1 Introduction
Accidents, fractures, emergency surgery. In the operating room, doctors must focus and act swiftly to provide the best medical care to their patients. If splints and screws are necessary to immobilize a fracture, the surgeon will pick up a bone drill and begin the procedure. This scene plays out daily in hospitals around the world. The widespread use of power instruments has significantly reduced the workload of surgeons. With the help of these instruments, surgeons can even treat severe injuries that previously required amputation. Technological advancements in power tools have reduced the invasiveness of surgical treatments, minimizing tissue damage and thus shortening recovery time.
2. High-speed removal of tissue
When we think of handheld surgical instruments, we often immediately picture the large machines used by craftsmen. However, surgical instruments must meet far higher requirements in terms of precision, heat generation, and vibration. Reliability is also a crucial factor. The DC motors powering these tools must meet the same high standards. Therefore, brushless DC drives are particularly suitable due to their long lifespan and high speed. These two characteristics are especially important for surgical curettes (see Figure 1) used by surgeons on knee or shoulder joints, as their purpose is to selectively and thoroughly remove specific tissues and cartilage during surgery. These instruments are equipped with a long stainless steel tube with a rotating blade at the open end. A brushless EC13 motor, for example, from Mackorton, can be used as the drive, paired with a GP13 planetary gearbox. This motor can reach speeds of 90,000 revolutions per minute and is sealed and corrosion-resistant. Sealing and corrosion resistance are critical for curettes, as they are frequently in direct contact with saline solution. Furthermore, the heat and vibration generated by the motor must be minimized to facilitate the surgeon's work.
Figure 1
3DC motors must be able to withstand frequent disinfection treatments.
“The motors in surgical instruments must operate under extremely harsh conditions,” says Anthony Mayr, senior program manager at maxonmotor. These drives must withstand intense vibrations and high temperatures under overload conditions (torque or speed); furthermore, they must withstand high humidity and be able to handle alkaline solutions to meet stringent sterilization and cleaning requirements. “Fortunately,” says Anthony Mayr, “even under such harsh conditions, Maxonmotor’s DC motors and gearboxes perform exceptionally well.” Extensive research and testing conducted by Maxonmotor in its own laboratories also contribute significantly to this. (See Figure 2.)
Figure 2
4. The motors in surgical instruments must operate under extremely harsh conditions.
One of the biggest challenges facing DC drives in the operating room is the need for constant sterilization. During surgery, all instruments that come into contact with the patient must undergo rigorous sterilization, mostly using steam sterilization. In this process, instruments are heated in an autoclave at 2.3 bar pressure and 100% humidity, at 134 degrees Celsius for 20 minutes. According to Anthony Mayr, recent test results show that through careful material selection and protection of critical components (such as vacuum-sealing the rotor), motors capable of withstanding over 2000 steam sterilization cycles can be manufactured. Furthermore, future drives will be smaller, lighter, and higher-performing, enabling surgeons to perform procedures more precisely and effectively, allowing patients to recover more quickly.
