Wound Closure Techniques and Medicinal Leeches

CVM 737A: Introduction to Surgery - Principles of Reconstructive Surgery - SA

• Course: CVM 737A, Introduction to Surgery
• Topic: Principles of Reconstructive Surgery - SA
• Date of Lecture: January 16, 2025
• Instructor: R. Randall Thompson, DVM, MSpVM (SA Surgery)
• Affiliation: Liaison, DeBusk Veterinary Teaching Center, Associate Professor of Small Animal Surgery
• Location: Lincoln Memorial University

Learning Objectives

• List methods for reducing tension when closing wounds surgically.
• Summarize the direction of surgical incisions and reasoning.
• Summarize considerations for planning 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 procedures: closing defects from trauma, correcting congenital abnormalities, and after removal of neoplasms.
• Importance of correct techniques: to prevent complications and unnecessary costs.

Techniques for Closing Defects

• Relaxing incisions (e.g., V-to-Y, Z-plasty): used for large or irregular defects.
• Tissue mobilization: moving tissue from other sites for large defects, especially on extremities.
• Pedicle flaps: tissues partially detached from the donor area and moved to cover a defect.
• Grafts: transferring a segment of skin to a distant (recipient) site.

Planning Reconstructive Surgery

• Factors to consider: location of the wound, elasticity of surrounding tissue, regional blood supply, and character of the wound bed (infection, granulation tissue, skin availability).

Tension Lines and Tension Relief

• Wound closure should be along tension lines for optimal healing and aesthetics.
• Methods for reducing tension include undermining wound edges, selecting appropriate suture patterns (e.g., cruciform > simple interrupted), using relief incisions, skin stretching, and tissue expansion.
• Positioning is crucial: avoiding pinning mobile skin, using pads, and appropriate joint flexion.
• Secondary intention healing or flaps/grafts are options if primary apposition isn't possible.

Tension Relief Methods

• Undermining wound edges
• Suture Patterns
• Relief Incisions
• Skin Stretching
• Tissue Expansion

Tension Lines

• Formed by fibrous tissue pull in the skin.
• Important to map in animals, considering breed, conformation, gender, and age variations.
• Incisions parallel to tension lines heal better.
• Perpendicular incisions cause gaping wounds and wider scar tissue.

Prevention of "Dog Ears"

• Correcting "dog ears" by placing sutures closer together on the convex side of a wound are crucial.
• Sutures should be spaced farther apart on the concave side.
• Outlining with an elliptic incision and removing redundant skin; apposing edges in linear or curvilinear fashion.
• Incising the dog ear to form two triangles for excision or repositioning is another method.

Relaxing Incisions

• Allows closure around fibrotic wounds or over crucial structures: e.g., before radiation therapy, after tumor excision, on distal extremities, around the eyes and anus, over tendons, ligaments, nerves, vessels, or implants.
• Different types include simple relaxing incisions, multiple punctate relaxing incisions.
• Healing time: 25-30 days by contraction and epithelialization.

V-to-Y Plasty and Z-Plasty

• V-to-Y: advancement flap to cover the wound.
• Z-Plasty: can be made adjacent to the wound to decrease tension and facilitate wound closure.
  • Central member should be parallel to tension lines and 1/3 to 1/2 the length of the incision.
  • "Limbs" of Z-plasty should form 60° angles towards the center of the Z.
  • Additional considerations include distance from primary incision (≥ 3 cm), rounding the Z tips, undermining tissue, and marking the tumor margins when removing tumors.

Skin Removal for Tumors

• Assess skin tension and elasticity, and avoid excessive tumor manipulation.
• Plan incision direction, excision shape, and closure method.
• Clip the large treatment area and perform aseptic preparation.
• Excision should include the tumor, previous biopsy sites, and appropriate margins in 3 dimensions (length, width, depth).
• Aggressive tumors require larger margins.

Additional Flaps, Grafts, and Stenting

• Techniques like advancement flaps, rotational flaps, transposition flaps, interpolation flaps, and tubed pedicle flaps.
• Axial pattern flaps, incorporating direct cutaneous vessels for better perfusion.
• Consider using stents to support suture loops beneath the tissue.