Problems in Maintenance of Stainless Steel Surgical Instruments

Corrosion of Stainless Steel Surgical Instruments is a common problem both to the Surgeon and the Instrument Maker. The blame is likely to fall on the Instrument Maker. There is a need for an explanation in regard to the grade of Stainless Steel used to make Surgical Instruments. Also a question that always arises is as to why Stainless Steel should rust under any circumstance. We wish to explain below the causes, which make rust or corrosion occur on any Surgical Instrument.

1.     A wide range of Metallurgical properties are constituted in one single classification of the metal called Stainless Steel. It has Iron & Chromium, but also may have Carbon, Nickel, Sulfur, Tungsten, Manganese and many other elements. But it is Chromium, which imparts the Stainless Steel quality. Hence the more Chromium is present in the Alloy the more resistant it is to corrosion. Carbon reduces this effect of Chromium. But it is necessary to harden the Instrument. Hardness is a primary requirement in Instruments, which have sharp edges, and for all kinds, which have to perform the application for which, they are meant for. For example, to cut, to hold, to open, to close etc. It is an unhappy circumstance that there are only a few Stainless Steel Alloys, which can be hardened sufficiently to manufacture any type of Surgical Instrument. These Alloys are high in Carbon content. They belong to the broad class known as Stainless Steel and are the least corrosion resistant in the group of metals. This problem is not evident on Stainless Steel Surgical Implants as they do not require hardening and are made of Alloys with zero Carbon content.

2.     The next type of corrosion, which is commonly seen on the Surgical Instruments, is that which takes place on the blades of knives, in box locks, between blades of scissors etc. In these cases the Instruments may become useless. The main causes for these kinds of corrosion are as follows:

a.     Inadequate cleaning & drying immediately after use
Any foreign material either organic or inorganic on the surface of any hardened Surgical Instrument is likely to promote corrosion. Instruments, which have been exposed to Blood, Tissue, Saline & Other Foreign matter have to be rinsed in, warm water before they are dried. Instruments can corrode if they are stored with trapped moisture. We recommend Ultrasonic cleaning to clean Instruments.

b.     Autoclaving
Corrosion can take place if the autoclave is not functioning properly. Autoclaves in which, large amount of corrosion takes place have to be checked immediately for leaking valves. Such Autoclaves may not be drying the Instruments adequately or may be drawing corrosive matter back from the drain. Cloth used to wrap Instruments to be autoclaved may contain residual detergents, bleaches or starch. These can promote corrosion at the operating temperature of the autoclave.

c.     Water
Corrosion can take place if tap water is used instead of distilled water to generate steam. Because tap water contains minerals which may cause discoloration and staining on the surface of the Instruments. When corrosion does occur in Surgical Instruments, it is usually of a superficial nature. This could be avoided by carefully adhering to the manufacturers guidance on maintenance of Surgical Instruments. In some cases the corrosion can be removed by repolishing the Instrument by the manufacturer.

General Instructions on Care and Maintenance of Surgical Instruments

Instruments used in surgery are the products of a few highly skilled craftsmen. At their best, they not only reflect craftsmanship but a high degree of artistic ability in design. When such Instruments are given the very special care, which they deserve, they will retain their workmanship and function well for long.

1.Treatment of brand new Instruments

Brand new instruments must be cleaned before the first sterilization or use. Protective caps and protective films must be removed completely, for example in the case of chisels, raspatories or microsurgical instruments

1.     After Use

a.     For machine cleaning, place instrument in a wire basket suitable for the cleaning process (make sure cleaning solution and rinse water from machine comes into contact with all parts of instrument).

b.     Completely dismantle any dismantable instruments.

c.     Preferably dry disposal. For wet disposal, use an active cleaning disinfectant. Rinse the instrument thoroughly with clear, flowing water before machine cleaning and disinfection.

d.     If necessary, treat with ultrasound according to the manufacture's instructions:

i.        For effective mechanical support during manual cleaning.

                             ii.        For pre-treatment of instruments with dried-on grime before machine cleaning.

                              iii.        Microsurgical instruments and instruments with fine working ends should not be treated with ultrasound. They should be cleaned either manually or in the washing machine. In case of cleaning in a machine please use a suitable storage rack.

e.     Clean manually or in a machine. Follow manufacturer's instructions.

2.     Manual Cleaning / Disinfection

a.     Place instrument into a suitable disinfectant with active cleaning properties so that all surfaces, inner cavities, lumens and openings come into contact with the solution.

b.     Follow the disinfectant manufacturer's instructions. After chemical disinfection, always rinse thoroughly with clear, flowing water. Follow the instructions provided by the manufacturer of disinfectant.

c.     Remove any dirt still clinging to the instrument with a soft synthetic brush. Do not use a scouring or metal brush.

d.     Clean any lumens and conduits with soft, round, synthetic brushes. Please note, the lumen and the brush must have the same diameter.

e.     Final rinsing to be done with distilled or deionized water.

f.      Dry instrument with an absorbent, soft and lint-free cloth.

g.     Dry lumens and conduits with compressed air. 

3.     Care / Testing / Storage

a.     Let instrument cool down to room temperature. Lubricate movable parts (e.g. joints and ends) slightly with special sterilization-capable, vapour-permeable lubricant.

b.     After each cleaning, disinfection process, check the instrument to make sure it is clean, it functions properly and it has not suffered any damage, e.g. bent, broken, fractured or worn parts.

c.     Discard any damaged and defective instruments and replace.

4.     Storage

a.     Place instruments with the fine working end and/or microsurgery instruments in a suitable storage racks.

b.     Secure instruments with lock in the first detent.

5.     Machine Cleaning / Disinfection

a.     Select the program according to the material (e.g. stainless instrument steel, aluminium) of the instrument to be cleaned. Follow the machine manufacturer's instructions.

b.     Final rinsing to be done with deionized water.

c.     Leave sufficient time for drying.

d.     Remove the instrument from the machine immediately after the program is do.

Sterilization Steam sterilization must be carried out according to a validated stream sterilization process (e.g. with a sterilizer meeting the specifications of EN 285 and validated according to EN 554). When using the fractional vacuum method, use the 134°C/2-bar program for sterilization with a minimum hold time of 5 minutes.