Sharon E. Fox

The use of silk-based devices for fracture fixation

Metallic fixation systems are currently the gold standard for fracture fixation but have problems including stress shielding, palpability and temperature sensitivity. Recently, resorbable systems have gained interest because they avoid removal and may improve bone remodelling due to the lack of stress shielding. However, their use is limited to paediatric craniofacial procedures mainly due to the laborious implantation requirements. Here we prepare and characterize a new family of resorbable screws prepared from silk fibroin for craniofacial fracture repair. In vivo assessment in rat femurs shows the screws to be self-tapping, remain fixed in the bone for 4 and 8 weeks, exhibit biocompatibility and promote bone remodelling. The silk-based devices compare favourably with current poly-lactic-co-glycolic acid fixation systems, however, silk-based devices offer numerous advantages including ease of implantation, conformal fit to the repair site, sterilization by autoclaving and minimal inflammatory response.

Neural processing of facial identity and emotion in infants at high-risk for autism spectrum disorders.

Deficits in face processing and social impairment are core characteristics of autism spectrum disorder. The present work examined 7-month-old infants at high-risk for developing autism and typically developing controls at low-risk, using a face perception task designed to differentiate between the effects of face identity and facial emotions on neural response using functional Near-Infrared Spectroscopy. In addition, we employed independent component analysis, as well as a novel method of condition-related component selection and classification to identify group differences in hemodynamic waveforms and response distributions associated with face and emotion processing. The results indicate similarities of waveforms, but differences in the magnitude, spatial distribution, and timing of responses between groups. These early differences in local cortical regions and the hemodynamic response may, in turn, contribute to differences in patterns of functional connectivity.

Delayed hypersensitivity reaction to acellular dermal matrix in breast reconstruction: the red breast syndrome?

BackgroundAcellular dermal matrix (ADM) has become a valuable tool in reconstructive breast surgery, in part because it has been considered to be a non-reactive and non-immunogenic entity. However, some patients who undergo breast reconstruction with ADMs develop postoperative erythema overlying their ADM grafts. The etiology of this phenomenon is poorly understood. MethodsIn this article, we summarize clinical cases in which patients developed localized breast erythema following reconstruction with ADMs. We review what is known about postoperative breast erythema after ADM-based breast reconstructions and the possible antigenicity of biologic mesh implants. ResultsWe report 4 implant-based breast reconstruction patients who developed erythematous reactions overlying the region where ADM was placed: one demonstrated a delayed-type hypersensitivity reaction on punch biopsy of the affected skin, leading to removal of the biologic product; 2 others had a similar clinical presentation that responded to corticosteroids without removal of the biologic material, with 1 patient experiencing recrudescence of erythema that responded fully to a second course of corticosteroids; and a fourth showed erythema that was only moderately responsive to antibiotic therapy but which improved consistently after the patient initiated chemotherapy. ConclusionWe propose that the etiology of erythema overlying ADM grafts, and the so-called red breast syndrome, may in some patients be a delayed-type hypersensitivity reaction to the ADM product. Affected patients may benefit from treatment with corticosteroids or similar medications, and that such treatment may, in some cases, enable patients to retain the ADM grafts and enable salvage of the reconstructed breast.

Neural processing of repetition and non-repetition grammars in 7- and 9-month-old infants.

An essential aspect of infant language development involves the extraction of meaningful information from a continuous stream of auditory input. Studies have identified early abilities to differentiate auditory input along various dimensions, including the presence or absence of structural regularities. In newborn infants, frontal and temporal regions were found to respond differentially to these regularities (Gervain et al., 2008), and in order to examine the development of this abstract rule learning we presented 7- and 9-month-old infants with syllables containing an ABB pattern (e.g., “balolo”) or an ABC pattern (e.g., “baloti”) and measured activity in left and right lateral brain regions using near-infrared spectroscopy (NIRS). While prior newborn work found increases in oxyhemoglobin (oxyHb) activity in response to ABB blocks as compared to ABC blocks in anterior regions, 7- and 9-month-olds showed no differentiation between grammars in oxyHb. However, changes in deoxyhemoglobin (deoxyHb) pointed to a developmental shift, whereby 7-month-olds showed deoxyHb responding significantly different from zero for ABB blocks, but not ABC blocks, and 9-month-olds showed the opposite pattern, with deoxyHb responding significantly different from zero for the ABC blocks but not the ABB blocks. DeoxyHb responses were more pronounced over anterior regions. A grammar by time interaction also illustrated that during the early blocks, deoxyHb was significantly greater to ABC than in later blocks, but there was no change in ABB activation over time. The shift from stronger activation to ABB in newborns (Gervain et al., 2008) and 7-month-olds in the present study to stronger activation to ABC by 9-month-olds here is discussed in terms of changes in stimulus salience and novelty preference over the first year of life. The present discussion also highlights the importance of future work exploring the coupling between oxyHb and deoxyHb activation in infant NIRS studies.

Delayed division of the thoracodorsal nerve: a useful adjunct in breast reconstruction.

Breast reconstruction utilizing the latissimus dorsi musculocutaneous flap with an underlying breast implant is a well-established technique. Postoperative shoulder limitation is usually limited if at all noticeable. The muscle itself may, however, remain active in the new anterior position. Many patients find the muscle twitches with extension of the humerus, despite the anterior translocation of the muscle. This leads to a disturbing contraction, superolaterally, of the entire reconstruction. In addition, the resting tone can lead to a sense of tightness, despite a lack of clinically obvious capsular contracture. Division of the thoracodorsal nerve during initial flap elevation can prevent this problem. When raising the routine flap however, the pedicle itself is often not visualized and there is anxiety related to dividing the nerve and accidentally injuring the vascular pedicle. In addition, many of the transferred muscles atrophy, thereby avoiding this potential problem. When the muscle remains active, delayed division of the thoracodorsal nerve via a 2.5-cm axillary incision will stop the active twitching, decrease the resting tone of the muscle, and in most patients offer significant relief from symptoms of tightness. During the past 2 1/2 years, 100 latissimus dorsi flap breast reconstructions in 80 patients were performed. Forty-one nerves in 28 patients have been divided, with successful denervation in 37 of the 41 reconstructions, for a success rate of 90%. Delayed division of the thoracodorsal nerve can offer relief to patients complaining of tightness and muscle activity post-latissimus flap breast reconstruction.

Equestrian-related injuries: implications for treatment in plastic surgery

Background: Equestrian activities have always been popular in the United States. As safety guidelines have become more stringent, horse-related injuries have diminished by 40 percent over the past 20 years. Although perhaps less critical than in the past, injuries to equestrians most frequently involve the face, upper extremity, and lower extremity and are commonly evaluated by the plastic surgeon. The purpose of this study was to determine the characteristics of these equestrian-related injuries. Methods: The National Electronic Injury Surveillance System database is a stratified probability sample of hospitals in the United States. The database was queried for mechanisms of equestrian-related injuries, and probability estimates were obtained based on 1200 cases reported for the year 2005 in the United States. Results: Based on the National Electronic Injury Surveillance System query, the most commonly injured areas are the upper extremities, lower extremities, and face. Common mechanisms of injury include fall from a horse (60 percent), stepped on by a horse (11 percent), kicks (11 percent), and bites (3 percent). The authors present four illustrative case reports seen in their institution. Conclusions: Equestrian injuries are commonly seen by plastic surgeons. Proper evaluation of the characteristics and mechanisms of injury can lead to optimal care and outcomes.

Increased Osteoid Formation in BMP-2-Loaded Silk-Based Screws.

Background: Resorbable osteosynthesis systems are used to treat craniofacial fractures. However, conventional synthetic polyester materials are potentially associated with inflammatory reaction and negative host response and may result in incomplete bone remodeling. The authors have developed a resorbable silk fibroin–based osteosynthesis system and propose that silk screws loaded with bone morphogenetic protein-2 (BMP-2) may exhibit biocompatibility and promote bone remodeling. Methods: Resorbable silk screws were prepared and loaded with BMP-2. The BMP-2–loaded and nonloaded silk screws were inserted into the distal femora in 15 Sprague-Dawley rats by self-tapping, similar to conventional metal systems. Animals were euthanized after 1, 3, and 6 months. The femora were explanted at the designated time points, dissected for histologic evaluation, and compared regarding osteoid formation and inflammatory response. Results: Increasing organization of newly formed bone tissue was observed over time in both groups. No appreciable difference in inflammation was noted between the BMP-2–loaded and nonloaded silk screws. Notably, mineralized collagen around the periphery of the screw appears to be greatest and more organized in the BMP-2–loaded samples. There was greater recruitment of osteoclasts and osteoblasts around the perimeter of the BMP-2–loaded screws at 3 and 6 months. Conclusions: The BMP-2–loaded silk-based fixation device in this study exhibited characteristics comparable to the current nonloaded silk screws with regard to integration and biocompatibility. However, functionalization of silk screws with BMP-2 appeared to allow for more organized collagen and osteoid deposition after 3 and 6 months and may increase the potential of successful remodeling.

Functional MRI To Evaluate “Sense of Self” following Perforator Flap Breast Reconstruction

Background Breast reconstruction is associated with high levels of patient satisfaction. Previous patient satisfaction studies have been subjective. This study utilizes functional magnetic resonance imaging (fMRI) to objectively evaluate “sense of self” following deep inferior epigastric perforator (DIEP) flap breast reconstruction in an attempt to better understand patient perception. Methods Prospective fMRI analysis was performed on four patients before and after delayed unilateral DIEP flap breast reconstruction, and on four patients after immediate unilateral DIEP flap breast reconstruction. Patients were randomly cued to palpate their natural breast, mastectomy site or breast reconstruction, and external silicone models. Three regions of interest (ROIs) associated with self-recognition were examined using a general linear model, and compared using a fixed effects and random effects ANOVA, respectively. Results In the delayed reconstruction group, activation of the ROIs was significantly lower at the mastectomy site compared to the natural breast (p<0.01). Ten months following reconstruction, activation of the ROIs in the reconstructed breast was not significantly different from that observed with natural breast palpation. In the immediate reconstruction group, palpation of the reconstructed breast was also similar to the natural breast. This activity was greater than that observed during palpation of external artificial models (p<0.01). Conclusions Similar activation patterns were observed during palpation of the reconstructed and natural breasts as compared to the non-reconstructed mastectomy site and artificial models. The cognitive process represented by this pattern may be a mechanism by which breast reconstruction improves self-perception, and thus patient satisfaction following mastectomy.