Traditionally manufactured implants have their limitations, as they can only be produced in a certain number of shapes and sizes, posing problems in terms of patient fit. Joint replacement devices can be agents of stress shielding — the process whereby metal implants remove stress from the patient's bone, which responds by reducing in density and becoming weaker. Cardiac implants require routine removals to replace batteries.
What’s a medical device designer to do? Make the implants smarter. The smart implant is medicine’s latest innovation, a tiny chip implanted in surgery which is able to measure patients’ pH and hormone levels, blood glucose concentration, bacteria, electrical activity and temperature, providing doctors with real-time biofeedback. Patients equipped with smart implants have a lower risk of serious infection post-op, suffer from less discomfort and pain, and could also be less likely to need revision surgeries in the future.
The advent of additive manufacturing offers a route to the design of patient-specific implants (PSIs). The manufacturing method also imposes fewer geometric constraints than subtractive manufacturing. PSIs designed and manufactured according to a patient's computed tomography scan encourages the implant to integrate with the patient's bone, reducing the risk of loosening. The use of 3D printing enables surgeons to control additional material properties and design implants that mimic a patient’s bone stiffness, density and trabecular structure, which can reduce stress shielding and improve physical function.
The European Union’s PRosPERoS (PRinting PERsonalized orthopedic implantS) research project is developing smart, 3D-printed implants for the repair of large bone defects. Personalized and biodegradable implants are being engineered based on magnesium and zinc alloys. By accurately scanning the vertebrae with advanced imaging techniques, PSI implants can be designed and printed.
Built-in sensors represent another opportunity for smartening up implants. Advanced sensor technology is fostering development of implants that can detect an infection and subsequently secrete the appropriate dose of antibiotic. Sensors can measure the strain exerted on the implant, which indicates the extent the fracture has healed.
Examples of implants include pacemakers that communicate data to smartphone apps for sharing with physicians, sensors that are embedded in orthopedic implants to communicate performance post-surgery, and glucose sensors that communicate diabetics’ glucose levels to smartphones or dedicated readers.
A pacemaker engineered at Rice University harvests energy wirelessly from radio frequency radiation transmitted by an external battery pack. The microchip can be implanted directly to pace multiple points inside or outside the heart.
Medtronic makes it easy for heart device patients to stay connected to their doctor. The MyCareLink Smart Monitor for pacemaker patients, including CRT-P, combines a reader and an app, making this a convenient way to send heart device information remotely to your doctor between clinic visits or whenever you’re not feeling well.
A smart sensor from Orthosensor, VERASENSE, enables surgeons to quantify ligament balance by giving them real-time, evidence-based data during primary and revision total knee arthroplasty. This disposable, 
A prototype of the implantable device provides microsensing technology for hydrocephalus shunts. Source: Alex Baldwin/Senseerintelligent device delivers data wirelessly to an intra-operative monitor that enables surgeons to make informed decisions regarding implant position and soft-tissue releases to improve balance and stability through a full range of motion. This monitor – the LinkStation MINI – displays intraoperative data on a high definition tablet screen, mounted to a rolling stand that is designed for easy navigation around the operating room while occupying minimal space.
Shunt implants traditionally used to treat hydrocephalus are being developed to do more than drain excess cerebrospinal fluid (CSF) from the brain. Researchers from the University of California Viterbi School Of Engineering are endowing these humble shunts with the capacity to measure pressure, flow and occlusion. Such data could lead to early intervention prior to device failure.
The global connected medical devices market is in its embryonic stage and occupied a 6 percent share of the total medical device market in 2016 and is expected to witness healthy growth in the near future. This market is anticipated to reach $73.1 billion by 2024 from $17.0 billion in 2016 and predicted to grow at an exponential CAGR of 20.0 percent during the 2016-2024 forecast period. Growing awareness and the importance of development in advanced healthcare solutions is expected to boost R&D investments in smart medical implants.
