The explanted device was returned to illuminoss for review.The following is a summary of the investigation: context: the device in question is an intramedullary balloon catheter (ibc) that is part of the illuminoss photodynamic bone stabilization system (pbss).It is a formed-in-place intramedullary implant used to stabilize bone fractures in much the same way as an intramedullary nail (imn) does.Details of the ibc are as follows: the ibc consists of a balloon attached to a catheter and y-body assembly that allows the user to infuse monomer material into the balloon to fill it once it is in the intramedullary canal and placed across the fracture site.The catheter and y-body also allow access for the light fiber into the balloon which provides the light necessary to harden the monomer into a polymer.The balloon, once hardened, is now able to stabilize the fracture during the healing process.Specific differences between the ibc and imn is that the ibc is a formed in place implant.The nail is not.The ibc, unlike the imn, must have cortical contact along its length.Because of this cortical contact, cross-locking screws are not required, which is also not the same as an imn as an imn requires these screws for stability.For humeral fracture treatments, it is recommended that the diameter of the created implant be a minimum of 13mm in order to provide optimal strength if used on its own.This is stated in the surgical technique guide (p/n 900510), it states that if the 13mm diameter is not achieved it is recommended to supplement the balloon implant with an fda cleared plate and screws.Complaint investigation results: the device's external appearance indicated that the balloon had not been sufficiently filled with monomer prior to the curing process.It was also mentioned via the illuminoss rep present at the procedure, that the surgeon "was not really sure if the implant had reached maximal volume".An insufficiently filled balloon will not allow it to make full contact with the cortical wall which is needed to provide the necessary stability to hold the fractured bone in place in order to heal.Without the full contact of the cortical wall it may be able to move and may lead to eventual fatique failure.Radiographs received showed two screws placed in the distal and proximal ends of the implant which were confirmed upon review of the explant.These were added for rotational stability.When both portions of the device were joined together using the central lumen as a means to align them as they should have been prior to the break, there appears to be a slight reduction in the balloon's diameter which could have been causeed by an anatomic variation in the patient (e.G.Tumor).This reduction in diameter, was considered a potential weak point.It should be noted that the recommended diameter for a humeral implant stated in the surgical technique guide (p/n 900510), be at least 13mm to achieve optimum bending strength.The observed reduction in the diameter of the balloon was less than 13mm.Because of the patient's condition at the time of the implantation, which was metastatic bone disease, a longer healing period would be anticipated.The reported implant break was reported 56 days after implantation.A review of x-rays indicated that there was minimal healing during that timeframe as there was no evidence of callus formation around the fracture site.Without any fracture healing, the implant must take on all of the load as opposed to sharing it with the healing bone.Conclusion: given the information presented above, it is suspected that the combination of the patient's anticipated longer healing time, the underfilled balloon which allowed for movement of the balloon in the canal, and the reduction in diameter at the break site, it appears that the break was the result of fatigue failure.
|