Standards on edge

Surgery

Surgical scissors are often less sharp than the cutting remarks made about them in operating theatres.. The consequences of blunt scissors vary from frequent irritation to occasional downright disaster. It is astonishing that this aspect of surgical instrument care, among others, has not been discussed more often.

Sharpness is an objective quality which can be tested in accordance with a British Standard Specification for surgical dressing and stitch scissors [1], or a similar specification for Mayo's operating scissors [2.] In the first, a single layer of lint (whose warp and weight are themselves. specified) is placed fiat on a firm table. It is then cut by a single firm application of continuous pressure to the smaller handle, which is uppermost, and with no lateral pressure. This omission of lateral pressure means that scissors should be capable of use in the left hand just as easily as in the right hand, and that the question of special left-handed scissors should be redundant, despite pleas for them [3]. More important, such complaints under. line the looseness of joint too often present in operating scissors, and indicate that much of the time doctors and nurses are working with substandard equipment.

The problem of sharpness for scalpel blades has been solved in an efficient if characteristic way by the throwaway society. A similar approach to scissors Is to buy a cheaper grade, of harder metal than normal, which cannot be re-ground. Such scissors, invariably used beyond their proper and second-rate life-span, are of inferior blade geometry and have a star-riveted screw joint, which prevents further care of the type to be described below. The other extreme is to buy the most expensive scissors, with tungsten carbide inserts, which in some cases are guaranteed for two years, but which may take weeks or months in travel back to the manufacturers for replacement of the hardened edges.

Surgeons also have much to answer for in the matter of poor instrument quality and care. At times one may wince to see wire being cut with suture scissors, or heavy fibrous tissue straining the screw joint of a delicate and light-weight instrument. Artery forceps, the subject of some future study, are abused in the same way; they grip not only bleeding points, but orthopaedic wires, vein strippers, plastic tubing looped about arteries in vascular surgery, and bulky thicknesses of linen. The strain is often enough to deform the instrument permanently, so that it no longer takes a secure or accurate grip of important vascular pedicles or fascial edges.

What of the actual technique of sharpening scissors? The cutlers of Sheffield and other traditional centres are not given to writing about their craft, and information is not easily got from commercial firms. One may learn much, however, by visiting one of the few Australian firms making surgical instruments, and thereby appreciate that in scissors sharpening, as in other fields, the best results by far are achieved by the trained and experienced professional expert. The occasional trier does not even appreciate the type of standard required.

First it is necessary to separate the blades. This may need only the heavy well-directed effort with one' of a whole range of specially-pointed screw-drivers, aided by a corrosion loosening chemical, or it may need the whole screw to be drilled out and a fresh thread cut for a larger replacement.

Blades of average size are ground on a wheel six or eight inches in diameter at 1,500 revolutions per minute, on a three horsepower motor, no less. A buffing wheel is prepared for this task by coating it with wood glue and then with 150 grade silicon carbide. (These are some of the many details, unpublished and the fruit of long experience, of which only a few can be presented.) The actual hollow grinding, carried out with a few firm accurate sweeps, must go beyond the joint to an area called the "ride", perhaps because this is one of the two places where the blades ride against one another as they are closed. Next, the edge of the blade is ground at as angle of fifteen degrees, with similar firm sweeps, without overheating. Vein scissors are sharpened on a three or four inch diameter wheel, and curved scissors need wheels specially shaped in wood, and others with a rim of lead for the inner blade. Final finishing and polishing are carried out with commercial buffing compound, a large bar of a substance which mysteriously contains mutton fat.

With the sharpness of scissors as an example, certain conclusions emerge about instrument care in general. One is that surgeons, as a body, should take a more constructive interest in this subject based on detailed technical information. Another is that instrument maintenance should not be entrusted to the part-time handyman, but to a professional craftsman, who must work for a group of hospitals in order to provide an economical service, even if less personal. Last, surgeons through their professional associations should establish and maintain strict high standards for these tools crucial to the work for patients entrusted to their care; there is more than metaphor to an unkind cut.

1 British Standard 3646 : 1963, "Specification for Surgical Dressing and Stitch Scissors", British Standards Institution. British Standard 3793 - 1964.
2 British Standard 3793 : 1964. "Specification for Mayo's Operating Scissors with Dished Blades)", British Standards Institution.
3 Med. J. Aust., 1966, 1: 193 (January 29).

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Medical Journal of Australia March 20, 1971 p.622
Standards on edge

In my many visits to surgical instrument factories and a few to standards authorities in several countries I found it impossible to track down the origin of important prevailing standards, often copied verbatim in many countries from the British Standard. It seemed like the last flicker of the British Raj.

Information on how to sharpen scissors just can't be found in books even now, and all I learned was from talking to people doing the work.

Tuttlingen [see my paper], the heart and home of the surgical instrument industry for two centuries after taking over from Paris, spawned many of the great American factories. This is reflected even now in the German family names in some of the car spaces in factories in St. Louis and Chicago, and a restaurant named "The Black Forest" not far from the Storz factory in St. Louis.

My obsessive interest in the details of instrument manufacture and peformance proved valuable in looking at the technology for the new fields of micro- and lap surgery.

On the way I learned a little of the tales and myths of surgeons of earlier generations and the instruments named after them.

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