What are the types of needle points and when are they used in suturing?

Updated: Mar 05, 2020
  • Author: Desiree Ratner, MD; Chief Editor: Dirk M Elston, MD  more...
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Answer

The point portion of the needle extends from the tip to the maximum cross-section of the body. Point types include the following (see the image below):

  • Cutting needles (conventional, reverse, or side [spatula])

  • Taper-point (round) needles

  • Beveled conventional cutting edge needles

  • Blunt-point needles

    Commonly used suture needles, with cross-sections Commonly used suture needles, with cross-sections of needles shown at point, body, and swage. (A) Taper-point needle. (B) Conventional cutting needle. (C) Reverse cutting needle.

A cutting needle has at least two opposing cutting edges (the point is usually triangular). This type is designed to penetrate dense, irregular, and relatively thick tissues. The point cuts a pathway through tissue and is ideal for skin sutures. Sharpness is due to the cutting edges.

Conventional cutting needles have three cutting edges (a triangular cross-section that changes to a flattened body). The third cutting edge is on the inner, concave curvature (surface-seeking).

In reverse-cutting needles, the third cutting edge is on the outer convex curvature of the needle (depth-seeking). These needles are stronger than conventional cutting needles and have a reduced risk of cutting out tissue. They are designed for tissue that is tough to penetrate (eg, skin, tendon sheaths, or oral mucosa). Reverse-cutting needles are also beneficial in cosmetic and ophthalmic surgery, causing minimal trauma.

Side-cutting (spatula) needles are flat on the top and bottom surfaces to reduce tissue injury. These needles allow maximum ease of penetration and control as they pass between and through tissue layers. Side-cutting needles were designed initially for ophthalmic procedures.

Taper-point (round) needles penetrate and pass through tissues by stretching without cutting. A sharp tip at the point flattens to an oval or rectangular shape. The sharpness is determined by the taper ratio (8-12:1) and the tip angle (20-35°). The needle is sharper if it has a higher taper ratio and a lower tip angle. The taper-point needle is used for easily penetrated tissues (eg, subcutaneous layers, dura, peritoneum, and abdominal viscera) and minimizes the potential tearing of fascia.

A beveled conventional cutting needle was developed with performance characteristics superior to those of other conventional cutting needles. It is composed of a unique stainless steel, ASTM 45500, that is heat-treated after the curving process to enhance its resistance to bending. The angle of presentation of the cutting edge is decreased to enhance sharpness. On the basis of the results of experimental and clinical studies done by Kaulbach et al, this beveled conventional cutting needle is recommended for closure of lacerations. [40]

Blunt point needles dissect friable tissue rather than cut it. The points are rounded and blunt, ideal for suturing the liver and kidneys. Additionally, blunt needles are being developed for more conventional uses in an effort to reduce needlestick injuries.


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