Bone gap healing in the dog using recombinant human bone morphogenetic protein-2

PURPOSE

This study investigated bone gap healing in a zygomatic arch defect using recombinant human bone morphogenetic protein-2 (rhBMP-2; Genetics Institute, Andover, MA) in an absorbable collagen sponge (ACS) carrier.

METHODS

Zygomatic arch osteotomies were completed 15 mm apart and the arch was mobilized in 6 adult female mongrel dogs. The segment was then repositioned laterally 8 to 10 mm and secured with a titanium reconstruction plate. Bone gaps in either the right or left arches received rhBMP-2, with the contralateral side being left empty in 4 animals and the defects received buffer/ACS without rhBMP-2 in 2 animals as controls. Submentovertex radiographs were taken immediately postoperatively and every 4 weeks until killing at 12 weeks.

RESULTS

Clinical evaluation indicated no significant differences in the degree of inflammation between the groups. However, the rhBMP-2 sites were found to be firm on palpation, in contrast to a soft tissue defect palpated in the control sites. Radiographic examination showed significant bone formation in all rhBMP-2 grafted sites as early as 4 weeks. The radiopacity of the bone continued to increase over the time of this study. Five of six control sites did not show bone formation through the course of this study. In addition to lack of bone formation, 5 of 6 control sites showed collapse of the repositioned arch. All arches in the rhBMP-2 sites remained in their lateral position and formed bone in the gaps. In 2 animals, bone formation moderately exceeded the confines of the gap, and in 2 animals excessive bone formation occurred.

CONCLUSIONS

This study confirms that rhBMP-2 has the potential to be used to stimulate bone gap healing in the craniofacial complex.

Clavicular hypoplasia, zygomatic arch hypoplasia, and micrognathia: a newly defined syndrome

We report on a 6-year-old boy with a previously undefined syndrome of clavicular hypoplasia, frontonasal malformation, zygomatic arch hypoplasia, micrognathia, and normal intelligence. His condition differs from similar syndromes on the basis of unique facial findings such as microcornea, stellate irises, and a midline maxillary cleft. We present his case, a review of the literature, and propose the acronym CHZAM, for clavicular hypoplasia, zygomatic arch, and micrognathia, to represent this syndrome.

Ewing's sarcoma of the facial zygomatic area bones in a young child: a case presentation

We present the case of a young patient with Ewing's sarcoma of the facial zygomatic area bones. This type of tumor in a very young child is a rare event and poses significant diagnostic and therapeutic challenges for the attending physician. In this case, the diagnosis was made by a computed tomography scan with subsequent histological confirmation. The differential diagnoses and therapeutic options are discussed.

Extensive temporal bone pneumatization: incidental finding in a patient with TMJ dysfunction

An 18-year-old male presented with symptoms of temporomandibular joint dysfunction. A panoramic radiograph revealed slight erosion of the condylar heads, and an incidental finding of multilocular radiolucencies in the zygomatic processes of the right and left temporal bones. CT scans were undertaken to exclude any sinister cause. The radiolucencies were shown to be extensive bilateral pneumatization of the temporal bones. Conservative management relieved the symptoms of TMJ dysfunction.

Computed tomographic characteristics of multilobular tumor of bone involving the cranium in 7 dogs and zygomatic arch in 2 dogs

Computed tomography (CT) images of nine dogs with a multilobular tumor of bone of the head were reviewed. The CT characteristics of the neoplasms involving the calvarium (n = 7) were rounded, well defined with a fine granular, nonhomogeneous bone opacity usually in the occipital region. Cranial vault invasion (5 of 7) was commonly found with a significant portion of the mass within the vault. The neoplasms involving the zygomatic arch (n = 2) were also generally rounded and well defined but with a more coarse granular appearance. The common CT findings were best seen when the images were viewed in a bone window.

[Exostosis of the zygoma. Apropos a case]

Exostosis is a benign bony process arising from cortical bone. It is generally localized at the fertile metaphysis of long and some flat bones. Localization to the zygoma and/or the coronoid process is exceptional (5 cases in the world literature). We report an original case of exostosis with isolated zygomatic localization in a 14-year-old girl and review the literature. We emphasize the clinical features and the diagnostic and therapeutic approach in this condition.

Stability of implants as anchorage for orthopedic traction

The aim of this animal study was to investigate the stability of osseointegrated fixtures when used as anchorage for orthopedic traction with extreme force magnitude. Three Brånemark fixtures were placed in the left zygomatic arch and three in the right of five adult dogs. An orthopedic nonaxial force of 5 N was applied using an intraoral coil system. The initial displacement immediately after force application was measured by means of speckle interferometry. After 2 months of continuous loading, bone adaptation and mineralization around all implants were analyzed. All the loaded implants were immobile. Significant marginal bone loss at the abutment-fixture interface (<1 mm) was observed around each loaded fixture implant. Bone remodeling was significantly more pronounced at the tension side of the implants, irrespective of fixture length. Radiographical and histological analyses showed bone with normal trabecular pattern around the implants.

Zygomatico-coronoid ankylosis: a case report

The clinical and radiographic diagnosis and treatment plan for a patient with a rare type of extracapsular ankylosis involving fusion of the zygoma and coronoid process are presented.

[The jugular fossa--observations in a Norwegian medieval population]

A high jugular bulb and fossa has been observed in cases of bleeding complications in neur-otologic surgery, conductive and sensori-neural hearing loss, tinnitus and vertigo. Comparison of 311 skulls from the Oslo mediaeval material with data from other studies showed good agreement regarding the frequency of high fossae, dehiscences, and side and sex differences. The correlation (Pearson's r) of fossa size between the two sides, with the right as the independent variable, and also the correlation between foramen size and fossa depth was less than expected from descriptions in anatomical texts based on visual observations.

3D-CT stereoscopic imaging in maxillofacial surgery

We obtained stereoscopic 3D-CT images in maxillofacial bone fracture patients. These images are made at two different angles. One is equivalent to the view obtained by a subciliary incision during surgery. Another is equivalent to the view obtained by oral incision during surgery. A stereoscopic image is created with a pair of images that differ from each other by a 6 degree shift of the z axis.

The pneumatic spaces of the temporal bone: relationship to the temporomandibular joint

OBJECTIVES

To assess the topographic relationship between the pneumatic spaces of the temporal bone and the temporomandibular joint (TMJ) using high-resolution CT.

METHODS

Findings from 100 consecutive patients who had undergone high-resolution axial CT of the base of the skull were reviewed on a digital imaging workstation. Additional multiplanar reformatted images were created in the sagittal and coronal planes through the TMJ. The extension of the pneumatic spaces of the temporal bone and their relation to the TMJ were determined on both sides.

RESULTS

The extent of pneumatisation of the temporal bone varied considerably. The roof of the TMJ fossa was pneumatised in 51 patients. The articular eminence contained air spaces in 12 patients, the root of the zygomatic process in five patients. Air cells in the peritubal area extended into the medial wall of the glenoid fossa 53 patients. In approximately 25% the extent of pneumatisation showed marked asymmetry.

CONCLUSIONS

Pneumatisation of the temporal bone frequently extends close to the TMJ. Knowledge of these air spaces is helpful for the interpretation of imaging studies such as panoramic radiographs and to understand the spread of pathological processes into the joint.

Use of intraoperative computed tomography during repair of orbitozygomatic fractures

OBJECTIVE

To assess the practicality and potential benefits of intraoperative computed tomography using a mobile scanner in the operating room during repair of orbitozygomatic fractures.

SETTING

Level I trauma center.

DESIGN

Twenty-five patients undergoing open reduction of a unilateral displaced fracture of the zygoma and/or repair of a blow-out fracture of the orbit with cranial bone grafts were placed into a radiolucent head holder and interfaced with the mobile scanner. Spatial vectors were drawn on scans displayed on a computer monitor to allow intraoperative side-to-side comparison of the position of the malar prominences and orbital walls. Corrections of fracture reduction or bone graft position were made as indicated by the comparisons.

RESULTS

All scans were accomplished without apparent contamination of the surgical field. Major revisions were performed, based on the scans, in 2 patients whose displaced, comminuted zygoma fractures had been initially reduced with wide exposure of all fracture sites. Minor revisions were performed in 3 patients with displaced but less severely comminuted fractures that had been reduced without exposure of all fracture sites. Bone grafts were repositioned within the orbit in 2 patients with large 2-wall blow-out fractures.

CONCLUSIONS

Intraoperative computed tomographic evaluation of the adequacy of repair of orbitozygomatic fractures is feasible with the mobile computed tomographic scanner. The scanner allows correction of discrepancies in position of the malar prominences and orbital walls at the time of acute repair, rather than during costly, more difficult delayed revisions. It may eliminate the need for direct visualization of all fracture sites to ensure adequate reduction in selected cases with displaced, comminuted fractures, thus decreasing operating room time and expense. Further study is required to fully document the cost-effectiveness of this approach to facial fracture management.

CT findings of hydatid cyst with unusual location: infratemporal fossa

Hydatid disease has a high incidence in the countries of the temperate zones such as Turkey. Only few cases in the head and neck region have been reported in the literature. Our case, an unusual localization of hydatidosis, i.e. hydatid disease of the infratemporal fossa of a 9-year-old male patient suffering from a swelling of the left maxillary region which was diagnosed by CT, is presented. The lesion visualized on CT images was compressing the neighbouring structures. The possible diagnosis was made based on the images obtained from CT examination.

Orbital reconstruction with individually copy-milled ceramic implants

Diagnostic advances such as computed tomography and new surgical techniques have dramatically improved both the functional and aesthetic outcome of orbital reconstructions. Taking a further approach, we designed ceramic implants (Bioverit) on the basis of stereolithographic models. After copy milling a resin template with a commercially available dental unit (Celay), the prefabricated implants were inserted for reconstruction of the lamina papyracea (n = 1), zygomatic complex (n = 2), infraorbital floor (n = 5), and rim (n = 3). Intraoperatively, only slight modifications of the implants had to be performed. The results were encouraging, as all cases showed a good aesthetic and functional postoperative outcome. Preoperative evaluation of the osseous defect and prefabrication of the required implant reduced operating time and patient morbidity significantly.

Aneurysmal bone cyst of the zygomatic arch

We present a case of aneurysmal bone cyst in the jaw investigated with plain film, US, computed tomography (axial, precontrast) and magnetic resonance (1 Tesla, axial T1 weighted before and after Gadolinium administration, axial and coronal T2-weighted after Gadolinium administration). The zygomatic arch is a very rare location for an aneurysmal bone cyst: as far as we know, only a few cases are found in the literature.

LeFort I orbitotomy: a new approach to the inferonasal orbital apex

Numerous approaches to the orbit have been elegantly described in the literature. One area of the orbit that remains difficult to approach with standard techniques is the inferonasal apex. We describe a new surgical procedure we have termed the LeFort I orbitotomy. The technique involves creation of a LeFort I osteotomy to separate the maxilla from the zygoma and nose bilaterally. The posterior inferomedial orbital bone is then removed and the periorbita opened. This approach allows a more direct, less tangential view to this area of the orbit than does a Caldwell-Luc approach. Wider access for tumor manipulation is gained than would be possible with a transnasal endoscopic approach. An illustrative case report is presented.

Computer-aided navigation in secondary reconstruction of post-traumatic deformities of the zygoma

Augmented reality technology was used in 5 patients for secondary reconstruction of post-traumatic unilateral deformities of the zygomaticomaxillary complex. Three electromagnetic sensors interfaced to a computer-aided navigation system (ARTMA Biomedical Inc.) were utilized. The computer navigation procedure was planned by drawing graphic lines on the CT scan at the level of the zygomatic arch, representing the outer surface of the zygoma. The desired position of the displaced zygoma was planned by mirroring from the healthy side, using a virtual mid-sagittal plane. These virtual graphics were presented intraoperatively on a TV monitor and also on the surgeon's see-through head-mounted display. Correct reduction was assumed when the virtual line representing the position of the zygoma before the osteotomy reached the virtual line defined preoperatively as the desired position. The advantages of the technique presented are that a complete exposure of the zygomatic bone is no longer necessary, and coronal and subciliary incisions may be avoided unless enophthalmos correction has to be carried out, which was in fact necessary in 2 patients. The results of zygomatic reconstruction have been satisfactory in all 5 patients.

Reduction malarplasty

One of the most frequently requested facial contour improvement procedures in the Orient is reduction malarplasty. However, until recently, osteotomies in the malar region have been performed by means of a coronal incision that required a larger incision and more invasive procedure than many patients are comfortable with when considering an elective cosmetic surgical procedure. We have developed a reduction malarplasty method to improve facial contours that circumvents the drawbacks inherent in the conventional method. In our method, the protrusion in the cheekbone area is corrected by performing an osteotomy of the zygoma through an intraoral incision and an osteotomy of the zygomatic arch through a small preauricular incision.

Use of hydroxyapatite for reconstruction after surgical removal of intraosseous hemangioma in the zygomatic bone

Two rare cases of intraosseous hemangiomas in the zygomatic bone that were repaired after surgical removal of the tumor with hydroxyapatite implants are reported. Case 1 is a 42-year-old woman, and case 2 is a 46-year-old man. They complained of swelling in the right cheek. An intraosseous tumor in the right zygomatic bone was observed in both patients. The tumor was resected, and hydroxyapatite was employed to repair the defect caused by removal. After 4 years since the operation in case 1 and 8 months in case 2, the patients show satisfactory cosmetic appearance. Hydroxyapatite implant was useful for reconstruction of the defect after surgical removal of hemangiomas in the zygomatic bone.

Endoscopic repair of a complex midfacial fracture

Inadequate treatment of complex midfacial fractures involving the orbit and zygomatic arch can result in important functional and aesthetic deformity. Accurate repair of fractures at the zygomatic arch and orbital floor has traditionally necessitated coronal scalp and lower eyelid incisions respectively. Complications such as facial nerve injury, alopecia, external scarring, ectropion, and eyelid edema have been associated with these traditionally open surgical techniques. We report an endoscopic-assisted technique of open reduction and rigid fixation of a complex midfacial fracture. The endoscopic-assisted technique facilitated the anatomic repair of associated zygomatic arch and orbital floor fractures. The technique minimized ocular globe manipulation and eliminated the need for coronal scalp and lower eyelid incisions.

Normal eruption of the maxillary canine quantified in three dimensions

The normal eruption path of maxillary canine teeth was quantified on annual lateral and depressed postero-anterior cephalometric radiographs of 15 females and 15 males aged 5-15 years. The lateral view was rotated so that the horizontal coincided with the Frankfort plane on the depressed views, thus orientating the two views in space. Successive positions of canine cusps were marked on tracings of both views superimposed on the anterior outline of the zygomatic process. All positions of the canine cusps were digitized and the horizontal, vertical and lateral annual differences found by subtraction, taking the first position of the canine as the origin. The chronological data were corrected for enlargement and adjusted to increments of 12 months. Adjustments were also made to take into account varying ages of eruption. Posterior movement occurred between 7 and 13 years (all three years before eruption, the year of eruption and the following year). Vertical movement occurred between 5 and 13 years (all of the six years before eruption, the year of eruption and the following year). Lateral movement tended to be in a palatal direction up to 2 years before eruption followed by significant buccal movement in the year before eruption, the year of eruption and the following year. Data are given for eruption in three planes.

Effects of experimental unilateral condylectomy followed by altered mandibular function on the maxilla and zygoma

The effect of protruded mandibular function on the maxilla and zygoma was studied in young unilaterally condylectomized growing rats. Forty-eight-4-week-old rats were divided into two experimental and two control groups as follows: group A, 12 animals unilaterally condylectomized on the right side; the mandible was allowed to function normally; group B, 12 animals unilaterally condylectomized on the right side; the mandible was protracted forwards immediately by means of an appliance; group C, 12 animals sham-operated on the right side; no condylectomy or mandibular protraction; and group d, 12 control animals not subjected to any operation or mandibular protraction. The mandibular protraction was achieved by an appliance consisting of an acrylic collar brace fitted to the animal's neck and supporting rubber bands pulling on an intraoral part cemented on the animal's lower incisors. Twenty-five grams of pulling force and protrusion to a clinically and radiographically testes anterior crossbite was exercised for 12 hours per day. The experimental period was 30 days. Lateral and dorsoventral radiographs were taken on days 1 and 30 following condylectomies and mandibular protraction. Cephalometric analysis was performed for each animal with measurements evaluating the maxilla and zygoma. Statistical analysis and comparison of the findings in the four groups of animals can be summarized as follows: (i) condylectomy and altered mandibular function may produce remote skeletal reactions in other parts of the cranial complex; and (ii) the ipsilateral maxilla is affected by condylectomy of the mandible, but altered mandibular function by protraction compensates for the results of condylectomy.