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Biomedical subjects

C Cutting

Publications and source records attributed to C Cutting.

At least 19 recordsLinked to original sources
PubMed2002

Use of three-dimensional computer graphic animation to illustrate cleft lip and palate surgery.

OBJECTIVE: Three-dimensional (3D) computer animation is not commonly used to illustrate surgical techniques. This article describes the surgery-specific processes that were required to produce animations to teach cleft lip and palate surgery. MATERIALS AND METHODS: Three-dimensional models were created using CT scans of two Chinese children with unrepaired clefts (one unilateral and one bilateral). We programmed several custom software tools, including an incision tool, a forceps tool, and a fat tool. RESULTS: Three-dimensional animation was found to be particularly useful for illustrating surgical concepts. Positioning the virtual "camera" made it possible to view the anatomy from angles that are impossible to obtain with a real camera. Transparency allows the underlying anatomy to be seen during surgical repair while maintaining a view of the overlaying tissue relationships. Finally, the representation of motion allows modeling of anatomical mechanics that cannot be done with static illustrations. The animations presented in this article can be viewed on-line at http://www.smiletrain.org/programs/virtual_surgery2.htm. CONCLUSIONS: Sophisticated surgical procedures are clarified with the use of 3D animation software and customized software tools. The next step in the development of this technology is the creation of interactive simulators that recreate the experience of surgery in a safe, digital environment.

Child↗
PubMed1998

Presurgical columellar elongation and primary retrograde nasal reconstruction in one-stage bilateral cleft lip and nose repair.

We present a new combined approach to primary bilateral cleft lip, nose, and alveolus repair using presurgical nasoalveolar molding combined with a one-stage lip, nose, and alveolus repair. Presurgical alveolar molding is used to bring the protruding premaxilla back into proper alignment with the lateral segments in the maxillary arch. Presurgical nasal molding produces tissue expansion of the short columella and nasal lining. A coordinated surgical approach involves a one-stage repair of the lip, nose, and alveolus. The nasal repair uses a retrograde approach in which the prolabial flap and columella are reflected over the nasal dorsum by continuing the dissection behind the prolabium up the membranous septum and over the septal angle. Tissues are dissected out from between the tip cartilages, and the domes are sutured together in the midline. This method joins a new class of bilateral cleft repairs that place the primary emphasis on correction of the deformity of the nasal tip cartilages.

Alveolar Process↗
PubMed1998

A virtual reality system for bone fragment positioning in multisegment craniofacial surgical procedures.

This article reports our clinical experience since 1994 with rigid-motion tracking of bone fragments during craniofacial surgical procedures, using a virtual reality approach. Three noncollinear infrared diodes are fixed to the skull base. A pointer is used to register anatomic features on the patient to those on the computerized tomography-based model of the patient within a computer work station. Three diodes are then attached to each fragment just before the osteotomy is completed. Rigid motions of the fragment are thus tracked and reported to the surgeon by using virtual reality techniques. Errors in fragment positioning are reported both graphically and numerically with respect to a precomputed optimum fragment position. This guidance system allows multisegment midface osteotomies to be performed more precisely. The main problems encountered so far have been devascularization-infection and difficulties in maintaining correct position during application of rigid fixation. Devascularization-infection problems have been addressed by minimizing surgical exposure of the bone. Soft-fixation plates and temporary Kirschner wire fixation have helped with intermediate positioning, but an intraoperative mechanical positioning device would be useful in the future.

Adolescent↗
PubMed1995

Sympathetic blockade of isolated rat hindlimbs by intra-arterial guanethidine: the effect on blood flow and arterial-venous shunting.

In order to improve the understanding of the role of sympathetic nerve degeneration in reimplantation failure, the hindlimbs of eight rats (Group I) underwent near-complete amputation. The soft tissues of the hindlimb were transected at the proximal thigh with the femoral artery, vein and femur left intact. The femoral vessels were clamped and guanethidine was infused into a branch of the femoral artery of the right leg of each animal, while saline was injected into the left leg. The clamps were removed after 15 minutes. A baseline preoperative injection of radiolabeled microspheres was made, and subsequent injections at 6, 12, 18, and 24 hours postoperation. Twelve rats (Group II) were then used to assess the amount of arterial-venous shunting preoperatively (n = 6) and at 18 hours postoperation (n = 6), by venous sampling. Blood flow to both limbs increased postoperation, but there was significantly more flow in the guanethidine treated limb at 18 and 24 hours postoperation. The amount of shunting was approximately 50% in both limbs at 18 hours, as compared to 10% preoperation. These results highlight the potential benefit of guanethidine and other sympathetic blocking agents in reimplantation to increase blood flow, decrease tissue ischemia and increase anastomotic patency rates. They also suggest that sympathetic nerve degeneration did not affect the volume of arterial-venous shunting in this model, but the difference in blood flow was likely due to arteriolar vasospasm. Further study is needed to elucidate the clinical significance of sympathetic nerve degeneration in reimplantation failure.

Animals↗
PubMed1995

A three-dimensional smooth surface analysis of untreated Crouzon's syndrome in the adult.

This study compares the three-dimensional smooth surface shape of five adult patients with Crouzon's disease with nine normal skulls. A new analysis method is described which is based on smooth surface curvature. Surface samples are subdivided by a common ridge curve structure. Three-dimensional images of an average normal and an average Crouzon skull are illustrated. Comparisons between groups are performed on landmarks, as well as ridge curve and surface patch midpoints. There was as much discriminant information in the ridge curves and surface patches between landmarks as there was at the landmarks themselves. When compared with normal samples, the Crouzon's syndrome sample exhibits the following major characteristics: The midface is concave and wide, with the piriform aperture in the center more recessed than the perifery of the midface. The forehead is recessed above a frontal sinus bulge. The orbits are shallow, wide, concave, and tilted inferiorly with a mild hypertelorism. These data suggest that advancement of large, one-piece osteotomy segments will not produce a normal face, and a multisegment approach should be considered.

Adolescent↗
PubMed1993

The prolabial unwinding flap method for one-stage repair of bilateral cleft lip, nose, and alveolus.

This paper describes a one-stage reconstruction of the complete bilateral cleft lip, nose, and alveolus using an asymmetrically designed prolabial flap. The columella of the nose and the central lip are produced by "unwinding" the columellar and labial sections of the prolabium around a small central tab, which is used to center the junction between the lip and columella. Only two scars are produced, both of which run vertically along each philtral column. Accurate preoperative orthopedics without lip adhesion is considered essential to this repair. The principal advantage/disadvantage to the method is its asymmetrical design. If asymmetries result, they have been easily corrected. Eight consecutive cases are presented with follow-up ranging from 1.5 to 6.3 years.

Alveolar Process↗
PubMed1988

The three-dimensional cephalogram: theory, technique, and clinical application.

The Broadbent-Bolton cephalostat produces intrinsically three-dimensional information about cranial form. Yet in the clinical setting, this information has been used primarily two dimensions at a time in the separate study of lateral or posteroanterior cephalograms. In this article we demonstrate an expedient use of existing cephalostat-based data sets to derive certain analyses of three-dimensional form. The technique is essentially the same as that of the Broadbent-Bolton "Orientator," an exploitation of the geometry of the cephalostat to simulate stereophotogrammetry. The three-dimensional method supports the usual biometrics of landmark locations, and takes advantage of a normative data base that is suited for semiautomatic analysis of syndromic data. The principal drawback of the method is its inability to represent curving form in three dimensions. However, in comparison with computed tomography (CT), it involves low radiation dose, is simpler to obtain, has an available normative data base, and is more practical for quantitative or long-term serial analysis.

Biometry↗
PubMed1987

Reconstruction of mandibular and floor of mouth defects using the trapezius osteomyocutaneous flap.

The trapezius osteomyocutaneous island flap has evolved in postablative head and neck reconstruction as a versatile and hardy local flap which can provide intraoral lining, well-vascularized bone, and muscle bulk for the reconstruction of a complex defect. This investigative study examines the anatomy of 20 osteomyocutaneous flaps in 10 fresh cadavers and in 8 clinical patients. In our series, 80 percent (type I) of the major vascular pedicle arose from the thyrocervical trunk. In 20 percent (type II), the major pedicle arose separately from the subclavian artery. The regions perfused by the vascular trunk were further examined with microopaque and Prussian blue injections through the transverse cervical artery. Consistent areas of cutaneous staining as well as bony staining were noted over the shoulder, arm, and back and into the scapula itself. Experience with eight clinical applications of this osteomyocutaneous flap resulted in successful healing with an excellent aesthetic and functional result. Long-term follow-up was maintained on the patients for up to 36 months. Panorex radiographs and biopsies of the grafted bone were obtained on several patients. These disclosed evidence of bony remodeling and viable bone tissue. Tetracycline labeling also revealed evidence of active bony turnover.

Cadaver↗
PubMed1986

Three-dimensional computer-assisted design of craniofacial surgical procedures: optimization and interaction with cephalometric and CT-based models.

A computer program is described which aids the clinician in planning craniofacial surgical procedures. It operates on a three-dimensional landmark data base derived by combining posteroanterior and lateral cephalograms from the patient and from the Bolton normative standards. A three-dimensional surgical simulation program based on computerized tomographic (CT) data is also described which can be linked to the cephalometrically based program. After the clinician has selected the number and type of osteotomies to be performed on the patient, an automated optimization program computes the postoperative positions of these fragments which best fit the appropriate normal cephalometric form. The clinician then interactively modifies the design to account for such variables as bone-graft resorption, relapse tendency, occlusal disparities, and the condition of the overlying soft-tissue matrix. Osteotomy movement specifications are easily transferred between the CT-based and the cephalometrically based surgical simulation programs. This allows the automated positioning step to be performed on the cephalometrically based model while the interactive step is performed using the superior image provided by the CT-based model.

Cephalometry↗
PubMed1985

The median forehead flap revisited: the blood supply.

In 6 fresh cadavers, an injection study of the facial vessels with disulfine blue dye and Microfil demonstrated visualization of large-caliber vessels of the median forehead skin even when the supraorbital and supratrochlear vessels were interrupted. The results of the study would suggest that the median forehead flap can be elevated without incorporating the supratrochlear vessels, but the flap design should be reserved for those clinical situations where the pedicle must be extensively mobilized, e.g., reconstruction of the nasal tip and columella and the presence of a low-lying frontal hairline.

Angiography↗
PubMed1982

The significance of distal arteriovenous shunting on skin flap survival an experimental study in pigs.

Skin flap survival was studied experimentally in porcine flaps of constant width and varied lengths. No significant differences in flap surviving lengths were noted between 4 by 12 cm and 4 by 18 cm flaps. The concept that arteriovenous shunting in the distal portion of the flap adversely affects flap survival leads to the expectation longer flaps will have shorter surviving lengths than shorter flaps of the same width. Results of this study contradicted this hypothesis. If skin flap survival is determined by a progressive decrease in perfusion pressure as distance from the base of a flap increases, then vascular demand distal to the line of capillary perfusion should be of no consequence. Results of this study are consistent with this hypothesis.

Animals↗
PubMed1982

Critical closing pressure, local perfusion pressure, and the failing skin flap.

A simple apparatus was devised to perfuse the rat groin flap to study the relationship between perfusion pressure and flow. Results demonstrate that a relatively high intraarterial pressure must be applied to this skin flap before blood flow will commence. Results suggest that this critical closing phenomenon is the result of surface tension, blood rheology, venous pressure, tissue pressure, and vascular smooth muscle tone. Correlating the experiments of Milton and Landis reveals that, beyond a certain distance, local perfusion pressure in a skin flap gradually decreases with increasing distance from the flap base. These observations suggest that the perfusion boundary in a skin flap forms at the point where perfusion pressure has fallen to the level of the critical closing pressure. Methods of increasing survival length of a flap by decreasing critical closing pressure are discussed. The effects of edema and pressure dressings on flap and replant survival are examined in terms of the closing pressure concept.

Animals↗
PubMed1982

Changes in quantitative norepinephrine levels in delayed pig flank flaps.

A quantitative norepinephrine assay was used to follow tissue norepinephrine concentrations serially in bipedicle delayed pig flank flaps. In contrast to a previous study by Palmer, norepinephrine concentration decreased significantly after 24 hr, but then gradually returned to normal at 10 days. This suggests that the pig flank flap maintains much of its adrenergic innervation following bipedicle delay. It appears unlikely that adrenergic denervation explains the delay phenomenon in this model. The combined results of this study and others suggest that the degree of adrenergic denervation of a flap is determined by the anatomic layout of the flap with respect to the underlying cutaneous adrenergic neural anatomy. This experiment suggests that the effectiveness of adrenergic blocking agents in improving flap survival is dependent on the degree of adrenergic denervation of the flap.

Animals↗