Evaluation of microcirculation and wound-closing tension after undermining the skin. A study in a porcine model using laser Doppler perfusion imaging

Quantification of skin wound tension using a newly designed wound tensiometer

OBJECTIVE

To (i) quantitatively measure wound tension in experimental skin wounds using a newly developed wound tensiometer and (ii) establish reference values for primary skin wound closure in medium- and large-breed dogs.

STUDY DESIGN

Experimental cadaveric study.

ANIMAL POPULATION

Nineteen dogs of medium to large breeds (BW 20 to 40 kg).

METHODS

Elliptical skin wounds of different sizes were created on the chest and abdomen. The wounds were gradually enlarged. Experienced surgeons (ECVS diplomates or professors of small animal surgery) and inexperienced surgeons (1st year after graduation) independently assessed wound tension through manual manipulation and determined whether the wound could be closed without tension-relieving measures. In addition, wound tension was objectively quantified using a newly developed wound tensiometer.

RESULTS

The upper threshold for wound tension at which direct appositional wound closure was recommended by the experienced surgeons was 5.4 N, and the median minimal tension without recommendations for closure was 6.0 N. The data also demonstrate that wound tension and wound size do not necessarily correlate, and inexperienced surgeons need to develop a feel for wound tension.

CONCLUSION

The intraoperative use of the wound tensiometer, in combination with established cut-off values, might facilitate decision-making regarding primary wound closure.

CLINICAL RELEVANCE

The findings of this study provide evidence for the applicability of a wound tensiometer in guiding inexperienced surgeons in their choice of the skin wound closure method.

Wound tension and 'closability' with keystone flaps, V-Y flaps and primary closure: a study in fresh-frozen cadavers

BACKGROUND

Previous publications have implied that the keystone flap provides mechanical benefits compared to primary closure. This has not been objectively demonstrated.

METHODS

Elliptical defects were created in 'fresh-frozen' cadaveric specimens. Two approaches were used to investigate the potential mechanical benefits of keystone flaps. Experiment 1 (wound closure): 18 defects were incrementally enlarged until they could not be closed primarily either with a single 'midpoint' suture or with a continuous suture. Attempts were then made to close these wounds with island flaps: 13 keystone flaps (seven 'type IIA' and six 'Sydney Melanoma Unit (SMU) modification') and five V-Y flaps. Experiment 2 (tension reduction): 28 defects were fashioned to be 'closable' under high tension. The 'pre-flap tension' was measured with a single midpoint suture and tensiometer. Fourteen keystone flaps (seven type IIA and seven SMU modifications) and seven V-Y flaps were then developed and mobilized with no flap constructed on the remaining seven 'primary closure' wounds. The secondary defects resulting from flap mobilization were closed leaving the primary defect unsutured. The primary defect 'post-flap tension' was then measured using the same technique.

RESULTS

For Experiment 1, V-Y flaps enabled closure in four of five 'unclosable' defects. Keystone flaps did not enable closure in any of the 13 cases (P < 0.001). For Experiment 2, the V-Y flap (n = 7) was the only group that produced a significant drop in wound tension across the primary defect (mean 'pre-flap' to 'post-flap' tension change: -53%, 95% CI: -67 to -39%, P < 0.001).

CONCLUSION

The data raise questions about the biomechanical benefits of keystone flaps.

A New Skin Tensiometer Device: Computational Analyses To Understand Biodynamic Excisional Skin Tension Lines

One of the problems in planning cutaneous surgery is that human skin is anisotropic, or directionally dependent. Indeed, skin tension varies between individuals and at different body sites. Many a surgeon has tried to design different devices to measure skin tension to help plan excisional surgery, or to understand wound healing. However, many of the devices have been beset with problems due to many confounding variables - differences in technical ability, material (sutures) used and variability between different users. We describe the development of a new skin tensiometer that overcomes many historical technical issues. A new skin tension measuring device is presented here. It was designed to be less user-dependent, more reliable and usable on different bodily sites. The design and computational optimizations are discussed. Our skin tensiometer has helped understand the differences between incisional and excisional skin lines. Langer, who pioneered the concept of skin tension lines, created incisional lines that differ from lines caused by forces that need to be overcome when large wounds are closed surgically (excisional tension). The use of this innovative device has led to understanding of skin biomechanics and best excisional skin tension (BEST) lines.

Microcirculatory Evaluation of the Abdominal Skin in Breast Reconstruction with Deep Inferior Epigastric Artery Perforator Flap

No studies have assessed the perfusion of the undermined abdominal skin in breast reconstruction with deep inferior epigastric artery perforator flap. A greater understanding of the procedure’s impact on the perfusion of the abdominal skin can be valuable in predicting areas susceptible to necrosis.