Japan’s manufacturing (monozukuri) sector has been supported by highly skilled craftsmen, and has achieved mass production of high-performance, high-quality products while maintaining and improving its global competitiveness. However, as human dexterity has limitations and it might be difficult to operate certain machine parts or cutting tools it also naturally limits product design. In 2007, we became the first company in Japan to introduce an electron-beam metal additive manufacturing (EBM) machine. We began research and development to apply this additive manufacturing (AM) technology, which enables the creation of free shapes of implants without restrictions.

Currently, optimal production conditions (parameters such as beam voltage and scanning speed) are provided as "recipes" for the combination of molding machines and applicable materials, so that moldings can be successfully produced in a relatively short period of time after installation. However, when the system was first introduced in 2007, such recipes were unclear; therefore, we began by searching for parameters to obtain a good additive model and then sought to optimize it. Through this R&D, we have independently established a series of manufacturing processes that can guarantee the efficacy and safety of implants.

Implants must have long-term stability and function in the body. Implants are composed of titanium alloys and other materials that have good biocompatibility; however, because they are artificial, they cannot be bonded directly with biological bone tissue. Therefore, by making the implant surface porous where it is in contact with the bone tissue, the bone tissue can penetrate the porous material. The resultant anchoring effect of the porous material and bone, fixes the bone and prosthesis. Conventionally, a fine wire woven mesh was stacked to form a porous body, which was then adhered to the joint replacement product base material. To address this issue, we pioneered the development of an acetabular cup for hip joint that combines strength and performance through metal additive manufacturing, and acquired approval to manufacture and commercialize medical devices as the "GS Cup."

• GS cup Japanese medical device manufacturing and marketing approval number: 22600BZX00463000

When humans remain at zero gravity in outer space for a long period, bone density and other parameters are significantly reduced. Thus, the properties of bones deteriorate in environments where there are no external forces. This holds true for bone that grows into a metal porous structure with the intention of anchoring the implant to the bone. Since the hard metal bears the main load from external forces, the bone that penetrates the perforated body becomes weak and less mechanically stimulated, resulting in insufficient fixation of the implant to the bone.

Therefore, based on the theory of bone matrix orientation proposed by Prof. Takayoshi Nakano (Biomaterials) of Osaka University Graduate School, we developed a UNIOS PL Spacer. It is a spinal cage with a special microstructure that aims to induce strong bones to meet mechanical requirements by regularly arranging osteoblasts that have invaded the implant in a micron-order groove structure, and promoting preferential orientation of biological apatite. The spinal cage causes the growth of strong bone into a special porous structure. This microstructure has an arranged submicron-order groove, and osteoblasts are arranged in a porous arrangement along the groove. The arranged osteoblasts enhance the orientation of the bone matrix without applying force, and a strong bone in the specified direction is generated in the porous structure.

This microstructure is precisely created by a 3D printer to a depth that cannot be achieved by human hands or cutting tools. Based on animal experiments, Osaka University reported that it enables strong bone growth in the direction of the implant loading.
Additive manufacturing technology has made it possible to develop innovative new products that go beyond the design limits of conventional manufacturing methods.

• UNIOS PL spacer Japanese medical device manufacturing and marketing approval number: 30300BZX00111000

1. T.Ishimoto, Y.Kobayashi, M.Takahata, M.Ito, A.Matsugaki, H.Takahashi, R.Watanabe, T.Inoue, T.Matsuzaka, R.Ozasa, T.Hanawa, K.Yokota, Y.Nakashima, T.Nakano(Corresponding author): Outstanding in vivo mechanical integrity of additively manufactured spinal cages with a novel “honeycomb tree structure” design via guiding bone matrix orientation, The Spine Journal, (2022), 1742-1757. DOI: https://doi.org/10.1016/j.spinee.2022.05.006
2. A.Matsugaki, M.Ito, Y.Kobayashi, T.Matsuzaka, R.Ozasa, T.Ishimoto, H.Takahashi, R.Watanabe, T.Inoue, K.Yokota, Y.Nakashima, T.Kaito, S.Okada, T.Hanawa, Y.Matsuyama, M.Matsumoto, H.Taneichi, T.Nakano(Corresponding author): Innovative design of bone quality-targeted intervertebral spacer: accelerated functional fusion guiding oriented collagen and apatite microstructure without autologous bone graft, in press The spine Journal, (2022). DOI: https://doi.org/10.1016/j.spinee.2022.12.011