O-arm in action

Study shows computer-assisted surgery making a difference in Canada

Surgeons at Vancouver General Hospital find hi-tech imaging and 3D navigation improves outcomes and delivers economic benefits.

In the first study of its kind, adult spine surgeon Dr. John Street and colleagues at the Vancouver Spine Surgery Institute at Vancouver General Hospital (VGH) recently compared clinical outcomes for two groups of patients.* One group received computer-assisted spine surgery (CAS) with Medtronic's O-armTM imaging device and StealthStationTM navigation system, while a control group received surgery with conventional fluoroscopy using the Philips C-arm device.

The study, which observed a total of 5,132 pedicle screws inserted in 502 patients during the study period (2,682 screws in 253 patients in the treatment group and 2,450 screws in 249 patients in the control group), found that the accuracy rate for screw placement was 95.2 per cent for the CAS group, significantly higher than 86.9 per cent for the conventional treatment group.


“CAS technologies provide real-time, 3D images of the bony anatomy of the patient's spine," said Dr. Street. "Adding that extra dimension makes a significant improvement in the accuracy of screw placement."

Only two patients in the CAS group (0.8 per cent) required a re-operation to address symptomatic misplaced screws, compared to 15 patients (6.0 per cent) in the fluoroscopy group. Nine of those patients had a re-operation during their original admission, and six patients were readmitted after discharge to revise malpositioned screws. The difference in revision rate between the CAS group and those in the fluoroscopy group was statistically significant (p=.014).

Economic Analysis Proves Technology Is Cost Effective

What's more, the O-armTM and StealthStationTMtechnology shows distinct cost benefits, a significant consideration in today's healthcare environment, where new technologies rarely have robust economic data available, and even fewer can claim a strong incremental cost-effectiveness ratio (ICER) with a conservative break-even point.

Based on an estimated cost of re-operation of C$12,618, the study concluded that the O-armTM and StealthStationTM are cost-neutral for sites performing more than 254 pedicle screw implant procedures per year over a period of seven years. As hospitals perform 255 or more procedures, they actually save their health system money.

In this study, the surgeons calculated an ICER of C$15,961 per re-operation avoided for the CAS group, a figure that falls well within the $25,000 or lower threshold amount many health systems use to indicate significant value. Given the ICER, hospitals performing fewer than 255 procedures also benefit from the significant value of the O-arm.

VGH performs between 500 and 600 surgeries per year, according to Dr. Street.

Lower Radiation Exposure and Teaching Benefits

In addition to a higher level of accuracy with screw placement, lower re-operation rate, and favourable economics, CAS provides additional environmental and teaching benefits over conventional fluoroscopy.


“There is no radiation exposure from the O-Arm as the team is out of the room when the O-arm takes an image of the patient at the beginning of the procedure," said Dr. Street. "That's a vast improvement from cumulative exposure over time even while wearing heavy lead aprons during five- to seven-hour surgeries." Additionally, he pointed out, the patient does not require the traditional post-operative CT scan two to three days later to check on screw placement.

The O-armTM and StealthStationTM technologies also function as educational tools, Dr. Street notes. "This technology not only allows me to show the resident the 3D anatomy lines, but I can watch them as they insert a screw and ensure they have the right direction and angle. You can't measure that in dollars, but that's a huge advance."

* The study was published in the January 2016 issue of The Spine Journal (and online October 2015).Medtronic supported the VGH study through the Investigator Initiated Research program, but did not have input into the data collection, analysis or economic evaluation by the study authors.

Read the study in The Spine Journal. To learn more about the Medtronic O-armTM and StealthStationTM technology, visit Medtronic.com.

Indications, Safety, and Warnings

O-arm Surgical Imaging System

For full details, please refer to your System Manual.

Intended Use:

The O-arm® O2 Imaging System is a mobile x-ray system designed for 2D fluoroscopic and 3D imaging for adult and pediatric patients weighing 60 lbs or greater and having an abdominal thickness greater than 16cm, and is intended to be used where a physician benefits from 2D and 3D information of anatomic structures and objects with high x-ray attenuation such as bony anatomy and metallic objects.

The O-arm® O2 Imaging System is compatible with certain image guided surgery systems.

United States law restricts this device to sale, distribution, and use by or on the order of a physician.

Use of Video Graphics Printer

Printouts from the optional Video Graphics Printer are not intended to be used for diagnostic purposes. The printer's primary use is for physician reference and documentation.

Use of the DVD/CD RW Drive

Information stored on DVDs is not intended to be used for diagnostic purposes. The primary use of such information is for physician reference and documentation.

Equipment Users

Users of the O-arm Imaging System should be trained, licensed, and/or certified in the proper use of medical x-ray equipment and its medical applications. Users should read this user manual and the labels on the Image Acquisition System (IAS) and the Mobile View Station (MVS).

Safety Overview

Potential hazards exist in the use of medical electronic devices and X-ray systems such as the O-arm Imaging System. Personnel using the equipment should understand the safety issues, emergency procedures, and the operating instructions provided in the User Manual.

StealthStation Navigation System

For full details, please refer to your System Manual.

Intended Use

Your Medtronic computer-assisted surgery system and its associated applications are intended as an aid for precisely locating anatomical structures in either open or percutaneous procedures. Their use is indicated for any medical condition in which the use of stereotactic surgery may be appropriate, and where reference to a rigid anatomical structure, such as the skull, a long bone, or vertebra, can be identified relative to a CT- or MR-based model, fluoroscopic images, or digitized landmarks of the anatomy.


Medical conditions which contraindicate the use of a Medtronic computer-assisted surgery system and its associated applications include any medical conditions which may contraindicate the medical procedure itself.


Do not modify the StealthStation S7 System.

The system and its associated applications should be used only by qualified medical professionals who are thoroughly trained and experienced in performing surgery with Medtronic computer-assisted surgery systems.

The system and its associated applications should be used only as an adjunct for surgical guidance. They are not a replacement for the surgeon's knowledge, expertise, or judgment.

If system navigation seems inaccurate and recommended steps to restore accuracy are not successful, abort use of the system.

Accessory equipment connected to the analog and digital interfaces of the Medtronic computer-assisted surgery system must be certified according to the applicable IEC standards (e.g., IEC 60601-1 for medical equipment, UL60601-1, and CSA C22.2 No. 601-1-M90). Furthermore all configurations shall comply with the system standard IEC 60601-1-1 or the system requirements of Clause 16 IEC 60601-1: 3rd Edition. Any person who connects additional equipment to the signal input part or signal output part configures a medical system, and is therefore responsible for ensuring that the system complies with the requirements of the system standard IEC 60601-1-1 or the system requirements of Clause 16 IEC 60601-1: 3rd Edition. If in doubt, contact technical support or your local Medtronic Navigation, Inc. representative.

The system is not suitable for use in the presence of a flammable, anesthetic mixture with air or oxygen or nitrous oxide.

Some system components may contain batteries. Do not recharge or disassemble batteries. Do not dispose of batteries in fire. Observe local regulations concerning battery disposal.

Inspect all instruments before use. If visibly damaged, do not use the instrument.

Inspect all system components before use. If visibly damaged, do not use the system.

Discard before use any pre-sterilized component whose sterile packaging appears to be compromised.

Do not re-process, re-sterilize, or re-use any single-use device. Attempts to re-process or re-sterilize a single-use device may be ineffective and may compromise its structural integrity. Any re-use creates a risk of contamination which could result in patient injury, illness, or death.

There is currently no effective sterilization method for components that are tainted with the infectious agent that causes Creutzfeld-Jakob Disease (CJD). Therefore, you must discard immediately after surgery any components that come into contact with biologic material from patients who carry or are suspected to carry this infectious agent. As a precaution, drape all non-disposable components that could otherwise come into contact with such material.

Do not open sterile-barrier packages or containers until surgical use. At time of use, inspect barrier for breach. If the sterile barrier was breached before surgical use, reprocess all devices contained in the package.

The StealthStation S7 System is not intended to be operated on battery power alone while instruments are connected to a patient.

To reduce the potential of electrical shock, the operator should not simultaneously touch the patient and the system input/output panel, mouse, keyboard, or batteries.

To avoid risk of electrical shock, the StealthStation S7 System must only be connected to a supply mains with protective earth.

The StealthStation S7 System should not be connected to a wired network while in the patient vicinity to avoid electric coupling to non-medical equipment.

Do not transport the carts in an undocked position. Carts must be properly placed in the transport position and docked together before moving. To secure the system from unwanted lateral movement (for example, on an incline), lock all the castor wheels of the docked system.

The StealthStation S7 System Staff Cart contains a high fidelity stereo system for music playback from a user provided audio player. This system may be capable of sound levels which can lead to permanent hearing loss at high volume. The volume is controlled at the user provided audio player. For hearing safety, follow all warnings prescribed by the user provided player. If these warnings are not available or understood, do not exceed a 50% volume output from the audio player.

The following 2 warnings are from the AXIEM system manual:

Use of the AXIEM™ system may interfere with implantable device communication. Do not use the portable AXIEM™ system while programming or interrogating any implantable device.

Use of the AXIEM™ system may interfere with patient monitoring equipment. Position the AXIEM™ system and Mobile Emitter as far as possible from any such equipment, and use interference filtering if possible. If you continue to experience interference, abort use of the AXIEM™ system and call technical support.


Federal law (U.S.A.) restricts this device to sale by or on the order of a physician.

The system and its associated applications contain no user-repairable parts. For repair or replacement of any part of the system or application, contact a technical support representative.

Verify that all relevant instrumentation has been properly cleaned and sterilized before surgery. Clean and sterilize the components according to the parameters in the Equipment Cleaning and Sterilization sheet (9730713). Clean non-sterilizable equipment according to the parameters in the Non-Sterilizable Equipment Cleaning sheet (9733205).

The system has been successfully tested against the requirements of IEC 60601-1-2. However, RF interference could hamper its operation or the operation of other nearby electrical devices. If you suspect either of these conditions, move the conflicting equipment farther apart, separate the equipment with an RF barrier, or discontinue use of the system.

Do not exceed the recommended electrical ratings for the system. Exceeding the ratings could damage the system.

The system mouse is not designed for sterilization, and may be damaged if sterilization is attempted.

System components are fragile. Use care when handling system components.

Before moving the system cart(s), shut down and stow all components, remove any loose items from the top of the cart(s), and dock the carts together (if applicable).

Avoid dripping any fluids into any enclosure on the StealthStation S7 System. Disconnect the power and allow the system to dry if you suspect fluids may have entered any part of the system.

The Staff cart storage drawer has a maximum load capacity of ten pounds 3.8 kg (8 lb).

The following 5 precautions are from the AXIEM system manual:

Metallic objects in or near the navigation field can degrade navigational accuracy. If metallic distortion causes excessive error, navigation will be disabled. To restore navigation, remove metallic objects from the navigation field.

Electrical noise in or near the navigation field can degrade navigational accuracy. If electrical noise introduces excessive error, the system will automatically disable navigation. To restore navigation, remove devices that produce electrical noise (such as electro-cautery equipment and electric drills) from the navigation field.

System components, including the Mobile Emitter, are fragile. Use care when handling system components.

Do not drop system components or mishandle them in such a manner as to cause them physical damage. This may impair device function. Even if the component works immediately after being dropped, operational damage may have occurred that may not be observed until some future time.

The AXIEM™ system is not sterilizable. Properly clean the system following the protocol in the Universal Cleaning and Sterilization instructions (9733205).