I’ll be honest: I have never worried much about breakage of the cephalomedullary nails I implant for proximal femur fractures. Instead, I’m focused on the fracture reduction, soft-tissue handling, and proper implant positioning. These nails are very strong. Sure, failures of these implants may occur and have been reported. But I have never had a lengthy discussion with a patient about the potential risk of the implant breaking during normal activity—and I doubt many other surgeons have either.
That is why the article by Lambers et al. in the May 1, 2019 issue of The Journal grabbed my attention. The authors carefully analyzed 16 cases in which a specific cephalomedullary nail (the TFNA, made from a titanium-molybdenum alloy) broke in 13 patients after an average of 5 months. Of note, 3 patients who underwent a revision with the same type of nail had a repeat fracture of the implant. The majority of these patients had been treated for a reverse oblique intertrochanteric fracture —a type that we all commonly see and treat—and all the fractures had been well reduced at the time of nail insertion.
The implant fractures all occurred at the proximal aperture of the nail and were consistent with fatigue fracture of the alloy. But they all showed a unique “stepped propagation” pattern, whereby, according to the authors, “a planar crack arrested, changed planes by 90°, progressed, arrested, and then changed planes again by 90° until final failure.”
These types of implant failures are not common for this nail, but they apparently happen more often than I thought. I am certain that the manufacturer will be responding to this data, and I look forward to future design changes—especially because the authors hypothesize that prior changes to this nail’s design and/or alloy may have contributed to these breakages. Then again, there may have been errors in technique that made these types of failures more common, or maybe a different implant would have been a better choice for some of these patients. To me, matching fracture type and implant choice is very important.
I look forward to learning more about this issue and will keep these types of implant failures in the back of my mind during hip-fracture cases. In the meantime, Lambers et al. advise “vigilant clinical and radiographic surveillance of patients with unstable hip fracture patterns who undergo osteosynthesis with use of a TFNA implant.”
Chad A. Krueger, MD
JBJS Deputy Editor for Social Media