Both of these methods of joint regeneration are under close study. There's not enough evidence to support one over the other yet. The lack of consistency in results among studies may be a matter of patient selection, specific surgical technique used, or some other factor. Further study is needed to sort out all the variables that can affect success or failure.
New biologic methods are being tested to find better ways to stabilize and grow chondrocytes (cartilage cells). If these are successful, chondrocyte implantation may become the preferred treatment for cartilage defects. Microfracture is more likely to create fibrous (tough) scar tisue. Over time, this tissue breaks down and painful symptoms return.
What the joint really needs is the formation of hyaline or hyaline-like cartilage. Hyaline cartilage is durable and holds up under repeated compressive loads placed on the joint.
Recovery may be slower after the chondrocyte implantation when open surgery is used. But the differences in clinical outcome disappear six months after surgery. If the regenerated chondrocytes hold up better over time, the slower pace of physical recovery may be worth the wait.