, patient fitted with
rigid external distraction apparatus for correction of midfacial
deficiency. C, D, after maxillary distraction. (Reprinted with
permission from Polley JW, Figueroa AA, Kidd M: Priciples of
Distraction Osteogenesis in Craniofacial Surgery. In: Lin KY,
Ogle RC, Jane JA (eds), Craniofacial Surgery. Science and
Surgical Technique. Philadelphia, WB Saunders, 2002; Ch 11,
pp 163-171.)
Craniofacial Distraction
SRPS Volume 10, Number 17, Part 2
Mandible
McCarthy’s protocol for mandibular distraction is
based on patient age and type of mandibular deformity,
as follows: 461
Under 2 years – DO of the mandible is not indicated
Age 2-6 years –
Pruzansky Type I – orthognathic surgery including
DO are deferred until adolescence490,491 Pruzansky Type I (severe) and Type II –
DO is indicated
Pruzansky Type III – Stage I: costochondral rib
graft at age 3-4 yrs; if absent, the glenoid is
reconstructed with a rib graft and fixed to
the zygoma. Stage II: DO of the rib graft at
6 months postinsertion of costochondral rib
graft
Age 6-teenager – primary DO is considered if no
previous treatment. Secondary DO is
considered in patients with significant deformity
after rib grafting.
Teenager – surgery is postponed until skeletal maturity
is reached.
Post skeletal maturation – minimal deformities are
best treated with classic orthognathic surgery. 492
Mandibular distraction should be considered in
patients with moderate to severe deformity and
bilateral disease. 493
McCormick and colleagues 494,495 investigated the
effect of osteodistraction on the temporomandibular
joint (TMJ), first in a canine model and then in human
subjects. Compression on the cartilaginous portion
of the condylar head has been shown to be detrimental
to subsequent TMJ morphology and function,
496–498 yet in this series initial condylar flattening
was transient and completely reversible. In fact, bone
distraction appears to improve the temporomandibular
joint. 499 When properly applied, the distraction
forces pull the mandible in a downward and forward
direction, leading to new bone deposition along
the posterior aspect of the mandible and resorption
along the anterior ramus region. 500 The overall conclusion
of these studies was that distraction was beneficial
to the TMJ complex.
Speech before and after mandibular DO was
assessed by Guyette et al, 501 who report worse
articulation and nasal resonance post-distraction.
These changes were temporary, however, and in
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