New Micro-Robotic Tools Power Precise Back Surgery

Approximately 75 percent to 85 percent of Americans will experience back pain during their lifetime, with more than 3 million cases of spinal disc herniation in the U.S. each year. The most common surgical spinal procedure in this country is lumbar discectomy — removing the herniated disc material in the lower back that is irritating or inflaming the nerve root — with over 350,000 cases annually. While this procedure has become minimally invasive, issues like limited control, “blind” spots and rigid instrumentation can injure the patient’s muscles, other soft tissue or nerve root.

Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2).

We’re overcoming these challenges with a new robotic surgical system that combines the advantages of existing technology with additive manufacturing (building products layer by layer, instead of cutting them to their final shape and size from solid material) and soft robotics (making robotic products from elastic, compliant materials). Additive manufacturing enables unlimited geometric complexity at no extra manufacturing cost, and soft robotics brings articulated control of flexible and soft mechanism designs.

Our startup, C2 Medical Robotics, is developing dexterous, remote-controlled instruments with soft manipulator end-effectors (the tools connected to the end of the robot arm). These instruments can fit inside a single tube (called a cannula, it’s a thin tube that can be inserted into the body) along with an endoscope (a flexible tube with a light and camera), and be operated with precision and control in a constrained workspace, such as the spine. Our novel manufacturing approach to making the end-effectors will greatly reduce cost and allow them to be disposable after a single use. The cannula will have multiple tool ports, as well as integrated robotic technology to allow for independent movement of the inserted instruments.

Other robotic tools assist surgeons during surgery, but they still require surgeons to manage multiple, rigid manipulators in a small workspace, which greatly increases the risk to patients. For lumbar discectomy, existing robotic tools are too big for dexterous operation in the limited workspace. That’s why we developed a new robotic surgical system with instruments that are small, soft and flexible to enable controlled and precise surgery, and also are less expensive.

Our Robotic Lumbar Discectomy (RLD) system and associated tools allow for smaller incisions, decreased tissue trauma and shorter hospital stays. They offer surgeons dexterity in the workspace that is not possible with existing spinal surgical tools, and more precise control of the instruments through the robotic interface. The disposable tools appeal to hospitals because they can reduce the risk of infection, and save time and resources by avoiding instrument sterilization. Since the tools are robotically controlled for accurate and safe tissue manipulation and removal, they will be attractive to surgeons who are not sufficiently skilled to perform manual lumbar discectomies and now can perform this procedure robotically.

The robotic cannula allows for the independent control of the translation and axial rotation of multiple instruments at the same time.
The developed nerve retractor instrument is fully articulated and used to move nerves out of the way to gain access to the herniated disk material during the surgical procedure.

We’ve filed two patents to protect the intellectual property associated with the RLD system, which also can be used for robotic assistance in other delicate surgical procedures that must be performed in small workspaces. We’ve designed two different disposable robotic surgical tools, and developed a teleoperated control platform for testing the instruments for kinematics, range of motion, applied force, and fatigue. We’ve constructed a prototype of a robotic cannula to independently control the axial position and rotation of the inserted instruments. Next steps will be commercial prototype development and testing, followed by application for FDA approval.

Our goal is fourfold: heal patients, reduce pain, assist surgeons, and lower healthcare costs.

Dr. David Cappelleri

David J. Cappelleri, PhD, Associate Professor of Mechanical Engineering, Purdue University College of Engineering


Purdue Engineering

Pioneering groundbreaking technology, unlocking revolutionary ideas and advancing humankind across the country, planet and universe. Explore how leading educators, thinkers and innovators at the Purdue University College of Engineering are shaping the future — and beyond.

Purdue College of Engineering

Written by

Known as the “Cradle of Astronauts,” with a long list of pioneers includes Neil Armstrong and Amelia Earhart. Ranked Top 10 nationwide by USNWR.

Purdue Engineering

Pioneering groundbreaking technology, unlocking revolutionary ideas and advancing humankind across the country, planet and universe. Explore how leading educators, thinkers and innovators at the Purdue University College of Engineering are shaping the future — and beyond.

Welcome to a place where words matter. On Medium, smart voices and original ideas take center stage - with no ads in sight. Watch
Follow all the topics you care about, and we’ll deliver the best stories for you to your homepage and inbox. Explore
Get unlimited access to the best stories on Medium — and support writers while you’re at it. Just $5/month. Upgrade