Spongialization is a new way to resurface joints damaged by osteoarthritis. The worn and pitted cartilage is removed. A thin layer of cortical or hard bone just under the cartilage is also removed completely.
This exposes the next layer of bone called cancellous bone. Cancellous bone is soft and spongy. This layer can also be referred to as "spongiosa." So the outer, bony part of the patella (kneecap) is cortical or hard. The inside is cancellous or soft.
New fibrous tissue can grow from the bony surface once it is opened up. The spongiosa turns into a type of tissue called granulation tissue. The blood supply is very rich to this tissue thereby enhancing healing.
In a spongialization procedure, the cortical bone right under the worn out cartilage is removed, leaving the spongy bone exposed. So far studies show that spongialization works faster and better than removing the patella in patients with severe osteoarthritis. Long-term studies are still needed.