The LunarGlide 9 is nominally a support shoe like the Structure 21, but is less focused on stability than on all-round versatility. It’s a half ounce lighter and notably more flexible, while its Lunarlon sole provides a smooth and cushioned ride. The LunarGlide 9 is the top-rated Nike shoe among runners experiencing knee pain, so maybe give it a try before a dual amputation starts to seem like the best option for solving your knee problems.