Robert W. Kreis

Graft Survival and Effectiveness of Dermal Substitution in Burns and Reconstructive Surgery in a One-stage Grafting Model

Survival of the autograft and objective parameters for scar elasticity were evaluated after dermal substitution for acute burns and reconstructive surgery. The dermal substitute, which was based on bovine type I collagen and elastin-hydrolysate, was evaluated by intraindividual comparison in a clinical trial. The substitute was applied in a one-step procedure in combination with a split-thickness autograft. This treatment was compared with the conventional treatment, the split-thickness autograft. After 1 week, the percentage of autograft survival was assessed. The Cutometer SEM 474 was used to obtain objective measurements of skin elasticity parameters 3 to 4 months postoperatively. Forty-two pairs of wounds (31 patients, age 32.9 ± 19.3 years; burned surface area, 19.8 ± 14.5 percent) were treated because of acute burns. Reconstructive surgery was performed on 44 pairs of wounds (31 patients, age 33.9 ± 17.5 years). Autograft survival was not altered by the substitute for reconstructive wounds, although a slight but significant reduction (p = 0.015) was established in the burn category for substituted compared with nonsubstituted wounds. However, the necessity for regrafting was not increased by substitution. Cutometer measurements of reconstructive wounds with a dermal substitute demonstrated a significant increase of pliability (50 percent, p < 0.001), elasticity (defined as immediate extension, 33 percent, p = 0.04), maximal extension (33 percent, p = 0.002), and immediate retraction (31 percent, p = 0.01), as compared with nonsubstituted wounds. After burn surgery, no improvement was found for the different elasticity parameters. Dermal substitution in a one-stage grafting model seems feasible with respect to graft survival. Skin elasticity was considerably improved by the collagen/elastin dermal substitute after reconstructive surgery. (Plast. Reconstr. Surg. 106: 615, 2000.)

Scar assessment tools: implications for current research.

Scarring is considered a major medical problem that leads to cosmetic and functional sequelae. Scar tissue is clinically distinguished from normal skin by an aberrant color, rough surface texture, increased thickness (hypertrophy), occurrence of contraction, and firmness. Marked histologic differences are the change in dermal architecture and the presence of cells such as the myofibroblast. Many assessment tools are available for analysis of pathologic conditions of the skin; however, there is no general agreement as to the most appropriate tools for evaluation of scar tissue. This review critically discusses currently available objective measurement tools, subjective assessment tools, and potential devices that may be available in the future for scar assessment.

Dermal substitution in acute burns and reconstructive surgery: a subjective and objective long-term follow-up.

&NA; Tissue engineering and dermal substitution are currently prominent topics of wound‐healing research. However, no extensive clinical trials with objective evaluation criteria have been published so far that support the clinical effectiveness of dermal equivalents in the long term. The dermal substitute that is discussed here is derived from bovine collagen and elastin‐hydrolysate and has been shown to improve skin elasticity during a short‐term clinical follow‐up of scar reconstructions. In this study we will present the long‐term outcome by means of objective and subjective scar assessment tools for dermal substitution in acute burn wounds and scar reconstructions. In a clinical trial, an intraindividual comparison was performed between the conventional split‐thickness autograft and a combination of the collagen/elastin substitute with an autograft. After 1 year, scars were evaluated by the Cutometer SEM 474 for objective elasticity measurements and by planimetry to establish scar contraction. An independent observer subjected scars to a generally accepted clinical scar assessment tool: the Vancouver Scar Scale. In addition, patients gave their impression of the outcome. Forty‐two paired burn wounds and 44 paired scar reconstructions were included and evaluated 1 year after surgery. Although substituted scar reconstructions demonstrated an elasticity improvement of approximately 20 percent compared with control wounds, no statistically significant differences were found for skin elasticity, scar contraction, Vancouver Scar Scale, and patients impression in both categories after 1 year. An extensive long‐term follow‐up shows that the dermal substitute, which was proven effective in a clinical trial on a short‐term basis, did not yield statistical evidence for a long‐term clinical effectiveness of dermal substitution. (Plast. Reconstr. Surg. 108: 1938, 2001.)

Widely expanded postage stamp skin grafts using a modified Meek technique in combination with an allograft overlay.

A method for obtaining widely expanded postage stamp autografts, first described in 1963 by C.P. Meek, has been evaluated in our burns unit. The technique, in which an expansion ratio of 1:9 is achieved with the aid of special prefolded gauzes, was combined with an overlay of glycerol-preserved allografts applied 1 week after grafting. This delay did not appear to affect graft take. In a series of 16 consecutive skin graft procedures performed on 10 patients with extensive burns, the mean epithelialization rate was 90 per cent (range 70-100 per cent) within 5 weeks. Cosmetic results were comparable to those achieved with widely expanded mesh grafts. The Meek technique utilizes small pieces of autograft, and has proved to be a practical alternative to mesh grafts when donor sites are limited.

Collagen morphology in human skin and scar tissue: no adaptations in response to mechanical loading at joints

Dermal collagen displays a random-like structure that has a major role in strength and function of the human integument. It is hypothesised that collagen bundles align in a parallel fashion in the direction of mechanical tension during scarring, which may explain the problematic scar formation that occurs specifically at joints. Scar tissue and normal skin were biopsied from joints and control areas and evaluated by the Fourier analysis. Collagen orientation was represented by an index ranging from 0 (perfectly random) to 1 (perfectly parallel). Collagen bundle packing signifies the average distance between the centres of collagen bundles. No differences were shown in collagen morphology of scar tissue and normal skin between joints and control areas. Normal skin had a significantly lower collagen orientation index than scar tissue (0.26 versus 0.44, P<0.001). The bundle packing of scar tissue differed significantly from normal skin (18.1 microm versus 23.7 microm, P<0.001). Collagen appeared less parallel orientated in deep dermis compared to superficial dermis especially for normal skin (0.27 versus 0.33, P=0.06). Normal skin had a less parallel organisation in sections that were cut parallel compared to those that were cut perpendicular to the epidermis (0.24 versus 0.30, P=0.02). Collagen orientation of scar tissue is more parallel compared to normal skin. Morphology differs with respect to superficial and deep dermal layers and parallel and perpendicular planes, but appears not to respond to mechanical tension.

Morphometry of dermal collagen orientation by Fourier analysis is superior to multi‐observer assessment

In human dermis, collagen bundle architecture appears randomly organized, whereas in pathological conditions, such as scar tissue and connective tissue disorders, collagen bundle architecture is arranged in a more parallel fashion. Histological examination by one or two observers using polarized light is the most common method to determine collagen orientation. The hypothesis on which this study is based is that an objective image analysis technique, Fourier analysis, would improve the reliability (are the measurements reproducible?) and the accuracy (does the method measure what it is supposed to measure?) of collagen orientation assessment, compared with observer ratings. Fourier analysis was applied to 271 images of scar tissue and normal skin that were acquired by confocal laser‐scanning microscopy. Observers rated the same areas using polarized light as well as the confocal microscopy images. Computer images consisting of different types of ellipses were generated with a fixed orientation. Observers and Fourier analysis evaluated the images to evaluate accuracy. The inter‐observer reliability was acceptable when at least three observers rated polarized light images (r > 0.69), whereas two observers were sufficient for rating confocal microscopy images (r > 0.71). Fourier analysis correlated better with observer ratings of confocal microscopy images (r = 0.69) than with polarized light microscopy images (r = 0.42). Fourier analysis was more accurate than four observers for the evaluation of the ‘true’ orientation for almost all types of computer‐generated images. For the first time it is shown that Fourier image analysis is suitable for the morphometry of dermal collagen orientation and leads to a superior measurement of collagen orientation compared with subjective histological evaluation by several experts. If an evaluation is performed by conventional light microscopy, at least three observers are required to attain an acceptable inter‐observer reliability. Copyright

The prognostic factors regarding long-term functional outcome of full-thickness hand burns

The treatment of the burned hand has always been a subject of special interest. In order to obtain a better understanding of the parameters involved in the long-term functional outcome of hand burns a retrospective study was performed on 88 consecutive patients with hand burns (143 hands), treated according to a standardised protocol. Patients were followed for at least 12 months postburn. Hand function was assessed by the seven objective test criteria (7-OTC) described by Jebsen. Logistic regression analysis produced five parameters that were found to have a significant predictive value for long-term hand function. In order of predictive value, these were finger amputations, age on admission, impaired autograft take, the full-thickness hand burn surface area and the full-thickness total body burn surface area. By fitting these five variables into an equation, a probability model was obtained, which could be applied to estimate a prognosis concerning the final hand function of an individual patient with a hand burn. No relationship was found between the postburn day of operation and the long-term hand function. This finding is inconsistent with the current consensus that functional outcome is improved by early excision and grafting. In practice, it suggests that hand function is well preserved when burns of uncertain depth are treated expectantly, followed by selective debridement and grafting. Advantages include reduced blood loss, no loss of vital tissue and a reduction of the need for donor sites.

Long-term results of a clinical trial on dermal substitution.: A light microscopy and Fourier analysis based evaluation

Although dermal substitution is a main topic of current wound healing research, there is a paucity of clinical trials with a long-term clinical and histopathological evaluation. A clinical trial was conducted to perform an intra-individual comparison of conventional treatment (split-thickness autograft) to a collagen/elastin dermal substitute in combination with an autograft. Promising results with this substitute were obtained with respect to dermal organisation and scar elasticity in animal studies and clinical trials with a short-term follow-up. Twenty-nine of the 42 pairs of the burn wounds and 28 of the 44 pairs of the scar reconstructions enrolled in the study were biopsied after 1 year. Promising but not statistically significant differences were found between substituted groups and control groups for epidermal thickness, basement membrane maturation, rete ridges (P=0.055), fibroblasts, myofibroblasts, inflammatory cells, vessels and extracellular matrix maturation. An objective and accurate technique, Fourier analysis, was used to evaluate collagen bundle orientation and packing. However, no statistically significant differences were obtained for these parameters. This microscopic evaluation provided no convincing evidence for a long-term effectiveness of a dermal substitute despite promising data over a short-term in in vitro and in vivo studies with the same material.

Reliability and accuracy of techniques for surface area measurements of wounds and scars.

The applicability of simple methods to measure the size of pathological skin lesions for management and research has been poorly studied to date. The interobserver reliability and accuracy (validity) was established for planimetry by photography and planimetry by tracing on a transparent sheet in this study. Drawings of 25, 50, and 75 cm 2 were created on 3 locations with increasing curvature (back, thigh, and forearm) in 20 healthy volunteers. Three investigators evaluated the drawings by both planimetry techniques. Both techniques showed a good reliability (r ≥ 0.82, intraclass correlation) for 25 cm 2 areas. Planimetry by photography was more reliable than planimetry by tracings for the 50 -and 75-cm 2 areas and was more accurate than planimetry by tracing for all areas except for the area with the greatest curvature, the forearm. The study permits the conclusion that planimetry by photography is more suitable for surface area measurements than planimetry by tracing except for extremely curved body parts, where it is likely that effects of distortion supervene.

Surgical release for intubation purposes in postburn contractures of the neck

Postburn contractures of the neck can cause difficult endotracheal intubation when cervical hyperextension and lifting of the mandible are impaired. alternative techniques to direct laryngoscopy may be hampered by the presence of rigid scar tissue which obscures the mandibular and laryngeal anatomy, or by the presence of microstomia following retraction of scar tissue in facial burns. This report describes our experience with a safe and quick surgical neck release to facilitate endotracheal intubation in such cases. Following release, intubation was established at the first attempt in all cases. Patients who have suffered flame burns to the thorax with an ascending involvement of the neck and mandibular region are particularly prone to develop extreme contractures. Problems with intubation should be anticipated in patients with healed burns of the neck, and equipment for aiding intubation should be on hand. Furthermore, the surgeon must be available during the induction of anaesthesia to perform an emergency neck release if necessary.