Therapeutic Goods Order No. 49 General standard for sutures: Appendices
These are the Appendices for TGO 49 General standard for sutures <http://www.tga.gov.au/docs/html/tgo/tgo49.htm>.
Note: If you intend to rely on any legislation referred to on this website, you should access copies of the official versions on the Attorney General's Department's ComLaw website <http://www.comlaw.gov.au> (incorporating the Federal Register of Legislative Instruments (FRLI)). Instruments are amended from time to time and may, on occasions, be replaced or new instruments made.
Appendix A: Test for length of suture
The test shall be carried out by -
- removing the suture from its container and laying it flat on a smooth surface;
- subjecting the suture to just sufficient tension to keep it straight during the measurement;
- measuring the length of the suture to the nearest cm; and
- repeating the procedure specified in paragraphs (a), (b) and (c) using a further four sutures.
Appendix B
B.1 - Test for diameter of suture - Apparatus
B 1.1 The gauge required for the determination of the diameter of sutures is a dead weight type instrument which is equipped with a direct reading dial graduated to at least 0.002mm.
B 1.2 The anvil of the gauge is approximately 50 mm in diameter and the presser foot is circular with a diameter of 12.7+/- 0.02 mm.
B.1.3 The presser foot and anvil surfaces are planed to be parallel to each other to within 0.005 mm.
B.1.4 The presser foot and the moving parts connected to it are weighted so as to apply a total load of 205+/- 5 g to the sutures under test.
B.1.5 The apparatus is fitted with two clamps capable of securing the sutures.
B.1.6 The clamps can be rotated through 90°.
B.1.7 When the apparatus is used to measure the diameter of sutures of metric size 0.5 or less, the weighting on the presser foot is such that the load on the sutures is not more than 60g and not less than 50g.
B.2 - Test for diameter of suture - Procedure
B.2.1 Where the sutures are monofilament or catgut sutures the test shall be carried out by -
- removing the suture from its container and immediately clamping it at one end, without carrying out any prior drying or conditioning of the suture;
- laying the suture across the centre of the anvil, drawing the suture sufficiently taut and clamping the other end;
- positioning the presser foot at the point one-quarter along the length of the suture and gently lowering the presser foot until its entire weight rests upon the suture;
- measuring the diameter of the suture;
- repeating the measurement of diameter at the points half and three-quarters along the length of the suture;
- recording the average diameter of the suture;
- repeating the procedure described in paragraphs (a), (b), (c), (d), (e) and (f) using a further four sutures; and
- calculating the overall mean diameter of the sutures.
B 2.2 Where the sutures are multifilament sutures the test shall be carried out by -
- removing the suture from its container, taking care to ensure that no alteration to the twist of the suture occurs;
- laying the suture across the centre of the anvil, clamping one end and attaching a suitable length of thread to the other end;
- passing the thread and suture through the unclosed clamp, positioning the clamp so that it is not in contact with the suture;
- attaching to the free end of the thread a weight of sufficient magnitude to achieve a tension on the suture of 50 per cent of the corresponding mean straight pull breaking load shown in Schedule 2;
- securing the suture with the unclosed clamp;
- positioning the presser foot at the point one-quarter along the length of the suture and gently lowering the presser foot until its entire weight rests upon the suture;
- measuring the diameter of the suture and if the suture is larger than metric size 2, rotating the suture through 900 by rotating the clamps, measuring the diameter again and recording the average of the two values;
- repeating the measurement of diameter at the points half and three quarters along the length of the suture;
- recording the average diameter of the suture;
- repeating the procedure described in paragraphs (a), (b), (c), (d), (e), (f), (g), (h) and (j) using a further four sutures; and
- calculating the overall mean diameter of the sutures.
Appendix C
C.1 - Test for knot pull breaking force - Apparatus
Note: This requirement does not apply to stainless steel sutures
C.1.1. The apparatus to be used in the test shall be a power-driven tensile strength testing machine which uses the principle of constant rate of extension and possesses suitable clamps for holding the specimen.
C.1.2 The instrument shall have an electronic load cell as the force measuring device. The breaking force of the suture should not be less than 10 per cent of the range of the load cell selected.
C.1.3 The instrument shall be capable of indicating the maximum force applied in breaking the specimen and this force shall be indicated clearly and continuously on a dial or chart or other output device (e.g computer).
C.1.4 The machine shall be capable of extending the specimen under test at a constant rate of 200 +/- 25 mm per min.
C.1.5 The weighting mechanism shall allow negligible movement in the direction of the applied force.
C.1.6 The jaws of the machine shall be constricted so that the specimen under test is not damaged. Suitable packing pieces or embedding techniques may be used whenever necessary to prevent slipping of the specimen in the jaws.
C.1.7 The machine shall comply with the requirements specified in Australian Standard AS 2193-1978, Methods for Calibration of Force-measuring Systems of Testing Machines.
C.2 Test for knot pull breaking force - Procedure
Note: This requirement does not apply to stainless steel sutures
C.2.1 If the suture is made of catgut carry out the test by
- setting the machine to give a constant rate of extension of 200+/- 25 mm per min;
- removing the suture from its container and, without carrying out any prior drying or conditioning of the suture, tying a surgeon's knot in the suture;
- placing the suture in the testing device with the knot approximately midway between the clamps and so that the distance between the clamps is not less then 120 mm and not more than 130 mm;
- attaching one end of the suture in the clamp at the load end of the machine and passing the other end of the suture through the opposite clamp;
- applying a tension of not more than 2.5 per cent of the corresponding knot pull breaking force, as specified in Schedule 2, to the suture and clamping the free end;
- setting the mechanism of the machine in motion and breaking the suture;
- recording the maximum force required to break the suture;
- discarding the result if the suture slips in the clamp or breaks within 10 mm of the point of attachment on the jaw face;
- repeating the test if the suture is 45 cm or longer and obtaining the average value of both measurements;
- repeating the procedure described in paragraphs (a), (b), (c), (d), (e), (f), (g), (h) and (i) using a further nine sutures; and
- calculating the mean result.
C.2.2 If the suture is a synthetic absorbable suture carry out the test by -
- setting the machine to give a constant rate of extension of 200+/- 25 mm per min;
- removing the suture from its container and, without carrying out any prior drying or conditioning of the suture tying a simple knot in the suture;
- carrying out the procedures described in paragraphs (1)(c) to (1)(l) inclusive.
Appendix D
Appendix D.1 Test for straight pull breaking force and elongation - Apparatus
Note: this test applies only to single filament and multifilament stainless steel sutures
D.1.1 The apparatus to be used in the test shall be a power-driven tensile strength machine which uses the principle of constant rate of extension and possesses suitable clamps for holding the specimen.
D.1.2 The instrument shall have an electronic load cell as the force measuring device and the breaking force of the suture should be not less than 10 per cent of the range of the load cell selected.
D.1.3 The instrument shall be capable of indicating the maximum force and maximum elongation applied in breaking the specimen and the force. The elongation shall be indicated clearly and continuously on a dial, chart or other output device (e.g. computer).
D.1.4 The machine shall be capable of extending the specimen under test at a constant rate of 100+/- 10 mm per min.
D.1.5 The weighting mechanism shall allow negligible movement in the direction of the applied force.
D.1.6 The jaws of the machine shall be constructed so that the specimen under test is not damaged. Suitable packing pieces or embedding techniques may be used whenever necessary to prevent slipping of the specimen in the jaws.
D.1.7 The machine shall comply with the requirements specified in Australian Standard AS2193 - 1978 - Methods for Calibration and Grading of Force Measuring Systems of Testing Machines.
Appendix D.2 Test for straight pull breaking force and elongation - Procedure
The test shall be carried out by -
D.2.1 setting the machine to give a constant rate of extension of 100+/- 10 mm per minute and setting the speed of the recorder to l00+/- 10 mm per min;
D.2.2 removing the suture from its container and placing it in the testing device so that the distance between the clamps is not less than 125 mm and not more than 130 mm;
D.2.3 attaching one end of the suture in the clamps at the load end of the machine and passing the other end of the suture through the opposite clamp;
D.2.4 applying sufficient tension to straighten the suture and clamping its free end;
D.2.5 setting the mechanism of the machine and the chart in motion and breaking the specimen;
D.2.6 recording the maximum force required to break the suture and the maximum elongation obtained when the suture breaks;
D.2.7 discarding the result if a specimen slips in the clamp or breaks within 10 mm of the point of attachment on the jaw face;
D.2.8 repeating the test if the suture is 45 cm or longer and obtaining the average value of both measurements;
D.2.9 repeating the procedure described in paragraphs (a), (b), (c), (d), (e), (f), (g) and (h) on a further four sutures; and
D.2.10 calculating the mean values from the results obtained for maximum load and elongation.
Appendix E
Test for strength of needle attachment
The test shall be carried out by -
E.1 using a tensile strength testing machine of the same type as described in Appendices C1 and D1;
E.2 using a constant rate of extension of 200+/- 25 mm per min;
E.3 fixing the suture in the mobile clamp of the machine and the needle in the fixed clamp so that the whole of the swaged end of the needle is free of the clamp and in line with the direction of pull on the suture;
E.4 determining the maximum force required to break the suture or to detach it from the needle;
E.5 repeating the procedures described in paragraphs (a), (b), (c) and (d) using another four sutures; and
E.6 calculating the mean value for strength of needle attachment.
Appendix F
Tests for identification of composition of sutures
Appendix F.1 linen sutures
Carry out the test by -
- isolating a few individual fibres and examining them under a microscope;
- verifying that the fibres are 25 to 50 mm in length and 12 to 31 micrometres in width, and have long finely pointed ends and a narrow lumen along the greater part of their length;
- verifying that the fibres have thick walls occasionally marked with fine longitudinal striations and observing unilateral swellings with transversal lines; and
- impregnating the fibres with iodinated zinc chloride solution which colours them violet blue.
Appendix F.2 nylon sutures
Carry out the test by -
- adding 40 ml of 5M hydrochloric acid to approximately 0.02g of suture cut into pieces of 5 mm length so that the suture disintegrates and dissolves completely within 15 minutes;
- adding 40 ml of 90 per cent formic acid to approximately 0.02 g of suture cut into pieces of 5 mm length so that the pieces of suture dissolve at room temperature;
- adding 40 ml of cold phosphoric acid to approximately 0.02 g of suture cut into pieces of 5 mm length in a boiling tube, gently bringing the solution to the boil and boiling for 2 min. so that the pieces of suture dissolve completely; and
- comparing the results obtained in paragraphs (a), (b) and (c) with the corresponding solubility for nylon sutures in Schedule 9.
Appendix F.3 polyester sutures
Carry out the test by -
- adding 40 ml of 5M hydrochloric acid to approximately 0.02 g of suture cut into pieces of 5 mm length so that the suture remains intact even after prolonged immersion;
- adding 40 ml of sulphuric acid to approximately 0.02 g of suture cut into pieces of 5mm length so that the suture disintegrates and dissolves completely within 10 min;
- adding 40 ml of cold phosphoric acid to approximately 0.02g of sample cut into pieces of 5 mm length in a boiling tube, bringing the solution quickly to the boil and boiling for 2 min so that the suture remains intact; and
- comparing the results obtained in paragraphs (a), (b) and (c) with the corresponding solubility for polyester sutures in Schedule 9.
Appendix F.4 polypropylene sutures
Carry out the test by -
- adding 40 ml of sulphuric acid to approximately 0.02 g of suture cut into pieces of 5 mm length so that the suture remains intact after 10 min;
- adding 40 ml of cold phosphoric acid to approximately 0.02 g of suture cut into pieces of 5 mm length so that the suture fuses together but remains intact;
- adding 40 ml of xylene to approximately 0.02 g of suture cut into pieces of 5 mm length and bringing to the boil so that the suture dissolves within 5 min; and
- comparing the results obtained in paragraphs (a), (b) and (c) with the corresponding solubility for polypropylene sutures in Schedule 9.
Appendix F.5 silk sutures
Carry out the test by -
- isolating a few individual fibres and examining them under a microscope;
- verifying that the fibres are approximately triangular to semicircular in cross section with rounded edges, without a lumen and sometimes marked with very fine longitudinal striations parallel to the axis of the fibre;
- adding 40 ml of 5M hydrochloric acid to approximately 0.02 g of suture cut into pieces of 5 mm length so that the suture remains intact;
- adding 40 ml of a mixture of one part of calcium chloride and ten parts of 90 per cent formic acid to approximately 0.02g of suture cut into pieces of 5 mm length at room temperature with a gentle swirling action so that the suture dissolves within 15 min; and
- comparing the results obtained in paragraphs (c) and (d) with the corresponding solubility for silk sutures in Schedule 9.
Appendix F.6 synthetic absorbable sutures
Carry out the test by -
- weighing approximately 25 mg of a sample of the suture and placing it in a vial which can be closed with a stopper;
- adding 1 ml of spectroscopic grade hexafluoroisopropanol and closing the vial with a stopper;
- shaking the solution until the entire sample is dissolved and placing several drops onto a potassium bromide plate or a KRS-5 plate;
- allowing the solvent to evaporate;
- annealing the film by heating the plate at 65 C for one hour;
- allowing the plate to cool and recording the infra-red spectrum of the polymer in accordance with the procedure described in 'Guidelines for the Determination of Infra-red Spectra' in Appendix D to the Code of Good Manufacturing Practice; and
- confirming the identity of the polymer by comparing the spectrum obtained with the spectrum for a reference substance which has been similarly treated.
Appendix G
Appendix G.1 - Test for content of soluble chromium - Preparation of solutions
Prepare the solutions for use in the test by carrying out the following procedures.
(1) stock chromium solution
Dissolve 0.1414 g of potassium dichromate in distilled water and dilute to 1 litre (1 ml = 50.0 micrograms Cr).
(2) standard chromium solution
Dilute 10.00 ml of stock chromium solution to 100 ml (l ml = 5.00 micrograms Cr).
(3) 50 per cent sulphuric acid solution
Dilute 100 ml of sulphuric acid to 200 ml with distilled water.
(4) methyl orange indicator solution
Prepare a 0.04 per cent w/v solution of methyl orange in 20 per cent alcohol.
(5) potassium permanganate solution
Dissolve 4.0 g of potassium permanganate in 100 ml of distilled water.
(6) sodium azide solution
Dissolve 0.5 g of sodium azide in 100 ml of distilled water.
(7) diphenylcarbazide solution
Dissolve 0.25 g diphenylcarbazide in 50 ml of acetone, store in a brown bottle and discard when the solution becomes discoloured.
Appendix G.2 - Test for content of soluble chromium - Preparation of calibration curve
Carry out the procedure for the preparation of a calibration curve by -
- pipetting measured volumes of standard chromium solution into a series of 125 ml erlenmeyer flasks to give a series of standards of from 5 to 50 micrograms of chromium;
- adding strong ammonia solution to each flask until the solution in the flask is just basic to methyl orange indicator solution;
- adding 50 per cent sulphuric acid solution dropwise until the solution is acidic;
- adding an additional 20 drops of 50 per cent sulphuric acid solution and adjusting the volume of the solution to approximately 40 ml;
- heating the solution to boiling and adding 20 drops of potassium permanganate solution;
- if fading occurs, adding potassium permanganate solution dropwise to maintain an excess of about 2 drops and boiling the solution for a further two minutes;
- adding 1 ml of sodium azide solution and continuing to boil the solution gently;
- if the red colour does not fade completely after 30 seconds, adding another 1 ml of sodium azide solution;
- continuing to boil the solution for one minute after the colour has faded completely and then cooling the solution;
- adding 0.25 ml of phosphoric acid, transferring to a 50 ml volumetric flask, diluting to volume and mixing the solution;
- adding 2.0 ml of diphenylcarbazide solution, mixing and allowing the solution to stand for 10 minutes;
- transferring a suitable portion of each coloured solution to a 1 cm absorption cell;
- measuring the absorbance at 540 nm against distilled water and, using a reagent blank, correcting the absorbance readings by subtracting the blank value; and
- preparing a calibration curve by plotting the corrected absorbance values against micrograms of chromium.
Carry out the test by -
- accurately weighing approximately 0.250 g of suture into a 125 ml erlenmeyer flask and adding 25 ml of distilled water;
- soaking the suture for 24 hours at 37°C;
- allowing the solution to cool, decanting the solution into another 125 ml flask and rinsing the original flask with distilled water;
- developing the colour according to the procedure described in paragraphs G.2 (b) to G.2 (k) inclusive;
- measuring the absorbance of the solution at 540 nm and correcting the reading by subtracting the reading for the solution blank; and
- determining the concentration of chromium present in the solution from the calibration curve.