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Biomedical subjects

O M Antonyshyn

Publications and source records attributed to O M Antonyshyn.

13 recordsLinked to original sources
PubMed2001

Postoperative infections in craniofacial reconstructive procedures.

The rate of, and possible risk factors for, postoperative craniofacial infection is unclear. To investigate this problem, we reviewed 349 cases of craniofacial skeletal procedures performed from 1996 to 1999 at our institution. Infection rate was determined and correlated with the use of implants, operative site, and cause of deformity. The inclusion criteria consisted of all procedures requiring autologous or prosthetic implantation in craniofacial skeletal sites, as well as all procedures involving bone or cartilage resection, osteotomies, debridement, reduction and/or fixation. Procedures that did not involve bone or cartilage surgery were excluded. The criteria for diagnosis of infection included clinical confirmation and one or more of 1) intravenous or oral antibiotic treatment outside of the prophylactic surgical regimen; 2) surgical intervention for drainage, irrigation, and or debridement; and 3) microbiological confirmation. Among the 280 surgical cases that fit the inclusion criteria and had complete records, there were 23 cases of postoperative infection (8.2%). The most common site for postoperative infection was the mandible (infection rate = 16.7%). Multiple logistic regression analysis revealed gunshot wound to be the most significant predictor of postoperative infection. Additionally, porous polyethylene implantation through a transoral route was correlated with a significant risk of postoperative infection.

Adult↗
PubMed2000

Spatial and temporal registration of CT and SPECT images: development and validation of a technique for in vivo three-dimensional semiquantitative analysis of bone.

UNLABELLED: The combined use of postoperative 3-dimensional CT and SPECT imaging provides a means of relating anatomy and physiology for the semiquantitative in vivo analysis of bone. This study focuses on the development and validation of a technique that accomplishes this through the registration of SPECT data to a 3-dimensional volume of interest (VOI) interactively defined on CT images. METHODS: Five human cadaver heads served as anthropomorphic models for all experiments. Four cranial defects were created in each specimen with inlay and onlay split-skull bone grafts reconstructed to skull and malar recipient sites. To acquire all images, each specimen was landmarked with 1.6-mm ball bearings and CT scanned. Bone surfaces were coated with 99mTc-doped paint. The locations of the ball bearings were marked with paint doped with 111In. Separate SPECT scans were acquired using the energy windows of 99mTc and 111In. RESULTS: Serial SPECT images aligned with an average root-mean-square (RMS) error of 3.8 mm (i.e., <1 pixel). CT-to-SPECT volume matching aligned with an RMS error of 7.8 mm. Total counts in CT-defined VOIs applied to SPECT data showed a strong linear correlation (r2 = 0.86) with true counts obtained from a dose calibrator. CONCLUSION: The capability of this multimodality registration technique to anatomically localize and quantify radiotracer uptake is sufficiently accurate to warrant further assessment in an in vivo trial.

Bone Transplantation↗
PubMed1999

Facial asymmetry: three-dimensional analysis using laser surface scanning.

This study evaluates six different techniques with respect to their ability to quantitatively describe facial asymmetry in three dimensions. Three-dimensional facial images were acquired using a Cyberware 3030RGB laser surface scanner. Image processing was performed on a Silicon Graphics Indigo computer workstation. The following techniques for facial asymmetry analysis were developed: asymmetry in the location of anthropometric landmarks, Euclidean distance matrix analysis (EDMA), scalar measurement of the lower ciliary margin and palpebral fissure area, clearance vector mapping, and determination of the volume of asymmetry. Techniques were applied and validated in three anthropometric models: a perfectly symmetrical plastic head model and a plaster head model with and without a unilateral cheek augmentation. In each of the anthropometric test models, each analytical technique was validated by means of static anthropometric facial models and was evaluated for intraobserver and interobserver reliability. Asymmetries in the location of anthropometric landmarks can be accurately determined to within 2 mm in x, y, and z directions of the Cartesian space. EDMA is a useful technique in describing both size and shape changes of discrete areas of the face. Measurement of the lower ciliary margin and palpebral fissure area is reliable. Clearance vector mapping is especially useful in quantifying facial surface asymmetries in facial areas where anthropometric landmarks are scarce. Volume of asymmetry is potentially useful in those patients for whom the use of injections or implants of known volume may be helpful in correcting unilateral facial deficiencies.

Cephalometry↗
PubMed1999

Soft tissue deformity after craniofacial fracture repair: analysis and treatment.

BACKGROUND AND OBJECTIVES: The primary repair of facial fractures requires sufficient subperiosteal dissection and mobilization of soft tissues to permit accurate fracture reduction. Improper repositioning of soft tissues predisposes the site to deformities with subsequent adverse effects on the aesthetics of the final result. The purpose of this paper is to describe these deformities, the modification of surgical approaches to avoid them, and the various techniques for secondary soft tissue reconstruction. METHODS AND MATERIALS: The paper reviews the assessment of soft tissue deformity and the principles of soft tissue reconstruction in addressing temporal contour deformity, cheek ptosis, eyelid deformities, and medial and lateral canthal dystopia. RESULTS AND/OR CONCLUSIONS: The morbidity of remote incisions and soft tissue degloving used in primary facial fracture repair can be minimized by using a meticulous technique and precise soft tissue repositioning at closing.

Cheek↗
PubMed1997

Application of a three-dimensional intraoperative navigational system in craniofacial surgery.

Recent advances in imaging technology have prompted the development of new instrumentation that permits direct interactive visualization of image data in the operating room. The ISG Viewing Wand (ISG Technologies, Mississauga, Ontario, Canada) is a frameless stereotactic system that combines three-dimensional computer-assisted imaging with a hand-guided, position-sensing, articulated arm. In this article we describe the use of the ISG Viewing Wand as a three-dimensional intraoperative navigational system in craniofacial surgery and review our initial clinical experience in 17 patients. The wand was used as an aid in the correction of craniofacial asymmetry in 12 patients and as a navigational device assisting in craniofacial skeletal resection in 5 patients. By orienting the surgeon to his exact location throughout the procedure, the ISG Viewing Wand was found to be useful in defining intraorbital anatomy, in determining ocular globe position, and in delineating tumor margins. Excellent anatomical spatial correlation was obtained, and the probe tip position was within 2 mm of its actual position in all cases. Use of the system added minimal additional time, and overall no adverse effects were attributed to use of the wand.

Analog-Digital Conversion↗
PubMed1996

Computed tomography artifacts associated with craniofacial fixation devices: an experimental study.

This study compares the artifacts caused by eight different craniofacial fixation devices in computed tomography (CT) images. Using a Teflon CT phantom model, part I of this study involved the quantitative evaluation of the X-ray absorption properties of each fixation device. Part II utilized a human cadaveric model to determine the degree to which the artifact interfered with the visualization of anatomic structures. In part I, each fixation device was secured to the surface of the phantom and then scanned. All artifacts were compared on the basis of standard deviation in CT number. The severity of the artifact was related to the physical size of the fixation device and its composition. Vitallium devices generated a greater degree of CT artifacts than titanium devices of comparable size. In part II, fixation devices were secured to the orbital rims of human cadaveric heads and then scanned. Visualization of specified anatomic structures was graded independently. The results revealed that titanium fixation devices did not cause significant bone or soft-tissue image degradation, whereas all vitallium fixation devices, except micro mesh and micro (1.0 mm) straight plates, generated an artifact that resulted in some image degradation. The extent of image degradation was related to the fixation device size. Only the thickest vitallium fixation device, mini fragmentation (2.0 mm), resulted in bony image degradation. The degree of soft-tissue image degradation decreased as the size of vitallium fixation devices decreased such that micro fragmentation (0.8 mm) and pan fixation (1.3 mm) devices interfered with soft-tissue visualization only in the immediate vicinity of the plate. The results of this study confirm the previous work of Sullivan and colleagues and Fiala and associates. The data indicate that when postoperative imaging is an important clinical consideration: (1) the fewest number of internal fixation devices should be used to achieve rigid bony fixation, (2) the proximity of fixation devices to the regions of interest should be considered at the time of fixation, (3) titanium implants produce less artifacts than vitallium implants of comparable size, and (4) vitallium micro mesh and micro (1.0 mm) straight fixation devices do not produce artifacts resulting in significant image degradation.

Artifacts↗
PubMed1995

Cranioplasty: indications, technique, and early results of autogenous split skull cranial vault reconstruction.

Since 1990, fresh autogenous split skull cranioplasty has been the preferred method of reconstructing complicated cranial defects at the Sunnybrook Hospital. Eight cases of split skull cranioplasties were reviewed to illustrate the indications and technical considerations of the procedure. Clinical factors believed to be detrimental to the outcome of split skull cranioplasty were identified by: 1) a history of an infected, failed, previous cranial reconstruction, 2) inadequate scalp or skin to cover the external surface of an anticipated skeletal vault reconstruction, 3) the communication of adjacent paranasal sinuses with the epidural space, 4) the presence of an avascular dead space posterior to the reconstructed cranium. These potentially negative influences were systematically addressed as part of the surgical routine in autogenous split skull cranioplasty.

Adult↗
PubMed1995

Temporal fascial periosteal and musculoperiosteal flaps in the pig: design and blood flow assessment.

The availability of a vascularized periosteal flap with bone-forming potential could greatly enhance the reconstructive capabilities of the craniofacial surgeon. Previous observations seem to indicate that the bone-forming potential of periosteal flaps depends on the vascularity of the flap. The purpose of the present experiment was to design temporal fascial periosteal and musculoperiosteal flaps in the pig and to compare the periosteal blood flow with unoperated periosteum in the same location. The radioactive microsphere (15-micron diameter) technique was used to measure periosteal capillary blood flow in periosteal flaps and unoperated control, randomized to each side of the head in nine pigs (Yorkshire; weight, 12-14 kg). The periosteum was (1) raised based on the temporalis muscle with vascular supply from the deep temporal vessels (n = 6), (2) raised based on temporoparietal fascia-deep temporal fascia with blood supply from the superficial temporal vessels (n = 6), or (3) left intact (n = 6). The mean periosteal capillary blood flow rates in the intact periosteum (0.107 +/- 0.001 ml/min/g), the temporal musculoperiosteal flaps (0.081 +/- 0.01 ml/min/g), and temporal fascial periosteal flaps (0.087 +/- 0.012 ml/min/g) were not significantly different. These observations indicate that the blood flows for both musculoperiosteal and fascial periosteal flaps were comparable to control intact temporal periosteum.

Analysis of Variance↗
PubMed1993

Reconstruction of composite facial defects: the combined application of multiple reconstructive modalities.

OBJECTIVE: To describe the combined use of craniofacial skeletal reconstruction, tissue expansion and microvascular free tissue transfer in the repair of major composite facial defects. DESIGN: Case series with an integrated team approach. SETTING: Craniofacial unit, university teaching hospital. PATIENTS: Three cases were selected to best illustrate the combined use of the three modalities in reconstruction of acute traumatic, congenital and post-traumatic facial defects. A 15-year-old boy had a shotgun wound to the face; a 23-year-old man had Treacher Collins syndrome; and a 55-year-old woman had a post-traumatic composite defect of the central midface. INTERVENTIONS: Preoperatively, complete neurologic, ophthalmologic and dental examinations, anthropometric analysis, prosthodontic assessment, computed tomography and computer graphics. Operatively, craniofacial exposure followed established surgical principles. Skeletal reconstruction was performed to provide accurate positioning of bony segments and three-dimensional stability. Bone grafting was used when necessary to restore bony continuity and increase stability. Tissue expansion was used to provide more locally available tissue for wound closure and resurfacing composite defects. Microsurgical free tissue transfer was used to provide functional replacement of deficient tissues. RESULTS: The results of the modalities used for reconstruction of these composite facial defects are illustrated for each case described. CONCLUSIONS: The use of multiple modalities, including craniofacial skeletal reconstruction, tissue expansion and free tissue transfer, allow the surgeon to address the specific functional and anatomical requirements associated with composite facial defects that are characterized by a combined deficiency of multiple tissues in the craniofacial region.

Adolescent↗
PubMed1992

Bending mechanics of bone grafts: an experimental study.

We compare the mechanical properties of rib and cranial grafts subjected to bending stresses and analyze the modification of those properties following miniplate fixation. Standardized side-paired rib and cranial bone samples were harvested from human cadavers. Twenty bone specimens were divided into four study groups, comprising rib and cranial grafts, with and without miniplate reinforcement. Bone segments were subjected to measured stresses in an Instrom unit with simultaneous strain recording. The stress/strain curves were analyzed to determine the modulus of elasticity, failure points, and elastic properties. Experimental findings and clinical implications are discussed.

Biomechanical Phenomena↗
PubMed1992

Dissecting folliculitis of the scalp. A case report of combined treatment using tissue expansion, radical excision, and isotretinoin.

Dissecting folliculitis of the scalp can develop into an extensive, hypertrophic scarred lesion that is unresponsive to routine treatment. In these situations, radical excision of the affected area and concurrent perioperative treatment with isotretinoin (13-cis-retinoic acid) may be effective. The authors describe a case, illustrating the successful clinical application of this technique.

Adult↗
PubMed1986

Arteriovenous fistulas after replantation surgery.

The delayed appearance of congenital arteriovenous fistula precipitated by local trauma is a rare event. However, these reports may provide some insight into pathogenetic mechanisms responsible for the opening of subclinical arteriovenous communications. This case of multiple arteriovenous fistulas in a previously "normal" hand followed a sharp, incomplete amputation at the wrist level with replantation.

Amputation, Traumatic↗