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Biomedical subjects

Stephen S Park

Publications and source records attributed to Stephen S Park.

12 recordsLinked to original sources
PubMed2006

Functional rhinoplasty: treatment of the dysfunctional nasal sidewall.

Treatment of nasal obstruction caused by nasal valve dysfunction requires a thorough evaluation of the mechanics of normal nasal anatomy and function. Surgical correction of nasal valve dysfunction is based on determining the epicenter of dysfunction, whether it is a static obstruction of the internal nasal valve or a dynamic collapse of either the external nasal valve or the intervalve area. Spreader grafts, flaring sutures, and butterfly grafts are used to widen and support the narrow internal nasal valve. Alar batten grafts will add support to the collapsing nasal sidewall seen in external nasal valve and intervalve dysfunction. Correction of dynamic collapse from paradoxical concavity of the lateral crura may be obtained from the lateral crural flip-flop graft or by reconstructing the lateral crura using cartilage grafts. A strut graft may correct dynamic obstruction caused by a malformed, easily collapsible lateral crura. This article discusses the evaluation, treatment, and correction of the dysfunctional nasal sidewall and emphasizes the avoidance of iatrogenic damage to the sidewall while performing cosmetic rhinoplasty.

Cartilage↗
PubMed2005

Lip reconstruction.

The lip presents a unique challenge to the facial plastic surgeon because of its prominent location, elegant form, and important functions. The anatomy and pathology relevant to the lip are considered herein, along with general concepts to guide lip surgery. The more common approaches to reconstructing lip defects are outlined, illustrated, and discussed.

Facial Muscles↗
PubMed2005

Rethinking auricular trauma.

OBJECTIVES/HYPOTHESIS: An unrecognized auricular hematoma can lead to a disfiguring deformity, the cauliflower ear, but it can be prevented with prompt and comprehensive management. Fine needle aspiration with pressure bandages remains the mainstay treatment but will occasionally fail. We review our experience with recurrent or recalcitrant auricular hematomas in terms of their pathophysiology and revision surgery. STUDY DESIGN: Retrospective chart review. METHODS: A review of patients undergoing surgical incision, drainage, and debridement secondary to recurrent auricular hematomas was conducted. Demographic data was collected, intraoperative notes were reviewed, and follow-up results were obtained. Our management included an open incision, aggressive debridement, and long term bolsters to the ear. RESULTS: Ten patients presented with a persistent auricular hematoma and deformity following outpatient management with either incision and drainage or fine needle aspiration. All were male with a mean age of 25 years, presenting for surgery on average 19 days following initial trauma. The location of the hematoma within this group was not limited to the potential space between the cartilage and perichondrium. The hematoma was clearly located within the cartilage itself and it is postulated that this is one of the primary reasons for initial failure. Following surgical incision and drainage there were no recurrences or complications. CONCLUSION: There is a select group of patients with refractory auricular hematomas that require more aggressive treatment over a fine needle aspiration. Open debridement is indicated for this group. The location of the hematoma, granulation tissue, and neo-cartilage is found to be within the cartilage itself rather than between the cartilage and perichondrium, thus explaining why a needle aspiration alone can be ineffective.

Adolescent↗
PubMed2004

Characteristics of tissue-engineered cartilage from human auricular chondrocytes.

This study was done to define the mechanical and histological properties of tissue-engineered cartilage (TEC) derived from human chondrocytes and to compare these findings with those of native cartilage. Chondrocytes were obtained from 10 human auricular cartilages and seeded onto a biodegradable template of polyglycolic acid and poly L-lactic acid. Each template was shaped into a 1 cm x 2 cm rectangle. The templates were implanted in athymic mice for 8 weeks. Eight human auricular cartilages were used for comparison. Mechanical analysis with a tensile testing device provided values of ultimate tensile strength (UTS), stiffness, and resilience. Statistical analysis was performed with the Student's t-test. Histological assessment was done with hematoxylin-eosin staining along with other special stains. The TEC had UTS of 2.07 MPa, stiffness of 3.7 MPa, and resilience of 0.37 J/m3. The control specimens had UTS of 2.18 MPa, stiffness of 5.11 MPa, and resilience of 0.42 J/m3. No statistical difference was found between the experimental and control groups for each of the three parameters. Histological analysis showed mature cartilage with characteristic collagen, glycosaminoglycans, and elastin in the TEC. The neo-cartilage showed slightly smaller size and more irregular distribution of chondrocytes and unique fibrous capsule formation with peripheral infiltration of fibrous tissue. This study showed that the mechanical qualities of TEC from human chondrocytes are similar to those of native auricular cartilage. It suggests that the engineered cartilage from human chondrocytes may have sufficient strength and durability for clinical uses. The histological findings revealed some differences with neo-cartilage.

Absorbable Implants↗
PubMed2004

Nasal reconstruction: the state of the art.

PURPOSE OF REVIEW: Cutaneous malignancies of the nose are common problems and create the need for nasal reconstruction within many otolaryngology practices. In spite of the fact that such reconstruction is an ancient art, there continue to be innovations and advances that allow for more predictable and functional long-term results. RECENT FINDINGS: Analyzing the nasal defect through an organized algorithm can be useful in many circumstances, especially when one needs to consider vectors of tension, minimizing alar base asymmetry, resultant scars, and preservation of the intranasal airway. Application of the principle of aesthetic subunits has greatly improved the cosmetic results for many large nasal defects, and there have been some proposals to modify the original definitions and concept. Structural reconstruction is paramount with complex defects that involve the nasal framework or with those that are located in functionally critical areas. Autogenous cartilage grafting remains the gold standard, but the use of alloplastic and homograft materials for grafting continues to be reported as an alternative. Internal lining repair is essential with larger defects and the versatility of intranasal flaps is understood, but at times not available. Other flaps have been described and may be useful on such occasions. SUMMARY: There are many considerations during nasal reconstruction, and the surgeon must be facile with a variety of options within his/her armamentarium.

Algorithms↗
PubMed2003

Surgery of the auricle.

Auricular reconstruction is a unique area of facial plastic surgery where a wide array of reconstructive options often must be considered. The external ear is unique in its aesthetic role where the normal auricle often goes unnoticed; yet even a small irregularity can stand out and become conspicuous. The reconstruction of large or total auricular defects is a combination of science and art. Two forms of auricular reconstruction are discussed: (1) those for a congenitally abnormal shape but no acquired tissue deficiency, that is, otoplasty, and (2) repairs requiring a reconstruction of discrete loss of tissue. A general algorithm is presented that can assist with flap selection and covers the techniques for grafts, framework repair, local and pedicled flaps, temporoparietal facial flaps, and auricular prostheses.

Cartilage↗
PubMed2002

Biomechanical properties of tissue-engineered cartilage from human and rabbit chondrocytes.

OBJECTIVE: To describe tissue-engineered cartilage from rabbit and human chondrocytes. STUDY DESIGN AND SETTING: Chondrocytes from rabbit and human ears were seeded onto a template and implanted for 8 or 16 weeks of in vivo incubation. RESULTS: For the 8-week and 16-week groups, the UTS for cartilage was 3.8 MPa and 3.7 MPa, stiffness was 62.4 MPa and 51.8 MPa, and resilience was 181.8 J/m(3) and 109.1 J/m(3), respectively. Experimental cartilage was significantly different from controls. From 5 human specimens, the UTS was 5.4 MPa, stiffness was 6.6 MPa, and resilience was 2.0 J/m(3). The control had UTS of 8.8 MPa, stiffness of 12.2 MPa, and resilience of 2.9 J/m(3). Histology showed mature cartilage but with a fibrovascular infiltrate and increased cellularity. CONCLUSIONS: Mechanical properties of tissue-engineered cartilage can be quantified and are less than that of controls.

Animals↗
PubMedDate not supplied

The single-stage forehead flap in nasal reconstruction: an alternative with advantages.

OBJECTIVE: To review the single-stage forehead flap for patient selection, technique, and main outcome measures. METHODS: Patients undergoing nasal reconstruction between January 1, 1995, and June 30, 2000, were reviewed from medical records, photographs, and personal communication. All work was performed in an academic medical center. RESULTS: Fifty-one patients had a forehead flap for nasal reconstruction, of which 10 (20%) were repaired in a single stage. All patients had no evidence of small vessel disease, eg, hypertension, diabetes mellitus, or tobacco use. Nasal defects were limited to the upper two thirds of the nose. The technique is modified from the original description by creating a unilateral, subcutaneous pedicle, wide undermining, and partial resection of the procerus muscle. One patient had superficial epidermolysis at the distal tip of the flap. The remaining 9 patients maintained complete viability with satisfactory outcomes. One debulking procedure was performed to the glabellar area for aesthetic reasons. The average interval for returning to work was 6.6 days compared with the minimal 3 weeks for conventional interpolated flaps. CONCLUSION: In select cases, a single-stage, island midline forehead flap can be used safely as an advantageous alternative to the conventional interpolated forehead flap.

Aged↗
PubMedDate not supplied

Effects of transforming growth factor Beta and insulinlike growth factor 1 on the biomechanical and histologic properties of tissue-engineered cartilage.

OBJECTIVE: To investigate the histologic and biomechanical properties of rabbit tissue-engineered cartilage exposed to insulinlike growth factor 1 and transforming growth factor beta. DESIGN: Controlled study. SUBJECTS: New Zealand white rabbits aged 3 to 4 weeks. INTERVENTION: A mean of 3.42 million rabbit chondrocytes were placed onto 2 x 1-cm polyglycolic/poly-L-lactic acid mesh templates. One group (n = 21) was placed in complete medium for 4 days. The experimental group (n = 19) was placed into complete medium with insulinlike growth factor 1 (50 ng/mL) and transforming growth factor beta (1 ng/mL). After 96 hours the templates were removed and implanted into the dorsum of the donor rabbit. The templates were harvested after 8 weeks and subjected to gross, histologic, and biomechanical testing. RESULTS: All samples showed histologic characteristics consistent with normal cartilage. No statistically significant differences were found with biomechanical testing between the control and experimental groups. CONCLUSION: In spite of more promising results from earlier studies, these results do not support improved histologic features or mechanical performance with the addition of insulinlike growth factor 1 and transforming growth factor beta to the chondrocyte/template complex.

Animals↗
PubMedDate not supplied

Defects of the nasal internal lining: etiology and repair.

OBJECTIVES: To analyze risk factors leading to full-thickness (FT) defects, to review methods of repair, and to present guidelines for management of aggressive basal cell carcinomas (BCCs) of the nose. DESIGN: Retrospective medical chart review of patients who underwent nasal reconstruction by the Department of Otolaryngology-Head and Neck Surgery between 1996 and 2003. RESULTS: Two hundred ten patients underwent nasal reconstruction; 183 had complete medical records and were included in this study. There were 53 patients with FT nasal defects, 38 (71.7%) of which were due to BCC. Among all patients presenting with an aggressive histologic subtype of BCC, 30.1% (22/73) developed FT defects. In contrast, 14.5% (16/100) with a nonaggressive subtype had FT involvement (P < .05). CONCLUSIONS: Internal lining defects are more likely to occur from aggressive histologic subtypes of BCC (infiltrative, morpheaform, and micronodular) than nonaggressive subtypes (P < .05). For BCCs 1 to 2 cm2 located on the nasal ala, histologic subtype is a significant risk factor for resulting in a FT defect, which should influence the method of excision (direct vs Mohs micrographic surgery) and the anticipated reconstruction. Large lesions (> 2 cm2) involving the ala have a high rate of internal lining involvement independent of pathologic subtype.

Basal Cell Carcinoma↗
PubMedDate not supplied

Transplanted tissue-engineered cartilage.

OBJECTIVE: To evaluate the feasibility of transplanting sculpted autogenous tissue-engineered cartilage (TEC) with the hope that it will retain precise 3-dimensional morphologic features after transplantation. Transplanted TEC is described in terms of the gross morphologic and histologic characteristics in contrast to pretransplanted TEC. METHODS: Synthetic scaffolds of a polyglycolic acid and poly-l-lactic acid polymer, coated with chondrocytes derived from rabbit auricular cartilage in concentrations ranging from 2.7 x 10(6)/mL to 6 x 10(7)/mL, were incubated in vivo on the dorsum of a rabbit for 8 weeks and then retrieved. The resultant TEC specimens were then sculpted into defined shapes and transplanted into a different location in the same rabbit, where they were allowed to incubate for another 8 weeks. The specimens were then retrieved and compared with the TEC before transplantation according to size, weight, and histomorphometric analysis. RESULTS: Thirteen chondrocyte-laden templates were successfully engineered to develop TEC. In each case, they were sculpted and transplanted to a different site in the same rabbit. Eight weeks after transplantation, all sculpted TEC specimens lost their original 3-dimensional morphologic features and experienced a significant decrease in mass. Histologically, the staining intensity of both hemotoxylin-eosin and safranin O was dramatically reduced following transplantation. In addition, there was a reduction in chondrocyte viability. Two consistent histologic findings were a foreign-body reaction to the synthetic polymer and ongoing cellular activity directed toward the formation of bone. CONCLUSIONS: Transplanting autogenous TEC does not allow the preservation of precise morphologic features that are needed for clinical implantation. The osteogenic progression and foreign-body reaction must also be controlled.

Animals↗