Episode 17 — Basic Principles of Surgery : Principles of Tissue Handling and Incision скачать в хорошем качестве

Episode 17 — Basic Principles of Surgery : Principles of Tissue Handling and Incision

1. The Surgical Incision An incision is made with a sharp **Bard-Parker (BP) knife**. In OMFS, we commonly use a *#15 blade* on a #3 handle for most incisions. A *#11 blade* is a "stab knife," used for incision and drainage of abscesses or for gingival crevicular incisions. *Note on Cautery:* Skin incisions are not made with an electrocautery knife due to the risk of tissue necrosis and impaired healing. However, cautery is acceptable for deeper tissues and mucosal incisions. *Principles of a Good Incision* 1. *Mark the Incision:* Always mark the intended line with sterile marking ink first to avoid mistakes. 2. *Placement (Langer's Lines):* The incision should be placed in *normal skin folds* or along **Langer's lines**. These are the lines of minimal skin tension. Incising along them minimizes tension, prevents wound dehiscence, and results in a more cosmetic, camouflaged scar. 3. *Sufficient Length:* The incision must be *long enough* to provide easy, passive access to the deeper structures. A short incision requires forceful retraction, which causes more tissue trauma and inflammation. It is a false notion that short incisions heal faster; healing is a simultaneous process independent of length. 4. *Avoid Vital Structures:* Plan the incision to avoid known major blood vessels and nerves. 5. *Hold the Knife Correctly:* The knife is held with a *"pen grip"* to provide maximum control. The hand should be rested on a stable surface. 6. *The Stroke:* The blade is held *perpendicular* to the tissue. The assistant stretches the skin taut, and the surgeon makes a *single, controlled, continuous stroke* through the full thickness of the tissue. Repeated, hesitant, or "sketchy" incisions lacerate the wound edges and severely compromise healing. *** 2. Flap Designing When we need broad access, we elevate a flap. The design of this flap is critical for its survival. *Base Wider than Apex:* This is the cardinal rule. The base of the flap must be wider than its apex to ensure adequate **afferent (arterial) and efferent (venous) vascularity**. A narrow base compromises blood flow and leads to flap necrosis. *Adequate Access:* The flap must be wide enough to provide passive access without stretching or tearing. *Full Thickness:* The flap should be full-thickness, for example, a *mucoperiosteal flap* that includes the mucosa and periosteum. *Rest on Sound Bone:* The edges of the flap must not lie over a bony defect. They must be sutured back onto a solid, healthy bone shelf to prevent the flap from collapsing into the defect and causing wound dehiscence. *** 3. Tissue Dissection Once the incision is made, we must separate the tissue planes. *Sharp Dissection:* *Method:* Using a knife or the sharp tips of scissors. *Pros:* This is *less traumatic* than blunt dissection, as it cuts cleanly without tearing. A knife is less traumatic than scissors, as scissors crush the tissue before cutting. *Cons:* It is dangerous to use near vital structures. *Blunt Dissection:* *Method:* Using the non-cutting edge of scissors or the tips of a hemostat in an "open and spread" motion. *Pros:* This is the preferred method for soft, friable tissues and for dissecting near anatomical proximity to vital structures (nerves and vessels). *Cautery Dissection:* *Method:* Using an electrocautery tip. *Pros:* It provides a *dry surgical field* by simultaneously cutting and coagulating small vessels. *Cons:* It inflicts more *thermal necrosis* (heat damage) to the tissue, which can compromise the quality of healing. *** 4. Tissue Retraction Retraction provides visibility and access. The choice of retractor is key. *Atraumatic Retraction:* For soft, friable tissues, use smooth, atraumatic retractors like the **Langenbeck's (L) retractor**. *Traumatic Retraction:* For tough, tenacious tissues like skin, muscle, or periosteum, use holding retractors like *Allie's forceps* or a **Cat's Paw retractor**. *Critical Precaution:* When using an Allie's forceps on a skin flap, never apply it to the outer (epidermal) surface. This will leave ugly bite marks. It should be applied to the *inner (dermal) surface* of the flap. *Specialized Retractors:* Different tissues require specific tools: *Glandular Structures (lymph nodes):* Held with **Babcock's gland-holding forceps**. *Fine Skin Flaps (plastic surgery):* Retracted with **skin hooks**. *Nerves:* Retracted with **blunt nerve hooks**. *Intraoral:* *Doyen's* or *Dingman's* mouth gags, or an *Austin's retractor* for third molar surgery. *Eyeball:* Retracted with a **copper malleable retractor**.