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 Neurological Deficit/Dysfunction (1982); Perforation (2001); Pleural Effusion (2010); Iatrogenic Source (2498); No Code Available (3191)

Event Date 02/29/2016

Event Type  Injury  

Manufacturer Narrative

Specific patient identifier not available from the journal article authors.Patient age not provided in the journal article.Mean patient age was 17.6 years (range 9 to 62 years).Therefore 18 years used.Patient sex not provided in the journal article.Female used as there were 61 male and 83 female in the study, therefore female used.Patient weight not available from the journal article authors.Event date is approximated.Date provided is used as the patients underwent surgery through (b)(6) 2016.Citation: jin, m., liu, z., qiu, y., yan, h., han, x.& zhu, z.Incidence and risk factors for the misplacement of pedicle screws in scoliosis surgery assisted by o-arm navigation¿analysis of a large series of one thousand, one hundred and forty five screws.International orthopaedics (sicot) (2017) 41:773¿780.Doi 10.1007/s00264-016-3353-6.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.Device serial number, unavailable.Device udi not provided as this product is no longer manufactured.Device manufacturing date is dependent on serial number, therefore, unavailable.The journal article reports that univariate analysis demonstrated that risk factors associated with screw malpositioning included aetiology, the instrumented level, gap difference, and concave pedicle.Pathological condition (cs, nf-1, etc.) middle-thoracic spine, gap difference over three levels, and concave pedicles were risk factors for predicting pedicle screw misplacement.Among these, gap difference (over 3 levels) ranks the highest of all.The study found that patients with nf-1 and cs were at high risk of pedicle screw misplacement.The reasons might be as follows: first, the dysplasia structures in these cases might result in improper fixation of the tracker to the implant, leading to a difference in angulation between the virtual and the intraoperative images.Second, the severe distorted and rotated pedicles in these cases posed great challenge for finding the optimal trajectory of screws.Accurate placement of pedicle screws in scoliosis remains a challenge, especially in severe cases as the pedicles are thinner, more sclerotic and dysplastic than those of mild scoliosis.The journal article also reports that, although the navigation system is extraordinary convenient, several tips are necessary for the future surgeons to shorten the learning curve and avoid the pitfalls of this technique: in cases where the pedicles are dysplasia such as nf-1 and cs, the perforation rate could be still high despite of navigation; even if under great vision, instrumentation of thoracic spine especially upper thoracic spine could be dangerous; it¿s better to locate the tracker within the apical region or around instrumented levels as close as possible; inserting the pedicle screws from distally to proximally to the tracker could reduce the incidence of tracker loosening and avoid accidental radiation exposure due to re-scan.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 attached journal article was forwarded by a medtronic representative.Use of the navigation plus system and imaging system was reported for scoliosis treatment with pedicle screw placement between september 2013 and february 2016.This is medical device report (mdr) report 1 of 2.See 1723170-2017-02799.A total of 144 patients (61 male and 83 female) were enrolled in the present study, and the mean patient age was 17.6 years (range 9 to 62 years).The patients were categorized into four groups according to pathological conditions.All surgeries were done by two senior surgeons with at least ten years of operative experience in spine surgery and very familiar with imaging and navigation system.A first intra-operative 3d scanning was acquired including four to six vertebral levels, depending on the size of vertebrae.Once all screws were in place, their positions were not evaluated with a second intra-operative 3d scan with the imaging system in order to reduce the extra radiation exposure for the patient as well as for the staff.Pedicle screw violations were categorized into four grades: grade 0, screws were completely within the pedicle; grade 1, penetration less than 2 mm; grade 2, penetration between 2 and 4 mm; and grade 3, penetration over 4 mm.Additionally, grade 0 and 1 perforations were considered satisfactory, while grade 2 and 3 were regarded as perforation).The overall post-operative accuracy of pedicle screw placement (grade 0, 1) was 90.2% (1,033/1,145 pedicle screws).Overall malpositioning rate was 7.7% (88/1,145 pedicle screws) in grade 2 and 2.1% (24/1,145 pedicle screws) in grade 3.The frequency of lateral perforation (54.5%, 61/112) was significantly higher than those of medial perforation (34.8%, 39/112) and anterior perforation (10.7%, 12/112) (p < 0.05).Moreover, a greater incidence of pedicle screw malpositioning was found in patients with cs (12.2%, 48/394) and nf-1 (11.6%, 24/207) than in patients with ais (6.6%, 27/ 411) and ds (9.8%, 13/133) (p < 0.05), in middle-thoracic spine (13.2%, 43/325) than those in other spine levels (upper-thoracic: 6.5%, 11/168; lower-thoracic: 11.6%, 41/353; lumbar spine: 5.7%, 17/299) (p < 0.01), in concave pedicles (11.5%, 71/620) than convex pedicles (7.8%, 41/525) (p < 0.05).Importantly, the malpositioning rate increased as the distance of the tracker away from the instrumented level increased.The malposition rate was 20.6% (53/207) when the gap difference was over three levels, which was significantly higher than 9.6% (33/345) when the gap difference was two levels and 4.8% (26/543) when the gap difference was one level (p <0.01).Prior studies reported that the malpositioning rate of pedicle screw ranged from 20 to 41% by free-hand technique.Peri-operative complications were seen in 11 patients (7.6%): a transient disappearance of somatosensory evoked potential (sep) and motor evoked potential (mep) was observed in one ais patient intra-operatively.Impermanent neurological deficit was observed in one ds patient (recovered within 24 hours post-operatively).Slight residual trunk shift (ts) occurred in six patients.Accidental pleural effusion without any relation to pedicle screw placement occurred in four cases.There were no other neurovascular complications potentially related to screw placement.The article concludes, that the study has shown that 90.2% of pedicle screws could be placed accurately and safely in severe scoliosis surgeries while using the intra-operative navigation system.However, patients with cs and nf-1 were at high risk of pedicle screw misplacement, most of which were located at middle thoracic spine and concave pedicles.Moreover, it is suggested to place the tracker as close as possible to the instrumented level.No additional information provided.

Manufacturer Narrative

Additional information: serial number, and device manufacture date provided.Correction: product, unique device identification (udi), procode and 510(k) updated to proper values.

Manufacturer Narrative

The article was reviewed by medtronic personnel.A review of the article found no indication that the navigation and/or imaging system failed to meet the specifications.The article reported the ¿malpositioning rate increased as the distance of the tracker away from the instrumented level increased¿.This observation is included in the instructions for use as a warning.Per 9732461, (rev 13) pg 30: ¿warning: navigational accuracy can degrade on vertebral levels that are not rigidly connected to the reference frame.¿ further review found the article discussed ¿improper fixation of the tracker¿ and "tracker loosening", the instruction for use also contains the following: "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.".

• 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: 6695775
• MDR Text Key: 79349606
• Report Number: 1723170-2017-02798
• Device Sequence Number: 1
• Product Code: HAW
• 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,foreig
• Reporter Occupation: Medical Equipment Company Technician/Representative
• Type of Report: Initial,Followup,Followup
• Report Date: 12/05/2017

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: 9733858
• Is the Reporter a Health Professional?: No
• Initial Date Manufacturer Received: 06/09/2017
• Initial Date FDA Received: 07/07/2017
• Supplement Dates Manufacturer Received: 07/07/2017; 11/09/2017
• Supplement Dates FDA Received: 08/04/2017; 12/05/2017
• Was Device Evaluated by Manufacturer?: Device Not Returned to Manufacturer
• Date Device Manufactured: 02/06/2013
• 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: 18 YR