Trends in medical instruments

How stainless steel is meeting the surge for advancements in surgical instruments

December 19, 2017

instruments

It’s a fast-growing sector fueling innovation and refinement of stainless steel alloy applications around the world. The global surgical instruments and equipment market is expected to double within the next decade. Valued at US $10.5 billion in 2016, according to Grand View Research Inc., it is projected to reach US $20.3 billion by 2025.

While handheld surgical devices, such as forceps, spatulas, retractors, and dilators represent a majority of the market, the electrosurgical devices and equipment market segment will witness steady growth, as a result of the trend towards Minimally Invasive Surgeries (MIS).

MIS—Less is more

Minimally Invasive Surgery is increasingly being opted for whenever possible. Why? Overall, it is safer for the patient and their recovery time is much faster. Other benefits include smaller incisions, considerably less tissue damage, less discomfort and decreased scarring.

Another significant advantage, is the higher accuracy rates, thanks to the use of video-assisted equipment. This gives the surgeon improved visualisation and magnification of internal organs.

Common types of MIS include laparoscopy and endoscopy procedures. Laparoscopy involves surgery through small holes, while endoscopy encompasses diagnostic and therapeutic procedures performed through the body’s organs and vessels, using specially designed, thin instruments.

From skilled hands to robotics

Currently, the majority of MIS procedures involve hand manipulation. However, major advances are being made in robotic technologies that allow surgeons to perform finer and more delicate interventions, providing crucial benefits especially in neurological and spinal surgery. Surgical robots are expected to provide intuitive control, enhanced visualisation and higher dexterity. Consequently, surgical procedures have become more complex and confined.

As techniques evolve, instruments also have to evolve

With more requirements placed on the surgical instruments, more is expected of the material they are made of. Using the most suitable alloys is critical for both performance and cost effectiveness. All surgical instruments are subjected to body fluids as well as pre- and post-surgical techniques. These involve disinfection solutions and autoclaves that use high pressure saturated steam to kill bacteria, spores and germs resistant to boiling water and powerful detergents.

Today’s instruments must be “autoclavable” and able to withstand this process. The right alloys are selected based on their corrosion resistance, yield strength, toughness, fatigue strength, hardness or wear resistance. Many applications will require a combination of these properties.

Tubular and non-cutting instruments

Austenitic stainless alloys Types 304/304L (UNS S30400/S30403) and 316/316L (UNS S31600/S31603) are commonly used in medical devices and non-cutting instruments where good corrosion resistance and moderate strength are needed. Enhanced strength Type 304 stainless steel is often the material of choice for the tubular components.

The outstanding formability of austenitic stainless steels is a key property for such applications that involve complex shapes. A smooth surface is necessary in order to facilitate easy cleaning of medical instruments.
These alloys are used to make surgical and dental instruments like pliers, clamps, and aspiration tubes, as well as trocars, not subjected to high stress or torsional loads.

Load bearing and cutting edge

Martensitic stainless steels, Type 410 (UNS S4100), Type 416 (UNS S41600), Type 420 (UNS S42000), Type 431 (UNS S43100) and Type 440 (UNS S44002/3/4) are extensively used in medical and dental instruments that require hardness or increased toughness for load-bearing applications, such as in cutting instruments, bone curettes, dental chisels, orthodontic pliers and scalpels.

Precipitation hardening (PH) stainless steels, such as 17-4 PH (UNS S17400) are also used in surgical instruments, especially in long and narrow shafts and gripping mechanisms used in MIS.

New solutions to autoclaving issues

With the popularity of autoclaving, martensitic stainless steels may not offer the required corrosion resistance, prematurely deteriorating some equipment. Manufacturers of dental and surgical instruments have experienced some problems with cutting edge retention, wear and galling, including prematurely dull edges, decreased performance, and the possibility of introducing metallic debris into the wound.

Innovative producers have responded to these issues to meet the exact material needs of the evolving surgical instruments industry. And nickel-containing materials are playing an important role.

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