Tissue Expanders in Staged Calvarial Reconstruction: A Systematic Review.

Cranioplasties are common procedures in plastic surgery. The use of tissue expansion (TE) in staged cranioplasties is less common. We present two cases of cranioplasties with TE and systematically review literature describing the use of TE in staged cranioplasties and postoperative outcomes. A systematic review was performed by querying multiple databases. Eligible articles include published case series, retrospective reviews, and systematic reviews that described use of TE for staged bony cranioplasty. Data regarding study size, patient demographics, preoperative characteristics, staged procedure characteristics, and postoperative outcomes were collected. Of 755 identified publications, 26 met inclusion criteria. 85 patients underwent a staged cranioplasty with TE. Average defect size was 122 cm 2 , and 30.9% of patients received a previous reconstruction. Average expansion period was 14.2 weeks. The most common soft tissue closures were performed with skin expansion only (75.3%), free/pedicled flap (20.1%), and skin graft (4.7%). The mean postoperative follow-up time was 23.9 months. Overall infection and local complication rates were 3.53 and 9.41%, respectively. The most common complications were cerebrospinal fluid leak (7.1%), hematoma (7.1%), implant exposure (3.5%), and infection (3.5%). Factors associated with higher complication rates include the following: use of alloplastic calvarial implants and defects of congenital etiology ( p = 0.023 and 0.035, respectively). This is the first comprehensive review to describe current practices and outcomes in staged cranioplasty with TE. Adequate soft tissue coverage contributes to successful cranioplasties and TE can play a safe and effective role in selected cases.

Piezo1-Regulated Mechanotransduction Controls Flow-Activated Lymphatic Expansion.

BACKGROUND: Mutations in PIEZO1 (Piezo type mechanosensitive ion channel component 1) cause human lymphatic malformations. We have previously uncovered an ORAI1 (ORAI calcium release-activated calcium modulator 1)-mediated mechanotransduction pathway that triggers lymphatic sprouting through Notch downregulation in response to fluid flow. However, the identity of its upstream mechanosensor remains unknown. This study aimed to identify and characterize the molecular sensor that translates the flow-mediated external signal to the Orai1-regulated lymphatic expansion. METHODS: Various mutant mouse models, cellular, biochemical, and molecular biology tools, and a mouse tail lymphedema model were employed to elucidate the role of Piezo1 in flow-induced lymphatic growth and regeneration. RESULTS: Piezo1 was found to be abundantly expressed in lymphatic endothelial cells. Piezo1 knockdown in cultured lymphatic endothelial cells inhibited the laminar flow-induced calcium influx and abrogated the flow-mediated regulation of the Orai1 downstream genes, such as KLF2 (Krüppel-like factor 2), DTX1 (Deltex E3 ubiquitin ligase 1), DTX3L (Deltex E3 ubiquitin ligase 3L,) and NOTCH1 (Notch receptor 1), which are involved in lymphatic sprouting. Conversely, stimulation of Piezo1 activated the Orai1-regulated mechanotransduction in the absence of fluid flow. Piezo1-mediated mechanotransduction was significantly blocked by Orai1 inhibition, establishing the epistatic relationship between Piezo1 and Orai1. Lymphatic-specific conditional Piezo1 knockout largely phenocopied sprouting defects shown in Orai1- or Klf2- knockout lymphatics during embryo development. Postnatal deletion of Piezo1 induced lymphatic regression in adults. Ectopic Dtx3L expression rescued the lymphatic defects caused by Piezo1 knockout, affirming that the Piezo1 promotes lymphatic sprouting through Notch downregulation. Consistently, transgenic Piezo1 expression or pharmacological Piezo1 activation enhanced lymphatic sprouting. Finally, we assessed a potential therapeutic value of Piezo1 activation in lymphatic regeneration and found that a Piezo1 agonist, Yoda1, effectively suppressed postsurgical lymphedema development. CONCLUSIONS: Piezo1 is an upstream mechanosensor for the lymphatic mechanotransduction pathway and regulates lymphatic growth in response to external physical stimuli. Piezo1 activation presents a novel therapeutic opportunity for preventing postsurgical lymphedema. The Piezo1-regulated lymphangiogenesis mechanism offers a molecular basis for Piezo1-associated lymphatic malformation in humans.

Analysis of Trends in the Selection and Production of U.S. Academic Plastic Surgery Faculty.

In academic plastic surgery, there is a paucity of data examining the relationship between program rank, faculty training history, and production of academic program graduates. The purpose of this study is to determine objective faculty characteristics that are associated with a high program reputation. METHODS: Accreditation Council for Graduate Medical Education-accredited integrated Plastic and Reconstructive Surgery (PRS) programs were ranked using Doximity and divided into Top-quartile programs and Other programs. Accredited medical schools were ranked using U.S. News and World Report. Individual faculty profiles were reviewed on program websites for information on prior training. RESULTS: Seventy-nine programs with 712 faculty were identified and objectively analyzed. Compared to Other PRS programs, Top-quartile programs had a higher proportion of faculty that trained at Top-quartile residency programs (P < 0.0001) and Top-quartile medical schools (P < 0.0001). Top-quartile programs also had the highest proportion of faculty that trained at the same institution for fellowship (P = 0.0001), residency (P = 0.03), medical school (P = 0.4), or any prior training (medical school, residency, or fellowship) (P = 0.002). Top-quartile programs were associated with the largest total faculty size (P < 0.0001) and the largest number of graduates entering the field of academic plastic surgery (P < 0.0001). CONCLUSIONS: Program reputation is associated with PRS faculty selection and production. Top-ranked programs are more likely to have faculty that previously trained at the same institution or at top-ranked programs. Top-ranked programs are more likely to graduate residents that will become academic plastic surgeons.

Prevention of postsurgical lymphedema via immediate delivery of sustained-release 9-cis retinoic acid to the lymphedenectomy site.

BACKGROUND AND OBJECTIVES: Previously, we have shown that 9-cis retinoic acid (9-cis RA) stimulates lymphangiogenesis and limits postsurgical lymphedema in animal models when administered via daily intraperitoneal injections. In this study, we investigate whether a single-use depot 9-cis RA drug delivery system (DDS) implanted at the site of lymphatic injury can mitigate the development of lymphedema in a clinically relevant mouse limb model. METHODS: Hind limb lymphedema was induced via surgical lymphadenectomy and irradiation. Animals were divided into two treatment groups: (1) 9-cis RA DDS, (2) placebo DDS. Outcomes measured included paw thickness, lymphatic clearance and density, epidermal thickness, and collagen deposition. RESULTS: Compared with control animals, 9-cis RA-treated animals had significantly less paw swelling from postoperative week 3 (P = .04) until the final timepoint at week 6 (P = .0007). Moreover, 9-cis RA-treated animals had significantly faster lymphatic clearance (P < .05), increased lymphatic density (P = .04), reduced lymphatic vessel size (P = .02), reduced epidermal hyperplasia (P = .04), and reduced collagen staining (P = .10). CONCLUSIONS: Animals receiving 9-cis RA sustained-release implants at the time of surgery had improved lymphatic function and structure, indicating reduced lymphedema progression. Thus, we demonstrate that 9-cis RA contained within a single-use depot DDS has favorable properties in limiting pathologic responses to lymphatic injury and may be an effective strategy against secondary lymphedema.

A Pre-clinical Animal Model of Secondary Head and Neck Lymphedema.

Head and neck lymphedema (HNL) is a disfiguring disease affecting over 90% of patients treated for head and neck cancer. Animal models of lymphedema are used to test pharmacologic and microsurgical therapies; however, no animal model for HNL is described in the literature to date. In this study we describe the first reproducible rat model for HNL. Animals were subjected to two surgical protocols: (1) lymphadenectomy plus irradiation; and (2) sham surgery and no irradiation. Head and neck expansion was measured on post-operative days 15, 30 and 60. Magnetic resonance imaging (MRI) was acquired at the same time points. Lymphatic drainage was measured at day 60 via indocyanine green (ICG) lymphography, after which animals were sacrificed for histological analysis. Postsurgical lymphedema was observed 100% of the time. Compared to sham-operated animals, lymphadenectomy animals experienced significantly more head and neck swelling at all timepoints (P < 0.01). Lymphadenectomy animals had significantly slower lymphatic drainage for 6 days post-ICG injection (P < 0.05). Histological analysis of lymphadenectomy animals revealed 83% greater subcutis thickness (P = 0.008), 22% greater collagen deposition (P = 0.001), 110% greater TGFß1+ cell density (P = 0.04), 1.7-fold increase in TGFß1 mRNA expression (P = 0.03), and 114% greater T-cell infiltration (P = 0.005) compared to sham-operated animals. In conclusion, animals subjected to complete lymph node dissection and irradiation developed changes consistent with human clinical postsurgical HNL. This was evidenced by significant increase in all head and neck measurements, slower lymphatic drainage, subcutaneous tissue expansion, increased fibrosis, and increased inflammation compared to sham-operated animals.

Analysis of the Microsurgery Match from 2014 to 2018 Reveals Increased Competition for Microsurgery Fellowship Positions.

BACKGROUND: There has been no peer-reviewed published data analyzing the microsurgery match since it was established. The aim of this study is to present and analyze match data to inform residents and programs regarding outcomes. METHODS: Anonymized data were requested from the San Francisco Match, which was plotted and analyzed utilizing Pearson's Chi-square, unpaired t-test, and one-way analysis of variance (ANOVA). RESULTS: Match data was obtained from the years 2014 to 2018. The match rate decreased from 84.6% in 2015 to 67.3% in 2018, mean = 73.7 (8.29%), and (p = 0.01735). The position fill rate fluctuated from 82.9% in 2014 to 90.0% in 2016, mean = 86.5 (3.0%). In 2014 and 2015, 66.7% of applicants matched their first or second choice compared to 48.0% in 2018, mean = 58.7 (8.3%), (p =.04785). Matched applicants ranked mean = 6.6 (1.4%) programs versus 3.4 (1.3) for unmatched, (p < 0.0001). Filled programs ranked a greater number of applicants per position, mean = 8.5 (1.8%), compared to partially filled, mean = 4.6 (2.6%), and unfilled mean = 3.6 (3.4%), programs (p = 0.0014). In 2015, 55.0% of programs matched their first or second choice compared to 30.4% of programs in 2018, mean = 43.0 (10.1%). CONCLUSION: The application process for microsurgery has become more competitive. Matched applicants rank more programs than do unmatched. Fully filled programs rank more applicants per position than do unfilled or partially filled. Applicants and programs are increasingly less likely to match their top choices.

Traumatic Lingual Hematoma Resulting in Bilateral Temporal Mandibular Joint Dislocations.

BACKGROUND: Lingual hematoma (LH) is a relatively uncommon entity seen after both medical and traumatic etiologies. Regardless of the cause, the feared complication is acute airway obstruction. CASE REPORT: Our case involves a 39-year-old man who presented to the Emergency Department via emergency medical services with an enlarging LH after an unwitnessed fall, suspected to be an alcohol withdrawal seizure. The bleeding was likely exacerbated by previously undiagnosed thrombocytopenia. Airway stabilization was rapidly established via nasotracheal intubation after standard intubation techniques were deemed unfeasible. Despite correction of the coagulopathy, the LH continued to expand, resulting in bilateral tympanomandibular joint (TMJ) dislocations. To our knowledge, this complication has not been previously reported as a complication of LH. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Despite being a relatively uncommon condition, LH has the potential to result in life-threatening airway obstruction with limited airway options. Prompt airway stabilization should be the first priority upon diagnosis. A rapidly evolving LH can limit standard orotracheal rapid sequence intubation options, and may require alternative airway procedures. Additionally, ongoing lingual swelling after airway stabilization has now been shown in our case to result in bilateral TMJ dislocations. Concurrent management of reversible coagulopathy may help prevent this complication or reduce its severity.