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During in-house engineering evaluation, it was determined that the robotic-assisted solution satellite station device had inaccurate cuts- greater than 3mm or unknown.It was initially reported that during a knee surgery, the tibia was cut, the tensor was used, and femur cuts were planned.The team executed distal, anterior, posterior, and posterior chamfer cuts.Before the anterior chamfer cut, the saw plane did not look accurate.When the checkpoint was checked, it was off by more than 3mm.The device was operated in conjunction with the robotic-assisted solution base station device.There was patient involvement.There were no injuries, no medical intervention, and no prolonged hospitalization.Patient treatments were not delayed or cancelled.All available information has been disclosed.
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This report is being submitted pursuant to the provisions of 21 cfr, part 803.This report may be based on information which has not been investigated or verified prior to the required reporting date.This report does not reflect a conclusion by depuy synthes, or its employees that the report constitutes an admission that the product, depuy synthes, or its employees caused or contributed to the potential event described in this report.If information is obtained that was not available for the initial report, a follow-up report will be filed as appropriate.H11: additional narrative:
investigation summary
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> log files were reviewed for investigation.The investigation could confirm the reported issue of "the saw plane did not look accurate and when checkpoint was checked it was off more than 3mm."
the investigation found that the most probable root cause of the reported issue is due to femur array movement during the anterior chamfer cut.Additional other contributing factors include bone or saw array not visible during resection, leg/robot movement during operation, and sub-optimal bone checkpoint.The investigation found that array movement cannot be assessed as the user placed the checkpoint on the array itself.The investigation found that femur fiducial landmark acquisition are done sub-optimally.The check point was created on the pin/array and not on the bone.Since the checkpoint was placed on the pin/arrays, they lose their purpose and it would be difficult to confirm if there was femur array movement as any array movement happens, the checkpoint also moves.It is recommended that the user follow the guidance on instructions for use (ifu); intraoperative use: bone checkpoints creation.- position each checkpoint at a site where the bone will not be resected, e.G., below the anticipated tibial resection plane.- create each checkpoint cautiously with the appropriate instrument and into the cortical bone.- the checkpoints must be easily identifiable later during the procedure.Marking the checkpoints with a surgical pen will facilitate finding their location.The investigation found that there was potential array movement during anterior chamfer cut step.The verify checkpoint was done before femur cut steps and was within system threshold limits but was done on the array so detecting array movement would be impossible.The system relies on the precise position of bone and saw arrays to track the anatomy and saw blade location.If an array moves, the system¿s reference to the bone or saw is lost or altered, leading to inaccurate guidance.Array movement can cause the system to misinterpret the actual position of the bone or saw.This may result in the saw blade being unable to reach the correct cutting plane or performing cuts in the wrong location.While the exact cause of the array movement cannot be established, array movement is generally caused by the arrays not being securely attached.Please ensure the array is properly secured during the procedure to avoid array movement.If the verify checkpoint step cannot be completed, please do not continue the operation.Adjustments are not permitted after the first bone resection: if bone array movement occurs the reference frame becomes inaccurate.The robotic-assisted procedure must be aborted, and the procedure must be completed using conventional manual instruments: ¿system troubleshooting¿.Use ¿verify checkpoint via toolbox¿ to confirm that the bone arrays have not moved.The investigation found that the potential cause for reported issue is that both saw array and bone array are not consistently visible to the camera and eventually the system cannot detect array position accurately.This is confirmed by multiple messages of "saw tracker visibility lost " displayed during multiple femoral cut steps.This indicates that both saw array and bone array are not consistently visible to the camera and eventually the system cannot detect array position accurately.Loss of visibility or improper positioning of the device array or saw arrays can disrupt the guided path of the saw, which would eventually result in saw not moving in the resection plane as expected.This would have been caused by the user by not positioning the camera, saw handpiece, and the target bone array during the cuts in such a way that the camera's line of sight to each array is clear.The arrays are frequently blocked throughout the cut steps.It is the intended behavior of the system to cut power to the saw if the bone array becomes blocked.The investigation found that there are multiple instances of blocked array messages popped up during multiple registration steps as well as femur and tibial cut steps.During robotic-assisted device movement to the resection plane, the device array must be visible to the camera.Once the robotic-assisted device is positioned and the saw is released from the robotic-assisted device, visibility of the device array is needed only once at the beginning and then no longer required.This provides space for assistant positioning and retraction.Conversely, in step 2 it is essential to maintain direct line of the sight between the saw array and the camera.The investigation also found that the following messages were observed multiple times during the workflow, including:
¿ "[saw disabled]" saw blade plane deviates too much from the cutting plane
¿ "[saw disabled]" saw blade ¿tip¿ point is too far from cut reference point
the investigation found significant robot movement during operation.The flags in the log file show that the robot is constantly trying to move to adjust and alternating between cut allowed and not allowed, meaning power to the saw handpiece would be cut.The most probable cause of the reported issue is use error related to saw handling and the saw not being in the target plane.This could be due to a number of factors such as excessive movement of the robot (as a result of cart mounted use) or due to the user's applied force conflicting with the saw position ("fighting the robot") in it's efforts to maintain the saw in the target cut plane.The investigation found in some instances the arrays are blocked prior to the cut, likely leading to some of the issues with the target plane not being reached or power being cut to the saw.During operation the robot moves rapidly.Robot movement is generally caused by the system not being properly mounted to the bedrail.The patient¿s leg must be stabilized during resections.The surgeon¿s preferred leg holder may be used to stabilize the leg if it does not inhibit the function of the velys¿ robotic-assisted solution.Prior to each resection, ensure the leg is stabilized in the desired position.The instructions for use (ifu) outlines: any large leg/robot movement will require a rapid adjustment by the robotic-assisted device and can potentially introduce inaccuracy.There are no defects found with the system or software.The software was performing as intended.The user indicated that there was no negative impact to the patient outcome and no patient harm and the investigation indicates that the system was behaving properly.Root cause:
the investigation found that the most probable root cause of the reported issue is due to femur array movement during the anterior chamfer cut.Additional other contributing factors include bone or saw array not visible during resection, leg/robot movement during operation, and sub-optimal bone checkpoint.The most probable root cause for those factors could be linked to improper handling by the user.Additional complaint information monitoring for potential safety signals is conducted through complaint trending as part of post market surveillance.
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