Guided Growth Implant Failure is a Result of Cyclic Fatigue: Explant Analysis With Scanning Electron Microscopy

Background: Guided growth is often used to correct limb deformity and yet implant screw failure in modular systems has been reported. There have been no reports of plate failure and we do not know the exact mode of failure when screws do break. Methods: We report the first published case of a fractured plate in a modular plate and screw construct that was used to correct Blount disease in a child through guided growth. The implants were removed and analyzed for method of failure using scanning electron microscopy. Results: Scanning electron microscopy of the explant confirms that the mode of failure was not a result of static tension from growth. Rather, analysis confirms cyclic fatigue that led to crack propagation across the anterior side of the plate until overload caused complete plate failure. Conclusions: This analysis confirms an in vivo cyclic compression-relaxation of the growth plate presumably to weightbearing, and that when excessive may lead to implant failure as seen here in this case. Level of Evidence: Level V.