Kristina D. O'Shaughnessy

Chronic wound pathogenesis and current treatment strategies : a unifying hypothesis

Summary: Most chronic wounds can be classified into three major types: pressure ulcers, venous ulcers, and diabetic ulcers. The authors propose a unifying hypothesis of chronic wound pathogenesis based on four main causative factors: local tissue hypoxia, bacterial colonization of the wound, repetitive ischemia-reperfusion injury, and an altered cellular and systemic stress response in the aged patient. Traditional strategies for the treatment of chronic wounds have shown limited success. The authors explore potential treatment regimens specifically aimed at each individual determinant of chronic wound pathogenesis. Furthermore, they explore a combined therapeutic approach that collectively targets all the components of chronic wound pathology. These innovative ideas and therapies could be of substantial interest for clinicians and researchers, while further offering significant benefit to patients with chronic wounds.

Antisense inhibition of connective tissue growth factor (CTGF/CCN2) mRNA limits hypertrophic scarring without affecting wound healing in vivo

Augmented expression of connective tissue growth factor (CTGF/CCN2) is observed in healing wounds and in a variety of fibrotic disorders. It appears to enhance many of the effects of transforming growth factor‐β and has been shown to have independent fibrogenic functions. Despite these observations, its importance to dermal wound healing and the transition from wound to scar remains poorly defined. In this study, we use established rabbit models to evaluate the roles of CTGF in dermal wound healing and hypertrophic scarring. We show that CTGF mRNA demonstrates persistent up‐regulation in hypertrophic scars. Treatment of wounds with antisense oligonucleotides to CTGF has no measurable effect on early wound closure. However, antisense therapy significantly limits subsequent hypertrophic scarring. Inhibition of CTGF is associated with a marked reduction in the number of myofibroblasts in scars and decreased transcription of TIMP‐1 and types I and III collagen. These findings confirm CTGF to be a key mediator of hypertrophic scarring in this model. Its effect on myofibroblasts in this setting suggests a mechanism whereby it plays this role. Its limited participation in early healing implies that it may be a useful and specific target for modulating hypertrophic scarring following injury.

Targeted reinnervation to improve prosthesis control in transhumeral amputees. A report of three cases.

Controlling an upper-limb prosthesis is challenging for transhumeral amputees. A central problem is the inability to move multiple prosthetic joints at the same time. With a body-powered prosthesis, an amputee uses shoulder motion to sequentially move the prosthetic elbow and lock it in place before switching to operation of the wrist, hand, or hook. With a myoelectric prosthesis, surface electromyographic signals from the residual biceps and triceps are used to control a motorized arm. Again, sequential control is required, as the biceps and triceps can only operate one joint at a time. The use of these prostheses rarely becomes intuitive. The patient is forced to use chest, shoulder girdle, or upper-arm muscles to move the prosthetic elbow, wrist, and hand in a slow, complex, and burdensome manner. Often, expensive prostheses are left untouched in the patients closet because the sequence of movements that is required to effectively use the prosthetic arm actions does not occur in a workable time frame for the patient. Use of a prosthetic arm will become more intuitive and facile if the nervous-system signals that formerly controlled arm movement can once again be used to direct the movement of the prosthesis. To date, most efforts at neural control have focused on brain-machine interface strategies in which electrodes implanted in the cerebral cortex1,2 and on peripheral nerve interfaces make use of electrode arrays placed in the amputated nerves of the arm3,4. These systems face the challenges of weak signals, signal instability over time, potential infections from implanted devices, implant-device failure, and difficulties with extracting the electrical signals to detectors outside the body. The ideal interface between patient and prosthesis would not break, become infected, need a power source, or require repeated trips to the operating room. Through the process of …

Targeted Reinnervation for Transhumeral Amputees: Current Surgical Technique and Update on Results

Background: Targeted reinnervation in upper extremity transhumeral amputees can improve control and dexterity of myoelectric prostheses. The operation as described previously required a long residual limb and the presence of a brachialis muscle. Methods: Brachial plexus dissections were performed to confirm and better understand the branching pattern of the radial nerve in the upper arm. A simplified surgical approach for targeted reinnervation in transhumeral amputees was devised. This study reports on the first six transhumeral amputees who have undergone this simplified procedure. Results: The long and lateral heads of the triceps receive distinct and separate motor nerves from the proximal radial nerve. This anatomy allows a nerve transfer of the distal radial nerve to the motor nerve of the lateral head of the triceps without injury to the innervation of the long head of the triceps. The median nerve transfer to the motor branch of the medial head of the biceps is performed on the anterior surface of the arm as described previously. All six patients had successful targeted reinnervation procedures using this simplified approach. Conclusion: Targeted reinnervation for transhumeral amputees can now be performed in patients with amputations at the level of the middle of the humerus or longer.

Homeostasis of the epidermal barrier layer: A theory of how occlusion reduces hypertrophic scarring

The mechanism of hypertrophic scar reduction using silicone gel sheeting remains elusive. We hypothesize that the decrease in scar formation is due to occlusion and homeostasis of the barrier layer. Using an established model of hypertrophic scarring, rabbits were divided into four groups and scars were tape‐stripped or occluded with Kelocote, Cavilon, or Indermil, with each rabbit serving as its own internal control. All wounds were harvested on day 28 and examined histologically to measure the scar elevation index (SEI), epithelial thickness, and cellularity. Immunohistochemistry fluorescence was used to quantify inflammation in the dermis. Transepidermal water loss (TEWL) was measured for each occlusive agent and tape stripping. Ultrastructural analysis was performed by electron microscopy. Kelocote, Cavilon, and Indermil all significantly decreased SEI when compared with controls. Each of the occlusive treatments was shown to decrease TEWL while tape stripping increased TEWL. Tape stripping significantly increased the SEI, epithelial thickness, and cellularity. Immunostaining for macrophages showed increased density of inflammatory cells in the tape‐stripped scars. Under electron microscopy, the tape‐stripped wounds displayed extensive inflammation and keratinocyte damage. Both unwounded skin and occlusion‐treated scars did not display these characteristics. In conclusion, hypertrophic scarring was reduced regardless of occlusive method used. Furthermore, repeated disruption of the permeability barrier by tape stripping led to an increase in scarring. Ultrastructural analysis suggests that occluded wounds may be in an advanced state of wound repair. Occlusion may mediate its effects through establishing homeostasis of the epidermal barrier layer.

Oblique Pedicled Paraumbilical Perforator-Based Flap for Reconstruction of Complex Proximal and Mid-Forearm Defects: A Report of Two Cases

Reconstruction of complex proximal and mid-forearm wounds can be challenging. Free tissue transfer might not be feasible in certain patients or at institutions lacking microsurgical expertise and equipment. Traditional pedicled flaps are either insufficient in length to reach more proximal forearm defects or are used sparingly due to donor site complications and extremity stiffness. We present a novel technique to reconstruct forearm defects using the oblique pedicled paraumbilical perforator (PUP) based flap. This flap is simple to harvest, has low donor site morbidity, and allows elbow and shoulder range of motion during the interval between flap transfer and pedicle division.

Three-Dimensional Imaging in Measuring Facial Aesthetic Outcomes†

Objectives/Hypothesis: Medical imaging techniques have continually improved. However, measuring esthetic outcomes using conventional two‐dimensional photography has inherent limitations visualizing in three dimensions such as the face.

The surgical TRAM flap delay: reliability of zone III using a simplified technique under local anesthesia.

The conventional superiorly based transverse rectus abdominis musculocutaneous (TRAM) flap continues to be a popular and reliable choice for autologous breast reconstruction after mastectomy but has limitations in the reliable use of contralateral zone III. Certain patient risk factors such as smoking,1 previous irradiation,2 midline lower abdominal scars,3 obesity,4 and large tissue volume requirements5 reduce the dependability of this flap. Complications such as partial flap loss and fat necrosis are related directly to tenuous blood supply.6 The delay procedure, originally described by Hartrampf et al.,7 is an alternative to enhance the safety and reliability of the pedicled TRAM flap. Over the past two decades, the delay procedure has evolved based on elegant anatomical and hemodynamic flow studies.8–11 Vascular delay has been shown to augment flap perfusion and decrease TRAM flap complications; however, its clinical application has been limited.11 Our purpose it to describe a simplified delay technique that can be performed in an office-based setting under local anesthesia or in the operating room under sedation without the use of specialized equipment. This type of delay allows reliable use of the contralateral abdominal tissue and may also be useful in the setting of deep inferior epigastric perforator flap reconstruction, extending the perfusion and use of contralateral zone III.

A new three-dimensional imaging device in facial aesthetic and reconstructive surgery

The conventional methods used for assessment of facial aesthetic outcomes are largely based on subjective observation instead of objectively measured data. It is not possible to quantify three-dimensional change on a twodimensional surface such as a photograph. Although attempting to make measurements based on photographs has been the state of art for many years, this method is inherently inaccurate, because the facial structure and other body structures are naturally three-dimensional. Previous authors have attempted to visualize the face in three dimensions. One of the most challenging issues of imaging in three dimensions is producing a reliable and consistent method of obtaining three-dimensional images both preoperatively and postoperatively over time. We have begun using a three-dimensional imaging device, the Minolta Vivid 300, which has a high degree of precision for studying the surface topography in facial reconstructive and aesthetic patients. Previously, three-dimensional imaging devices have been traditionally used in industry for quality control during manufacturing, and surface topography and engineering surveys. In the current application, this three-dimensional device can accurately capture the fine details of a human face over different time points. Collating each time point, we may study these images to quantify topographic changes of the face over time. Continually improving the means of imaging technology is crucial for more accurately assessing the outcomes of patients in the long term. In essence, three-dimensional imaging can serve as an improved objective guide, over conventional photography, with which changes in surface topography can be studied in the immediate and long-term postoperative period.