Andrew Lynn wants to phase out metal joint replacements by coaxing the human body to rebuild damaged bone and cartilage. Lynn, CEO and cofounder of Ortho­mimetics, in Cambridge, England, developed a biodegradable scaffold that a surgeon can implant into any joint weakened by injury or age.

Microscopic pores draw blood cells and stem cells into the plug-shaped scaffold, which is made of collagen and glycosaminoglycans, the materials in human cartilage. The part of the plug that extends into the bone also contains calcium phosphate, which is found in bone. The stem cells take cues from those materials to grow into bone or cartilage where appropriate, repairing the damage as the plug slowly dissolves. The scaffold is already approved for use in Europe, and Orthomimetics is performing more trials to gain approval from the U.S. Food and Drug Administration, which it anticipates in about two years. Scaffolding designed to regrow tendons and ligaments is also a couple of years away. --Neil Savage

1. Andrew Lynn's biodegradable scaffold mimics the composition of both bone (bottom half) and cartilage (top half) to help heal damaged joints.

2. A surgeon drills a small hole in the surface of a bone like the knee joint.

3. A cylindrical plug of the scaffold is inserted into the hole.

4. Blood containing stem cells derived from bone marrow impregnates the scaffold. The plug's structure and composition guide the cells to become either bone or cartilage.

5. As the scaffold degrades, newly formed bone and cartilage cells replace it, repairing the joint.

Credit: Bryan Christie Design