Ortho- and heterotopic bone grafts in bifocal transport osteogenesis for craniofacial reconstruction--an experimental study in sheep

An overview of de novo bone generation in animal models

Some of the earliest success in de novo tissue generation was in bone tissue, and advances, facilitated by the use of endogenous and exogenous progenitor cells, continue unabated. The concept of one health promotes shared discoveries among medical disciplines to overcome health challenges that afflict numerous species. Carefully selected animal models are vital to development and translation of targeted therapies that improve the health and well-being of humans and animals alike. While inherent differences among species limit direct translation of scientific knowledge between them, rapid progress in ex vivo and in vivo de novo tissue generation is propelling revolutionary innovation to reality among all musculoskeletal specialties. This review contains a comparison of bone deposition among species and descriptions of animal models of bone restoration designed to replicate a multitude of bone injuries and pathology, including impaired osteogenic capacity.

Transport distraction osteogenesis with recombinant human bone morphogenic protein-2 for large calvarial defect reconstruction

BACKGROUND

Transport distraction osteogenesis (TDO) has been used in attempts to treat large calvarial defects but has, until now, lacked consistency and reliability. To achieve sufficient bone formation, the effect of TDO was compared to the effect of TDO combined with recombinant human bone morphogenic protein-2 (rhBMP-2).

METHODS

Fourteen dogs were divided into 2 groups; 6 animals in the control group received TDO only, and 8 received TDO combined with rhBMP-2. A calvarial defect 33 × 35 mm in size was generated, and the drug-delivering internal distractor was applied. After a 5-day latency period, distraction with rhBMP-2 at 10 μg/day was initiated at a rate of 2 mm/day. This was followed by a consolidation period of 3 months, after which areas of osteogenesis and strength were measured and histologic examinations were conducted.

RESULTS

The average area of osteogenesis was higher in the experimental group (P < 0.01). Regenerated bone of the experimental group showed increased strength (P < 0.05). Histological examination showed typical mature bone in the experimental group. Prominent osteoblastic rimming was observed in the bone marrow of the experimental group.

CONCLUSIONS

TDO with an internal distraction device delivering rhBMP-2 can enhance bone regeneration of large calvarial defects in a dog model. These results suggest the potential for human clinical testing of TDO combined with rhBMP-2.

Trifocal distraction osteogenesis for reconstruction of skull defect

OBJECTIVE

To apply trifocal distraction osteogenesis in canine model of skull segmental defects and to provide reference for clinical treatment.

METHODS

Six labrador dogs were selected in this study and divided into observation group and control group randomly. Each group contained 3 dogs. Skull segmental defects models were established by surgery, and dogs in bservation group received trifocal distraction osteogenesis treatment. Bone density was observed and compared between two groups during treatment.

RESULTS

There were no significant difference in bone density between two groups on th 1st day (P>0.05). The bone density of observation group on the 30th day, and 60th day were higher than that of control group (P<0.01).

CONCLUSIONS

Trifocal distraction osteogenesis has significant clinical effect, and it would be widely used in clinical treatment.

Trifocal biplanar distraction-compression osteosynthesis: a new method for three-dimensional reconstruction of the calvarial defects

Surgical treatment of calvarial defects and deformities has some drawbacks such as donor site morbidity or use of allogenic materials. In this experimental study, we presented a three-dimensional reconstruction of cranial defects by using trifocal biplanar distraction-compression osteosynthesis (TBDCO).Eight sheep with a mean age of 2 years were divided into 2 groups as the control (n = 3) and distraction groups (n = 5). All the animals were operated on under general anesthesia, and 80 x 50-mm full-thickness calvarial defects were created. In the control group, no treatment was performed. In the distraction group, TBDCO was performed with a custom-made distraction device with 2 transport segments. After 5 days of latency period, the anterior transport segment was distracted to a posterior and superior direction (0.7 and 0.3 mm, respectively) and the posterior transport segment was distracted obliquely to an anterior and superior direction (0.7 and 0.3 mm, respectively) with a resulting total vectorial movement of 0.75 mm/d. Active distraction was approximately 29 days, and the consolidation period was 60 days.No major complications were seen during the whole procedure. In the control group, the bone defects remained unhealed. In the distraction group, defects healed and the reconstructed calvarium was dome shaped. Preoperative and postoperative cranial volume measurements of the distraction group animals revealed an increase in cranial volume (P < 0.05). Histologic evaluation showed inductive bone regeneration and mature bone structure development within the distraction zone. Trifocal biplanar distraction-compression osteosynthesis is an effective and safe technique for three-dimensional closure of the cranial defects. In clinical practice, it could provide several advantages over currently available reconstructive procedures.

Effect of platelet-rich-plasma on cranial distraction osteogenesis in sheep: preliminary clinical and radiographic results

The purpose of this study was to investigate the effect of platelet-rich-plasma (PRP) on cranial distraction osteogenesis. Standardized calvaria critical size defects (6 cm x 5 cm) were created in 16 adult female sheep. Bifocal cranial transport distraction osteogenesis with autogenous free calvaria bone grafts (2 cm x 4 cm) was performed at a rate of 1mm once daily to a total of 30 mm. The 16 sheep involved in the experiment were randomly divided into four groups, four animals in each: Group 1 (no PRP, latency 5 days); Group 2 (no PRP, latency 0 day), Group 3 (PRP, latency 5 days) and Group 4 (PRP, latency 0 day). After a consolidation phase of 6 weeks, the animals were sacrificed and specimens harvested for conventional radiological and 3D quantitative computer tomographic (3D-QCT) assessment. New bone was generated in the distraction zone in all groups. There were significantly (P < 0.05) higher densities in the proximal region of the distraction regenerate in Group 4 (PRP, latency 0 day) compared to Group 2. However, no significant differences in mean density of the total distraction regenerate were found, neither in volume of the bony regenerate between the experimental groups. This study showed that PRP only had an effect on bone regeneration if active distraction was started immediately after application of PRP in the distraction gap.