Dynamic spring-mediated cranioplasty in a rabbit model

Since the beginning of craniofacial surgery, there has been an ongoing search for surgical techniques to enhance outcome while, at the same time, decreasing the invasiveness of the surgical treatment of craniofacial deformities. The purpose of this study was to test a recently reported minimally invasive treatment modality, the dynamic spring, in a rabbit calvarial model for efficacy and safety. Specifically, the results of spring cranioplasty on skull growth, the underlying brain, and adjacent bone were to be assessed. The study population consisted of 36 7-week-old New Zealand white rabbits. The rabbits were divided into four treatment groups (9 rabbits each): control, sham surgery, stainless steel springs, and memory metal springs. Postoperative analysis included weekly radiographs to evaluate movement of amalgam markers placed at standardized locations. Additionally, 16 rabbits (4 from each group) were killed at 14 days after surgery, and postmortem histological analysis was done. The remaining rabbits were followed until they were adults and were then killed and similarly analyzed. No morbidity or mortality occurred in the immediate perioperative period secondary to the surgery. Postmortem histological analysis of all study animals revealed no intracranial, subcutaneous, or skin infections and no technical complications related to the surgery. Statistical analysis using ANOVA and pair-wise comparisons between treatment groups revealed a statistically significant difference (P < 0.05) between the marker movement in the spring groups versus the sham and control groups. There were no significant differences between the sham and control groups or between the two spring groups. In conclusion, this study confirms the efficacy and safety of the dynamic spring in a rabbit model.     

Zygomaticomaxillary fracture repair with resorbable plates and screws

The use of nonmetallic plate and screw fixation composed of a resorbable copolymer of poly L-lactic acid and polyglycolic acid (LactoSorb) for the repair of isolated malar fractures was studied in 53 patients. Other than technique variations in application for screw insertion and plate adaptation, no clinical differences were observed in intraoperative bone stability or postoperative long-term results from prior experience with traditional metal devices. No occurrences of postoperative infection, soft-tissue swelling, or maxillary sinusitis occurred in this series with a 6-month to 2-year follow-up.     

BMP-2-based repair of large-scale calvarial defects in an experimental model: regenerative surgery in cranioplasty

Pediatric craniofacial surgery is complicated by a shortage of autologous bone. Children between 2 and 10 years of age are especially problematic, as the dura has lost its potential to spontaneously heal large calvarial defects by approximately 2 years of age, and split calvarial grafts are often unavailable because of the underdeveloped diploic space until later childhood. We demonstrate the efficacy of a BMP-2-based system in repairing large-scale cranial defects in a rabbit model. Calvarial defects, 15 mm, were created in 18 adult New Zealand white rabbits, treated as follows: group 1, no repair (n = 6); group 2, absorbable collagen sponge (ACS) (n = 4); and group 3, recombinant human bone morphogenetic protein 2 delivered on ACS (rhBMP-2/ACS) (n = 8). Bone regeneration 6 weeks postoperatively was evaluated by 2- and 3-dimensional standard computed tomography, micro-computed tomography. Analysis of variance was performed using SPSS. The generated bone was also evaluated histologically. After 6 weeks, group 1 defects were on average 32.8% (SD, 8.8%) ossified. Group 2 defects were on average 34.4% (SD, 17.1%) ossified. Defects in group 3 were on average 96.9% (SD, 3.7%) ossified, significantly (P < 0.005) more than the defects in groups 1 and 2. rhBMP-2-induced bone was histologically and radiographically consistent with native bone. This study demonstrates the efficacy of rhBMP-2/ACS for the repair of calvarial defects in the rabbit model. rhBMP-2/ACS may offer a viable treatment option for craniofacial surgeons facing a shortage of bone, with the potential to replace autologous bone grafts and render their attendant morbidities obsolete.     

Comparison of circummandibular wiring with resorbable bone plates in pediatric mandibular fractures

Pediatric patients present a unique challenge to maxillofacial surgeons in terms of their treatment planning as well as in their functional and nutritional needs which are different from that of adult patients. Early literature has advocated conservative closed management of pediatric fractures to prevent complications. However recent advances in maxillofacial surgery has enabled us to use biodegradable plates and screws, which overcomes the limitations of metallic plates. We present a comparison of two cases of parasymphysis fracture treated with circum-mandibular wiring and biodegradable plate fixation their outcome in terms of fracture healing and functional stability.     

Outcomes and complications based on experience with resorbable plates in pediatric craniosynostosis patients

The structure and functional relationship of polymers have long been the purview of engineers and polymer chemists. Bioabsorbable fixation devices have been used for decades as dissolvable suture meshes and, recently, routinely by orthopedic surgeons. During the past decade, bioabsorbable fixation systems have become available for use by craniomaxillofacial surgeons for cranial vault remodeling. This study evaluates the application of a bioabsorbable fixation system in reconstructive craniofacial procedures in a pediatric population. We reviewed 146 cases of cranial vault reconstruction including 98 boys and 48 girls ranging from 2 months to 16 years (mean, 15 months) in age. The procedures were performed for 6 years between January 1998 and June 2004. Bioabsorbable plates and screws were used in each case; most of these cases were craniosynostosis reconstructions. There were 69 cases of frontal sagittal craniosynostosis, 36 metopic, 20 unicoronal, 12 bicoronal, 5 lamboid, 2 deformational plagiocephaly, and 2 multiple fusion of sutures. Postoperative evaluation consisted of clinical examination and three-dimensional computed tomography scan reconstructions at 3, 6, and 12 months. Items specifically screened for on the clinical examination included wound healing, signs of infection, and palpability of implant through the skin. Six patients had palpable plates, 2 patients had palpable screw, and 5 patients had infection at the incision site (of which only 3 were treated with inpatient care including incision drainage and intravenous antibiotics). Our experience has been overwhelmingly positive, and we feel that our results suggest that resorbable fixation is a superior option in pediatric plastic and craniofacial surgery.     

Role of resorbable plates and screws in craniofacial surgery.

Twenty patients underwent craniomaxillofacial fixation procedures with the use of the LactoSorb (Walter Lorenz Surgical, Jacksonville, FL) resorbable plating system. The patients ranged in age from 4 months to 67 years. No significant problems from the use of this plating system were noted. The resorbable plating system offers several distinct advantages over traditional metallic systems.     

Autologous cranial particulate bone graft: an experimental study of onlay cranioplasty

The purpose of this study was to determine whether particulate bone graft maintains its volume when used for onlay cranioplasty. Twenty-five adult, male, New Zealand white rabbits were divided into 5 groups (n = 5/group). Groups 1 to 3 were controls: group 1, untreated; group 2, sham procedure; and group 3, burring the cortical surface. Group s 4 and 5 had augmentation of the parietal bones with particulate graft harvested from the frontal bone with a brace and bit. The particulate graft was placed on native parietal bone (group 4) or on parietal bone that had been abraded to punctuate bleeding with an electric burr (group 5). Volume maintenance and osseointegration of the grafts were determined by micro-computed tomography and histology. At 16 weeks postoperatively, the mean (SD) volumes of the parietal bones in control groups 1, 2, and 3 were 555.8 (29.2), 550.8 (36.8), and 539.0 (39.0) mm, respectively. Immediately after cranioplasty, the mean (SD) volumes of augmented parietal bone were 846.0 (10.8) mm for group 4 and 831.8 (11.8) mm for group 5. Sixteen weeks postoperatively, 100% of the group 4 grafts had resorbed (551.8 [SD, 24.0] mm), and parietal volume was no different from controls (P = 0.89). Group 5 maintained 54.2% of volume (695.6 [SD, 22.0] mm), which was greater than those of the controls (P < 0.0001). Particulate graft may be used for onlay cranioplasty if the recipient site is burred. Approximately one half of the onlay graft is resorbed, and its original shape is not maintained.     

Use of resorbable plates and screws in pediatric facial fractures.

PURPOSE: The use of resorbable plates and screws for fixation of pediatric facial fractures is both well tolerated and effective. It enables realignment and stable positioning of rapidly healing fracture segments while obviating any future issues secondary to long-term metal retention. PATIENTS AND METHODS: Forty-four pediatric facial fractures were treated over a 10-year period at our institution using differing techniques of polymeric bone fixation. Twenty-nine mandible fractures in patients under the age of 10 (age range, 6 months to 8 years) were treated. Displaced fractures of the symphysis, parasymphysis, body, and ramus underwent open reduction and either 1.5-mm or 2.0-mm plate and screw fixation in 14 patients. Subcondylar fractures were treated by a short period of maxillomandibular fixation (3 weeks) achieved with suture ligation between resorbable screws placed at the zygoma and symphysis or a circummandibular suture attached to a zygomatic screw. Fifteen patients (age range, 4 to 11 years) with isolated frontal, supraorbital, intraorbital, or orbitozygomatic fractures were treated by open reduction and internal fixation with 1.5-mm resorbable plates, mesh, and screws. RESULTS: No long-term implant-related complications were seen in any of the treated patients. CONCLUSIONS: Resorbable polylactic and polyglycolic acid plates and screws can be an effective fixation method for facial fractures in children in the primary and secondary dentition periods.     

Comparison between resorbable plates vs. titanium plates for treatment of zygomatic fractures: a systematic review with meta-analysis

Purpose

To compare resorbable plates with titanium plates for the fixation of zygomatic fractures, taking into account postoperative complications.

Methods

This systematic review followed the guidelines of PRISMA and the recommendations of the Cochrane Handbook and was registered in PROSPERO. The electronic search was performed in the Web of Science, PubMed, Virtual Health Library, and Cochrane Library databases and in the gray literature. The study selection and the data extraction were performed by three calibrated and independent researchers. The assessment of the risk of bias in the studies was performed using the Cochrane Risk of Bias Tool for clinical trials. Meta-analyses were performed using Review Manager Software version 5.3, using the Peto’s Odds Ratios (PORs), and when I² > 30, the random effect model was used. The evaluation of the quality of the evidence was carried out through GRADE.

Results

A total of 2651 studies were screened and only nine were included; 7 of which were used for quantitative assessment. The follow-up time for patients ranged from 6 months to 5 years. All studies showed a low risk of bias in the “incomplete outcome data” domain. The need for plate removal (POR: 0.11, 95% CI: 0.02 to 0.81, I² = 0%) and dehiscence (POR 0.12, 95% CI 0.02 to 0.63, I² = not applied) was lower for the group of patients who used resorbable plates than for titanium plates.

Conclusion

There was no difference in the occurrence of infection, diplopia, or paresthesia between the fixation methods. Resorbable plates showed better postoperative clinical performance.

     

Biomechanical properties of resorbable poly-L-lactide plates and screws: a comparison with traditional systems

Poly-L-lactide (PLA) plates and screws were tested in vitro in porcine ribs for uniaxial pullout and four-point bending strength. Results were compared to conventional systems (stainless steel and titanium). The biomechanical testing suggests that PLA screws have properties suitable for fixation of sagittal split osteotomies. Poly-L-lactide plates have indications in areas of low stress and noncompressive load.     

生物降解性骨内固定夹板行颧弓骨折内固定的实验研究

目的：研究ＤＬ－聚乳酸（ＰＤＬＬＡ）夹板行颧弓骨折内固定的疗效及材料生物和物理性能。方法：选用４只狗造成颧弓骨折后用ＰＤＬＬＡ夹板内固定,采用大体、组织学、四环素荧光活体骨标记、Ｘ线摄片,观察骨折内固定效果;并与微型钢板内固定比较。结果：①ＰＤＬＬＡ板具有良好的力学性能,在颧弓骨折内固定中可达到与微型钢板相同的内固定效果。②ＰＤＬＬＡ板具有良好的组织相容性,不引起周围组织的炎症和异物反应。③ＰＤＬＬＡ板植入后逐渐降解,何时完全吸收有待更远期观察。结论：ＰＤＬＬＡ是一种很有应用价值,比较理想的骨折内固定生物材料。     

Treatment of fractures of the condylar head with resorbable pins or titanium screws: an experimental study

We aimed to compare in vivo the stability of fixation of condylar fractures in sheep using sonic bone welding and standard titanium screws. We assessed stability of the osteosynthesis and maintenance of the height of the mandibular ramus. Height decreased slightly in both groups compared with the opposite side. The volume of the condyle increased considerably in both groups mainly because callus had formed. The results showed no significant disadvantages for pin fixation compared with osteosynthesis using titanium screws.     

Fixation of bimaxillary osteotomies with resorbable plates and screws: experience in 20 consecutive cases.

PURPOSE: This study evaluated the potential effectiveness of resorbable plate and screw fixation for skeletal stabilization of simultaneously performed maxillary and mandibular osteotomies. PATIENTS AND METHODS: Twenty consecutive patients underwent simultaneous maxillary and mandibular osteotomies that were fixed using copolymeric poly L-lactic acid/polyglycolic acid (PLLA/PGA) plates and screws. Prefabricated acrylic intermediate and final splints were used as guides and then removed at completion of the surgery. Guidance elastics were applied at 2 weeks postoperatively. RESULTS: The LeFort I osteotomies included segmentalizations with and without bone grafts (7/20), impactions (4/20), advancements (8/20), and unilateral downgrafting with a bone graft (2/20)- one of which was segmental. The mandibular sagittal split osteotomies involved advancements (11/20), setbacks (5/20), and asymmetric rotation (4/20). Three patients had simultaneous genioplasties, which were also stabilized with resorbable fixation. All maxillae were fixed with four 2.0-mm L-shaped plates and screws. The mandibular rami were maintained with three 2.5-mm bicortical screws per side. The mandibular symphyseal segments were held in position with two or three 2.5 mm bicortical screws. All surgeries were accomplished uneventfully, and no problems in the immediate postoperative stability of the occlusion were encountered. Follow-up ranged from 12 to 25 months. CONCLUSIONS: The initial clinical findings suggest that this form of bone fixation is a viable alternative to standard metallic fixation techniques for certain maxillomandibular deformities in which excessive bony movements are not performed. Differences exist in both intraoperative application and postoperative management of masticatory function. This is partially a US government work. There are no restrictions on its use.     

Dose-dependent effect of radiation on resorbable blast material titanium implants: an experimental study in rabbits

Background: Radiotherapy is a commonly used treatment modality in head and neck cancer; however, it also negatively affects healthy structures. Direct damage to oral soft and hard tissue frequently occurs with radiotherapy. In this study, we aimed to evaluate the effect of radiotherapy on bone surrounding titanium dental implants via biomechanical and molecular methods.

Materials and methods: Fifty-four implants were inserted in the left tibiae of 18 adult male New Zealand rabbits (3 implants in each rabbit). After 4 weeks of the implant surgery, the left tibiae of 12 rabbits were subjected to a single dose of irradiation (15?Gy or 30?Gy). Four weeks after the irradiation, rabbits were sacrificed and removal torque test was done for the biomechanical evaluation. Bone morphogenetic protein-2 (Bmp-2) and fibroblast growth factor-2 (Fgf-2) expression analyses were performed with Real-time PCR. Statistical analysis was done using SPSS.

Results: The control group showed significantly higher removal torque value than the 15 and 30?Gy irradiation groups, and the 15?Gy irradiation group had higher removal torque value than the 30?Gy irradiation group (p?p?p?p?Conclusion: Radiotherapy with 15 and 30?Gy doses can adversely affect osseointegration of implants by reducing the quality of bone and impairing the bone-to-implant contact. The mechanism of action seems to be related to alterations in Bmp-2 and Fgf-2 mRNA expressions.     

Ultrasound-aided resorbable osteosynthesis of fractures of the mandibular condylar base: an experimental study in sheep

We evaluated the osteosynthesis of condylar fractures using resorbable mini plates and ultrasound-aided insertion of pins clinically and histologically. Stability was greater than that with resorbable screws because of the fusion of pin and plate. Long term evaluation showed complete resorption of the polymeric osteosynthesis material.     

Salvation for hardware failure of resorbable fixation plates in bilateral mandibular angle fractures

The resorbable fixation system is used for the treatment of facial bone fractures and has many merits. It does not require a fixture removal procedure and is biologically nontoxic. Also, it does not disturb normal growth in growing children. However, there are also many points to be considered, such as resorption time, foreign body reaction, infection rate, or fixation stability depending on the fracture pattern. Because of these factors, there is still controversy over the use of a resorbable system.We present a case of a patient who experienced malunion after using a resorbable fixation system to treat bilateral mandibular angle fracture, which was recovered by corrective osteotomy and vertical ramus osteotomy in our department.     

Orbital floor reconstruction with an alloplastic resorbable polydioxanone sheet

The orbital floor is frequently reconstructed after blow-out fractures or midface fractures to avoid a relapse of the repositioned orbital tissue and to prevent enophthalmos. A total of 31 patients underwent reconstruction of internal orbital wall fractures with a resorbable 0.25 mm or 0.5 mm-thick polydioxanone implant (PDS). Skeletal and functional outcome was evaluated retrospectively with regard to fracture size. Fracture size was graded as small, moderate or large by CT scans and operating records. Two of the 25 patients with small or moderate defects showed an enophthalmos of 2-3 mm. Five of the six patients with large defects or two orbital wall fractures had enophthalmos. The scar that formed after implant resorption was to weak to provide adequate support of the globe or to compensate the enlarged orbital volume. Endoscopic follow-up examination of 12 patients showed yielding of the scar in the orbital floor already in moderate defects. Eight patients had diplopia in extreme gaze and two had significant diplopia. Blow-out and midfacial fractures with small to moderate defects in the orbital floor (up to a size of 2.5 cm2) can be reconstructed by polydioxanone sheet to avoid enophthalmos. Polydioxanone implants should only be used in cases without massive orbital fat herniation. The scar formed after implant resorption may influence functional outcome.     

Bone response to machined and resorbable blast material titanium implants: an experimental study in rabbits

The aim of the present study was a comparison of implants' responses to a machined surface and to a surface sandblasted with hydroxyapatite (HA) particles (resorbable blast material [RBM]). Threaded machined and RBM, grade 3, commercially pure, titanium, screw-shaped inplants were used in this study. Twenty-four New Zealand white mature male rabbits were used. The inplants were inserted into the articular femoral knee joint according to a previously described technique. Each rabbit received 2 inplants, 1 test (RBM) and 1 control (machined). A total of 48 implants (24 control and 24 test) were inserted. The rabbits were anesthetized with intramuscular injections of fluanisone (0.7 mg/ kg body weight) and diazepam (1.5 mg/kg b.wt.), and local anesthesia was given using 1 mL of 2% lidocaine/adrenalin solution. Two rabbits died in the postoperative course. Four animals were euthanatized with an overdose of intravenous pentobarbital after 1, 2, 3, and 4 weeks; 6 rabbits were euthanatized after 8 weeks. A total of 44 implants were retrieved. The specimens were processed with the Precise 1 Automated System to obtain thin ground sections. A total of 3 slides were obtained for each implant. The slides were stained with acid and basic fuchsin and toluidine blue. The slides were observed in normal transmitted light under a Leitz Laborlux microscope, and histomorphometric analysis was performed. With the machined implants, it was possible to observe the presence of bone trabeculae near the implant surface at low magnification. At higher magnification many actively secreting alkaline phosphatasepositive (ALP+) osteoblasts were observed. In many areas, a not yet mineralized matrix was present. After 4 to 8 weeks, mature bone appeared in direct contact with the implant surface, but in many areas a not yet mineralized osteoid matrix was interposed between the mineralized bone and implant surface. In the RBM implants, many ALP+ osteoblasts were present and in direct contact with the implant surface. In other areas of the implant perimeter it was possible to observe the formation of an osteoid matrix directly on the implant surface. Mature bone with few marrow spaces was present after 4 to 8 weeks. Beginning in the third week, a statistically significant difference (P < .001) was found in the bone-implant contact percentages in machined and RBM implants. It must be stressed that these results have been obtained in a passive, nonloaded situation.