Brent M. Egeland

Hybrid Conducting Polymer–Hydrogel Conduits for Axonal Growth and Neural Tissue Engineering

Successfully and efficiently bridging peripheral nerve gaps without the use of autografts is a substantial clinical advance for peripheral nerve reconstructions. Novel templating methods for the fabrication of conductive hydrogel guidance channels for axonal regeneration are designed and developed. PEDOT is electrodeposited inside the lumen to create fully coated-PEDOT agarose conduits and partially coated-PEDOT agarose conduits.

Management of difficult pediatric facial burns: reconstruction of burn-related lower eyelid ectropion and perioral contractures.

Despite significant burn treatment advances, modern multidisciplinary care, and improved survival after burns, facial burn scars remain clinically challenging. Achieving a successful reconstruction requires a comprehensive approach, entailing many advanced techniques with an emphasis on preserving function and balancing intricate aesthetic requirements. Pediatric facial burns present the same reconstructive challenges seen in adults, with additional developmental and psychologic concerns. In this paper, we describe the basic principals of facial burn care in the pediatric burn population, with a specific focus on lower-eyelid burn ectropion and oral commissure burn scar contracture leading to microstomia. Several cases are demonstrated.

In vivo electrical conductivity across critical nerve gaps using poly(3,4-ethylenedioxythiophene)-coated neural interfaces.

Background: Bionic limbs require sensitive, durable, and physiologically relevant bidirectional control interfaces. Modern central nervous system interfacing is high risk, low fidelity, and failure prone. Peripheral nervous system interfaces will mitigate this risk and increase fidelity by greatly simplifying signal interpretation and delivery. This study evaluates in vivo relevance of a hybrid peripheral nervous system interface consisting of biological acellular muscle scaffolds made electrically conductive using poly(3,4-ethylenedioxythiophene). Methods: Peripheral nervous system interfaces were tested in vivo using the rat hind-limb conduction-gap model for motor (peroneal) and sensory (sural) nerves. Experimental groups included acellular muscle, iron(III) chloride–treated acellular muscle, and poly(3,4-ethylenedioxythiophene) polymerized on acellular muscle, each compared with intact nerve, autogenous nerve graft, and empty (nonreconstructed) nerve gap controls (n = 5 for each). Interface lengths tested included 0, 5, 10, and 20 mm. Immediately following implantation, the interface underwent electrophysiologic characterization in vivo using nerve conduction studies, compound muscle action potentials, and antidromic sensory nerve action potentials. Results: Both efferent and afferent electrophysiology demonstrates acellular muscle–poly(3,4-ethylenedioxythiophene) interfaces conduct physiologic action potentials across nerve conduction gaps of at least 20 mm with amplitude and latency not differing from intact nerve or nerve grafts, with the exception of increased velocity in the acellular muscle–poly(3,4-ethylenedioxythiophene) interfaces. Conclusions: Nonmetallic, biosynthetic acellular muscle–poly(3,4-ethylenedioxythiophene) peripheral nervous system interfaces both sense and stimulate physiologically relevant efferent and afferent action potentials in vivo. This demonstrates their relevance not only as a nerve-electronic coupling device capable of reaching the long-sought goal of closed-loop neural control of a prosthetic limb, but also in a multitude of other bioelectrical applications.

A Minimally Invasive Approach to the Placement of Tissue Expanders

Plastic surgeons are frequently faced with difficult and challenging soft tissue defects in all areas of the body. To reconstruct these defects, there are many operative approaches available to the reconstructive surgeon including skin grafts, local flaps, regional flaps, and free-tissue transfer. Despite these many options, occasionally the best alternative for reconstruction of a wound is tissue expansion, where skin of similar quality, texture, and color can be used to close a soft tissue defect. Unfortunately, there are significant problems related to tissue expander reconstruction including a complication rate as high as 50%. As a result, tissue expander reconstruction has not achieved the widespread popularity commensurate with its potential clinical utility. To reduce the complication rate related to open tissue expander placement, and consequently to improve its clinical utility, we have employed endoscopic techniques for the placement of tissue expanders. Endoscopic approaches are currently being used in many areas of surgery and have resulted in substantial benefits. Endoscopic placement of tissue expanders has the benefit of reducing operative time, major complication rate, time to full expansion, and length of hospital stay. The purpose of this article is to critically examine the current open technique for tissue expander placement and to compare this technique with minimally invasive endoscopic tissue expander placement. We will discuss in detail the current problems associated with open tissue expander placement, the benefits of endoscopic tissue expansion, the technique of endoscopic tissue expander placement, and the outcomes for these techniques.

Horizontal Misalignment in Patients With Unilateral Superior Oblique Palsy

PURPOSE To determine the frequency and distribution of horizontal misalignment in patients with unilateral superior oblique palsy (SOP) and to determine the indications for combining horizontal with vertical strabismus surgery. METHODS Patients included in the study had a vertical heterophoria or tropia that fit Parks three-step test for SOP and had no previous strabismus surgery or other ocular motility disturbance. Ocular motility and alignment were recorded. Outcomes between patients who had vertical surgery alone and those who had combined vertical and horizontal surgery were compared using the Students t test. RESULTS Of 205 patients, 121 (59.0%) had a horizontal misalignment in addition to vertical strabismus. Ninety-six patients (46.8%) required strabismus surgery. Of these, 29 had 8 prism diopters (PD) or more horizontal deviation. Twenty-two had vertical combined with horizontal surgery (V+H group). Although their initial deviation was greater, these patients had better surgical outcomes than patients who had vertical surgery alone (V group). The V+H group had a final mean horizontal deviation of 2.18 PD compared with 6.85 PD in the V group (P < .01). Postoperative vertical alignment in the V+H group was also superior with a final mean vertical deviation of 3.7 versus 6.8 PD for the V group (P = .12). CONCLUSION These results indicate that horizontal misalignment is common in patients with SOP. Patients with 8 PD or more horizontal deviation benefited from surgical correction of the horizontal deviation in addition to the vertical surgery.

72A: AN ORGANIC WIRE: CONDUCTIVE POLYMER COATINGS ON AN ACELLULAR NERVE SCAFFOLD - IN VITRO CHARACTERIZATION AND BIOCOMPATIBILITY

Introduction: A biocompatible neural conductor may reduce the scarring and signal-degradation associated with conventional peripheral nerve interfaces necessary for long-term prosthetic limb control. This study evaluates the biocompatibility of a bioengineered organic wire created by polymerizing the highly stable biocompatible electroconductive polymer poly (3,4-ethylenedioxythiophene) (PEDOT) on acellular nerve scaffolds.

Optimization of Peripheral Nerve-Prosthetic Device Interface Conduction and Flexibility Using Electro-Chemical Polymerization of PEDOT Onto Decellular Nerve

INTRODUCTION: The purpose of this study is to optimize the process by which poly-3,4, ethylenedioxythiophene (PEDOT) is polymerized into decellular nerve scaffolding for interfacing to peripheral nerves. Our ultimate aim is to permanently implant peripheral nerve interfaces as ion, electron connectors between amputee stump nerve and prosthetic electronics. We hypothesize that optimizing PEDOT polymerization with DN increases conductivity while minimizing incompatible stiffness.