A Cheap Lesson About Expensive Arthroplasty Devices
Skip the new bicruciate-stabilized TKA, and use the example it offers to think differently about new devices
What’s the Claim?
A well-designed randomized trial found no benefits in terms of validated patient-reported outcomes or objective functional testing between a bicruciate-stabilized TKA design over a conventional posterior-cruciate substituting (posterior-stabilized) design by the same manufacturer six months after surgery.
How’s It Stack Up?
There is little to suggest that newer knee implants outlast older ones, and much to suggest that the opposite is true as often as not, or at least that the new ones are no better. Despite that, every year brings us new devices that are rationalized with something like this: “Because approximately one in five patients are dissatisfied with their knee replacements, it’s important to continue to refine the design and kinematics of the knee.” In fact, an earlier generation of the bicruciate design studied here was rationalized along just those lines, but it was associated with complications and was replaced with the newer implant. (Note that the current device is called the “Journey II” knee; names like that don’t arise if the “Journey I” was a world-beater). But here, as well, there was no apparent benefit to the new device, no particular reason to think it will improve with time, and some reasonable concerns that it won’t — at least one other “modern” bicruciate TKA design is coming up short. Inconsistent performance of new arthroplasty implants is the rule, not the exception. A wonderful large registry–based study found that 5 of 11 TKA implants that underwent design modifications delivered survivorship that was no better than or actually inferior to the earlier version of the same device.
