The New Star Material in the Medical Field: Nitinol
Nitinol is a special metal alloy consisting of two elements: nickel (Ni) and titanium (Ti). Its name, “Nitinol,” combines its composition and place of discovery, the Naval Ordnance Laboratory in Maryland, USA (Ni-Ti-NOL).
Nitinol has two remarkable properties: shape memory and superelasticity. These properties make it useful in various engineering applications and medical fields.
Superelasticity
Superelasticity: Nitinol has superelasticity, which allows it to return to its original shape even after large deformations. This makes it helpful in manufacturing medical devices and implants that need to withstand deformation and return to their original shape, such as stents and implants.
Shape Memory Effect
Shape Memory Effect: Nitinol has a shape memory effect, meaning it can remember and return to a predefined shape at a specific temperature. This allows it to adapt to different temperatures and shapes within the body and is used to manufacture medical devices and implants that require adaptability, such as stents, implants, and catheters.
Biocompatibility
Biocompatibility: Nitinol is compatible with human tissue without causing significant rejection or allergic reactions. This makes it safe to manufacture various implants and medical devices, such as implants, stents, catheters, etc.
Corrosion Resistance (Corrosion Resistance)
Corrosion Resistance: Nitinol has good corrosion resistance and can remain stable in the body for long periods of time without being corroded by body fluids or tissues. This allows it to manufacture long-term implants and medical devices such as cardiac stents and orthopedic implants.
High Strength and Lightweight (HSPL)
High Strength and Lightweight: Nitinol is a high-strength and lightweight alloy that provides sufficient strength while keeping devices and implants lightweight. This makes it helpful in manufacturing medical devices and implants that require strength and lightweight.
These properties of Nitinol make it widely used in the medical field to manufacture stents, implants, catheters, and other medical devices. It is also used in various engineering applications such as aerospace, automotive, eyeglass frames and specialized applications such as temperature controllers and smart materials.
The following is a short description of the application of this material in the medical field.
1. Cardiovascular
Stents: Cardiovascular stents are metal mesh structures that expand and support blood vessels. Due to their superelasticity and shape memory effect, Nitinol alloys allow the stent to be compressed to a smaller diameter when inserted and then return to its original shape when released, thus ensuring that the supporting vessel is open.
Guidewires and Catheters: In interventional cardiac procedures, catheters and guidewires are used to guide and position other devices, such as stents and balloons. The superelasticity and shape memory of nickel-titanium alloys allows catheters and guidewires to travel inside blood vessels and return to their pre-designed shape when needed.
Thrombectomy Devices: These devices remove blood clots from blood vessels. The superelasticity and shape memory of the Nitinol alloy allow the Thrombectomy Devices to travel through the blood vessel and adapt to different vessel shapes, thus removing blood clots more efficiently.
Heart Valves: Some heart valves are made of Nitinol to support and enhance valve function. These valves can be implanted through interventional procedures to treat heart valve disease.
Aneurysm Repair: Nitinol alloys are also used to repair aneurysms, which are localized swellings of the blood vessel wall. Stents and other shape memory devices can also support and repair blood vessel walls.
2. Peripheral Vascular
Peripheral Vascular Stents: Similar to cardiac stents, peripheral vascular stents treat peripheral arterial disease, such as narrowing or occlusion of leg arteries. The superelasticity and shape memory effects of Nitinol stents allow them to adapt to the shape of the blood vessel and keep it open.
Aneurysm Repair: Repair of peripheral aneurysms, such as abdominal aortic aneurysms, often requires using stents or other devices to support and repair the artery wall. Nitinol stents can provide the needed support and help prevent rupture of the aneurysm.
Guidewires and Catheters: In peripheral vascular interventions, catheters, and guidewires are used to guide and position other devices, such as balloon expanders or stents. Nitinol’s superelasticity and shape memory effects allow catheters and guidewires to navigate through narrow and tortuous vessels.
Peripheral Artery Occlusion Treatment: Devices such as Nitinol stents and balloon expanders are commonly used to treat peripheral artery occlusions and help restore blood flow.
Endovascular Interventions: In peripheral endovascular procedures, Nitinol’s superelasticity and shape memory effects allow the interventionalist to more easily manipulate and position the treatment device to remove plaque or blood clots from the artery.
3. Cerebrovascular
Cerebral Aneurysm Repair (Cerebral Aneurysm Repair): Cerebral aneurysm is a dangerous condition in the cerebral vascular system that can lead to bleeding or rupture. Nitinol stents and spiral devices can be used for cerebral aneurysm repair. These devices can be inserted through a blood vessel and deployed inside the cerebral aneurysm to support the vessel wall and reduce the risk of the aneurysm continuing to expand.
Treatment of Cerebral Arterial Stenosis: Stenosis of the cerebral arteries can lead to dangerous conditions such as ischaemic stroke. Devices such as Nitinol stents and balloon dilators can treat cerebral arterial stenosis by dilating the blood vessels and restoring normal blood flow.
Aneurysm Embolisation: This interventional procedure blocks blood flow to a brain aneurysm and reduces the risk of rupture. The superelasticity of the Nitinol alloy allows the implanted spiral device to fill the aneurysm and prevent blood from entering it.
Angioplasty: Nitinol balloon dilators are commonly used in cerebral angioplasty to improve blood flow by dilating narrowed blood vessels.
Endovascular Aneurysm Treatment: This interventional procedure uses a catheter and a Nitinol stent to manage cerebral aneurysms.
4. Electrophysiology
Electrode Leads: Nitinol may make electrode leads for pacemakers and defibrillators. These lead wires must be flexible and durable to ensure they remain in stable contact with cardiac tissue for long periods to provide reliable control of cardiac rhythms.
Neurostimulators: In neuroscience and neurosurgery, NiTi alloys may be used for electrodes or other components in neurostimulators. These devices treat chronic pain, Parkinson’s disease, and other conditions and, therefore, need to be compatible with neural tissues and have appropriate flexibility and stability.
Electrophysiology Research Equipment: In scientific research, Nitinol may be used to make electrophysiology research equipment, such as microelectrodes or other probes for recording neuronal activity. These devices must be highly sensitive and stable to measure bioelectrical signals accurately.
5. Gastroenterology
Esophageal Stents: Nickel-titanium alloy stents treat conditions such as esophageal strictures or cancer. They are inserted endoscopically and deployed to support the dilated oesophagus and help restore oesophageal patency.
Gastrointestinal Stents: Like esophageal stents, Nitinol stents treat gastrointestinal stenosis, obstruction, or cancer. These stents can be inserted endoscopically or via a percutaneous route to support and dilate the appropriate part of the gastrointestinal tract.
Gastrointestinal Closure Devices: Nitinol can create closures in gastrointestinal surgery by suiting or pinching tissues for surgical closure and anastomosis.
Gastrointestinal Probes: In endoscopy or surgery, Nitinol may be used to manufacture probes, such as biopsy or therapeutic probes, obtain samples, or perform therapeutic procedures.
Intestinal Molds: In treating certain intestinal disorders, molds made of Nitinol may be required to help shape the intestinal structure, promote healing, or prevent strictures.
6. Urology
Urethral Stents (Urethral Stents): Nitinol stents can treat urethral strictures or obstructions. They are inserted through the urethra and deployed to support and expand it and help maintain urethral patency.
Ureteral Stents (Ureteral Stents): Nitinol stents, similar to urethral stents, can also treat ureteral strictures or obstructions. These stents can be inserted through the urinary tract to support and dilate the ureter and facilitate the smooth drainage of urine.
Nephroscopes and Stone Retrieval Baskets: Nitinol may fabricate nephroscopes or stone retrieval baskets to examine and remove intra-renal stones during kidney stone surgery.
Bladder Stents: Nitinol may expand and support bladder passages when treating bladder strictures or obstructions.
Urological Probes: Probes made of Nitinol, such as biopsy or therapeutic probes, may be required to obtain samples or perform therapeutic procedures during urological examinations or surgeries.
Artificial Urinary Sphincter: In treating urinary incontinence or urethral sphincter dysfunction, an artificial urethral sphincter made of Nitinol may be required to restore urinary control.
Urethral Stents (Urethral Stents): Nitinol stents can treat urethral strictures or obstructions. They are inserted through the urethra and deployed to support and expand the urethra and help maintain urethral patency.
Ureteral Stents (Ureteral Stents): Nitinol stents, similar to urethral stents, can also treat ureteral strictures or obstructions. These stents can be inserted through the urinary tract to support and dilate the ureter and facilitate the smooth drainage of urine.
Nephroscopes and Stone Retrieval Baskets: Nitinol may fabricate nephroscopes or stone retrieval baskets to examine and remove intra-renal stones during kidney stone surgery.
Bladder Stents: Nitinol may expand and support bladder passages when treating bladder strictures or obstructions.
Urological Probes: Probes made of Nitinol, such as biopsy or therapeutic probes, may be required to obtain samples or perform therapeutic procedures during urological examinations or surgeries.
Artificial Urinary Sphincter: To restore urinary control and treat urinary incontinence or urethral sphincter dysfunction, an artificial urinary sphincter made of nickel-titanium alloy may be required.
7. Orthopaedics
Bone Implants: Nitinol is commonly used in the manufacture of bone implants such as bone plates, nails, and screws. These implants can treat fractures, bone fractures, or defects, provide stability and support, and promote bone healing.
External Fixators: External fixators are devices used to treat severe fractures or bone breaks by stabilizing the bone through an external framework and promoting healing. Nickel-titanium alloys may be used in the constructional components of external fixators to provide strength and durability.
Vertebral Screws: Vertebral screws used in spinal surgery may be made of Nitinol. These screws are implanted into the spine and are used to hold the vertebral bones in place to stabilize the vertebrae and promote spinal healing.
Joint Replacement Implants: In joint replacement surgery, Nitinol may be used to make joint implants, such as artificial hips or knees. These implants can rebuild damaged joints, provide motor function, and relieve pain.
Dental Implants: Nitinol may be used to manufacture dental implants to support artificial teeth or bridges. These implants can be inserted into the alveolar bone to provide a solid foundation and mimic the function of natural teeth.
8. Dental
Orthodontic Appliances: Nickel Titanium Alloy is a common material used to manufacture orthodontic appliances such as braces and arches. Due to its shape memory and super-elastic properties, lighter and more comfortable aligners can be manufactured, and they can provide longer-lasting strength to facilitate tooth movement and straightening.
Dental Implants: Dental implants are artificial tooth roots used to replace missing teeth. They are usually made of nickel-titanium alloy. This material is biocompatible and strong enough to be implanted into the alveolar bone to provide solid crown support, restoring the tooth’s function and aesthetics.
Endodontic Instruments: Nickel-titanium alloy is commonly used to manufacture endodontic instruments. These instruments are used to perform root canal treatment, removing infected tissue from the canal and filling the canal to preserve and restore the tooth.
Dental Surgical Instruments: Nitinol may be used to manufacture surgical instruments such as alveolar bone cutters and bone-cutting saws in dental surgery. These instruments must be corrosion-resistant and durable to perform alveolar bone restoration or removal surgery.
Dental Expansion Appliances: Expansion appliances may be required to expand the dental arch or alveolar bone during dental treatment. Nickel-titanium alloys’ superelasticity and shape memory effects make them ideal for manufacturing expansion appliances.
9. Ophthalmology
Intraocular Implants: Some ophthalmic procedures may require intraocular implants, such as IOLs, made from NiTi alloys. These implants replace or supplement the natural lens to correct cataracts or other vision problems.
Ophthalmic Surgical Instruments: Specialised surgical instruments such as corneal scalpels or implants may be required during eye surgery. The excellent mechanical properties and biocompatibility of Ni-Ti alloys may make them one of the candidates for manufacturing these instruments.
Ophthalmic Corrective Devices: Some ophthalmic corrective devices, such as retinal imaging or tonometers, may use Nitinol components to provide structural support and stability.
Implantable Ophthalmic Devices: In addition to intraocular implants, Nitinol may be used to manufacture other types of implantable medical devices, such as corneal implants or glaucoma treatment devices.
Ophthalmic Research Equipment: In ophthalmic research, special experimental equipment or tools, such as eye trackers or intraocular pressure meters, may be necessary. The mechanical properties and stability of Ni-Ti alloys may make them suitable for manufacturing these devices.
