1887

Surgical instruments – materials, manufacture and care

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Abstract

Instruments have been designed and manufactured specifically for surgery since at least 3000 BC when Sumerians (in present-day Iraq) created small copper knives as surgical scalpels. Relatively sophisticated instruments, including bone-holding forceps, were found in the ruins of Pompeii (Vesuvius eruption AD 79). The requirement for special materials in instrument manufacture was recognized by the Roman surgeon philosopher Galen, who specified that his instruments should be made exclusively from iron ore found only in a quarry in the Celtic kingdom of Noricum (present-day Austria). The production of today's specialized surgical instruments relies on a long history of manufacturing skills and sophisticated metallurgy. This chapter discusses Materials; Manufacture of surgical instruments; Instrument care; and Marking instruments.

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Figures

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3.3 Scissors manufacture. (top) Raw material stainless steel AISI 420. (middle) After initial forging. (bottom) The forged blank.
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3.4 Scissors with a tungsten carbide insert. (top) After machining. (middle) After welding in the tungsten carbide. (bottom) After grinding back the tungsten carbide insert.
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3.5 Grinding back the tungsten carbide on the scissor blade, using an abrasive wheel.
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3.6 Setting the scissors.
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3.7 Polishing stage. (top) Scissors after assembly and setting. (middle) After blade sharpening and polishing. (bottom) After gold plating of the scissor rings ‘bows’.
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3.8 Adding microserrations to a supercut blade using a grooved steel wheel.
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3.9 Scanning electron microscope images showing different blade types. Standard cut stainless steel. Standard cut tungsten carbide. Supercut tungsten carbide. SS= Stainless steel; TC=Tungsten carbide.
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3.10 Scanning electron microscope images contrasting mirror finish (left) with matt (brushed) finish (right).
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3.11 Corrosion due to retained moisture on matt-finish instruments. There are stained corroded areas on the matt knurled area of the scaler and the matt finish of the cutters, especially the grooved grip area. Water accumulates and is retained in these areas.
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3.13 Protection of sharp and delicate tips using silicone caps.
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3.14 Instrument marking systems: coloured autoclave-resistant tape; silicone rings.
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3.15 Before and after removal of biological residues from the joint of a pair of Olsen-Hegars. Most of the visible discoloration here is not rust but baked-on residues. These will contain chloride molecules which, in solution, act as reducing agents, stripping the protective chromium oxide layer and exposing ferric elements to corrosion. In the ‘after’ photograph the residues have been removed by repeated cycles through an ultrasonic bath. The newly cleaned surface reveals pits of corrosion.
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3.16 Cracking of a joint (arrowed) due to build-up of biological residues in a pair of Allis tissue forceps. A build-up of residues with resulting corrosion in the joints of instruments creates increased friction, which makes the instrument difficult to use and leads ultimately to cracking and failure. Once cracked, the instrument is beyond repair.
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3.17 Areas of wear towards the tips of Olsen-Hegar tungsten carbide needle-holders.
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3.18 Castroviejo needle-holders damaged by inappropriate use with a large needle.
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3.19 Implant cutter with failed tungsten carbide inserts (arrowed). Tungsten carbide, while being very hard, is also very brittle and relies on the surrounding stainless steel for support. If the support from the stainless steel is insufficient, the stainless support will deform and the tungsten carbide insert will break. At the tips of implant cutters the stainless steel support tapers down for improved access. This makes the tungsten carbide vulnerable (X). It is important to avoid cutting at the very tip, especially when using on materials outside the specification of the instrument. Stainless steel implants have a high tensile strength and are difficult to cut.

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