Wound Closure Techniques Quiz

CVM 737A - Introduction to Surgery

• Course title: Introduction to Surgery
• Course subtitle: Principles of Reconstructive Surgery - SA
• Lecture date: January 16, 2025
• Lecturer: R. Randall Thompson, DVM, MSpVM (SA Surgery)
• Affiliation: Liaison, DeBusk Veterinary Teaching Center, Associate Professor of Small Animal Surgery
• Institution: Lincoln Memorial University, College of Veterinary Medicine

Learning Objectives

• List methods of reducing tension during surgical wound closure.
• Summarize the direction and rationale for surgical incisions.
• Summarize considerations for planning surgical skin tumor removal.
• Summarize methods for recruiting skin to close wounds under tension.
• Illustrate methods for preventing or correcting "dog ears" or puckers.

Reconstructive Surgery

• Common uses: closing trauma-induced defects, correcting congenital abnormalities, and post-neoplasm removal.
• Importance of appropriate techniques: prevent complications and costs.

Reconstructive Surgery Techniques

• Closing large or irregular defects: relaxing incisions (e.g., V-to-Y, Z-plasty).
• Mobilizing tissue from other sites for large defects: pedicle flaps, skin grafts (full-thickness, sheet, plug/punch/seed, strip, mesh, split-thickness).
• Considerations for preventing complications: careful planning, atraumatic techniques, avoiding excessive tension, kinking and proper circulatory compromise.

Hirudiniasis

• Leech application: only for tissues with impaired venous circulation.
• Leech species: Hirudo medicinalis.
• Leech effect: produces a small bleeding wound mimicking venous outflow.
• Average blood consumption: 5 ml.
• Blood oozing duration: 24 to 48 hours post-leech removal due to anticoagulants and vasodilators introduced into the wound.
• Infection risk: Aeromonas hydrophila.

Tension Lines and Tension Relief

• Planning considerations: wound location, tissue elasticity, regional blood supply, characteristics of the wound bed.
• Minimizing tension: undermining wound edges, selecting appropriate suture patterns (e.g., simple interrupted, mattress, cruciate), using relief incisions, skin stretching, tissue expansion.
• Positioning: proper animal positioning avoids pinning mobile skin.
• Secondary intention: a wound may heal without primary apposition, or by reconstructive flap or graft surgery if these methods are not helpful.

Tension Lines

• Formation: predominant pull of fibrous tissue within the skin.
• Variation: based on breed, conformation, gender, and age.
• Healing: incisions parallel to tension lines heal better, faster, and with more aesthetic results.
• Incision direction: perpendicular to tension lines generally widens scars.
• Minimizing dog ears: placing sutures close together on the convex side of the defect and farther apart on the concave side; incising and excising a triangular section of the offending skin.

Tension Relief Methods

• Techniques for reducing tension: undermining wound edges, selecting appropriate suture patterns, using relief incisions, skin stretching, and tissue expansion.

Skin Stretching and Expansion

• Technique: takes advantage of skin's inherent elasticity.
• Pre-stretching: stretching hours to days before surgery for less tension during procedures.
• Techniques: presuturing, adjustable sutures, skin stretchers, skin expanders (inflated, gradual expansion).

Suture Patterns

• Subdermal Sutures: place sutures in subdermal/subcuticular tissue for better tension management, less scarring. Sutures used include 3-0 or 4-0 polydioxanone, poliglecaprone or polyglyconate suture with a buried knot; appropriate suture material chosen based on tension and other tissue composition.
• Walking Sutures: advance skin edges towards defect center using interrupted subdermal sutures, distributing wound tension.
• External Tension-Relieving Sutures: prevent suture loop pressure exceeding blood flow. Techniques include placing sutures farther from the skin edge or with mattress or cruciate patterns; these methods are often used in conjunction with other relieving tension techniques.

Other Suture Patterns that Relieve Tension

• Vertical Mattress Sutures: standard tension-relieving suture that involves a secondary row of stitches placed 1-2cm apart to help distribute tension during wound healing.
• Alternating wide/narrow simple interrupted sutures, as well as far-far-near-near or pulley suture patterns.
• Horizontal Mattress Sutures with/without rubber tubing stenting may be used, reducing potential for hindering blood flow; these techniques may complement other methods

Prevention of "Dog Ears"

• Suture spacing: place sutures close together on the convex side of the defect and farther apart on the concave side.
• Outlining: use elliptic incision and remove excess skin when possible for linear or curvilinear fashion.
• Dog ear incision and excision: incising and resecting a triangle in the center of dog ears reduces the puckered shape; other methods of correction also exist
• Thin vs. thick skin: thin skin is less prone to dog ear formation; understanding tissue characteristics is crucial

Relaxing Incisions

• Purpose: skin closure around fibrotic wounds or over important structures.
• Usage: before radiation therapy, after extensive tumor excision, distal extremities, around the eyes/anus for tendon, ligament, nerve coverings.

Simple/Multiple Punctate Relaxing Incisions

• Simple: heal by contraction and epithelialization in 25 to 30 days. Allows faster wound healing in compliant tissue.
• Multiple punctate: small, parallel, staggered incisions made in skin adjacent to a wound to reduce tension. Provides a more cosmetic closure but has a greater risk for circulatory compromise.

V-to-Y and Z-Plasty

• V-to-Y: advance skin flap over defect for coverage.
• Z-Plasty: reduces wound tension by shaping a Z in the surrounding tissue. Aids in facilitating wound closure and reduces tension.

Removal of Skin Tumors

• Assessment: skin tension and elasticity before removal, limiting manipulation.
• Planning: direction of skin tension, excision shape, closure method.
• Tumor margin: benign - 1cm, malignant - 2-3 cm margins necessary, including deep margin if feasible; margin distances vary based on aggressiveness and tissue characteristics
• Aggressive, Infiltrative Tumor Margin: greater margin necessary
• Types of tumors: Mast Cell Tumors, Melanomas, Squamous cell carcinomas, Soft tissue sarcomas, Feline Mammary Adenocarcinomas, Hemangiopericytomas, Infiltrating Lipomas; understanding tissue characteristics (dense collagen vs vascular) is critical
• Tissue considerations during resection: fat, subcutaneous tissue, muscle, and parenchyma should be included; cartilage, tendon, ligaments and fascia are resistant to invasion and should be spared
• Radical Excision: used for poorly localized or high grade malignant tumors, minimizing recurrence rates
• Marking tumor borders: critical for adequate margins for complete excision, minimizing the risk for tumor recurrence

Skin Flaps for Wound Closure

• Types: Advancement, Rotational, Transposition, Interpolation, Tubed Pedicle.
• Advancement Flaps: Local flaps are used to close defects around the area, using a single-pedicle, bipedicle or H-plasty design and sliding the flap into place.
• Rotational Flaps: pivoting flaps over the defect, providing coverage without tension.
• Transposition Flaps: Rectangular, local skin flaps, aligned to tension lines to cover the area without tension.
• Interpolation Flaps: variation of transposition flaps, lacking common border, leaves skin segment separating the donor and recipient beds; this requires special care.
• Tubed Pedicle Flaps: a multistage procedure used to move a distant skin flap into a wound, creating a tube; this is an advanced technique.

Axial Pattern Flaps

• Vessels: include a direct cutaneous artery and vein at the base of the flap; these branches supply the subdermal plexus; understanding vascular anatomy is critical for flap survival.
• Perfusions: better perfusion than pedicle flaps, due to the superior blood supply. The vessels provide support during flap rotation.
• Placement: flaps elevated and transferred into cutaneous defects within their radius.

Skin Grafts

• Advanced procedure: performed by specialist.
• Types: full thickness, sheet, plug/seed/strip, mesh, split thickness
• Meshed skin grafts: small full-thickness incisions in the graft are aligned in parallel rows.