Towards Deployable Implants: Conceptual Designs of a Novel Deployable Interposition Wrist Implant Using Origami, Scissor, And Sliding Block Mechanisms

Objective. Minimally invasive joint replacement offers benefits like little tissue damage, reduced pain, and fast recovery. Traditionally, the surgery has been adapted to the (size of the) implant limiting the true surgical potential. The aim of this study was to explore and conceptualize deployable implant spacer for minimally invasive surgery. Methodology. Different deployment mechanisms have been researched and evaluated according to the suitability for joint implants. Origami, scissor, and sliding block were identified as most promising and integrated into a quadri-elliptical-shaped wrist implant spacer. The final designs were prototyped out of PLA using 3D printing and underwent compression testing of up to 1000 N in the lab. Results. The deployment ratios were 140% for the origami, 150% for the scissor, and 160% for the sliding block. In the compression test, the origami prototype failed at 925 N, whereas scissor and sliding block survived the maximum load. Conclusion. To the best of our knowledge, we explored for the first time a deployable implant spacer. Offering the highest deployment ratio and non-discrete height adaptation, the sliding block appeared to be most promising for in depth future research.