Pressure, shear stress, and friction from compression/release stabilized prosthetic sockets can contribute to soft tissue damage on the users’ residual limbs. With that in mind, a team of researchers studied density-graded lattice structures for their potential in mitigating the risk of tissue damage. They also assessed the ability to produce more gradual transitions between high-compression and low-compression areas.
The researchers tested the effects of changes among three variables: lattice geometry, density alteration, and displacement magnitude. A total of 144 experimental conditions were examined.
They used 3D printing for lattice samples representing areas of compression and release based on a novel cushioned transhumeral-level socket design and performed compression testing on two types of lattice structures that incorporated one of eight design elements to alter density and axial stiffness. The effect on stiffness of the sample as a function of lattice type and density alteration was recorded under three loading conditions.
Only one set of samples met the criteria for compression areas of the socket, and no samples satisfied criteria for release areas. The research team was able to produce transitional density lattices that gradually tapered between the best performing compression and release values. Their future work will focus on lattice optimization to improve release behavior within a modified compression/release stabilized socket.
The open-access study, “Assessing 3D printable density-graded lattice structures to minimize risk of tissue damage from compression-release stabilized sockets,” was published in Prosthetics and Orthotics International.
