Instrument Tie Suture Technique: Step-by-Step Guide

Surgical instrumentation is organized by four phases: diérese (tissue cutting), hemostasia (bleeding control), exérese (tissue removal), and síntese (wound closure). Diérese instruments include bisturys (scalpels) in three types: fixed blade, electric, and disposable (numbers 3 and 4 most common). Mayo scissors have shorter cutting edges with larger pressing surfaces, while Metzenbaum scissors have longer cutting edges with smaller pressing surfaces. Hemostasia instruments include Kelly forceps (grooves only in first two-thirds of pressing portion) and Hemostatic forceps for small vessels (grooves along entire pressing portion). Exérese instruments include tissue retractors (C-shaped), Collins forceps (heart-shaped), Ales forceps (tooth-like structures), and anatomical forceps (toothed or non-toothed). Síntese instruments include needle holders (tungsten-coated or reticulated pattern), Yan aspirator, and Bacus forceps. Forceps differ from scissors by having cremalheiras (locking mechanisms). Proper instrument delivery requires facing the surgical table with curved tips oriented upward. A skilled instrumentator should begin and end surgery with an organized table, returning sharp instruments closed to the tray.

A needle holder consists of two proximal rings, a ratchet system, a body, and a tip for fixing needles during surgical suturing. Two primary handling techniques exist: palming (using palm and hypothenar region) for versatility in large/small stitches and preventing suture twisting, and finger grip (thumb and fourth finger in rings) for maximum precision and control. The finger grip technique is specifically recommended for vascular and soft tissues requiring careful handling, while palming suits larger or non-soft tissues.

Proper instrument handling is essential for safe and effective surgery. Forceps should be held between thumb and middle fingers for control, with index finger providing stability and ring/pinky fingers planted on the surface for support. Flat-tipped forceps (DeBakey) should not be used on skin to prevent crush injuries; pointed tips are preferred. Needle drivers can be held traditionally (ring finger in bottom loop, thumb in top), palmed (without fingers in loops for better pronation/supination), or with intermediate variations. Needles should be loaded two-thirds back from the tip with slight outward angle, and protected by rotating the point against the shaft when returning to assistants. Scissors must be held with screws pointing upward, blades pushed together with thumb and ring fingers, and entered with blades closed to prevent inadvertent cutting.

This comprehensive section covers essential surgical instruments used in medical procedures. Scissors are held using thumb and index finger with ring finger inside the handle. Straight scissors cut superficial skin and muscle, while angled scissors target deep muscle tissue. Myotomy scissors specifically address deep muscle cutting. Bandage cutting scissors require holding the long side inward. Suture cutting scissors handle both tight sutures (curved design) and loose sutures (standard design). Forceps include red toothed forceps for tough tissues like heart, simple forceps for delicate tissues like intestine, and artery forceps for bleeding control. Large artery forceps handle superficial bleeding, while curved artery forceps address deep bleeding. Mosquito forceps control small vessels, with curved variants for deeper locations. Needle holders differ from artery forceps by having smaller heads with a longitudinal groove for needle placement. Ellis peritoneum holding forceps retract tissue during surgery. Surgical clips fix draping towels to the skin. Traumatic needles are sharp for tough tissues like cattle and sheep skin, while atraumatic needles are less sharp for delicate tissues like muscle. Instrument identification involves distinguishing needle holders from artery forceps by head size and groove presence. Size classification helps: small instruments like mosquito forceps fit within the palm, while larger instruments like kidney forceps extend beyond the hand.

This comprehensive section covers essential surgical instrument selection and handling. Needle holders serve three functions: holding needles securely, grasping during tissue passage, and manipulating needle curves. Selection depends on needle size—larger needles require wider holders, while delicate tissues need finer instruments. Four grip techniques exist: palm grip (maximum power, poor release), thanar grip (easy release, pops apart), thumb-ring finger grip (precision, preferred), and pencil grip. Consistent practice of one technique builds foundational skills. Tissue forceps vary by application: Debakeys for delicate tissues, Adson-Browns for skin (avoid if possible). Hold forceps like finger extensions for optimal control. Proper needle placement on the driver requires 90-degree positioning with thumb and ring finger grip. Wrist positioning and needle curve utilization are critical for controlled passage. Palming the needle enables continuous rotation without releasing, but requires stable tissue. Always visualize the needle tip throughout—animal skin elasticity varies significantly between species and breeds, and conditions like cutaneous asthenia cause abnormal stretching. Losing a needle under tissue can be disastrous.

Sutures are classified as absorbable (dissolve in body) or non-absorbable (remain permanently). Absorbable sutures contain 'G' in spelling: Polyglycolic acid, Polyglactin, Polydioxanone (collagen), Chromic catgut. Non-absorbable sutures lack 'G': Polypropylene, Nylon, Monocryl, Stainless steel. Monofilament sutures (single thread) require 6-8 knots, are weaker but have fewer infection risks. Multifilament sutures (braided) require 2-3 knots, are stronger but have higher infection risks. Selection depends on wound location and healing requirements.

Sutures are classified by thread structure and absorption properties. Monofilament sutures (single thread) have lower infection risk but require 6-8 knots; multifilament sutures (multiple threads) are stronger but increase infection risk and need only 2-3 knots. Non-absorbable sutures require removal: multifilament includes Silk and Polyester; monofilament includes Nylon (Polyamide), Stainless Steel, Prolene (Polypropylene), and PVDF. Absorbable sutures dissolve in the body: multifilament includes Vicryl (56 days) and Vicryl Rapide (21 days); monofilament includes Catgut (Plain: 5-14 days, Chromic: 10-90 days), Monocryl (15-30 days), and PDS (90-96 days). A useful mnemonic: sutures containing 'G' are typically absorbable.

Suture materials are classified by source (natural, synthetic, metallic), structure (monofilament vs multifilament), and absorption characteristics (absorbable vs non-absorbable). Natural absorbable sutures include plain catgut (submucosa of sheep intestine) and chromic catgut (with chromium salt). Synthetic absorbables are PGA, PLA, and PDS; non-absorbables include nylon and polypropylene. Metallic sutures (stainless steel) serve hard tissue approximation. Monofilament offers smooth passage and reduced infection risk but requires more throws for secure knots; multifilament provides easier knotting but carries higher infection potential due to capillary action between strands.

Suture selection depends on understanding material characteristics (absorbable vs non-absorbable, natural vs synthetic, monofilament vs polyfilament), needle tip types (taper, cutting, reverse cutting), and needle shapes (circle, half-circle, etc.), with proper handling techniques including gripping the needle at the body portion and using appropriately sized needle holders to minimize tissue trauma and achieve optimal cosmetic outcomes.

Surgical sutures are categorized by absorption (absorbable vs non-absorbable), needle type (tapered for soft tissue, cutting for tough tissue), and filament structure (monofilament single strand vs multifilament braided). Common sutures include Vicryl (absorbable multifilament for general closure), PDS (absorbable monofilament for peritoneum), Monocryl (most common monofilament for skin closure), silk and Ethibond (non-absorbable multifilament for chest tubes and hernia repairs), Prolene and Nylon (non-absorbable monofilament for vascular and skin), and Chromic Gut (highly absorbable for pediatric procedures).

The square knot is tied by doing left over right, then right over left, creating a secure knot that won't come untied. The granny knot is tied by doing left over right, then left over right, which creates an insecure knot that will unravel even when locked down. The key difference is the direction of the second pass: opposite directions create a secure square knot, while the same direction creates an insecure granny knot.

In surgical suturing, square knots are preferred over granny knots because granny knots consist of two consecutive clockwise or counterclockwise throws that prevent the half-knots from locking together, allowing them to slip unpredictably under tension; square knots alternate clockwise and counterclockwise throws, creating a secure lock that only loosens when the suture ends are held at right angles to each other, but remains secure when tightened at 180° angles.

The square knot is a secure knot used in wilderness shelter building, but it must be tied with the same line on top each time when crossing the lines; if you alternate which cord is on top, you create a granny's knot, which comes apart very easily under pressure and can be untied by simply pulling on one line and capsizing the other, making it dangerous for lifeline applications.

The square knot is the fundamental knot used for tying shoes and tying two things together securely. To tie a square knot: cross left over right, then right over left, creating two loops that go together. The ends should go in the same direction as the bottom strings. The granny knot is a common mistake where you cross left over right twice, which causes the knot to slip and come undone. The square knot is the basic knot of Boy Scouts and is essential for everyday use.

Three main types of surgical knots are used: 1) Square knot (reef knot): Both ends are together either above or below the knot, with crossing in each throw. It is relatively stable. 2) Surgeon's knot: Two wraps in the first throw, one wrap in the second throw, with crossing in each throw. It is the easiest to identify and most stable. 3) Granny knot (pseudo square knot): No crossing in either throw, with one end above and one end below the knot. It is unstable and more prone to slip. Identification is based on whether ends are together (stable) or apart (unstable).