For centuries, the surgeon’s kit was a collection of simple, single-function tools designed primarily for basic amputations and cuts. The first engineering advancement began during the 19th century with the introduction of anesthesia and antiseptic techniques, which demanded cleaner, more specialized implements. This change continued into the 20th century by blending careful craftsmanship with new material science, such as new steel alloys and plastics, leading to an explosion of new instruments for intracavity, visceral, invasive, resection, and excision procedures [1].
The process of designing a surgical tool begins with selecting the right material. The chosen material affects the strength, durability, magnetic properties, weight, and effectiveness of the surgical tools. The most common materials used are stainless steel, titanium, and polymers.
Stainless steel is an alloy, or mix, of iron, chromium, carbon, and sometimes nickel [2]. Carbon, which makes up at most 2.1% of steel, provides strength and hardness, while chromium makes it corrosion-resistant by oxidizing in air and in water and creating a protective layer that prevents further scratches and surface damages on the surgical tool [2]. Most surgical tools are made out of austenitic stainless steel, which contains 16%-30% chromium and 2%-20% nickel and is malleable when heated, allowing the alloy to be manipulated into certain tools more easily. Once it’s cured and set, it is one of the strongest forms of metals, making it a preferable material for surgical tools [2]. Austenitic steel specifically is non-magnetic due to its nickel content, allowing tools to be used in highly magnetic MRI environments [2].
Titanium, another common tool material, is a transition metal significantly lighter than most metals while also being strong and durable [3]. Similar to steel, titanium is highly resistant to corrosion for the same reasons and has the ability to be shaped into complex forms. But, considering titanium’s strength compared to its lower density makes it favorable for medical applications that need weight reduction [3]. Its ability to withstand continuous usage while being lightweight makes it most optimal for tools will be used for long operations.
Stainless steel and titanium are both materials that are able to withstand high temperatures. Steel has a melting point of 1370°C (2498°F) [2] while that of titanium is 1668°C (~3034°F) [3]. This is key when it comes to repeated sterilization using an auto-clave, machines that use steam under pressure to kill harmful bacteria, viruses, fungi, and spores [4].The moisture in the steam efficiently transfers heat to the surgical tools, destroying the protein structures of bacteria and thereby killing them to sterilize the tools [4]. With autoclave temperature ranges from 250°F (121°C) to 275°F (135°C) [4], the high melting points of materials like steel and titanium prevent them from degrading over time.
Polymers, medical grade plastics engineered to meet strict needs, are equally as important as metals in the medical field [5]. A variety of polymers are used: while polyethylene (PE) is commonly found in disposable IV bags and syringes, polypropylene (PP) is used for surgical masks, gowns, and test tubes. Equipment like oxygen masks are typically made from polyvinyl chloride (PVC), whereas anesthetic masks and incubators are made from acrylic (PMMA) [5]. Polymers are often used because of their biocompatibility, non-permeability, sterilization resistance, lightweightness, and durability [5].
With these materials, we can make surgical tools used in almost any operation, such as forceps, clamps, scalpels, and scissors.
Forceps are one of the primary tools used in surgery, offering the ability to grasp, hold, and extract tissues or objects from the patient [6]. They come in various shapes, sizes, and designs, each suited to their specific surgical task. Some forceps have serrated jaws, where the tip is textured to offer better grip, while others have delicate tips for fine tissue manipulation [6]. Modern surgical forceps are typically made from high-quality stainless steel, alloy, or titanium [6].
Another important medical instrument, clamps are designed to temporarily close up blood vessels during operations [7]. They are mainly used to control bleeding, to prevent fluid leaks, and to decrease risk of injury when manipulating organs [7]. Clamps can be straight or curved depending on their usage. Straight clamps are generally used for clamping larger vessels while curved clamps are preferred for reaching deeper vessels [7]. Common clamp materials include stainless steel, titanium, and medical polymers [7].
Scalpels are one of the most essential tools as their primary function is to provide surgeons with the capability to perform high precise incisions [8]. The blade’s geometry is either straight, curved, or angled, creating smooth and controlled incisions by maintaining precision. [8]. Having ergonomic gripped handles, the surgeon is able to maintain command over the instrument at all times and reduces fatigue during long procedures [8]. The materials of stainless steel, titanium, alloys, polymers, and ceramic coating all contribute to its sharpness and durability.
Also designed for cutting, surgical scissors come in many forms based on their operation. For example, bandage scissors are used to cut gauze and bandages [9]. Designed to have an angled and blunt bottom tip, they are able to cut thin fabric while protecting the skin [9]. Dissecting scissors provide more leverage than scalpels when making incisions, removing skin, tissue, and stitches; with their curved blade, they are able to protect incisions when probing [9]. Stitch scissors are designed with a hook-shaped tip to remove sutures, offering a firm grip on the suture before making the cut [9]. For all these scissors, the main materials used include stainless steel, titanium, and tungsten carbide [9].
Ultimately, the advanced engineering of medical tools and equipment has made surgical procedures widely successful. By relying on the unique properties of titanium, medical-grade polymers, and alloys, engineers have done more than creating durable equipment; they have fundamentally improved patient outcomes, saving millions of lives in operations.