Ian T. Jackson

Midface advancement in sheep by gradual distraction: a 1-year follow-up study.

PURPOSE The purpose of this study was to find a solution to the unsatisfactory postoperative maxillary relapse after major maxillary advancement or inferior repositioning of the maxilla. MATERIALS AND METHODS Major midface advancement by gradual distraction was performed on three young adult sheep over 21 days. Using an external device, the midface was advanced 36 mm in the nasofrontal area and 43 mm in the lateral aspect of the maxilla. The apparatus remained as an external fixation device for 6 weeks after the distraction to allow better ossification. After removal of the device, a 1-year clinical and radiographic follow-up was conducted. RESULTS Direct measurements between the markers showed 2- to 3-mm relapse after 1 year. Radiologic measurements demonstrated that the relapse occurred during the first 3 months after removal of the distraction apparatus. CONCLUSION It was concluded that midface advancement by gradual distraction may obviate the need for bone grafting and offer a greater movement of bone segments with good skeletal stability.

Penetration of the skull base by dissecting keratocyst

The extensive destructive potential of the keratocyst has been well recognized but penetration of the keratocyst into the skull base is rare. 3 cases showing such aggressive behavior and rare location were seen and treated; 2 are reported in this paper. Both cases illustrate the importance of early radical treatment once the aggressive nature of keratocyst is recognized.

Midface Membranous Bone Lengthening: A One-Year Histological and Morphological Follow-Up of Distraction Osteogenesis

Abstract. Midface bone lengthening was performed on three young, adult sheep using distraction osteogenesis following osteotomy of the maxilla and mounting of an extraoral fixation device. The midface was gradually distracted, 2 mm/day, for 21 days, up to approximately 40 mm. A marked midface advancement was noted. Following a further 6 weeks of retention, the device was removed and the animals were followed for 1 year. Biopsies specimens were taken from the distracted area at the end of the distraction period, after the additional 6 weeks of retention, and finally 1 year later. A nondistracted area of the maxillary bone served as control. The specimens were analyzed histologically, histochemically, and by scanning electron microscopy for the ultrastructural pattern, mineralization, mineral content, and approximate Ca2+ concentration. Clinically and radiographically, all sheep fully bridged the experimental gap. Histologically, at the completion of distraction, collagen bundles and slender bone trabeculae oriented in the direction of the distraction could be seen. At the end of the retention period, the trabeculae thickened noticeably and were partially replaced by mature lamellar bone. At the end of 1 year and after completion of the process of remodeling, the pattern of the distracted area resembled the control area. The mineralization, as reflected by quantitative calcium analysis, compared with the nondistracted area, demonstrated a low rate of mineralization after 3 weeks of lengthening, increased 6 weeks later, and after 1 year became nearly the same as in the nondistracted area. In conclusion, distraction osteogenesis provides satisfactory quantitative and structural new bone.

An anatomical classification of maxillary ameloblastoma as an aid to surgical treatment

Maxillary ameloblastoma is a different entity from its mandibular counterpart. It is reported to behave more aggressively and have a poorer prognosis. Eleven maxillary ameloblastomas (three recurrent) are reported with a follow-up ranging from 1 month to 12 years with no recurrences. It is proposed that radical treatment of these tumours, with good reconstruction, can give satisfactory function and survival. To that end, the tumours have been classified as to their position in the maxilla and surgical resection related to this.

Spontaneous bone healing in the rabbit

&NA; Cranioplasty is the most common method for correcting cranial defects. A number of innovations have been made to optimize bone repair. Before their use in humans, extensive animal trials must be performed to establish efficacy. However, the literature provides only scant and inconsistent data regarding animal controls. The purpose of this study, therefore, was to determine the critical size cranial defect in the rabbit model. Cranial defects ranging from 0.5 to 1.5 cm were created in 18 New Zealand White rabbits. The rabbits were then killed at 9 and 18 weeks and the defects examined using CT imaging and histologic analysis to determine bone healing. It was determined that cranial defects greater than 1.5 cm failed to heal spontaneously. Thus, the critical size cranial defect in the rabbit model is 1.5 cm.

Therapeutic Embolization Angiography for Extra-Axial Lesions in the Head

Percutaneous transcatheter arterial embolization has played an increasingly important role in the management of vascular lesions in the head. Embolization can promote thrombosis within vascular tumors and malformations, reduce bleeding and decrease the need for transfusion intraoperatively, and facilitate surgical approaches to otherwise unresectable lesions. It is important for the clinician to be aware of this interventional technique because many of the patients who are considered for embolization are triaged through several different clinical areas, and much can be gained from the collaboration of the clinician, the surgeon, and the angiographer. We performed 31 therapeutic particulate embolization procedures for extra-axial head lesions in 23 patients by using flow-directed techniques. Of these procedures, 11 resulted in vascular occlusion and 15 resulted in 80 to 95% obstruction, as demonstrated by angiography. In 14 patients, embolization was performed preoperatively both to decrease blood loss and to occlude inaccessible or unresectable portions of a lesion. In nine patients, embolization was the sole means of treatment for occluding an abnormal vascular shunt. Two patients (9%) experienced a minor transient neurologic change after the procedure.

Epidermoid cyst and cholesterol granuloma of the orbit.

Epidermoid cyst and cholesterol granuloma have been confused, but these are different lesions. A case of recurrent orbital epidermoid cyst and another case of orbital cholesterol granuloma are presented in order to describe their distinct pathological, clinical and imaging characteristics and their surgical management. Advanced investigation using our custom-designed three-dimensional imaging allowed a better appreciation of the exact location, and optimal planning of the surgical treatment. The same surgical approach was used for both lesions: total resection via a coronal incision and immediate reconstruction of residual defects using skull bone grafts.

A new design of a dorsal flap in the rat to study skin necrosis and its prevention

BACKGROUND The Mcfarlane flap or dorsal pedicled flap has become the standard model for pedicled rat skin flap study but its reliability has been called to question. In the past, there were possible confounding variable with the McFarlane flap and various methods were used to adjust these variables. We have developed a new model for studying skin flap necrosis and its prevention that eliminates these confounding variables. METHODS The flap is a significant modification of the McFarlane flap where we form a blind ended pedicled tube using a 3 cm x 9 cm dorsal flap. Survival area is measured using digital photography and computer assisted analysis. This new flap is compared with the standard McFarlane flap with n=25 in each group. RESULTS The mean survival area of the new flap (15.673 cm(2)+SD3.37) is comparable with the McFarlane flap (18.904 cm(2)+SD3.79). The relative merit lies in the elimination of the confounding variable of the graft bed influence on our flap without a significant reduction in the survival area. CONCLUSION A new rat model is presented that may be used in studying the effect of various treatment modalities on pedicled skin flaps. This model has the benefit of eliminating graft bed effect without the risk of flap and wound infection or desiccation that have been encountered using other models. The new flap also has better demarcation of necrosis area in this study.

Facial lawn mower injury treated by a vascularized costochondral graft

Abstract Mandibular defects present a difficult condition to treat, especially when the condyle is involved. The method chosen for reconstruction of the missing ramus and condyle must provide facial symmetry and a functional joint. In children, there is an additional requirement of allowing facial growth to proceed normally. Autogenous costochondral rib grafts have been accepted as a satisfactory replacement for mandibular rami and condyles in adults as well as children.1,2 Several studies have shown that in children costochondral grafts have the potential to grow. However, the growth of these grafts is unpredictable, ranging from resorption to overgrowth.3–6 In 1989, Poole7 reported the use of vascularized soft tissues in the early surgical treatment of children with hemifacial microsomia. Although it is expected that vascularized costochondral grafts may provide more predictable growth than nonvascularized free grafts, this potential advantage has still to be demonstrated. This article presents the surgical treatment and follow-up of a case with an extensive facial defect caused by a riding lawn mower injury. The patient was treated with a composite transfer of a vascularized costochondral rib graft with associated soft tissue.

The volume limitation of the galeal temporalis flap in facial augmentation

Galeal temporalis flaps based on the superficial temporal vessels have been used for facial augmentation and can be extended to the contralateral side beyond the midline in order to achieve maximum volume. In five patients, the volumes of extended galeal flaps were measured intraoperatively using a water displacement method. The calculated volume varied between 28 and 38 cm3. Experience with this flap showed satisfactory results with no complications; therefore, it is concluded that the extended galeal temporalis flap may be a first choice in the correction of facial soft tissue deficits less than 40 cm3. Clinical cases are presented.