1. Suture and Ligature

2. Definations
Ligature is specially prepared and sterilized thread which is used to tie the blood vessels.
Suture is specially prepared and sterilized thread which is used to sew the tissues together.

3. Ideal properties Must be sterile.
Must have sufficient tensile strength.
Must be non irritating.
Gauge should be as fine as possible.
Absorption time for the absorbable suture and ligature should be known.

4. Types
Absorbable
Non absorbable

5. Absorbable
Catgut
Kangaroo tendons
Brocafil

6. Non absorbable Silk Linen Cotton Synthetic polyester suture Horsehair
Metals and alloys

7. Cat gut
Catgut is prepared from intestine of the sheep.

8. Preparation of catgut Raw materials
7 mt Intestine collected and kept in cold storage.
Selection and washing
Cleaning with hand and soaking in water
Splitting the casing
The gut is cut into smooth ribbons.

9. Removal of unwanted layers
The layers of gut like outer mesentric, muscular, mucous layer are scrapped off by blunt knife. This process is aided by soaking in alkaline solution.
Orientation of fibres
During scraping operation the fibre of gut arrange in parallel way which increase the tensile strength of gut.
Hardening
Ribbons are tanned or hardened by soaking in solution of chromic salts.
The time of absorption depend on the strength of chromic solution used.

10. Spinning
The ribbons are tied together at one end , pulled and spin.
Drying
Strings are kept in suitable heat and temperature condition under suitable tension.
Finishing
Dried strings are polished by mechanical means. The strings are rubbed against a abrasive surface to get smooth uniform string of circular section. Very important part.

11. Gauging
Length of the strings are checked and there should be uniformity between batches and along the length of each string.
Sterilisation
Gut may be sterilized by heat, chemicals, ionising radiation.
Chemical process include use of iodine.But disadvantage is that long immersion time in iodine solution and variable absorption time. Best one is by gamma radiation.

12. Difficulties
a)Sheep intestine is normally infected with bacteria and pathogenic organism such as sporing anaerobic bacteria responsible for tetanus and gas gangrene. b)Collagen converted to gelatin if moisture is present during heat sterilization.

13. Remedy
The heat process-The gut is coiled with a heat resistant fibre card, placed in a glass tube, along with a label. The tubes are placed in a basket and dried in a drying oven in which temperature is slowly raised.
The dried gut is placed in autoclave and heated at C for several hours. Anhydrous fluid such as toluene and xylol is incorporated in the autoclave.
Heating may be done in a non pressure vessel using anhydrous liquid of high boiling point.
The tubes are then filled with sterile fluid and sealed by fusion.

14. Remedy
The irradiation process- Guts are packed in Al foil containing 90% alcohol as a preservative.
The envelops are then passed through an irradiation area on a conveyer system.
Very rapid process. Strength is 2.5 megarads.

15. Tests(B.P.C.)
Sterility test- A sample is taken in glass tube and immersed in a disinfectant fluid for example 10% lysol for a sufficient time to sterilize the exterior. If the suture has been sterilized in iodine solution , then the suture is removed , drained and placed in 50 ml distilled water and incubated for 24 hours. Then it is transferred to 50 ml of a sterilized solution of 1% sodium carbonate and 1% sodium thiosulfate for 24 hours. The temperature of incubation here is 37 C.Then it is tranferred to suitable medium like thioglycollate
Sutures sterilized by dry heat and stored in toluene need only to be rinsed in sterile water before transfer to the culture media.
Gauge-Measurement is done by dial reading micrometer at several points along the strand.
Tensile strength-Load necessary to rupture the gut is measured. The test being performed on straight and knotted samples. The instrument used is tensilometer.

16. Other absorbable Material
Natural (Kangaroo tendons)-Obtained from tails of kangaroo. Slowly absorbed from the body. Used in hernia and bone repair.

17. Other absorbable Material
Synthetic(Brocafil)- Prepared from animal sinew (a piece of tough fibrous tissue uniting muscle to bone; a tendon or ligament) by maceration in acid solution to disintegrate the tissue and then homogenized. The fluid is sprayed continuously into a basic liquid where it solidifies as a ribbon.
Advantages
Little contamination.
Exact and uniform gauging.
Threads may be as long as required.
Good tensile strength.
Ease of sterilisation.
Good absorption qualities.

18. Non absorbable CHARACTERISTICS OF NON-ABSORBABLE SUTURES
Permanent only used when long term support is required
Removed when used for skin
Tissue reaction generally low (except silk)
Easily obtainable and easily sterilized.
Silk, linen and even nylon will lose tensile strength over a period of time
True non-absorbable sutures include polyester, polyethylene, polybutester, polypropylene and steel

19. Synthetic non absorbable
Silk, linen and nylon
Easily obtainable and easily sterilized by autoclaving.
Lose tensile strength over a period of time.

20. Synthetic non absorbable
Metals and alloys
Non irritant
High tensile strength in fine gauge.
Useful in plastic and orthopaedic surgery.
Readily sterilized.

21. Natural non-absorbable
Silk worm gut
Prepared from the sacs of viscous material in the silk worm which the insect spun into silk if allowed to mature.
The sacs are pulled out , dried . Graded, polished.
Non uniform, brittle,limited length
Strong and smooth.

22. Natural non-absorbable
Horse hair
Hair from the tail is very fine, non capillary and non irritant.
Low tensile strength
Chances of contamination.
Readily sterilized by autoclave.

23. Reference
Cooper and Gunn’s Tutorial Pharmacy