United States Pharmacopeia online
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871 SUTURES—NEEDLE ATTACHMENT
Absorbable (collagen) surgical sutures and nonabsorbable surgical sutures with Standard Needle Attachment are such that the needles are firmly attached and are not intended to be separated. Sutures supplied with eyeless needles attached fall into either the category of Standard Needle Attachment or the category of Removable Needle Attachment. Removable Needle Attachment of both absorbable and nonabsorbable surgical sutures is such that the needle may be deliberately separated from the suture by means of a quick tug. Both types of attachments are tested on equipment as specified under Tensile Strength 881.

Procedure— Clamp each of 5 sutures in the tensilometer so that the needle is in the fixed clamp with all of the swaged portion exposed and in line with the direction of force applied to the suture by the moving clamp. Determine the force required to detach the suture from the needle. In the case of Standard Needle Attachment, the suture may break without needle detachment.
Standard Needle Attachment— The requirements are met if neither the average of the 5 values nor any individual value is less than the limit given for the designated size in Table 1.
Table 1. Standard Needle Attachment for Absorbable and Nonabsorbable Sutures
Metric Size (Gauge No.) Limits on Needle Attachment
Absorbable Collagen Suture Nonabsorbable and Synthetic Absorbable Sutures USP Size Average (in kgf) (Min.) Individual (in kgf) (Min.) Average (in N) (Min.) Individual (in N) (Min.)
0.1 11-0 0.007 0.005 0.069 0.049
0.2 10-0 0.014 0.010 0.137 0.098
0.4 0.3 9-0 0.021 0.015 0.206 0.147
0.5 0.4 8-0 0.050 0.025 0.490 0.245
0.7 0.5 7-0 0.080 0.040 0.784 0.392
1 0.7 6-0 0.17 0.08 1.67 0.784
1.5 1 5-0 0.23 0.11 2.25 1.08
2 1.5 4-0 0.45 0.23 4.41 2.25
3 2 3-0 0.68 0.34 6.67 3.33
3.5 3 2-0 1.10 0.45 10.8 4.41
4 3.5 0 1.50 0.45 14.7 4.41
5 4 1 1.80 0.60 17.6 5.88
6 and larger 5 and larger 2 and larger 1.80 0.70 17.6 6.86
Removable Needle Attachment— The requirements are met if the individual values of the 5 sutures are within the limits shown in Table 2.
Table 2. Removable Needle Attachment for Absorbable and Nonabsorbable Sutures
Metric Size (Gauge No.) Limits on Needle Attachment
Absorbable Collagen Suture Nonabsorbable and Synthetic Absorbable Sutures USP Size Minimum (in kgf) Maximum (in kgf) Minimum (in N) Maximum (in N)
1.5 1 5-0 0.028 1.59 0.274 15.6
2 1.5 4-0 0.028 1.59 0.274 15.6
3 2 3-0 0.028 1.59 0.274 15.6
3.5 3 2-0 0.028 1.59 0.274 15.6
4 3.5 0 0.028 1.59 0.274 15.6
5 4 1 0.028 1.59 0.274 15.6
6 5 2 0.028 1.59 0.274 15.6
[NOTE—For either type of attachment, if not more than 1 of the individual values falls outside the prescribed limits, repeat the test on an additional 10 sutures: the requirements of the test are met if none of the 10 additional values falls outside the individual limit requirements.]

Auxiliary Information— Staff Liaison : Radhakrishna S Tirumalai, Scientist
Expert Committee : (GTMDB05) General Toxicology and Medical Device Biocompatibility
USP29–NF24 Page 2775
Phone Number : 1-301-816-8339