Drill Penetration Injury to Extensor Tendons: A Biomechanical Analysis.

BACKGROUND: Little is known about extensor tendon failure following drill injury at the time of volar plate fixation. Our goals were to analyze extensor tendon injury following simulated drill penetration, and change in tendon displacement during cyclic loading following simulated drill penetration injury. METHODS: Extensor pollicis longus (EPL) and extensor carpi radialis brevis (ECRB) tendons were harvested from 9 fresh frozen cadaveric arms. Eighteen EPL and 18 ECRB samples were created from harvested tendons. Drill penetration injury was performed in either a continuous or an oscillating mode. Injured tendons were subjected to 1200 cycles at 1- to 15-kg cyclic load at a frequency of 1 Hz, and analyzed for failure at drill sites and change in displacement throughout the testing cycle. RESULTS: Ten EPL samples and 16 ECRB samples completed testing without failure. Tendon type (ECRB, EPL), mode of injury (continuous, oscillating), and location (proximal, distal) did not affect tendon displacement during loading. A single EPL tendon failed following continuous drill penetration injury. Extensor carpi radialis brevis samples had a mean change in displacement of 2.8 (standard deviation [SD]: 1.5 mm) and 5.9 mm (SD: 4.7 mm) for oscillating and continuous modes, respectively. Six EPL samples had a mean change in displacement of 4.7 (SD: 2.7 mm) and 4.3 mm (SD: 1.8 mm) for oscillating and continuous modes, respectively. CONCLUSIONS: Complete extensor tendon failure due to drill penetration was rare. Drill mode did not affect the degree of elongation. Increasing cyclic loading of extensor tendons after drill injury caused modest extensor tendon elongation.

A Twelve-Year Consecutive Case Experience in Thoracic Reconstruction.

BACKGROUND: We describe the second largest contemporary series of flaps used in thoracic reconstruction. METHODS: A retrospective review of patients undergoing thoracomyoplasty from 2001 to 2013 was conducted. Ninety-one consecutive patients were identified. RESULTS: Thoracomyoplasty was performed for 67 patients with intrathoracic indications and 24 patients with chest wall defects. Malignancy and infection were the most common indications for reconstruction (P < 0.01). The latissimus dorsi (LD), pectoralis major, and serratus anterior muscle flaps remained the workhorses of reconstruction (LD and pectoralis major: 64% flaps in chest wall reconstruction; LD and serratus anterior: 85% of flaps in intrathoracic indication). Only 12% of patients required mesh. Only 6% of patients with <2 ribs resected required mesh when compared with 24% with 3-4 ribs, and 100% with 5 or more ribs resected (P < 0.01). Increased rib resections required in chest wall reconstruction resulted in a longer hospital stay (P < 0.01). Total comorbidities and complications were related to length of stay only in intrathoracic indication (P < 0.01). Average intubation time was significantly higher in patients undergoing intrathoracic indication (5.51 days) than chest wall reconstruction (0.04 days), P < 0.05. Average hospital stay was significantly higher in patients undergoing intrathoracic indication (23 days) than chest wall reconstruction (12 days), P < 0.05. One-year survival was most poor for intrathoracic indication (59%) versus chest wall reconstruction (83%), P = 0.0048. CONCLUSION: Thoracic reconstruction remains a safe and successful intervention that reliably treats complex and challenging problems, allowing more complex thoracic surgery problems to be salvaged.

Reconstructive surgery and patients with spinal cord injury: Perioperative considerations for the plastic surgeon.

BACKGROUND: Patients with spinal cord injury (SCI) requiring reconstructive surgery, particularly for pressure ulcers, are ubiquitous in Plastic and Reconstructive Surgery practices. Much of the current literature focuses on operative techniques, antibiotic indications, sitting protocols, and dressing and bedding choices. METHODS: This paper reviews normal neuroanatomy, outlines changes in neurophysiology observed in spinal cord injury, and addresses concepts related to perioperative care that are highly relevant but often under-emphasised. RESULTS: Vascular disturbances such as autonomic dysreflexia and orthostatic hypotension are dangerous phenomena occurring in this patient population that, if not properly recognised and treated, may result in complications such as haematoma, flap loss, inadequate tissue perfusion, and death. The management of spasticity, deep venous thrombosis, and perioperative pain are also relevant and discussed in this paper. CONCLUSION: A basic understanding of these concepts is essential for the Plastic Surgeon involved in the care of patients with SCI and pressure ulcers, particularly before and after debridement or reconstruction.

Inhalation of nebulized perfluorochemical enhances recombinant adenovirus and adeno-associated virus-mediated gene expression in lung epithelium.

Use of perfluorochemical liquids during intratracheal vector administration enhances recombinant adenovirus and adeno-associated virus (AAV)-mediated lung epithelial gene expression. We hypothesized that inhalation of nebulized perfluorochemical vapor would also enhance epithelial gene expression after subsequent intratracheal vector administration. Freely breathing adult C57BL/6 mice were exposed for selected times to nebulized perflubron or sterile saline in a sealed Plexiglas chamber. Recombinant adenoviral vector was administered by transtracheal puncture at selected times afterward and mice were killed 3 days after vector administration to assess transgene expression. Mice tolerated the nebulized perflubron without obvious ill effects. Vector administration 6 hr after nebulized perflubron exposure resulted in an average 540% increase in gene expression in airway and alveolar epithelium, compared with that with vector alone or saline plus vector control (p<0.05). However, vector administration 1 hr, 1 day, or 3 days after perflubron exposure was not different from either nebulized saline with vector or vector alone and a 60-min exposure to nebulized perflubron is required. In parallel pilot studies in macaques, inhalation of nebulized perflubron enhanced recombinant AAV2/5 vector expression throughout the lung. Serial chest radiographs, bronchoalveolar lavages, and results of complete blood counts and serum biochemistries demonstrated no obvious adverse effects of nebulized perflubron. Further, one macaque receiving nebulized perflubron only was monitored for 1 year with no obvious adverse effects of exposure. These results demonstrate that inhalation of nebulized perflubron, a simple, clinically more feasible technique than intratracheal administration of liquid perflubron, safely enhances lung gene expression.

Perfluorochemical (PFC) liquid enhances recombinant adenovirus vector-mediated viral interleukin-10 (AdvIL-10) expression in rodent lung.

Adenovirus and cationic liposome mediated transfer of Interleukin-10 (IL-10), a potent anti-inflammatory cytokine, has been shown to decrease pro-inflammatory cytokine levels and overall lung inflammation in models of lung transplantation and injury. Limitations to current approaches of IL-10 gene therapy include poor vector delivery methods and pro-inflammatory properties of human IL-10 under certain conditions. We hypothesize that using perfluorochemical (PFC) liquid to deliver the highly homologous viral IL-10 (vIL-10), which is predominantly anti-inflammatory with minimal pro-inflammatory activities, can potentially be a more effective strategy to combat inflammatory lung diseases. In this study, we compare the use of PFC liquid versus aerosolized method to deliver adenovirus encoding the vIL-10 gene (AdvIL-10) in C57Bl6 mice. Detectable vIL-10 levels were measured from bronchoalveolar lavage fluid and lung homogenates at one, four, ten and thirty days after AdvIL-10. Furthermore, we determined if use of PFC liquid could allow for the use of a lower dose of AdvIL-10 by comparing the levels of detectable vIL-10 at different doses of AdvIL-10 delivered +/- PFC liquid. Results showed that PFC liquid enhanced detectable vIL-10 by up to ten fold and that PFC liquid allowed the use of ten-fold less vector. PFC liquid increased detectable vIL-10 in lung homogenates at all time points; however, the increase in detectable vIL-10 in BAL fluid peaked at four days and was no longer evident by thirty days after intratracheal instillation. In summary, this is the first report utilizing PFC liquid to enhance the delivery of a potentially therapeutic molecule, vIL-10. We believe this strategy can be used to perform future studies on the use of the predominantly anti-inflammatory vIL-10 to treat inflammatory lung diseases.

Transient increase in lung epithelial tight junction permeability: an additional mechanism for enhancement of lung transgene expression by perfluorochemical liquids.

Intratracheal instillation of perfluorochemical (PFC) liquids enhances lung epithelial transgene expression by improved vector propulsion throughout lung airways. We now demonstrate that PFC liquids also facilitate gene transfer by increasing transepithelial permeability. Apical application of PFC liquid to well-differentiated human airway epithelial cells resulted in a transient decrease in transepithelial resistance peaking approximately 2 h after PFC liquid administration and returning to normal approximately 24 h later. The permeability change was sufficient to enhance access of apically applied 100-nm latex beads and adenoviral vectors to the basolateral side of the culture. Adenovirus-mediated gene expression was concurrently enhanced. Following intratracheal instillation of PFC liquid into mouse lungs, tight junction permeability, as assessed by electron microscopic evaluation of lanthanum deposition, was increased with peak effect between 6 h and 1 day after instillation. Importantly, alveolar-capillary permeability remained unchanged with the treatment. Administration of PFC liquid 6 h or 1 day, but not 3 days, prior to instillation of a recombinant adenovirus vector enhanced gene expression comparable to that observed with concurrent administration of PFC liquid and vector. We conclude that transient increase in epithelial permeability after PFC liquid administration contributes to the enhancement of adenovirus vector-mediated gene expression in lung epithelium.

Comparison of surfactant and perfluorochemical liquid enhanced adenovirus-mediated gene transfer in normal rat lung.

Both surfactant- and perfluorochemical (PFC)-based vehicles enhance adenovirus-mediated gene transfer in the lung. To compare the relative effects of surfactant and PFC liquid, we infected orotracheally intubated Sprague-Dawley rats with 4 x 10(9) pfu of an E1a(-)/E3(-) adenovirus expressing either an Escherichia coli lacZ (AdlacZ) mini-gene or no cDNA (Adnull). Surfactant-mediated delivery was achieved via instillation of four, 200-microl aliquots of virus suspended in a 50% surfactant (Survanta) vehicle over a 15-minute period. PFC rats received virus in 100 microl of saline followed by instillation of the PFC liquid FC-75 (10 cc/kg body weight) over a 2- to 3- minute period. Lungs were collected 3 days later for measurement of beta-galactosidase (beta-gal) expression and indices of inflammation. Both PFC liquid and surfactant-based vehicles produced widespread beta-gal expression and increased total beta-gal activity over that observed with instillation of vector alone. Both vehicles comparably increased bronchoalveolar lavage fluid (BALF), total cell counts, neutrophils, total protein, and IFN(gamma). FC-75 was also associated with increased BALF IL1beta. In conclusion, surfactant and FC-75 are similarly effective vehicles for adenovirus-mediated gene transfer to the lung.