|
The agent reported "(cross threaded screw from 4 hole drill guide, retaining screw for glenosphere would not lock in.)." the event occurred during surgery near the patient.There was no negative outcome attributed to the event, there was no delay in surgery, and the surgery was completed as intended.The agent was present in surgery and inspected the device, believing it to appear acceptable before use.Another suitable device was not available after the surgeon encountered difficulty using the drill guide.Date rma returned: 1/12/20 rma examination: the drill guide has returned for examination.It shows signs of wear consistent with its years of use.While the thumb screw threads do not exhibit any immediately noticeable malformation or damage, the inability to remove the thumb screw from the rest of the drill guide is evidence of some damage to its threads.A review of the device history record has been conducted.There were no nonconforming material reports associated with the production of the drill guide that may have contributed to the reported event.The drill guide met design and manufacturing requirements when released for use.Eight complaints have been filed against other parts from this lot.One prior complaint, cc-(b)(6) has been filed against a drill guide, alleging that its thumb screw was responsible for damaging a baseplate's threads in a way that it couldn't accept a retaining screw.The most likely root cause of this issue is cross-threading between screw interfaces during surgery.A drill guide has a thumb screw that is threaded into a baseplate during surgery to maintain alignment while peripheral screws are being attached to the baseplate.The screw hole in the baseplate that accepts the drill guide's thumb screw is the same screw hole that will later accept a retaining screw after the glenosphere is attached to the baseplate.It's possible that the drill guide's thumb screw, if malaligned during installation or damaged, can cause damage to the threads of the baseplate, leaving the baseplate susceptible to later rejecting a retaining screw or causing a retaining screw to break if installed with enough force.Destructive testing was performed with the returned drill guide, in an attempt to replicate the surgeon's complaint that the drill guide's thumb screw caused damage to the baseplate's threads.The testing was successful at achieving this end goal, but it's still not clear whether the damage to the baseplate's threading was the result of the drill guide's thumb screw or if it was the result of rough handling during the installation of the retaining screw with a hex driver.Either method seems to be capable of damaging a baseplate's threads.While testing didn't prove that any/all cross-threading issues with the rsp system are the result of the thumb screws of drill guides, it did prove that drill guides' thumb screws can be a source of damage to the center screw hole of an rsp baseplate.
|