Midface distraction osteogenesis: Internal vs. external devices


This study compares internal and external distraction devices in the treatment of midface retrusion. 20 patients were treated with midface distraction (12 Crouzon, 4 Apert, 4 others); 12 with internal distraction (MID device), 8 with external distraction (Red or Blue device). The two groups were compared regarding operation time, peroperative blood loss and complications. The groups were comparable regarding patient age, sex, weight and diagnosis. In the MID-group, 7 of 12 patients (58%) underwent Le Fort III, 5 underwent 12 monobloc (32%). In the Blue device group, three of eight patients underwent Le Fort II (38%), three of eight underwent Le Fort III (38%), and two of eight underwent monobloc (25%). Operation time was shorter in the Blue device (mean 298 min) than in the MID group (mean 354 min). Peroperative blood loss and complication rates were similar. The internal distraction device is the ‘gold standard’ for treating midface retrusion. The use of an external distraction device in midface distraction osteogenesis is associated with a shorter operation time; peroperative blood loss and complications were similar. An external device affords better 3-dimensional control during the distraction process, so external distraction is preferable in patients who will tolerate this treatment.

Treatment of the hypoplastic midface in syndromic craniosynostosis remains a challenge, from a functional and an aesthetic point of view. Several surgical techniques have been developed to advance the midface, including the Le Fort II, the Le Fort III and monobloc osteotomies. Skeletal advancements using traditional surgical techniques were often inadequate , necessitating numerous reoperations . With the advent of craniomaxillofacial distraction osteogenesis , significantly larger and safer skeletal advancements were allowed, leading to several studies on midface distraction at the Le Fort III level and at the monobloc level .

The distraction apparatus can consist of an internalized push-screw device, as developed by C ohen et al. in 1995 ( Fig. 1 A and B ), an external halo-frame-based pulling device, as developed by P olley & F igueroa in 1997 ( Fig. 1 C and D), or an internal distraction spring or coil, as developed by L auritzen et al. in 1998 . Each system has its pros and cons.

Fig. 1
Clinical photo (A) and 3D CT (B) of patient with Crouzon’s syndrome undergoing Le Fort III midface distraction osteogenesis with an internal device. Clinical photo (C) and 3D CT (D) of patient with Crouzon’s syndrome undergoing monobloc midface distraction osteogenesis with an external device.

The potential benefits of internal devices include: elimination of skin scarring caused by translation of transcutaneous fixation pins; improved patient compliance during the consolidation phase; and improved stability of the attachment of the device to the bone . The major drawbacks are: the need for precise positioning of the device, regarding alignment between the two sides and the angulation, which can be challenging in patients with numerous previous operations and subsequent cranial thinnings or deficiencies; the inability to alter the distraction vector during the distraction process; and the need for a second major operation to remove the device, although this can be overcome by using biodegradable devices .

The potential benefits of external devices include: unsurpassed three dimensional (3D) control during distraction; the ability to alter the distraction vector during the process; and the avoidance of major resurgery for device removal after the consolidation phase. The major drawbacks are: skin scarring caused by translation of transcutaneous fixation pins and/or skin infections around the pins ; pin loosening ; the need for patient compliance during the consolidation phase; and intracranial pin migration, either accidental or gradual .

The authors compared the clinical outcomes of patients who underwent midface distraction osteogenesis using either an internal or an external device in the treatment of syndromal midface retrusion.

Patients and methods

20 subjects with syndromal midface retrusion underwent distraction osteogenesis between October 1999 and September 2007, some of whom have been reported previously . There were 9 male and 11 female patients with a median age of 11.3 years (range 1.4–25.0 years) ( Table 1 ). Five patients had Apert’s syndrome, 12 had Crouzon’s syndrome and four had other craniofacial syndromes.

Table 1
Patient characteristics.
Internal device External device
Number 12 8
Sex (male/female) 6/6 3/5
Age (mean, range) 10.2 years, 1.4–16.8 14.3 years, 6.2–25.0
Weight (mean, range) 33.7 kg, 9.0–67.5 40.3 kg, 14.3–60.0
Previous CF-operations (mean, range) 3.9, 1–8 2.0, 0–8
Apert (number, percent) 2, 17% 2, 25%
Crouzon (number, percent) 9, 75% 3, 38%
Other (number, percent) 1, 8% 3, 38%

Abbreviations : CF, craniofacial.

Most patients were complex cases and had undergone several previous craniofacial surgeries (mean 3.2, range 0–8), including previous monobloc osteotomy in one patient, Le Fort III surgery in 4 patients and fronto-orbital advancements in 15, as well as miscellaneous craniectomies ( Table 1 ). 12 patients had undergone shunt surgery for hydrocephalus (60%).

Nine patients had mental development within the normal range, nine had mild mental retardation, and two had severe retardation. In the severely mentally retarded patients, the indications for surgery were severe exophthalmos and severe airway obstruction. The remaining patients had combinations of moderate-to-severe midface deficiency presenting as retrusion associated with Angle’s class III malocclusion.

Seven patients underwent monobloc distraction, seven had Le Fort III distraction only, three had Le Fort III distraction in combination with an acute fronto-orbital advancement, and three had Le Fort II distraction ( Table 2 ).

Table 2
Length of operation, peroperative blood loss, relative peroperative blood loss, time on mechanical ventilator postoperatively, time on PICU, length of postoperative use of antibiotics, length of hospital stay, length of midface distraction, effect of operation, and complications of patients treated with midface distraction.
Internal device External device
Number pts 12 8
Operation type
Monobloc 5 2
LeFort III 5 2
LeFort III + acute frontoorbital 2 1
LeFort II 0 3
Length of operation (mean, range) 354 min, 240–535 298 min, 210–420
Peroperative blood loss (mean, range) 1383 ml, 280–2700 1388 ml, 0–4000
Peroperative blood loss (mean, range) 53 ml/kg, 8–121 40 ml/kg, 0–90
Time on ventilator postop. (mean, range) 48 h, 0–144 23 h, 0–36
Time on PICU (mean, range) 3 days, 1–7 2 days, 1–4
Length of antibiotics-use postop. (mean, range) 13 days, 2–35 16 days, 5–53
Length of hospital stay (mean, range) 27 days, 16–38 27 days, 12–41
Distraction distance (mean, range) 24 mm, 15–30 19 mm, 14–28
Consolidation (mean, range) 143 days, 88–188 118 days, 21–218
Reoperation 6 pts 2 pts
Local wound infection 4 pts 3 pts
Subcutaneous infection 1 pts 1 pts
Ostemyelitis 0 pts 0 pts
CSF leak 0 pts 0 pts
Pin readjustments under GA 0 pts 4 pts

Abbreviations : PICU, pediatric intensive care unit; Pts, patients; GA, general anaestesia.

The patients were operated on by the Norwegian craniofacial team. A Le Fort II ( Fig. 2 A) , Le Fort III ( Fig. 2 B) or monobloc osteotomy ( Fig. 2 C) was performed in the standard fashion and craniofacial disjunction was undertaken.

Feb 7, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Midface distraction osteogenesis: Internal vs. external devices
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