[From April Issue 2014]

Nakashima Medical Co., Ltd.
Our body has numerous joints: elbows, knees, shoulders, hips… If these parts become unusable because of disease or accident, it becomes difficult to easily bend and stretch the body. With this in mind, efforts are underway to recover damaged motor functions through using artificial joints made of metal or plastic.
The world’s first artificial joint was made in 1951. About 90 percent of the artificial joints currently used for medical treatment in Japan are produced abroad. But Japanese people have smaller bodies than Westerners, and they regularly sit seiza style (kneeling with legs folded beneath the body). As a result, foreign-made artificial joints are not necessarily user-friendly for Japanese. This has led to the development of such products in Japan.
One domestic manufacturer of artificial joints is Nakashima Medical Co., Ltd. (President NAKASHIMA Yoshio) in Okayama Prefecture. This young company was founded in 2008, but was formerly the medical operations department of a firm named Nakashima Propeller, a company that had been carrying out research for new products since 1987. Nakashima Propeller is a global corporation that manufactures propellers for motorboats, supertankers and various types of ships.
Propellers and artificial joints are manufactured using similar methods. Both processes begin with “casting” (pouring molten metal into casts and leaving it to solidify), then continue with “machine processing” (filing down the material) and finish off with “polishing” (rubbing it until it shines like a mirror). Developed through the production of propellers, Nakashima Medical’s products are characterized by intricate three-dimensional manipulation techniques and skilled engineers’ attention to detail.
Depending on the part of the body they are manufactured for, artificial joints consist of two to four components. As joints vary from patient to patient, the optimum combination of components can be chosen in a wide range of sizes. Production processes, from machine processing to polishing, in addition to final checks of the finished products, are all done in-house. Since these products are put inside the human body, their exteriors and measurements are rigorously inspected before being thoroughly washed and sterilized.
Nakajima says: “We are focusing on developing artificial joints suited to the bone structure of Japanese people and to their lifestyles. That’s why we always strive to make products that even our employees and their families would feel safe using.” In cooperation with hospitals throughout Asia, the company has collected about 750 data relating to bone size. They are now striving to manufacture joints with an optimum size to suit each race.
It is said that there are 400 million elderly people aged 65 or older in the world who are in need of medical devices. This number is expected to rise to 700 million by 2023. In turn, the number of people requiring artificial joints will increase. “Artificial joints will enable people in wheelchairs to walk, and this is something that really motivates us,” says Nakashima, emphasizing the importance of his company’s products.
Nakashima Medical Co., Ltd.
Text: ITO Koichi[2014年4月号掲載記事]


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