A study from the University of Kentucky Equine Center presents some disturbing data on the effectiveness of microfracture.

When a horse gets an injury to articular cartilage (the cartilage that caps the ends of long bones) in one of its joints, the horse's owner hopes that there is sufficient healing so that normal joint function is restored. Unfortunately, even if the horse recovers, there's a high probability that osteoarthritis will cause chronic pain and inhibit normal joint function.

Jamie MacLeod, VMD, PhD, and Michael Mienaltowski, DVM, PhD, researchers at the Gluck Equine Research Center, studied the repair tissue that forms within full-thickness damage to articular cartilage (that is, damage that penetrates all layers of the cartilage).

They compared repair tissue from full-thickness lesions, on which surgeons performed arthroscopic debridement and microfracture treatment (a procedure performed where small holes are drilled into the underlying bone so that blood and marrow cells leak into the joint), to normal articular cartilage of the distal femur (upper leg bone) in horse stifles four months after surgery. When they evaluated the tissue microscopically, they saw the new repair tissue within the injury was clearly different from the surrounding normal cartilage.

The research team used a new scientific technique called microarray-based transcriptional profiling to compare gene expression of the new repair tissue and the normal cartilage. The technique allowed them to evaluate the expression of thousands of genes instantaneously. By doing this, they were able to conclude that the tissues have substantial functional differences.

The cells within the repair tissue do not achieve a normal pattern of gene expression necessary to restore and maintain healthy articular cartilage structure and function. Future research will focus on how to direct the cells in repair tissue to function more like cells in articular cartilage. New treatment options could allow for better, more normal cartilage-like healing, which restores the biomechanical integrity of the joint surface.

On a brighter note, researchers at the Kula Lumpur Sports Medicine Centre and the University Putra Malaysia followed ten patients with full thickness cartilage defects treated with arthroscopic drilling. All patients received the standard post-procedural care but four patients also underwent treatment with harvested peripheral blood stem cells mixed with hyaluoronic acid injected into the knee. Each of the patients received five weekly injections. Sequential MRI scans showed healing of bone and evidence of cartilage healing. Second-look arthroscopy with biopsy on the four patients confirmed new cartilage growth as well as the incorporation of the new cartilage with the surrounding older cartilage.

A more recent development is that the University of Pittsburgh cartilage group will be evaluating the relative efficacy of microfracture vs stem cells alone in the treatment of osteoarthritis in an animal model.

Authors note: personally, I think microfracture surgery is barbaric. The recuperation can take up to a year with non-weightbearing to boot. My opinion is that autologous stem cell procedures are far superior in their effect and also are much better tolerated as far as recovery time. Granted, the data so far is mostly anecdotal as far as autologous stem cell procedures are concerned; however, there is increasing evidence that this approach has significant promise.