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

Wounds should be closed parallel to tension lines. Will reduce the incidence of biologic tourniquet, places less tension on the sutures, and minimizes dog ears.

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). These structures also contribute to the viscoelastic properties of skin (mechanical and biologic creep, and stress relaxation).

Question 4

What are Halsted’s principles (7)?

Answer 4

Question 5

What wound factors should be considered in primary wound closure?

Answer 5

Size, geometric shape, anatomic location, chronicity, bacterial load, structural damage, periwound status.

Question 6

What patient factors should be considered in primary wound closure?

Answer 6

Age, species, breed, body condition, temperament, systemic factors.

Owner factors and surgeon factors should also be considered.

Question 7

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

Answer 7

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

Question 8

What are some tension relieving suture techniques?

Answer 8

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 9

What suture patterns can be used for stent/bolster sutures?

Answer 9

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

Question 10

How many days following placement are bolster sutures typically removed?

Answer 10

3rd or 4th post-operative day once stress relaxation of the skin has occurred.

Question 11

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

Answer 11

Appositional. Unlike the vertical mattress suture the needle is not reversed in the needle holder.

Question 12

Why are horizontal mattress sutures generally not recommended for tension relief during primary wound closure?

Answer 12

May impede vascular supply to the wound edges. Vertical mattress may be preferred although can be everting under tension (as compared to far-near-near-far, or far-far-near-near suture patterns).

Question 13

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

Answer 13

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 14

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

Answer 14

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

Question 15

How much skin stretching is achieved with intraoperative stretching?

Answer 15

Limited, but does provide a degree of stress relaxation and limited mechanical creep.

Question 16

What is a skin expansion device?

Answer 16

A silicone elastomer device that is surgically placed in the subcutaneous tissues and expanded by 10-15% every 2-3 days.

Question 17

What phenomenon do skin expansion devices rely on?

Answer 17

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 18

What is the maintaining period following placement of a wound expansion device?

Answer 18

The addition of several weeks following skin expansion to allow the quality of the expanded skin to improve.

Question 19

What are some methods of pretensioning suturing that are described?

Answer 19

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

Should be performed 48-72 hours before definitive wound closure.

Question 20

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

Answer 20

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

Question 21

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

Answer 21

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 22

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

Answer 22

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

Question 23

How far away from the wound edge should mesh expansion incisions be made?

Answer 23

1cm from the wound edge, 1cm between incisions. Should be staggered.

Vascular compromise can occur if mesh incisions are too large. Are not recommended for use in skin flaps.

Question 24

In a Z-plasty in which direction is tension relaxation achieved?

Answer 24

Along the central limb (this should be directed along the line of tension).

Question 25

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

Answer 25

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 26

What are some methods of closing a circular incision?

Answer 26

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 27

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

Answer 27

Should be the same length (or 1.5 times the 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.

Question 28

What tension relieving technique is depicted?

Answer 28

Mesh incisions

Question 29

What tension relieving technique is depicted?

Answer 29

Simple relaxing incision (or bipedicle flap)

Question 30

What tension relieving technique is depicted?

Answer 30

V-Y plasty

Question 31

What tension relieving technique is depicted?

Answer 31

Z-plasty

Question 32

What tension relieving technique is depicted?

Answer 32

M-plasty (also useful for closure of cranial mastectomy wounds).

Question 33

What closure technique is depicted?

Answer 33

Bow-tie technique for closure of crescent shaped wounds with a large discrepancy in size.

Question 34

What closure technique is depicted?

Answer 34

Combined V-plasty for closure of a circular defect.

Question 35

What closure technique is depicted?

Answer 35

O- to S-plasty for closure of a circular defect.