Tension relieving techniques

Question 1

What determines skin tension?

Answer 1

The predominant pull of the collagen and elastin fibers in the dermal and hypodermal tissue. Can have regional anatomic differences.

Question 2

Describe the tension lines in the dog

Answer 2

Question 3

What are the structural components of skin that are central to its ability to be mobilized?

Answer 3

Collagen fibers, elastin fibers, and the lubricating extracellular matrix (various proteoglycans)

Question 4

What are Halsted’s principles

Answer 4

Question 5

Should undermining be performed superficial or deep to the panniculus carnosus layer (cutaneous trunci, platysma, sphincter colli superficialis)?

Answer 5

Deep in order to preserve the deep subdermal plexus. Efforts should also be made to preserve the perforating direct cutaneous vessels.

Question 6

What are some tension relieving suture techniques?

Answer 6

Bolster/stent placement, far-near-near-far/far-far-near-near sutures, horizontal or vertical mattress sutures, walking sutures, strong subcutaneous sutures (additional intradermal layer)

Question 7

What suture patterns can be used for bolster sutures?

Answer 7

Simple interrupted, vertical mattress, loops created on both sides of the closure

Question 8

Are far-near-near-far and far-far-near-near appositional, everting or inverting suture patterns?

Answer 8

Appositional (as compared to horizontal and vertical mattress sutures)

Question 9

How do the phenomena of mechanical creep and stress relaxation apply to the skin?

Answer 9

Mechanical creep: with a force applied to the skin the collagen fibers straighten and release water molecules, increasing skin viscosity and resulting in elongation with the same applied load.

Stress relaxation: with prolonged mechanical loading delicate elastic fibers in the ECM start to fracture and lose their elasticity resulting in decreasing stress at the same amount of deformation.

Question 10

What are some skin stretching techniques that can be employed during wound closure?

Answer 10

Pretensioning, posttensioning, pre-suturing, intra-operative stretching, wound expansion devices

Question 11

What phenomenon do wound expansion devices rely on?

Answer 11

Biologic creep. This is the formation of new dermal and epidermal components when the skin is applied under constant stress. With expansion of the skin the hypodermis and dermis are thinned and the epidermal layer thickens. The skin becomes less pliable as a result.

Question 12

What are some methods of pretensioning suturing that are described?

Answer 12

Simple continuous pattern, continuous horizontal intradermal running pattern, use of tensioning devices (such as velcro pads)

Question 13

What are some of the proposed benefits of NPWT in an open wound?

Answer 13

Reduced edema, enhanced granulation tissue formation, increased blood flow, increased systemic cytokine levels.

Question 14

What are some of the proposed benefits of NPWT over a closed wound?

Answer 14

Reduced shear and tensile forces, as well as reductions in interstitial edema (have been shown to reduce SSI, dehiscence, seroma and hematoma in high risk human patients)

Question 15

What are some examples of relaxing incisions that can be used for wound closure?

Answer 15

Mesh expansion, simple relaxing incision (or bipedicle advancement flap), V-Y plasty, Z-plasty, M-plasty. See Tobias page 1440 for images.

Question 16

What are some techniques for apposing a crescent shaped incision when the discrepancy in edges is less than 20%

Answer 16

Fudging, suturing from the center outward and excising the dog ears at the end, suturing toward the center and excising the dog ear in the middle. For larger defects a ‘bow-tie’ technique may be required. See Tobias page 1443 for images.

Question 17

What are some methods of closing a circular incision?

Answer 17

Linear closure with excision of dog ears, conversion to fusiform shape, dividing the circle into 3 equal arcs, v-plasty or O to S-plasty. See Tobias page 1445 for images.

Question 18

When creating a simple relaxing incision how long should the incision be in relation to the wound?

Answer 18

Should be the same length as the wound, and the width of the bipedicled skin the width of the wound. The length:width ratio of the bridge should not exceed 4:1 otherwise vascular compromise will result.