Implantable Sensor Monitors Orthopedic Recovery

Sometimes medical devices just make you say "Wow". Maybe you say it for all the bells and whistles, but it's probably because of the simplicity, versatility, for the fact that it makes you think "Why didn't I think of that before." "Wow" is what I said when I saw a recent invention created by Dr. Eric Ledet, an assistant professor at my alma mater, Rensselaer Polytechnic Institute. He and his team created an orthopedic sensor that can monitor healing in the body.

An orthopedic implant is a medical device submitted to forces in the body as it replaces or provides fixation of bone, or replaces articulating surfaces of a joint. Orthopedic implants are used in most areas of the body including hips, knees, spine, maxillofacial, shoulders, etc. Great progress has been made in researching the best material, shapes, pastes, and procedures to use when implanting a orthopedic device. And while this ultimately leads to less device failure there is still some disconnect in how the surgeons monitor the device after is has been implanted. Currently, after a patient undergoes an orthopedic procedure, the surgeons rely on X-rays or MRIs to monitor the progress of the patient's recovery. These methods often leave the surgeon making a subjective and incomplete assessment of how the area is healing, the status of scar tissue, and the ability of the area to bare weight.

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The wireless, implantable sensor is able to transmit data from the site of the surgery or trauma for accurate and less invasive monitoring. The sensor is 4 millimeters in diameter and 500 microns thick and looks like a small coil of wire. It does not require a battery or any electronics within the body. The sensor is attached to commonly used orthopedic musculoskeletal implants such as rods, plates, or prostheses. The sensor is powered by an external device that captures the sensors data and provides the surgeon with detailed, real-time information from the actual surgery site. A small wand is waved over the area with the sensors and the data is transmitted to a screen for the surgeon. Click here to see a video of the sensor in action.

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The data includes information on the load, strain, pressure, or temperature of the healing site. This level of data allows the surgeon to make personalized, and very objective diagnoses for the patient. "The sensor provides opportunities to make specific and detailed diagnostics for a particular patient and to tailor care based on very objective and quantitative measures," said Eric H. Ledet, PhD, Assistant Professor, Rensselaer Polytechnic Institute. The device is passive, meaning that it isn't sending out signals until asked to do so by the appropriate antennae.

The simplicity of the design makes the implant very inexpensive to produce and repair. Since there are few parts, it is also less prone to failure. The device is simple and inexpensive but it is also durable and can remain in the body as long as the orthopedic implant does. Being able to accurately monitor a patient's progress means that the doctor can determine when the patient can safely return to work and other daily activities - reducing the number of days missed and the chance of being reinjured.

Dr. Ledet thinks that if everything goes well the sensor could hit the market within 5 years.

Resources

Implantable, Wireless Sensors Share Secrets of Healing Tissues

Orthopedic Implants