Prior to release, all arx modular tulip heads had been approved through life spine's quality control department and found to meet specifications.Based on the returned implants and the description of the reported event, it is hypothesized that the taper lock within the tulip head was not fully seated as rod reduction activites were performed.Which prevented the screwassembly from properly locking up.The taper lock experienced interference conditions that did not allow this seating condition to occur and the tulip head assembly dissociated from the bone screw with the same mechanical function as it was able to be intially assembled.The tulips not attached then put irregular forces on parts of the construct, leading to the condtion seen in the 2-week follow-up x-rays.Using a tulip priming device and/or investigating the potential interference conditions could help prevent this issue and a potential solution for future cases that require excessive reduction forces as it prepares the tulip head and taper lock into a proper position for lock down.
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