A miniature, high precision hexapod with 6 DOF is used as guidance assistance for spinal surgery. The bone-mounted system, named SpineAssist, will accurately guide the surgeon for maximized precision when placing implants destined to stabilize spinal (vertebrae) fusions in both open and minimally invasive surgery. A part from the miniature hexapod robot, the system also consists of preoperative planning software with automatic fluoroscopic and CT image processing and a set of rigid bone fixation clamps and platforms.
The inventor of the SpineAssist system and surgical procedure, Mazor Surgical Technologies, was established in 2001 as a spin-off of the mechanical department of the Israel Institute of Technology. The company’s offices are located in Caesarea, Israel and Norcross, GA, USA (Mazor Surgical Technologies Inc.). Mazor specializes in development of medical robots whereas the precision mechanics manufacturing is outsourced to the Swiss based Faulhaber Group company, MPS Micro Precision Systems AG.
Accuracy in implant placement is very important in spinal surgery since most procedures are performed close to the nerve roots and spinal cord, where every millimeter counts. This, together with other biomechanical considerations makes accuracy and precision of the utmost importance.
Spinal fusion is a surgical intervention that is performed for example to straighten the spine and prevent further deformation due to scoliosis or other disorders; to support a weakened or injured spine, or to reduce or prevent pain from pinched or injured nerves. Although spinal fusion is associated with a high rate of success, implant displacement is disconcertingly high, up to as much as 25% for scoliosis related interventions according to some sources. Misplacement is associated with a heightened risk of neural and vascular complications, as well as injury to the spinal cord membrane.
Intervention The intervention using the SpineAssist consists of five steps: 1) preoperative planning based on a CT scan of the patient’s spine; 2) rigid fixation of the SpineAssist platform to the patient’s spine; 3) positioning calibration by matching a fluoroscopic image of the bone mounted platform to the CT-image from the preoperative plan; 4) rigid mounting of the SpineAssist robot to the platform; 5) the robot guide arm is now ready to automatically position itself at the exact location according to the preoperative plan and serve as a guiding tool when the surgeon drills or performs some other intervention on the bone. The SpineAssist intervention has FDA and CE approval and has, as of today, been clinically used in over 250 cases in hospitals all over the world.
Benefits Minimally invasive surgery (MIS) is one on the most important trends in the medical device industry. The benefits from a minimally invasive procedure are potentially many: a smaller incision - and smaller scar - reduces the risk of infection and bleeding. Less pain and trauma, as well as decreased length of hospital stay and recovery time are other advantages that incite the medical device industry to constantly develop new instruments supporting MIS. With the SpineAssist a spinal fusion intervention can be performed with only a couple small incisions compared to open surgery where a large incision potentially causes more muscle damage. The miniature size of the robot with no need for “line of sight” and its high accuracy simplifies the surgical procedure and minimizes the risk for screw misplacement. Since the robot is rigidly attached to the patient there is no need for a tracking coordinate system. The procedure using the SpineAssist only requires a few fluoroscopic images, adding reduced radiation exposure for the surgeon and the patient as an important benefit to the system.
The SpineAssist software