Gordon R. Tobin

Physiology and Healing Dynamics of Chronic Cutaneous Wounds

In the last few decades, a great deal of progress has been made in understanding the cellular and biochemical interplay that comprises the normal wound healing response. This response is a complex process involving intricate interactions among a variety of different cell types, structural proteins, growth factors, and proteinases. The normal wound repair process consists of three phases--inflammation, proliferation, and remodeling--that occur in a predictable sequence and comprise a series of cellular and biochemical events. A review of the biochemical and physiologic processes that regulate wound healing and the cascade of cellular events that gives rise to the healing process is presented here.

Impediments to wound healing

Chronic wounds will often heal in a short period of time if factors that inhibit wound healing are identified and managed. Recombinant growth factor therapy may provide an added stimulus to healing in certain types of chronic wounds. However, there remains no substitute for a physiologic environment conducive to tissue repair and regeneration, without which the efficacy of growth factor therapy is questionable. Some of the most commonly encountered and clinically significant impediments to wound healing include wound hypoxia, infection, presence of debris and necrotic tissue, use of anti-inflammatory medications, a diet deficient in vitamins or minerals, or general nutritional deficiencies, tumors, environmental factors, and metabolic disorders, such as diabetes mellitus. Treatment of chronic wounds should be directed against the main etiologic factors responsible for the wound. Moreover, factors that may impede healing must be identified and, if possible, corrected, for healing to occur.

Vaginal and pelvic reconstruction with distally based rectus abdominis myocutaneous flaps.

This report introduces a new method of vaginal reconstruction using a single rectus abdominis myocutaneous flap based distally. Applications of this flap in reconstruction of major abdominal wall and pelvic defects, such as hemipelvectomies, are also described. The flap is designed to carry a paddle of upper abdominal skin on a distally based muscle and vascular pedicle. Advantages of this flap design are (1) the technique is straightforward and rapid, (2) flap viability is reliable, (3) the epigastric skin-fascial donor defect preserves the anterior rectus fascia distal to the linea semicircularis, which prevents hernia, (4) a large arc of rotation is provided, and (5) the epigastric donor site does not interfere with colostomy and urinary conduit stomas in the pelvic exenteration patient. We have done 11 vaginal reconstructions and 9 major pelvic defect reconstructions with this flap during the last 3 1/2 years. In these 20 patients, the only complications were two partial flap losses. No major flap losses or ventral hernias occurred.

The intramuscular neurovascular anatomy of the latissimus dorsi muscle: the basis for splitting the flap.

This study identifies and describes a consistent proximal brandling of the neurovascular supply to the latissimus dorsi muscle. This anatomical feature makes possible splitting the muscle and overlying cutaneous territory into independent branched musculocutaneous units. A parallel study of neurovascular anatomy in dogs suggests that this animal is an appropriate model for testing and developing clinical applications of the split latissimus dorsi flap.

Acute ischemic preconditioning of skeletal muscle prior to flap elevation augments muscle-flap survival.

&NA; Ischemic preconditioning of the myocardium with repeated brief periods of ischemia and reperfusion prior to prolonged ischemia significantly reduces subsequent myocardial infarction. Following ischemic preconditioning, two “windows of opportunity” (early and late) exist, during which time prolonged ischemia can occur with reduced infarction size. The early window occurs at approximately 4 hours and the late window at 24 hours following ischemic preconditioning of the myocardium. We investigated if ischemic preconditioning of skeletal muscle prior to flap creation improved subsequent flap survival and perfusion immediately or 24 hours following ischemic preconditioning. Currently, no data exist on the utilization of ischemic preconditioning in this fashion. The animal model used was the latissimus dorsi muscle of adult male Sprague‐Dawley rats. Animals were assigned to three groups, and the right or left latissimus dorsi muscle was chosen randomly in each animal. Group 1 (n = 12) was the control group, in which the entire latissimus dorsi muscle was elevated acutely without ischemic preconditioning. Group 2 (n = 8) investigated the effects of ischemic preconditioning in the early window. In this group, the latissimus dorsi muscle was elevated immediately following preconditioning. Group 3 (n = 8) investigated the effects of ischemic preconditioning in the late window, with elevation of the latissimus dorsi muscle 24 hours following ischemic preconditioning. The preconditioning regimen used in groups 2 and 3 was two 30‐minute episodes of normothermic global ischemia with intervening 10‐minute episodes of reperfusion. Latissimus dorsi muscle ischemia was created by occlusion of the thoracodorsal artery and vein and the intercostal perforators, after isolation of the muscle on these vessels. Muscle perfusion was assessed by a laser‐Doppler perfusion imager. One week after flap elevation, muscle necrosis was quantified in all groups by means of computer‐assisted digital planimetry. Our results show that ischemic preconditioning resulted in a significant reduction (p < 0.05) in muscle‐flap necrosis immediately and 24 hours following ischemic preconditioning. Perfusion changes after flap elevation were similar among the three groups. Ischemic preconditioning of skeletal muscle prior to flap creation significantly reduces subsequent muscle‐flap necrosis caused by the ischemia of flap creation immediately and 24 hours following ischemic preconditioning. Further elaboration of the mechanisms of ischemic preconditioning may allow pharmacologic preconditioning to be used in the augmentation of skeletal muscle‐flap survival in the clinical setting. (Plast. Reconstr. Surg. 100: 58, 1997.)

Outcomes of the First 2 American Hand Transplants at 8 and 6 Years Posttransplant

PURPOSE The feasibility of hand allotransplantation has been demonstrated. The purpose of the article is to report the (1) functional return, (2) psychosocial outcomes, (3) clinical and histological assessment for rejection, (4) complications, and (5) graft survival in the 2 American hand transplant recipients. METHODS We present 2 patients 106 and 81 months, respectively, after unilateral transplantation of an allogeneic hand and forearm. We analyzed clinical course, number of rejection episodes, adverse events, function of the allograft, and quality of life. Clinical laboratory results, biopsy histology, and patient clinical examinations were used to compare the clinical course. Standard hand function tests were used to evaluate function. Psychological interviews were used to assess acceptance and quality of life. RESULTS Our patients have allograft survival with improvements in intrinsic muscle activity, total active motion and return of functional grip, pinch strength, and sensibility. Rejection episodes were restricted primarily to the first 6 months after transplantation, and all responded to treatment. The major posttransplantation complications were a cytomegalovirus infection in patient 1 and osteonecrosis of the hip requiring both hips to be replaced, 1 at year 4 and the other at year 6, as well as transient immunosuppression-related diabetes in patient 2. Recently we have weaned both patients off maintenance steroids. Current Carroll scores are fair for patient 1 (72/99) and fair for patient 2 (55/99), although patient 2 has not had good recovery of intrinsic function. Both patients are back at work and report an excellent quality of life at nearly 9 and 7 years, respectively, after transplantation. CONCLUSIONS Our intermediate long-term results of hand transplants have demonstrated functional return similar to that of replants. Graft survival and quality of life after hand transplantation has far exceeded initial expectations. We conclude that allogeneic hand transplant is feasible and holds promise as a treatment modality for catastrophic upper extremity loss. TYPE OF STUDY/LEVEL OF EVIDENCE Therapeutic IV.

Pectoralis major segmental anatomy and segmentally split pectoralis major flaps.

This report presents the anatomic studies, animal studies, and initial clinical experience that provide a basis for splitting pectoralis major muscle and myocutaneous flaps into independent segmental subunits. The anatomic study of 105 human cadaver pectoralis major muscle and myocutaneous units and their neurovascular supply indicated a consistent segmentation of muscle morphology, neurovascular supply, and myocutaneous territory. Three major independent segments (clavicular, sternocostal, and external) were identified. These findings provide the anatomic basis for segmentally splitting pectoralis major flaps, and the surgical technique that evolved is described. Segmentally split pectoralis flaps were experimentally tested in animals and subsequently used in 36 clinical reconstructions. The variety of forms of segmentally split pectoralis major flaps used in this series is described and analyzed. The technique of segmentally splitting flaps provides a method both for leaving innervated muscle segments in situ to preserve donor motor function and for deriving two independent flaps from one muscle.

The split latissimus dorsi myocutaneous flap.

Consistent proximal branching of the latissimus dorsi neurovascular anatomy permits surgical splitting of the myocutaneous unit into two flaps. Either or both branches of the split flap can be independently transferred. Experimental and clinical applications of this flap, which illustrate several of

Distally based rectus abdominis flap for reconstruction in radical gynecologic procedures

The distally based rectus abdominis myocutaneous flap is an important adjunct to radical pelvic surgery. It can be used to fashion a functional neovagina or to create a patch to cover perineal defects created by exenterative surgery. This report reviews the technical aspects of the creation of this flap and our experience with 22 patients who have undergone this procedure. The flap has been found to be technically easy to create. It is reliable with little tissue loss, and donor site complications are acceptable. Healing is aided by filling the pelvic dead space, thereby decreasing bowel complications, and by bringing a new blood supply into the operative site which has often been heavily irradiated. Operative time is minimized since the procedure requires only unilateral mobilization. Subsequent abdominal surgery has been performed without fascial complications.

Vascular Delay of the Latissimus Dorsi Muscle: An Essential Component of Cardiomyoplasty

BACKGROUND Cardiomyoplasty (CMP) uses the latissimus dorsi muscle (LDM) to assist the heart in cases of cardiac failure. Distal ischemia and necrosis of the LDM is a recognized complication of CMP that can reduce distal muscle function and the mechanical effectiveness of CMP. METHODS Canine (n = 9) LDMs were subjected to a 10-day period of vascular delay followed by a simulated CMP. Two weeks after simulated CMP (corresponding to the healing delay between CMP and the onset of LDM stimulation used in the clinical setting), LDM perfusion was measured in the distal, middle, and proximal segments of the muscle, and circumferential (distal and middle squeezing muscle function) and longitudinal (proximal pulling muscle function) force generation and fatigue rates were measured. The results were compared with the contralateral nondelayed simulated CMP. RESULTS Muscle perfusion was significantly (p < 0.05) greater in the distal and middle segments of vascular-delayed LDMs. Circumferential muscle force generation and fatigue rates were significantly (p < 0.05) improved in the vascular-delayed LDMs. CONCLUSIONS Vascular delay can significantly improve LDM perfusion and function in a model that closely reflects clinical CMP, and the use of vascular delay may improve clinical outcomes in CMP.