MAUDE Adverse Event Report: MEDTRONIC NAVIGATION, INC. (LOUISVILLE) STEALTHSTATION S7 SYSTEM; NEUROLOGICAL STEREOTAXIC INSTRUMENT

Model Number S7

Device Problem Adverse Event Without Identified Device or Use Problem (2993)

Patient Problems Perforation (2001); Spinal Column Injury (2081); Iatrogenic Source (2498)

Event Date 09/30/2013

Event Type  Injury  

Manufacturer Narrative

Specific patient identifier not available from the journal article authors.Patient weight not available from the journal article authors.Event date is approximated.Date provided is used as the patients underwent surgery through september 2013.Citation: miller, ca., ledonio, cg, hunt, ma., siddiq, f., & polly jr, dw.(2016).Reliability of the planned pedicle screw trajectory versus the actual pedicle screw trajectory using intra-operative 3d ct and image guidance.International journal of spine surgery, 10(38), 1-13.Doi: 10.14444/3038.Brand name, common device name and procode not provided in the journal article.The article mentions a navigation system (model not specified).Further information unavailable.Those selected are suspected to be for the device used.Further information unavailable.Device serial number was not provided in the journal article.The selected is suspected to be for the device used.The selected 510k is suspected to be for the device used as the specific navigation system was not provided in the journal article.Per the journal article conclusion, the virtual projection view is clinically accurate compared to the actual placement on intra-operative ct in both the axial and sagittal views.There is slight imprecision (~2°) in the axial and sagittal planes and a minor difference in the sagittal thoracic and lumbar angulation, although these did not affect clinical outcomes.In general, we find that pedicle screw placement using intraoperative cone beam ct and navigation to be accurate and reliable, and as such have made it a routine part of our spine practice.It was noted in the article that some of the possible causes may be due to the length of screw, poor bone quality, misalignment with rest of construct, fracture of screw head, and poor placement.Pedicle perforations are known inherent risks to any spinal surgical procedure.Multiple attempts have been made to obtain additional information.No further information provided in the journal article or from the authors.No request for service have been received from the customer regarding these events.No parts have been replaced or returned to the manufacturer for evaluation.

Event Description

The journal article was forwarded by a medtronic representative.A retrospective study from january 2013 to september 2013 evaluated the accuracy of the virtual screw placement (navigation system projection) compared to actual screw thoracic and lumbosacral pedicle screws placement (intra-operative imaging system) and examined for differences based on the distance from the reference frame.A reference frame was attached to a spinous process and the imaging system was used for intraoperative computed tomography (ct) scan.The positions of the navigated instruments in relation to the reference frame were projected on the axial, coronal, and sagittal images acquired from the ct scan.Precision of the navigation is checked periodically by positioning a navigated probe on a known anatomic landmark such as a spinous process.Using anatomic landmarks and verifying with navigation, the pedicle was identified and a trajectory planned.A virtual screw projection was laid along this trajectory and a screen snapshot is taken using the stealth system.At the discretion of the operating surgeon, any concerning screws identified on the second confirmation ct were removed or redirected prior to closure.Thirty-one consecutive patients who had all necessary imaging were included in the study.A total of 240 screws were placed from t1 to s1.Two cases used a percutaneous technique (a minimally invasive technique) and twenty-nine were open surgeries.Surgeries were performed for a variety of indications including trauma, degenerative disease, scoliosis, and pseudarthrosis.No vascular, visceral, or neurologic complication occurred in any of these cases.Three screws (3/240 = 1.25%) were revised intraoperatively at the discretion of the operating surgeon as they were noted to have breached the cortical surface on intraoperative ct scan.Two screws were removed as the pedicles were so diminutive as to not accept a redirected screw and one screw was exchanged for a shorter screw at the same trajectory.Axial and sagittal differences for these screws ranged from 5-8° and 2-10°, respectively.In the 122 excluded patients out of the 153 total procedures, (53 male, 69 female; ages 3-80), 977 screws were placed.Thirty-nine of these surgeries were revisions and five patients required future revisions - four were fusion extension for adjacent segment degeneration and one was performed for pseudoarthrosis and loosening of hardware.No screws were revised for suboptimal positioning in the subsequent surgeries.Eighteen screws were revised or removed during the index surgery (18/977 = 1.8%).Reasons for screw revision included too long of screw (5), fixed screw exchanged for polyaxial screw (3), screw pullout during compression due to poor bone quality (2), misalignment with rest of construct (2), fracture of screw head (1), and poor placement (5).In two screw revisions for poor placement, there was a 5° and 7° difference from an ideal pedicle screw, as a virtual snapshot was not available for comparison.Two screws were replaced for sagittal deviations and one screw was noted to be revised in an operative report, however the specific screw was not reported.The mean angular difference between the virtual and actual image in all screws was 2.17° ± 2.20° on axial images and on sagittal images was 2.16° ±2.24° (table 4).Out of the 240 screws placed, only 18 were placed more than 5 vertebral levels away from the reference frame.There was no statistically significant difference in accuracy of pedicle screws distanced up to 10 vertebral segments away from the reference frame.The results show that the virtual screw trajectory when compared to the actual trajectory had excellent and statistically significant test-retest reliability.There was no statistically significant difference between thoracic and lumbosacral screws in the axial plane, however greater imprecision was noted in the sagittal plane.Some of these differences may be attributed to the lumbar spine being more mobile than the thoracic spine.The sagittal plane also had greater imprecision in sacral screws, and may be related to the challenging angulation of the sacrum in some patients or interference with adjacent level screw heads.The authors report that there are several potential sources of use error using this system (page 8) such as in some patients with flexible curves, it is possible to ¿push¿ with the instruments and affect the navigation, inadvertently moving reference frame, etc.However, both surgeons and staff at this institute have become experienced in its application and technique given its routine use.

Manufacturer Narrative

Patient age not provided in the journal article.Age range of the included patients was (b)(6) years; therefore mean age of (b)(6) years was used.Patient sex not provided in the journal article.Female used as there were (b)(6) females and (b)(6) males in the included study.

Manufacturer Narrative

The reported issue was evaluated by medtronic personnel, the journal article identified several potential sources of use error using the navigation system, such as: frame movement, patient movement, instrument manipulation, etc.Note: the frame movement was not alleged to be a deficiency of the medtronic frame but operational technique (i.E.Bumping the frame) that caused frame movement.The instructions for use (p/n 9732461 rev 13) which accompany this device contains the following warnings: "warning: do not bump or reposition the reference frame after registration.Such movement may result in inaccurate navigation.If the reference frame moves in relation to the patient anatomy at any time after registration, you must reregister." and "warning: make sure that the reference frame assembly is rigidly attached and locked (tightened) with respect to the relevant anatomy.If the post or clamp moves in relation to the anatomy, navigational inaccuracy may result." there was no allegation of malfunction or deficiency of the medtronic system to have caused or contributed to the reported adverse event(s).

• Brand Name: STEALTHSTATION S7 SYSTEM
• Type of Device: NEUROLOGICAL STEREOTAXIC INSTRUMENT
• Manufacturer (Section D): MEDTRONIC NAVIGATION, INC. (LOUISVILLE); 826 coal creek circle; louisville CO 80027
• Manufacturer (Section G): MEDTRONIC NAVIGATION, INC. (LOUISVILLE); 826 coal creek circle; louisville CO 80027
• Manufacturer Contact: peter verhey ; attn:product quality experienc; 826 coal creek circle; louisville, CO 80027-9710
• MDR Report Key: 6679024
• MDR Text Key: 78766983
• Report Number: 1723170-2017-02710
• Device Sequence Number: 1
• Product Code: HAW
• UDI-Device Identifier: 00613994450944
• UDI-Public: 00613994450944
• Combination Product (y/n): N
• Reporter Country Code: US
• PMA/PMN Number: K050438
• Number of Events Reported: 1
• Summary Report (Y/N): N
• Report Source: Manufacturer
• Source Type: company representative,health
• Reporter Occupation: Medical Equipment Company Technician/Representative
• Type of Report: Initial,Followup,Followup
• Report Date: 12/07/2017

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: No
• Device Operator: Health Professional
• Device Model Number: S7
• Device Catalogue Number: 9733856
• Is the Reporter a Health Professional?: No
• Initial Date Manufacturer Received: 06/01/2017
• Initial Date FDA Received: 06/29/2017
• Supplement Dates Manufacturer Received: Not provided; 11/14/2017
• Supplement Dates FDA Received: 06/29/2017; 12/07/2017
• Was Device Evaluated by Manufacturer?: Device Not Returned to Manufacturer
• Date Device Manufactured: 06/01/2011
• Is the Device Single Use?: No
• Is This a Reprocessed and Reused Single-Use Device?: No
• Type of Device Usage: Reuse
• Patient Sequence Number: 1
• Patient Outcome(s): Other; Required Intervention
• Patient Age: 44 YR