Faculty Bibliography

Presently, several different graft materials are employed in regenerative or corrective bone surgery. However current misconceptions about these biomaterials, their use and risks may compromise their correct application and develop- ment. To unveil these misconceptions, this work briefly reviewed concepts about bone remodeling, grafts classifica tion and manufacturing processes, with a special focus on calcium phosphate materials as an example of a current em- ployed biomaterial. Thus a search on the last decade was performed in Medline, LILACS, Scielo and other scientific electronic libraries using as keywords biomaterials, bone remodeling, regeneration, biocompatible materials, hy- droxyapatite and therapeutic risks. Our search showed not only an accelerated biotechnological development that brought significant advances to biomaterials use on bone remodeling treatments but also several therapeutic risks that should not be ignored. The biomaterials specificity and limitations to clinical application point to the current need for developing safer products with better interactions with the biological microenvironments

Homeostasis and wound healing rely on stem cells (SCs) whose activity and directed migration are often governed by Wnt signaling. In dissecting how this pathway integrates with the necessary downstream cytoskeletal dynamics, we discovered that GSK3β, a kinase inhibited by Wnt signaling, directly phosphorylates ACF7, a > 500 kDa microtubule-actin crosslinking protein abundant in hair follicle stem cells (HF-SCs). We map ACF7's GSK3β sites to the microtubule-binding domain and show that phosphorylation uncouples ACF7 from microtubules. Phosphorylation-refractile ACF7 rescues overall microtubule architecture, but phosphorylation-constitutive mutants do not. Neither mutant rescues polarized movement, revealing that phospho-regulation must be dynamic. This circuitry is physiologically relevant and depends upon polarized GSK3β inhibition at the migrating front of SCs/progeny streaming from HFs during wound repair. Moreover, only ACF7 and not GSKβ-refractile-ACF7 restore polarized microtubule-growth and SC-migration to ACF7 null skin. Our findings provide insights into how this conserved spectraplakin integrates signaling, cytoskeletal dynamics, and polarized locomotion of somatic SCs.

This case study will describe the journey of a patient admitted to an urban, tertiary medical center for bariatric surgery and the unexpected challenges encountered by the clinical staff in caring for him. Despite having awell-established bariatric surgical program, it took only one patient who deviated from the "norm" to cause thestaff to reexamine the way that bariatric patients are cared for in the facility, particularly with regard to their mobility and safe patient handling needs. The lessons learned from this experience and the patient’s own perspective have enabled a more informed approach to how bariatric patients are cared for throughout the hospital and led to an adjustment of protocols in this area of practice

OBJECTIVE: To evaluate the biomechanical scenario of platform switching geometric implant-abutment configuration relative to standard configurations by means of finite element analysis. STUDY DESIGN: A 3D Finite Element Analysis (FEA) was performed on 3 different implant-abutment configurations: a 3.8 mm implant with a matching diameter abutment (Standard Control Design, SCD), a 5.5 mm implant with matching diameter abutment (Wider Control Design, WCD), and a 5.5mm implant with a 3.8 mm abutment (Experimental Design, ED). All the different experimental groups were discretized to over 60000 elements and 100000 nodes, and 130N vertical (axial) and 90N horizontal loads were applied on the coronal portion of the abutment. Von Mises stresses were evaluated and maximum and minimum values were acquired for each implant-abutment configuration. RESULTS: The load-induced Von Mises stress (maximum to minumum ranges) on the implant ranged from 150 MPa to 58 Pa (SCD); 45 MPa to 55 Pa (WCD); 190 MPa to 64 Pa (ED). The Von Mises stress on the abutment ranged from 150 MPa to 52 MPa (SCD); 70 MPa to 55 MPa (WCD), and 85 MPa to 42 MPa respectively (ED). The maximum stresses transmitted from the implant-abutment system to the cortical and trabecular bone were 67 Pa and 52 MPa (SCD); 54 Pa and 27 MPa (WCD); 64 Pa and 42 MPa (ED), respectively. When the implant body was evaluated for stresses, a substantial decrease in their levels were observed at the threaded implant region due to the diametral mismatch between implant and abutment for the ED configuration. CONCLUSION: The platform switching configuration led to not only to a relative decrease in stress levels compared to narrow and wide standard configurations, but also to a notable stress field shift from bone towards the implant system, potentially resulting in lower crestal bone overloading.

BACKGROUND: Most head and neck reconstructions are performed for wound closure or functional rehabilitation with aesthetic restoration being an important but secondary consideration. METHODS: Contour deformities in 40 patients undergoing head and neck resections were reconstructed immediately with adipofascial perforator flaps, including 37 anterolateral thigh and 3 deep inferior epigastric perforator flaps. RESULTS: Reconstructions could be grouped into 1 of 3 defect areas: temporal fossa (n = 3), malar cheek (n = 13), and parotid-mastoid (n = 24). The mean time needed for reconstruction in excess of the oncologic resection was 3.1 hours. There were no flap losses. In no case did a complication delay adjuvant therapy and no patient experienced a decrease in level of activity related to donor site morbidity. CONCLUSION: Immediate restoration of facial contour with adipofascial perforator flaps is warranted in head and neck oncologic patients to help improve self-image and maintain quality of life.

BACKGROUND: Unintentional injury is a leading cause of preventable mortality in elderly populations and is most often related to accidental falls and motor vehicle accidents. Hispanic ethnicity has been previously associated with decreased risk of accidental fall death as well as improved outcomes in other health states, the "Hispanic paradox." A timely analysis of national data with consideration for multiple injury types and age could provide insight into this epidemiologic phenomenon and help guide the use of prevention efforts. MATERIALS AND METHODS: Search of the Center for Disease Control's WISQARS database was performed to identify the number of fatalities in the U.S. between 2003 and 2006 by age group, gender, Hispanic ethnicity, and injury type. Total U.S. population and group populations for the years examined were obtained from the U.S. Census Bureau's American Community Survey for each year. Mortality was calculated as fatalities over the total group population for the years examined. RESULTS: Independent of gender and age group, elderly Hispanics were at decreased risk of death from accidental fall or as an occupant in a motor vehicle accident, but increased risk of pedestrian fatality compared with white-NH. CONCLUSIONS: The reduced fall and occupant mortality seen in elderly Hispanic populations may come at the cost of increased pedestrian-related mortality. This is consistent with and likely reflects differences in culture, socioeconomic status, and geographic distribution for the U.S. Hispanic population. Effective targeting of injury prevention programs, especially community based, should consider the role of Hispanic ethnicity and its impact on lifestyle.

BACKGROUND: The authors' goal was to develop an updated and comprehensive algorithm for skull base reconstruction based on data from the 10-year period following their initial report. METHODS: Reconstructive outcomes were analyzed from 250 patients undergoing skull base reconstruction from 2000 to 2009. RESULTS: Thirty-nine local or regional pedicled flap reconstructions and 211 free flap reconstructions were performed. Free flaps were usually selected over pedicled flaps for patients with a history of prior surgery, irradiation, or chemotherapy (p = 0.003, p < 0.001, and p = 0.04, respectively). Reconstructions were performed for 36 region I defects, 39 region II defects, 124 region III defects, and 51 defects involving more than one region. Complications occurred in 29.6 percent of patients. There were no significant differences in the overall complication rates between pedicled and free flap reconstructions (p = 0.70). The recipient-site complication rate decreased from 31 percent in the authors' prior report to 18.4 percent. A facial nerve repair was performed in 30 patients. By 12 months, 75 percent of patients had signs of reinnervation. Recovery was not significantly less likely in patients with preoperative weakness, postoperative irradiation, or age 60 years or older (p = 1.00, p = 1.00, and p = 0.11, respectively). CONCLUSIONS: Based on the largest series of skull base reconstructions to date, the authors recommend pedicled flaps for limited defects because of minimal donor-site morbidity and shorter operative times and hospital stays. For extensive defects and cases involving prior surgery, irradiation, or chemotherapy, free flaps are preferred. Facial nerve repair should be attempted whenever feasible, even in the setting of preoperative weakness, anticipated postoperative irradiation, or advanced age. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

BACKGROUND: Fine-needle aspiration (FNA) biopsies are the most accurate method for diagnosis of thyroid nodules. Unfortunately, biopsies are indeterminate 15-30% of the time and surgery is thus required for a definitive diagnosis. We aimed to determine whether specific descriptors of cytologic atypia mentioned in indeterminate FNA reports were associated with malignancy on final histopathology. METHODS: Retrospective review of 1000 surgery patients identified 466 indeterminate FNA lesions that underwent either a hemi- or total thyroidectomy between 1998 and 2009. We screened FNA reports for specific descriptors of nuclear atypia. Univariate and multivariate analyses were performed to evaluate the independent effect of cytologic atypia descriptors on the risk of malignancy. RESULTS: Nuclear atypia on FNA conferred a risk of malignancy of 42% (P < 0.0001). Risk of malignancy increased from 17% for zero descriptors to 81.2% when four or more descriptors of atypia were described. Nuclear grooves and inclusions together conferred a risk of malignancy, specificity, and false positive rate of 79.3%, 98.2% and 1.8% respectively. CONCLUSIONS: The presence of four or more descriptors of cytologic atypia or the presence of both nuclear inclusions and grooves together confers a high risk of malignancy on final histopathology and a low false positive rate. These findings should be taken into consideration when interpreting FNA reports and total thyroidectomy should be considered for those patients at higher risk.

PURPOSE: We evaluated the operative time of microdissection testicular sperm extraction in successful and failed procedures to identify the chance of sperm retrieval during longer microsurgical procedures. MATERIALS AND METHODS: A total of 793 men with nonobstructive azoospermia underwent a first attempt at microdissection testicular sperm extraction from January 2000 to September 2009. Clinical factors were analyzed, including age, testicular volume, endocrinological data and histology. Operative time was calculated from incision until the procedure was terminated. RESULTS: Testicular sperm were successfully retrieved in 57% of the men. Sperm were found within 2, 2 to 4 and 4 to 7 hours in 89%, 30% and 37% of the men, respectively. There were no differences in preoperative clinical characteristics, age, follicle-stimulating hormone, testicular volume, incidence of a Klinefelter's syndrome diagnosis and distribution of most advanced histopathology in patients in the 3 operative time groups. In men in whom sperm were retrieved the clinical pregnancy and live birth rates were 48%, 45% and 29%, and 37%, 30% and 29% for operative times up to 2, 2 to 4 and 4 to 7 hours, respectively (p >0.05). ROC curve analysis of the different operative times for detecting sperm showed that 125 minutes was the most accurate time (AUC 0.81) with 84% sensitivity and 95% specificity. CONCLUSIONS: The chance of sperm retrieval during microdissection testicular sperm extraction was best during the first 2 hours of the operation. However, sperm were still found in up to 37% of men who required greater than 4 hours of microdissection. Retrospective analysis of our data indicated no cutoff point after which sperm retrieval was uniformly unsuccessful.