Introduction
Sensor technology employs embedded or surface devices to detect physical, chemical, and biological signals and provide a means for measuring and recording them. Sensor technology products have been adopted in a variety of medical fields. These applications have been used in healthcare to diagnose, treat, and monitor diseases. Computer and design technology advancements have enabled researchers to broaden the application of sensor technologies in orthopedic surgery.
What Is SMART?
SMART (self-monitoring analysis and reporting technology) implants, along with sensor technology, have been created to improve diagnostic and therapeutic functions in the management of a variety of musculoskeletal diseases. Microchip technology has advanced, resulting in the evolution of SMART implants. This article investigates the role of sensor technology in trauma and orthopedics. Experimental research, in-vivo, and contemporary clinical applications of sensor technology in total hip replacement, total knee replacement, spine surgery, and fracture healing assessment are discussed. Overall, sensor technology has substantial potential that can be used to improve patient happiness and functional ratings while managing orthopedic disorders.
The application of sensor technology in orthopedics has the potential to enable continuous long-term monitoring of a variety of patient and clinical data. These can provide objective information on bone healing and joint replacement integration status. Furthermore, using sensor technology can help orthopedic surgeons identify the need for intervention at an earlier stage by providing precise and sensitive information regarding impending failure or consequences.
The application of SMART (self-monitoring analysis and reporting technology) sensor technology in orthopedics is centered on the use of 'SMART implants'. These are built similarly to conventional orthopedic implants but with smart sensors implanted within the implants and/or prostheses. The sensor device can offer real-time or post-implantation data to help monitor implant performance and patient outcomes. These sensors are devices that can detect changes in the physical environment, such as strain, temperature, pressure, alignment, and changes in the biochemical milieu of implants. This in-vivo data is subsequently sent to the outside world via various methods, including Bluetooth and radiofrequency (RF). The monitoring computer then analyzes the data, enabling clinicians to interpret the changes.
What Is the Application of SMART Implants and Sensor Technology in Trauma and Orthopedics?
1. Total Hip Replacement:
Since its introduction in the 1960s, total hip replacements (THR) have been successfully employed to treat end-stage hip diseases such as osteoarthritis (OA) and hip fractures. THR has resulted in satisfactory patient outcomes after 15 and 20 years of follow-up. However, this surgery is not without complications. One of the most prevalent reasons for hip discomfort following total hip replacement is prosthesis loosening caused by mechanical wear (aseptic loosening) or infection (septic loosening).
A variety of diagnostic methods have been employed to detect aseptic loosening. Examples include plain radiography, MRI, CT scans, bone scintigraphy, subtraction arthrography, and nuclear arthrography. However, these modalities are limited due to insufficient sensitivity and specificity. Sensor technology has been used to detect loosening of the hip prosthesis. The mechano-acoustic sensor, when inserted inside the hip implant, may assess and detect hip prosthesis loosening. This sensor detects mechanoacoustic vibrations when activated by an external coil, causing the sensor to impinge on the implant.
2. Total Knee Replacement:
Osteoarthritis is among the most common orthopedic disorders worldwide. In patients with osteoarthritis of the knee who have failed conservative treatment, Total Knee Replacement (TKR) remains one of the most common surgical procedures used to relieve pain and improve activity. TKR is a popular treatment with favorable results and low complications rates.
However, other factors, including surgical technique and implant design, influence the result.
SMART knee implants with incorporated strain gauge sensors can be utilized to assess biomechanics during surgery to determine component alignment and sizing and after surgery to arrange rehabilitation and physiotherapy. Furthermore, by employing sensor technologies to better understand the knee's biomechanics, implants can be designed.
3. Fracture Healing and Assessment:
Sensor technologies can be used to track the healing of fractures. These sensors are included in orthopedic implants, such as plates and external fixator devices for fractures. Initially, the load is transmitted across the fracture entirely via the implant. As the fracture heals, the load communicated through the callus gradually increases, whereas the load sent through the implant eventually decreases. SMART (self-monitoring analysis and reporting technology) orthopedic implants with strain gauges can detect this load. Thus, successive assessments of the load over the implant can inform decisions about the weight-bearing of the limb following fracture repair. It can also aid in the early detection of non-union and advise surgeons on the need to intervene surgically to treat non-union.
4. Sensor Technology in Spine Pathologies:
Another intriguing application of sensors in spine surgery is embedded sensors to monitor strain across the spine and implants postoperatively to assess spinal fusion. Currently, surgeons use clinical examination and radiography to evaluate spine fusion. Embedded sensors can improve the accuracy with which spine fusion is completed. Strain gauzes were applied to vertebral lamina and posterior fusion implants in a study conducted on scoliosis patients to evaluate using sensors to detect spine fusion.
Serial postoperative strain measurements revealed that the strain over the fusion rod dropped significantly as the fusions progressed. At the same time, peak bone strain gradually increased before leveling out. This pattern of strain change suggested the typical course of spinal fusion. Fusion failure can be detected relatively early if there is a divergence from this pattern in serial post-operative measurements.
5. Infection-Sensor Technology in Orthopaedic Infection:
Infection remains one of the most dangerous problems linked with the use of iron in fracture repair and joint replacement surgery. The establishment of a biofilm distinguishes chronic infections. Biofilm is formed when bacterial microcolonies are enclosed in a protective extracellular matrix. These biofilms can form on any artificial surface put into the human body, including orthopedic implants. Once a biofilm is created, the infection is nearly impossible to eliminate, even with large medicines.
Sensor technology has also been utilized to detect biofilm formed due to illness. Sensor technology has addressed a variety of physical and biological features of biofilms, including oxygen concentration, pH, the presence of particular ions, and temperature, to offer precise and sensitive biofilm information. Micro electro-mechanical systems (MEMS) have been used to create sensors based on needle-based electrodes, planar optodes, and nanoparticles that can detect various biofilm features. These SMART (self-monitoring analysis and reporting technology) implants, which include implanted sensors capable of detecting biofilms, can provide surgeons with enormous information regarding biofilm features.
Conclusion
SMART implants and sensor technology applications in trauma and orthopedics are developing. Sensor technologies can aid in the intraoperative assessment and postoperative monitoring of orthopedic patients as research and implant design continue to advance. It can help scientists adapt or improve innovative implant designs, improving patient outcomes. The majority of these technologies and developments are now in the experimental stage. Some gadgets have been tested on animal and cadaveric models. Furthermore, research and development are required in this field so that these can be used broadly in healthcare systems worldwide. The economic feasibility of their use remains a significant concern.
