Desirable factors in surgical sutures: with special reference to the absorbability of surgical Catgut

Abstract

1. The existence of different types of surgical catgut has been confirmed and their fundamental differences investigated.2. The main types found in commerce have been reproduced under controlled conditions and compared with each other and with samples obtained in the open market.3. The reasons for these differences - which are mainly reflected in absorption rates - have been sought and largely explained by comparing the chemical constitutions of the catguts with their behaviour in living tissues.4. Reference has been made to results obtained by previous workers and the lack of a basis for comparisons of absorbability remedied by the production of a Standard Plain catgut.5. A technique has been devised whereby a practicable comparison can be made in living tissue between the absorption rates of different types of catgut and in which the sutures to be tested are observed in circumstances strictly analogous to those obtaining at actual operation.6. From 5 (above) it appears that no attempt should be made to produce catgut in more than two or three absorption groups.7. The over -riding effect of sterilisation methods on absorption rates has been shown. Although the durations intimated on labels are frequently at variance with the actual resistance of the catgut to absorption, the error has mainly been found to be on the "safe" side; that is, the period for which the sutures retain effective holding power is generally in excess of that claimed.8. Excessive reaction of the tissues to catgut, which has been put forward by various workers as a reason for using non-absorbable suture materials, has been shown to be avoidable by using fine gauges - a procedure whit is justified not merely by the absence of undesirable effects but also by the fact that fine catgut has ample ¡tensile strength. Advocates of the use of non-absorbable suture materials to the partial or complete exclusion of catgut have not been lacking but experiment demonstrated that several non-absorbable materials were themselves not without a reactive effect. Moreover, although some non-absorbable materials may be more desirable than others, the fact remains that catgut is ultimately absorbed and no unaltered foreign bodies remain which might become a focus for trouble at some future time.9. From this present investigation and confirming the observations of other workers, it is recommended that genuinely plain catgut should never be used except in the very finest gauges; and, even then, only for surface suturing.10. As a result of the co-relation of the chemical constituents of catgut with its absorption rate in the tissues, it is suggested that this could be used as an adjunct in controlling and determining the absorption group into which the finished product is required to fall.11. The "proportionate load" apparatus has been devised as being the most satisfactory means for performing in vitro digestion tests but the results obtained indicate that reliance should not be placed on this method alone for determining the absorption rate of catgut in the tissues. It is quite possible, however, that it would serve as a routine laboratory control in that fluctuations in the absorbability of the finished product might be revealed, but the main reliance should be placed on implants in living tissue.12. Finally, the suggestion is offered that a living tissue test, based on the technique already described, might be considered by the authorities concerned for addition to the existing standards for surgical catgut using Standard Plain catgut as a reference and prescribing not more than three absorption period Groups.