A comparison of two types of free bone grafts as transport discs in segmental distraction for reconstruction of calvarial bone defects: an experimental study.

INTRODUCTION: Several investigations over the past few years have shown that the importance of preserving the blood supply of the transport disc during segmental distraction has been overestimated. It was clearly demonstrated that distraction osteogenesis by local bone transportation could be achieved even with free bone grafts. So far, there have been no systematic investigations into how different types of free bone grafts vary in their function and suitability as transport discs in segmental craniofacial distraction. The aim of this study was to develop criteria to aid the clinician in selecting the most suitable free bone graft for distraction purposes. MATERIALS AND METHODS: Under general anesthesia, calvarial defects measuring 6 x 5 cm were created in 12 adult black head sheep in order to reconstruct them by segmental distraction using two different types of bone grafts as transport discs. Group 1 (n=6) received autotopical membranous bone of the calvarium as the transport segment, while group 2 (n=6) received heterotopical enchondral material from the iliac crest. Distraction was started postoperatively after 5 days at 0.6 mm/day and continued for 7 weeks. After a further 6 weeks of consolidation, the animals were killed and specimens examined macroscopically, radiographically and histologically. RESULTS: The significantly better quality of bone regenerates of group 1 was clearly influenced by the significantly better stability of the transport disc's connection to the distraction device, the calvaria grafts showing better volume stability and better mechanical resistance during transport than the iliac bone. The influence of both types of bone grafts on the macro- and microstructure of the newly formed bone was clearly evident. The mineralization density of group 2 regenerates was significantly lower than that of group 1 specimens. CONCLUSION: High mechanical stability of the bone graft is a very important point to consider when selecting a free graft for use as transport disc in local bone transport, especially if transport is necessary over long distances.

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

Bifocal transport osteogenesis (BTO) is a promising technique for the reconstruction of extended osseous craniofacial defects. Aim of this study was to determine the potential of this technique related to various donor sites of the transport segment. In 10 adult sheep critical size defects of the calvaria were treated by gradual movement of a transport segment consisting either of autogenous regional free calvarial bone grafts (n=5) or autogenous illiac free bone grafts (n=5). Latency period was 5 days; the rate of distraction was 1mm per day and extended approximately 40 days. The consolidation period was 28 days. After harvesting, specimens were investigated by conventional radiography, CT-scans, histologically and by fluorescence. In both groups transport osteogenesis resulted in a complete closure of the critical size defect. Membranous bone formation and remodeling occurred during the entire period of distraction and consolidation. The volumes and thickness of newly formed bone at the defect site were increased significantly when calvarial bone grafts were used (P<0.05). Iliac bone grafts became progrediently smaller during distraction, while the volume of calvarial grafts remained relatively constant (P<0.05). In conclusion, transport segments consisting of calvarial and iliac bone resulted in a reliable closure of craniofacial critical size defects in adult organisms; the application of calvarial bone grafts resulted in an increased extend of bone formation.

Craniofacial distraction osteogenesis: a review of the literature: Part 1: clinical studies.

A review of the literature dealing with distraction osteogenesis (DO) of the craniofacial skeleton, provided by a PUBMED search (National Library of Medicine, NCBI; revised 3 April 2000) from 1966 to December 1999 was conducted. Key words used in the search were distraction, lengthening, mandible, mandibular, maxilla, maxillary, midface, midfacial, monobloc, cranial, craniofacial and maxillofacial. This search revealed 285 articles. One hundred and nine articles were clinically orientated and were analysed in detail in this study. The type of distraction, indications, age, type of surgery, distraction rates and rhythms, latency and contention periods, amount of lengthening, follow-up period, relapse, complications and the nature of the distraction device were analysed. This review revealed that 828 patients underwent DO of the craniofacial skeleton; 579 underwent mandibular DO, 129 maxillary DO, 24 simultaneous mandibular and maxillary DO and 96 midfacial and/or cranial DO. Craniofacial DO has proven to be a major advance for the treatment of numerous congenital and acquired craniofacial deformities. Treatment protocols and success criteria for craniofacial DO are suggested on the basis of these results. There is still, however, a lack of sufficient data, especially on follow-up and relapse, so that treatment strategies have to be validated by long-term studies in the future.

[Autogenous bone transplants in repair of the traumatically damaged orbit. Functional and esthetic results in 42 cases]. / Autogene Knochentransplantate zur Versorgung der traumatisch geschädigten Orbita. Funktionelle und ästhetische Ergebnisse in 42 Fällen.

BACKGROUND: Autogenous bone transplantation is a well established aspect of craniofacial traumatology. This study evaluated functional and esthetic success in repairing traumatically damaged orbits by autogenous bone transplantation. PATIENTS AND METHODS: We repaired 102 osseous orbital defects by autogenous bone transplantation, 98 by calvarium split graft and 4 by iliac crest transplant. Of 42 surgical patients 34 were followed up. RESULTS: Autogenous bone transplants have proven themselves for repair of traumatically damaged orbits. Calvarium split grafts are particularly suitable for this purpose. Good esthetic and functional results can usually be achieved with primary osseous defect repair. However, more protracted functional defects can often no longer be helped. CONCLUSION: Autogenous bone transplants can be broadly recommended for providing primary care.

[Vertical distraction osteogenesis of the alveolar process using a tooth-borne device]. / Vertikale Distraktion des bezahnten Alveolarfortsatzes mittels einer zahngetragenen Apparatur.

Since the communication of McCarthy et al. in 1992, applications for distraction osteogenesis in the maxillofacial complex have increased enormously. The advantages as compared to conventional reconstructive procedures are missing donor-site morbidity for bone graft harvesting, reduced blood loss and also a gradual gain in the soft tissue envelope. Meanwhile, even the vertical lengthening of the alveolar process has become a clinically reliable method. The case presented illustrates the treatment of a 16-year-old patient who suffered a sporting accident at the age of 7 years, leading to ankylosis of the upper middle incisors with subsequent underdevelopment of the frontal alveolar process. After fabrication of a custom-made distraction device, an osteotomy of the tooth-bearing segment in the upper front was performed and the segment was attached to the distraction device. Bone lengthening was started on the seventh postoperative day at a daily rate of 0.5 mm. The distraction was maintained until closure of the open bite was achieved. On the 22nd day, the segment was fixed using an orthodontic arch wire and the distraction device was removed. A retention period of 6 weeks was maintained until sufficient stability was detectable. Now, 1.5 years after the treatment, the situation is stable with a good consolidation of the bone fragments and a physiologically shaped gingivobuccal sulcus. Lengthening of the alveolar process by vertical distraction osteogenesis using a tooth-borne device may be indicated in certain cases. With this technique a second operation can be avoided and there is less risk of laceration of dental roots by fixation screws.

Maxillary distraction osteogenesis: a two-dimensional mathematical model.

Patients with cleft lip and palate with severe maxillary retrusion usually have a mandible with anterior-superior autorotation and subsequent overclosure and loss of the vertical facial dimension. Maxillary distraction osteogenesis can correct the sagittal maxillomandibular relationship and should simultaneously reestablish vertical dimension through maxillary vertical height increase and clockwise rotation of the mandible to restore facial balance. We present a two-dimensional mathematical model in the sagittal plane, which reestablishes sagittal and vertical skeletal deficiencies and proper occlusal alignment for planning maxillary advancement with distraction osteogenesis in patients with cleft lip and palate. The model is illustrated in a case of a 13-year-old boy with a complete bilateral cleft lip and palate and severe maxillary retrusion. The two-dimensional mathematical model described in this article allows the surgeon and orthodontist to calculate in a simple and accurate way the ideal distraction vector to advance the maxilla to its desired position.

[Complex reconstruction of the area of the maxilla and mid-face after radical tumor surgery]. / Komplexe Rekonstruktion des Oberkiefer- und Mittelgesichtsbereichs nach radikalchirurgischer Tumoroperation.

The esthetic and functional restoration of facial defects is always a daunting challenge. The advent of free vascularized tissue transfers in combination with oral implants enables the surgeon to attain a high level of flexibility in the treatment of such defects. Due to its anatomical properties, the osteocutaneous scapula flap qualifies to a high degree for reconstruction purposes in the midfacial area. From July 1990 to February 1997, reconstruction of complex facial defects after oncologic surgery was performed in 17 patients using free vascularized tissue transfer. In four cases, a free scapula flap was used. Advantages and disadvantages of this technique are illustrated in these patients. Complete oral rehabilitation requires bony continuity of the jaws and stable dentition. To attain this goal, additional grafting procedures are required in most cases when insertion of oral implants is planned. As for the soft tissues, the problem of measuring the amount of tissue needed often leads to an overcorrection, requiring several debulking procedures.

[Masticatory rehabilitation of tumor patients by endosseous implants. 10 year analysis]. / Wiederherstellung der Kaufunktion bei Tumorpatienten durch enossale Implantate. 10-Jahres-Analyse.

A total of 409 implants was inserted into 83 consecutive patients, who had tumor-related intraoral resections of soft tissue and bone. A life table analysis was used to determine the survival rate of the implants placed over a period of 13 years. Log rank tests and a Cox regression analysis were employed to identify relevant effects of surgical parameters on implant survival. A total of 38 implant failures were encountered. Most of the losses (n = 16) occurred during the first year of functional loading. The cumulative, overall survival rate of implants was 56.5%. Previous radiation therapy, insertion into grafted bone or original jaw bone, and insertion into microsurgically revascularized grafts did not significantly affect the survival rates. In the Cox regression, only the timing of implant placement was significantly related to the survival rate in the group of patients with bone grafts (P = 0.0197), with a lower survival rate of 36.2% of primary inserted implants and 67.1% survival in the group with secondary implant placement.

[Reconstruction of severe facial defects due to noma]. / Die Rekonstruktion schwerer Gesichtsdefekte nach Noma-Erkrankung.

Noma is an ulcerative-necrotizing gingivo-stomatitis eventually leading to severe destruction of the midface, including lips and cheek, maxilla/mandible, nose and rarely the orbit. The defects are usually unilateral. Children from economically underdeveloped countries are predominantly affected. Medically untreated the disease has a high mortality rate, which can be dramatically lowered by adequate antibiotic therapy started in time. Predisposing factors include malnourishment, immunosuppression, and poor oral hygiene. Forty-eight noma patients were surgically treated in Sokoto, Nigeria during October 1997 by an Interplast Germany team sponsored by AWD Stiftung Kinderhilfe. Interdisciplinary surgical strategies and results, e.g. ankylosis release, local flap coverage and 12 pedicled musculocutaneous latissimus dorsi island flaps, as well as a noma classification (NOMAC), are presented.

[Experiences with distraction osteogenesis in therapy of severe peripheral airway obstruction in infancy and early childhood]. / Erfahrungen mit der Distraktionsosteogenese bei der Therapie schwerer peripherer Atemwegobstruktionen im Säuglings- und Kleinkindalter.

Children with craniofacial malformations are at special risk for the development of peripheral airway obstruction. The problems are magnified in patients with retroposition or hypoplasia of the mandible. In these cases, the base of the tongue is posteriorly displaced, hereby decreasing the airway diameter. By application of distraction osteogenesis the mandible can be lengthened to move the base of the tongue forward and open the airway. Three female patients aged between 7, 11, and 15 months suffering from peripheral airway obstruction caused by mandibular hypoplasia were treated by gradual distraction. All of them had a gastrostomy or a nasogastral tube in place, respectively, due to severe nutrition problems. In the youngest patient tracheostomy was performed shortly after birth and was already planned in the 15-month-old child, who had received a permanent nasopharyngeal tube. The 11-month-old child suffered from severe refractory sleep apnea. Exercises in oral feeding were possible in the youngest patient after 10 days of distraction. In the oldest one, the airway tube was removed on the six day of distraction and, thus, tracheotomy was successfully avoided. In the 11-month-old child apneic events a rapidly decreased. Our experience suggests that distraction osteogenesis after careful preoperative evaluation can be successfully performed for the treatment of peripheral airway obstruction in patients with selected craniofacial anomalies.

Elevated levels of testosterone receptors in keloid tissue: an experimental investigation.

Testosterone-binding receptor protein analyses were performed in keloids of 24 patients. According to their clinical appearance (hyperemia, pain, rapid growth, etc.), the lesions were subdivided into regions of minor and major clinical keloid activity. Biopsies were taken from active and inactive parts of the keloids, respectively, as well as from normal adjacent skin. The mean receptor amount in femtomoles per milligrams of tissue was 0.046 for active (SD = 0.037), 0.038 for inactive keloidal lesions (SD = 0.032), and 0.012 for normal skin. The corresponding receptor amount per microgram of DNA was 3.356 fmol (SD = 2.171) for active, 2.077 fmol (SD = 1.427) for inactive keloidal, and 1.010 fmol (SD = 1.190) for normal tissue. Statistical evaluation was performed using a two-way analysis of variance, with the two factors being individual subject and type of tissue. When differences were found, then Tukey's comparison was done to assess where those differences were. Comparisons of the receptor amount per milligram of tissue significant at the 0.05 level revealed significant differences between active keloid tissue and normal skin tissue and inactive and normal tissue (p < 0.01) respectively, while different receptor amount per microgram of DNA was significant between active and inactive and active and normal tissue (p < 0.01). These data suggest that elevated androgen receptor levels exist in clinical active keloid tissue and that possible therapeutic means might include topical antiandrogen therapy.

One- or two-plate fixation of mandibular angle fractures?

Standard treatment of mandibular angle fractures with miniplates, according to the recommendations of Champy et al. (1976), consists of fixation with one plate at the superior border of the mandible ventral to the external oblique line. In certain constellations, a second miniplate at the lower mandibular margin may provide additional stability. In contrast, extremely high complication rates following two-plate fixation of mandibular angle fractures were reported by Ellis and Walker (1994). In a prospective randomized study, 31 consecutive patients were treated with 2.0 mm (mini) plates (Synthes Co., Switzerland). One group was treated with one plate, the other one with two plates. In none of the patients was intermaxillary immobilization used. Follow-up was performed 6 months postoperatively, consisting of clinical and radiographic examination. No significant differences (P = 0.74 for infection, and P = 1.0 for occlusal and postoperative sensory disturbance) in postoperative short- or long-term complications were found between the two groups. The results are compared with our experimental investigations presented at the annual congress of the Germany Society of Oral and Maxillofacial Surgery, 1995. Two-plate fixation may not offer advantages over single-plate fixation in general. However, individual fracture constellations may benefit from variation in plate(s) localization. Factors contributing to complications in mandibular angle fractures are discussed.

[Modern principles in treatment of complex injuries of the facial bones]. / Moderne Prinzipien in der Behandlung komplexer Gesichtsschädelverletzungen.

Concepts in the treatment of craniomaxillofacial fractures have changed over the last 15 years. Modern imaging techniques have become a central part in establishing a proper diagnosis. Advanced life support and intensive care medicine allow for early primary fracture treatment. The former principles of minimal exposure of bone fragments using small incisions have been replaced by principles from reconstructive craniofacial surgery comprising extensive subperiosteal dissection, exposure of all fracture lines, open reduction and rigid internal fixation. Missing bony structures are replaced primarily by autogenous bone grafts. Using these concepts, most late esthetic and functional sequelae of facial fractures can be diminished remarkably.

[Facial asymmetry after vascular pedicled muscle transfer. Additional criterion for evaluating outcome in managing chronic facial paralysis]. / Gesichtssymmetrie nach gefässgestieltem Muskeltransfer. Zusätzliches Kriterium zur Erfolgsbeurteilung bei der Versorgung langbestehender Fazialisparesen.

Today neurotization and muscle transplantation are considered an ideal method of reconstructing the function of the facial nerve and the mimetic muscles in long-established facial palsy. Transplantation of the gracilis muscle as a segmental muscle provides an appropriate size for the face; however, determining the amount of muscle is difficult in order to obtain the desired dynamic and symmetric results. Prompted by the question of an "ideal" transplant size, a retrospective study was undertaken. Since 1991, 11 microneurovascular gracilis muscle transfers have been performed in 10 patients with long-established facial palsy (one patient underwent an additional transfer due to excessive scarring in a severe case of neurofibromatosis). Computed axial tomography scans were performed on six patients using a method for obtaining muscle-volume measurements of corresponding areas in each individual by using bony landmarks for reference. Cross-section area measurements by a digitalized mode were obtained from each scan, determining 20-70 Hounsfield units as appropriate for muscle tissue. Muscle-volume measurements ranged on the transplantation sites between 3.85 and 62 cm3 compared to 1.4 and 22.3 mm3 for the corresponding sites. The increments in muscular tissue by a factor between 2 and 3 are due to an increase in each single scan of the corresponding sides: when comparing the corresponding operated and unoperated sides in each patient, soft-tissue volumes were significantly (P < 0.005) elevated on the operated side. The findings presented in this study demonstrate not only encouraging functional results, but also show significant improvement of facial symmetry at rest. The results of our investigation support those of other authors, who also saw the main difficulty as determining the appropriate graft size. Secondary corrective procedures of the muscle puts the pedicle at risk of vascular and neural damage. Meticulous shaping of the graft and proper fixation and suspension technique cannot be overemphasized.

[Experimental studies of the biomechanical stability of different miniplate configurations for the mandibular angle]. / Experimentelle Untersuchungen zur biomechanischen Stabilität unterschiedlicher Miniplattenkonfigurationen am Kieferwinkel.

Miniplate fixation of mandibular fractures has become the treatment of choice in most cases. In fractures of the mandibular angle one 4- or 6-hole miniplate is applied ventral to the oblique line of the buccal cortex of the mandible. Not in every case adequate stabilization is being accomplished by one plate. In order to find out if stability might be increased by a two miniplate fixation technique in which a second plate is applied at the inferior border of the mandibular angle 16 polyurethane and 16 humane mandibles were used and standardized osteotomies were performed at the right mandibular angle. These two groups were divided in 4 sub-groups of four mandibles each and plate fixation of the sub-groups was performed as follows: 6-hole plate on the buccal side of the oblique line, 6-hole plate as before and an additional 2-hole plate at the inferior margin of the mandible, 2-hole plate at the oblique line and 6-hole at the inferior margin and finally two 4-hole plates at the same position. The stability of fixation was measured according to Kroon's method (Kroon et al. 1988), based on a three-dimensional in-vitro model in which muscle forces during mastication acting on the mandible were simulated. Axial loading forces close to the fracture site produced significantly inferior splaying and lingual compression in single miniplated angle fractures. Application of a second miniplate at the inferior border provided significantly higher resistance to loading forces close to the fracture line where two 4-hole miniplates showed superior results. We conclude that two miniplates are an effective method of treating mandibular angle fractures with minor fracture surfaces by establishing a second line of osteosynthesis to neutralize rotational forces.