In vitro microdistraction of preosteoblasts: distraction promotes proliferation and oscillation promotes differentiation.

Osteoblast biology is influenced in vivo by a 3-dimensional (3D) extracellular matrix that mediates their adhesion and interaction and by a constant state of compressive and tensile forces. To study the role of mechanical stress on osteoblasts in vitro, these parameters must be addressed. Therefore, this study describes the use of a novel, in vitro system that subjects cells to distractive and compressive forces in a 3D environment. This system, termed a microdistractor system, was used to apply linear forces to 3D collagen type I gels containing preosteoblasts. Gels were induced for up to 16 days in osteogenic medium and subjected to either constant linear distraction (distraction gels) or to repeating cycles of distraction and compression (oscillation gels). The effect of these stresses was evaluated over time by measuring proliferation rates, protein synthesis (i.e., cellular activity), and osteogenic differentiation levels. While linear forces in general appeared to increase protein synthesis, force-specific effects on proliferation and differentiation were observed. Specifically, distraction forces appeared to enhance MC3T3 proliferation while distraction/compressive forces appeared to accelerate their osteogenic differentiation program. Therefore, these results suggest that the microdistraction system may be an appropriate in vitro system for the study of mechanobiology in osteoblast phenotype.

Case report of optic atrophy in pansynostosis: an unusual presentation of scalp edema from hair braiding.

Pansynostosis (fusion of all cranial sutures) and optic atrophy were found as incidental CT scan and ophthalmological findings in an 8-year-old who presented to the emergency room with scalp edema from tight 'cornrow' hair braiding. Cranial vault expansion was successfully performed. Ophthalmological problems have stabilized but have not reversed. Late presentation of craniosynostosis and the pathophysiology of secondary optic atrophy are discussed.

Improved malar projection with transconjunctival hydroxyapatite granules.

BACKGROUND: Augmentation of the zygomatic body enhances appearance and provides a more youthful look. Porous hydroxyapatite granules offer an alternative to alloplastic implants. METHODS: Hydroxyapatite granules were placed by means of a transconjunctival approach into subperiosteal malar pockets (n = 8). From the preoperative, postoperative, and 1-year follow-up lateral views, malar projection was measured as the right angle distance from the point of malar prominence to the nasale-subnasale line. RESULTS: Patients were either very satisfied (six of eight) or satisfied (two of eight). Malar projection was significantly improved postoperatively and was maintained after 1 year. CONCLUSION: This technique, performed for cosmetic and reconstructive indications, resulted in measurable improvement in malar projection, minimal complications, and optimal patient satisfaction.

Monobloc advancement by distraction osteogenesis decreases morbidity and relapse.

BACKGROUND: Treatment of midface hypoplasia and forehead retrusion with monobloc advancement is associated with significant complications, including meningitis, prolonged intubation, and frontal bone flap necrosis. To see whether distraction of the monobloc segment offered decreased morbidity, the authors compared clinical outcomes of patients who underwent conventional monobloc advancement with those of patients who underwent monobloc distraction. METHODS: Group 1 (conventional monobloc; n = 12) underwent traditional monobloc advancement with bone grafting. Group 2 (modified monobloc; n = 11) did not receive ventriculoperitoneal shunts and underwent the above procedures with placement of a pericranial flap and fibrin glue over the midline defect. Group 3 (monobloc distraction; n = 24) underwent advancement of the monobloc segment by distraction osteogenesis using internal distraction devices. Complications included meningitis, cerebrospinal fluid leak, frontal bone flap loss, and wound infection. Preoperative, postoperative, and follow-up lateral cephalograms were used to assess horizontal changes of the forehead, midface, and maxilla. RESULTS: Group 3 (distraction monobloc) had the lowest complication rate (8 percent), followed by groups 2 (modified monobloc; 43 percent) and 1 (conventional monobloc; 61 percent) (p < 0.05). Group 3 achieved greater advancement (12.6 mm) than did group 2 (9.4 mm) or group 1 (9.1 mm) (p < 0.05). Relapse was least in group 3 (8 percent) compared with groups 2 (67 percent) and 1 (45 percent). CONCLUSIONS: Monobloc advancement by distraction osteogenesis had less morbidity and achieved greater advancement with less relapse compared with conventional methods of acute monobloc advancement with bone grafting. Monobloc distraction is superior to conventional methods of acute monobloc advancement and is an alternative to staged fronto-orbital advancement followed by Le Fort III advancement.

Genioplasty distraction osteogenesis and hyoid advancement for correction of upper airway obstruction in patients with Treacher Collins and Nager syndromes.

BACKGROUND: Treacher Collins and Nager syndromes may present with mandibular hypoplasia that causes posterior collapse of the tongue base and a decreased oropharyngeal airway. Mandibular distraction and orthognathic advancement are effective treatments to correct the airway, but failure may occur despite achieving class I occlusion. For this select population, the authors propose a novel procedure of genioplasty distraction and hyoid advancement to optimize epiglottal positioning. METHODS: Patients diagnosed with Treacher Collins (n = 5) or Nager syndrome (n = 3) with obstructive sleep apnea or tracheostomy dependency (n = 8) underwent genioplasty distraction and hyoid advancement. Airway outcome was assessed by preoperative and 1-year follow-up comparison of (1) laryngobronchoscopy, (2) sleep studies, and (3) tracheostomy dependency. For genioplasty outcome, three groups were used: group I (distraction genioplasty, syndromic) (n = 8), group II (acute genioplasty, syndromic) (n = 7), and group III (acute genioplasty, nonsyndromic) (n = 10). Lateral cephalogram measurements were used in the preoperative, postoperative, and follow-up periods to assess horizontal and vertical advancement and relapse. RESULTS: Epiglottal position was optimized by the procedure in all patients based on direct endoscopic assessment. All five patients with obstructive sleep apnea had resolution of symptoms, and two of three patients achieved removal of their tracheostomy. Mean advancement for groups I, II, and III was 25, 14, and 8 mm, respectively. Follow-up horizontal advancement for groups I, II, and III were 18, 4, and 6 mm, respectively. Cephalometric measurements showed a horizontal relapse for groups I, II, and III of 10, 62, and 11 percent, respectively. CONCLUSIONS: Data suggest that genioplasty distraction allows for a greater advancement and decreased relapse rate than acute procedures alone; and genioplasty distraction with hyoid advancement is a useful technique for resolution of obstructive sleep apnea or to achieve tracheostomy removal in those syndromic patients who have already undergone mandibular advancement into a class I occlusion.

Improved outcomes in cleft patients with severe maxillary deficiency after Le Fort I internal distraction.

BACKGROUND: Correction of severe maxillary deficiency in cleft lip-cleft palate patients often results in undercorrection, relapse, and need for secondary corrective procedures. Le Fort I internal distraction osteogenesis offers an alternative to one-step orthognathic advancement, with advantages of gradual lengthening through scar and earlier treatment in growing patients. METHODS: Patients with cleft lip-cleft palate deformities and maxillary deficiency were divided into three groups treated by Le Fort I advancement: group 1, mild to moderate deficiency (< 10 mm) with conventional orthognathic procedure; group 2, severe deficiency (> or = 10 mm) with conventional orthognathic procedure; and group 3, distraction procedure for severe deficiency (> or = 10 mm) (n = 51). Preoperative, postoperative, and follow-up (> 1 year) lateral cephalogram measurements were compared including angular (SNA and SNB) and linear (Deltax = horizontal and Deltay = vertical) changes. The Pittsburgh Speech Score was used to assess for velopharyngeal insufficiency (score > 3). RESULTS: Results demonstrated that group 1 patients had a mean SNA change from preoperatively (78.7) to postoperatively (83.8), and a horizontal change of 5.0 mm, with no relapse. Group 2 patients had a mean SNA change from preoperatively (76.3) to postoperatively (82.0) and a horizontal change of 7.2 mm, with 63 percent relapse. Group 3 patients had a mean SNA change from preoperatively (74.1) to postoperatively (84.9) and a horizontal change of 16.5 mm, with 15 percent relapse. Thus, for severe maxillary deficiency, the distraction group had 48 percent less relapse than the conventional Le Fort I group. Postoperative speech evaluation showed velopharyngeal insufficiency in the following: group 1, four of 20 patients (20 percent); group 2, nine of 11 patients (82 percent); and group 3, nine of 20 patients (45 percent). CONCLUSION: These data suggest that Le Fort I internal distraction for severe cleft maxillary deficiency leads to better dental occlusion, less relapse, and better speech results.

Favorable morphologic change of preosteoblasts in a three-dimensional matrix with in vitro microdistraction.

BACKGROUND: Distraction osteogenesis has been used to correct hypoplastic and asymmetric bony deformities in the growing patient, yet its underlying cellular mechanisms are poorly understood. Using a new in vitro model, the microdistractor, morphologic properties of preosteoblasts under mechanical strain were studied. METHODS: Mouse calvarial MC3T3 cells were suspended in a polymerized three-dimensional collagen gel and stressed for 14 days as one of three groups (n = 30): (1) distraction (0.5 mm/day); (2) oscillation (1 mm/day for 2 days alternated with 1 mm/day for 2 days); and (3) control (no force). A computer modeling system, KS-300, was used to record cell shape (aspect ratio) and orientation (deviance from axis of stress). RESULTS: In part I of the study, morphologic cellular changes were found to be even throughout different regions of the gel (central versus peripheral, versus different vertical layers), suggesting the force was evenly applied to all cells in the gel. In addition, when linear distraction forces were applied, morphologic change occurred over time, suggesting a morphologic response to the applied stress. In part II of the study, with different forces applied, morphologic changes occurred over time such that linear distraction forces caused cells to elongate and align in a parallel direction to the force, whereas oscillation caused cells to switch from parallel (with distraction) to perpendicular (with compression) orientation relative to the force applied. CONCLUSION: The authors' data suggest that the microdistractor device is an effective in vitro model for studying the cellular response to distraction stresses. It may be used in future studies to optimize clinical methods of distraction.

The K stitch for hypertelorbitism: improved soft tissue correction with glabellar width reduction.

After correction of moderate to severe hypertelorbitism (greater than 40 mm interdacryon distance) with facial bipartition or orbital box osteotomy, excess glabellar soft tissue and brow width should be addressed. Traditional methods described used a midline excision down the forehead and nasal dorsum, and left an unsightly scar. With a series of 12 patients, the authors document the K stitch technique with no external vertical scar. A mean 38.8% reduction of interbrow distance was noted using this technique. Two patients underwent revisions, and two patients had temporary eyelid ptosis. All patients reported satisfaction once the skin contracture was completed.

Improved nasal tip projection in the treatment of bilateral cleft nasal deformity.

The cleft nose deformity in bilateral cleft lip and palate patients with severely flattened alar cartilages, a short, scarred columella, and thickened skin is a reconstructive challenge. The Wolfe double-arch tip rhinoplasty technique was compared with a cartilage release and tip grafting technique to determine the optimal modality for tip projection and columella lengthening. Patients with significant bilateral cleft nasal deformities and previous bilateral cleft lip repairs were divided into two groups (n = 22). Group 1 (double-arch) patients underwent an open rhinoplasty using conchal cartilage grafts to create a columellar strut and new lower lateral arches placed over the existing arches (n = 12). In group 2 (release and tip graft), the lower lateral cartilages were released, and nasal tip grafting was performed (n = 10). Preoperative and 6-month postoperative measurements, including (1) columellar length, (2) alar base-nasal tip-columellar base (ATC) angle, and (3) lateral tip projection, were compared. The lateral tip projection is the perpendicular distance between the nasal tip and a line created from the connection of points at the nasion to the subnasale. In group 1 (double arch), the mean columella length increased 47.2%, whereas in group 2 (release and tip graft), it only increased 14.1%. The ATC angle had a mean decrease or narrowing of 26.7 degrees in group 1, compared with a 12.5 degrees decrease in group 2. Lateral tip projection improvement was greater in group 1 (52.2% increase) compared with group 2 (19.9% increase). The authors' data showed that for the difficult bilateral cleft nasal deformity with significant tip flattening, the double-arch tip rhinoplasty provides improved nasal tip projection.