The early use of a perforator flap of the lateral lower limb in maxillofacial reconstructive surgery.

The development of perforator-based flaps led to new donor sites and enlarged the spectrum of recipient vessels using arteries and veins of very small calibres. Although these flaps, which are directly anastomosed at their terminal cutaneous branches, are becoming more and more important for reconstructions in other regions of the body, perforator-based flaps have not played an important role in maxillofacial surgery until now. This study reports the experience with 24 consecutive perforator flaps from the lateral lower limb for intra- and extraoral defect coverage. Septo- or myoseptocutaneous perforators from the peroneal artery served as the flap pedicle having a length of 4-7 cm and diameters of 1-2 mm. Indications were reconstructions of the floor of the mouth (10), soft palate (3), tongue (6), closure of perforating cheek defects (2) and reconstruction of the facial skin (3). Anastomoses were performed to the lingual, facial, temporal or thyroid superior artery. Except for 2 cases, all perforator-based flaps were healed well and the morbidity of the donor site was nearly negligible. According to the early experience in this study, perforator-based flaps from the lateral lower limb may have an indication if recipient vessels available are close to the defect and if very low donor site morbidity is important to the patient.

Histology of the porcine mandibular distraction wound.

The purpose of this study was to document the progression and pattern of endosteal bone formation in a porcine mandibular distraction wound. Bone formation was assessed in a 0-day latency model (n=24 pigs) using distraction rates of 1, 2, or 4 mm/day to create a 12-mm gap. Macro-radiographs and sagittal histologic sections, from the center of the mandible, were evaluated by computer morphometrics (% bone fill) and by a semi-quantitative bone formation score. Mean percent area of new bone was 12.4% (0-25.9%), 7.5% (0-21.3%) and 3.8% (0-10.5%) in mandibles distracted at 1, 2 or 4 mm/day respectively. At all time points, percent area of new bone was highest in mandibles distracted at 1 mm/day. Bone was deposited from the margins of the osteotomy toward the center of the wound and occurred first around the inferior alveolar canal and tooth bud regions. New bone formed by intramembranous ossification alone. The results of this experiment document the contribution of endosteal bone formation in this model of distraction osteogenesis.

Correlation of biomechanical stiffness with plain radiographic and ultrasound data in an experimental mandibular distraction wound.

The aim of this study was to determine the stiffness of a porcine mandibular distraction wound at the end of neutral fixation.Twenty-four Yucatan minipigs underwent unilateral mandibular distraction: zero-day latency, rates of 1, 2, and 4 mm per day, distraction gap of 12 mm. Radiographic and ultrasound bone fill scores at 0, 8, 16 and 24 days of neutral fixation were used to evaluate interval healing. At sacrifice, biomechanical stiffness was determined using an Instron machine to produce a downward force of 2 mm/min at the premolar occlusal surface. Force (kilo-Newton, kN) and displacement (mm) were recorded at a rate of 10,000 points/second. Stiffness across the distraction wound, plain radiographic and ultrasound bone fill scores all increased with duration of neutral fixation and were highest for the 1 mm per day group at all time points. At the end of fixation, even in the most clinically stable group, stiffness across the distraction wound was only 25.5% of control.Despite clinical stability and high bone fill scores by X-ray and ultrasound, the distraction wound did not achieve normal stiffness at the end of neutral fixation in this model. This may have implications for the management of patients who undergo large movements by distraction.

Assessment of bone formation in a porcine mandibular distraction wound by computed tomography.

The purpose of this study was to document the progression of bone formation in a porcine mandibular distraction wound, at various distraction rates and fixation times, using three-dimensional computed tomography. Bone formation was assessed in a 0-day latency model (n=24 minipigs) using distraction rates of 1, 2, or 4 mm/day to create a 12 mm distraction gap. Animals were sacrificed at 0, 8, 16, or 24 days fixation. For experimental and control sides, three-dimensional data from computed tomographic scans were used to calculate the percent bone volume in the regions of interest. Standardized plain radiographs were used to evaluate bone formation with a semiquantitative scale: 0, 1, 2, 3. Mean percent bone volume and radiographic bone fill scores (pooled sample) increased with fixation time from 16.8% and 0.17 at 0 days, to 64% and 2.0 at 24 days fixation. Mandibles distracted at 1mm/day had higher CT values and bone fill scores than mandibles distracted at 2 or 4 mm/day. At 24 days fixation, the maximum percent bone volume (64%--1 mm/day; 24 days fixation) remained below control values (81.3%). The results of this study indicate that despite high bone fill scores on plain radiographs, the highest percent CT bone volume achieved in this model was 64%.