Faculty Bibliography

Bone tissue is characterized by a constant turnover in response to mechanical stimuli, and osteocytes play an essential role in bone mechanical adaptation. However, little to no information has been published regarding osteocyte density as a function of implantation time in vivo. The aim of this retrospective histological study was to evaluate the osteocyte density of the peri-implant bone in implants retrieved because of different reasons in a time period from 4 weeks to 27 years. A total of 18 samples were included in the present study. Specimens were divided into 3 groups depending on the loading history of the implants: loading between 4 weeks and 7 months (group 1); loading between 1 and 5 years (group 2); loading between 14 and 27 years (group 3). All the samples were histologically evaluated and osteocyte density was obtained using the ratio of the number of osteocytes to the bone-area (mm2 ). The osteocyte density values significantly increased in the Group 2 (1-5 years) compared with Group 1 (4 weeks-7 months), and significantly decreased in the Group 3 (14-27 years) compared to Group 2. No significant differences were detected between Group 1 and Group 3. The decrease in osteocyte density observed in samples that were in vivo for long periods of time under loading is possibly because of the fact that once the bone structure is well aligned and biomechanically competent, a lower number of osteocytes are necessary to keep the tissue homeostasis under loading. (c) 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.

The present study describes the development of a microsphere capsule based on polylactide-co-glycolide (PLGA) loaded with simvastatin that was subsequently incorporated into synthetic bone cement. The osteogenic effect of simvastatin-loaded bone cement was in a critical sized defect in vivo to test the hypothesis the biologic response would be different depending on the dosage of simvastatin applied to bone cement. Our results showed that simvastatin loaded PLGA microspheres can be successfully obtained through O/W emulsion/solvent evaporation method with appropriate morphologic characteristics and high encapsulation efficiency for incorporation in bone cements. The biodegradable characteristic of the microspheres successfully presented a slow release and the duration of the release lasted for more than 1 month. The in vivo experiment revealed that the microspheres containing simvastatin significantly enhanced bone formation in the rabbit calvaria critical size defect.

Particulate bone augmentation is an established clinical alternative to regenerate bone. However, in regions of poor bone quality or previously infected sites, the clinical outcomes are more inconsistent. For that purpose, peptides have been added to particulate materials in an attempt to render them with antibacterial properties or to improve their osseoconductivity. For instance, competence-stimulating peptide (CSP) has been studied to decrease the division rate of Streptococcus mutans. Also, the addition of a specific short amino acid sequence peptide derived from type I collagen (P-15) to the bone substitutes has been introduced in an attempt to increase its osseoconductivity. The present study hypothesized that xenogeneic graft materials with and without CSP would present improved host-to-biomaterial response when used in combination with P-15. Particulate graft materials with and without P-15, OsteoGraf with CSP and OsteoGraf, were implanted in an 8-mm rabbit calvarial defect for 4 weeks, and thereafter, histological and histomorphometrical evaluation was performed. The results showed that both OsteoGraf and CSP groups with the addition of P-15 induced bone growth towards the center of the defect. Furthermore, the addition of CSP to Osteograf showed a tendency to increase its osteoconductivity when combined with P-15. The results of the current study suggested that P-15 had some impact on osteogenesis; however, the effect differed between different bone substitute materials. Further investigation is necessary to clarify its effectiveness when used in combination with bone substitutes.

PURPOSE: A core concept in plastic surgery has been the replacement of "like-with-like" tissue. Applying this concept to the lower extremity, the anterolateral thigh (ALT) perforator flap has become a frequently used free flap for restoration of soft tissue defects involving the distal lower extremity. The objective of this study was to evaluate the rate of early postoperative complications associated with the ALT perforator free flap for coverage of high-energy traumatic open fractures of the lower extremity (Gustilo IIIB) and explore related patient risk factors. METHODS: A retrospective chart review of 74 patients undergoing free tissue transfer for lower extremity limb coverage was performed. Early postoperative complications were defined as any 1 or more of the following having occurred within 6 months from surgical reconstruction: hematoma, wound infection, deep venous thrombosis, thromboembolism, partial flap loss, complete flap loss, continued osteomyelitis, and progression to amputation occurring within the first 6 months after the injury. Statistical analyses were performed using GraphPad software. Fisher exact test was performed to identify risk factors associated with greater morbidity. RESULTS: Of all patients, 26 (35%) were identified as those habitually using tobacco product and 48 (64%) were identified as nonusers of tobacco product. Moreover, 10 patients (14%) had other risk factors for atherosclerotic disease and 64 patients (86%) did not have other risk factors for atherosclerosis. Mean (SD) time to reconstruction was 4.74 (1.3) days (range, 3-8 days). Of all defects, 34 (46%) were reconstructed using adipocutaneous flaps and 40 (54%) were reconstructed using fasciocutaneous flaps. The most frequent complication was partial flap loss or superficial epidermolysis 4 (5.4%). Fisher exact test was performed, showing that patients who used tobacco product (cigarette smokers) and had other risk factors for atherosclerosis were significantly more at risk for complications (P < 0.001). CONCLUSIONS: In this retrospective review, those patients who had a positive history of tobacco use at the time of injury and those with risk factors for atherosclerosis had a significantly increased risk of flap complications. Although this is not surprising given the vasoconstrictive effects of nicotine and the impaired blood flow to the lower extremity in patients with atherosclerosis, this study will allow the surgeon to better counsel patients who have a history of tobacco use through complex reconstruction of the lower extremity. This analysis is a preliminary investigation into the safety and efficacy of the ALT fasciocutaneous or adipocutaneous flap to reconstruct high-energy open fractures of the lower extremity.

PURPOSE: Currently, nearly 1 in 5 Americans is at least 60 years of age. Bone atrophy, decreased capacity for tissue repair, and chronic disease are known to influence fracture patterns and operative algorithms in this age group. This study presents craniofacial trauma injury patterns and treatment in an elderly population at a major urban trauma center. METHODS: Patient records were retrospectively reviewed from February 1998 through December 2010. Patients at least 60 years of age who met the inclusion criteria for craniofacial fractures identified by International Classification of Diseases, Ninth Revision code review and confirmed by author review of available computed tomograms were studied. Demographic information, fracture type, concomitant injuries, and management were recorded. RESULTS: Of 11,084 patients presenting with facial fracture, 1,047 were older than 60 years. The most common mechanism of injury was falls (50%), and most patients were men (59%). Commonly fractured areas included the nose (n = 452, 43%), maxilla (316, 30%), zygoma (312, 30%), orbital floor (280, 27%), and mandible (186, 18%), with 51 patients (5%) having a concomitant basilar skull fracture. Inpatient mortality and length of stay were significantly increased compared with the nongeriatric population (P < .01), although only 5% of all fractures were treated operatively. CONCLUSIONS: Fractures in the elderly tend to be minimally displaced midfacial fractures that do not warrant surgical intervention. Despite conservative management, the elderly are hospitalized longer than their younger counterparts, have increased critical care needs, and have higher mortality. These data support national medical preparedness in anticipating the craniofacial trauma needs of the aging US population and can be used to update treatment algorithms for these patients.

In preparation for the donor and recipient facial vascularized composite allotransplant (VCA), the marginal mandibular nerve branch should be identified and co-apted to the recipient's nerve to allow for re-innervation. We describe a method to identify the marginal mandibular branch of the facial nerve in facial VCA donors and recipients. Through cadaver dissections, the posterior facial vein was traced posteriorly to identify the marginal mandibular branch of the facial nerve. In cases where we were unable to use this relationship, we found the posterior facial venous system to be diminutive. This technique is useful for finding the marginal mandibular branch when dissecting anterograde to the parotid gland.

Use of the ulnar forearm flap (UFF) is limited by concerns for ulnar nerve injury and impaired perfusion in the donor extremity. Twenty UFFs were performed over a 6-year period. All patients underwent postoperative bilateral upper extremity arterial duplex studies. A subset of postoperative patients (n = 10) also had bilateral upper extremity sensory and motor evaluations, and functional evaluation via the Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH). Motor function was tested by digital and key grip dynamometry. Ulnar nerve sensation was tested by evaluation of one- and two-point perceived pressure thresholds and two-point discrimination using the Pressure-Specified Sensory Device (Sensory Management Services, LLC, Baltimore, MD). All UFFs were viable postoperatively. Mean follow-up was 28.8 months for vascular studies and 45.3 months for motor, sensory, and QuickDASH evaluations. Although mid and distal radial artery flow velocities were significantly higher in donor versus control extremities evaluated at less than 1 year postoperatively, there was no significant difference in extremities evaluated at later time points. Digital pressures, grip strength, key pinch strength, and ulnar sensation were equivalent between donor and control extremities. The mean QuickDASH score was 17.4 +/- 23.8. The UFF can be harvested reliably and long-term follow-up shows no evidence of impaired vascular, motor, or sensory function in the donor extremity.