Reconstruction of a Severe Maxillofacial Deformity After Tumorectomy and Irradiation Using Distraction Osteogenesis and LeFort I Osteotomy Before Vascularized Bone Graft

Enhancement of BMP-2 and VEGF carried by mineralized collagen for mandibular bone regeneration

Repairing damage in the craniofacial skeleton is challenging. Craniofacial bones require intramembranous ossification to generate tissue-engineered bone grafts via angiogenesis and osteogenesis. Here, we designed a mineralized collagen delivery system for BMP-2 and vascular endothelial growth factor (VEGF) for implantation into animal models of mandibular defects. BMP-2/VEGF were mixed with mineralized collagen which was implanted into the rabbit mandibular. Animals were divided into (i) controls with no growth factors; (ii) BMP-2 alone; or (iii) BMP-2 and VEGF combined. CT and hisomputed tomography and histological staining were performed to assess bone repair. New bone formation was higher in BMP-2 and BMP-2-VEGF groups in which angiogenesis and osteogenesis were enhanced. This highlights the use of mineralized collagen with BMP-2/VEGF as an effective alternative for bone regeneration.

Is Distraction Osteogenesis of the Irradiated Craniofacial Skeleton Contraindicated?

BACKGROUND

Craniofacial distraction osteogenesis (DO) is a common treatment modality today. Despite its numerous advantages, however, concerns have been expressed regarding the use of DO in the irradiated setting.

METHODS

A systematic review was performed to identify all published reports of patients who underwent DO of the irradiated craniofacial skeleton. The following parameters were of particular interest: postoperative complications, specifically, insufficient bone formation, fracture, and hardware exposure (intraoral and cutaneous), as well as the need for additional bone grafting.

RESULTS

The initial search retrieved a total of 183 articles of which 20 articles (38 patients) met predetermined inclusion criteria. The most common site of distraction was the mandible (76.3%). The median radiation dose was 50.7 Gy (range, 30-70 Gy). Bone defects ranged from 30 to 80 mm (median, 42.5 mm). Complications were encountered in 19 patients (50%), with insufficient bone formation being most common (9 patients; 23%). The overall incidence of complications was not significantly associated with radiation dosage (P = 0.79). The remaining procedural and demographic variables also failed to meet statistical significance when compared against the overall complication rate (P = 0.27-0.97).

CONCLUSION

The complication rate associated with craniofacial DO of the irradiated skeleton does not appear to be substantially higher than what is reported for DO in the nonirradiated setting. As such, patients should be offered this treatment modality, particularly in light of the fact, that it offers the option to decrease patient morbidity as well as treatment complexity.

Treatment of irradiated mandibles with mesenchymal stem cells transfected with bone morphogenetic protein 2/7

PURPOSE

The study aimed to evaluate whether mesenchymal stem cells transfected with bone morphogenetic protein (BMP) 2/7 could increase bone regeneration after radiotherapy using a rabbit model of mandibular distraction osteogenesis.

MATERIALS AND METHODS

Twelve rabbits were randomly assigned to the sham control, radiotherapy control, nontransfected mesenchymal stem cells (MSCs), and MSCs transfected with BMP-2/7 groups. All rabbits, except those in the sham control group, received preoperative radiation of 9 Gy for 5 fractions. One month after radiotherapy, all rabbits underwent unilateral mandibular distraction at a rate of 0.9 mm/d for 11 days. At the end of active distraction, MSCs combined with bovine collagen were injected into the distraction zone. After 4 weeks of consolidation, the mandibular samples were collected and subjected to radiographic, microcomputed tomographic, and histologic examinations.

RESULTS

By radiographic examination, animals injected with nontransfected MSCs or MSCs encoding BMP-2/7 exhibited more bone formation than the control groups. Histologic examination showed that the group with MSCs encoding BMP-2/7 had a more mature medullary cavity than the nontransfected MSCs group.

CONCLUSIONS

MSCs encoding BMP-2/7 can increase bone healing in irradiated mandibular bone.

A low-grade myofibroblastic sarcoma in the abdominal cavity

Background

Rhabdomyosarcoma is the most common malignant tumor in the nasal and paranasal sinus area at childhood. Multimodal treatment for this disorder has severe side effects due to normal tissue damage. As a result of this treatment, facial growth retardation and oral abnormalities such as malformation of teeth and microstomia can cause esthetic and functional problems.

Case reports

Two cases are presented of patients with severe midfacial hypoplasia and reduced oral function as a result of treatment of rhabdomyosarcoma of the nasopharyngeal and nasal–tonsil region. With a combined surgical (osteotomy, distraction osteogenesis, implants) and prosthetic (implant-based overdenture) treatment, esthetics and function were improved.

Effect of icariin on bone formation during distraction osteogenesis in the rabbit mandible

The aim of this study was to evaluate the effect of icariin on bone formation during mandibular distraction. 40 Rabbits were randomly divided into experimental and control groups. Mandibular distraction was performed 5 days after unilateral mandibular osteotomy using a custom-made external distractor at a rate of 0.5mm/12h for 10 days. From the first day of distraction, icariin (2.5mg/kg · day) was orally administered to the experimental group and placebo to the controls. 10 Rabbits were killed at the end of weeks 2 and 4 of the consolidation phase. The distracted hemimandible was harvested and newly formed bone was evaluated by soft radiography, histology and bone histomorphometry. Regenerated bone was evaluated for bone mineral density by dual-energy X-ray absorptiometry. The experimental group had fewer radiolucent areas on soft radiography. Bone mineral density of regenerated bone was higher in the experimental than in the control group at 2 and 4 weeks. At 4 weeks, the experimental group had greater volumes of new bone, higher trabecular number, and less trabecular separation than the controls. Oral administration of icariin could promote bone formation during mandibular distraction osteogenesis and might be a promising method for shortening the course of distraction osteogenesis.