Olympic swimmer Dara Torres, who has won 12 medals
in five Olympic games, including 3 silver medals at the 2008 Olympic
Games in Beijing, has recently undergone a cutting edge procedure on her knee to repair severe arthritis.
The 43-year-old was the oldest swimmer on the U.S. Olympic swim team, but has won at least one medal in each of the five Olympics in which she has competed, making her one of only a handful of Olympians to earn medals in five different Games.
Torres is currently featured in the campaign by Brigham and Women’s Hospital in Boston where she had the surgery performed. She explained that after the Beijing games, she had to undergo surgery on her shoulder. During her rehabilitation, she focused her training on core and lower body strength. As a result, the mild arthritis she had in her knees worsened dramatically.
According to Torres:
“When I realized how bad my knee injury was, the biggest thing I was scared about was that I wouldn’t be able to take care of my daughter and to possibly continue to swim. I didn’t know if I would have to have a total knee replacement at my age, which was only 43, and I didn’t know if I would be able to walk again or run after my daughter … I was basically limping.”
Torres underwent the procedure, called autologous chondrocyte implantation in the fall of 2009. She is pleased with the results: “I notice big differences. I’m not limping anymore and I have a lot more flexibility. I have had about three MRIs since then and they’ve shown the progression of cartilage cells growing on my kneecap, you could see a nice thick layer of cartilage growing.”
Hyaline cartilage plays an important role in the functioning of the knee joint. Unfortunately, chondral injury that does not involve the underlying subchondral bone doesn't heal spontaneously. Three types of procedures have been designed to address this problem -- microfracture, autologous chondrocyte implantation(ACI) and osteochondral autograft (OCG).
In a microfracture procedure, multiple small holes are cut into the bone under the cartilage defect. This allows the deeper, more vascular bone to access the surface layer and stimulate cartilage growth. However the cartilage that is formed is fibrocartilage, the kind that is found in scar tissue. Fibrocartilage does not have the same strength and resiliency as hyaline cartilage, so questions about durability have been raised with this procedure. Microfracture does seem to work best for small areas of cartilage replacement (<2 cm).
Osteochondral aurograft involves the harvesting of multiple individual osteochondral cores from the donor site, typically from a peripheral non-weight-bearing area of the femoral condyle. The grafts are pressed into the lesion in a mosaic-like fashion within the same-size drilled recipient tunnels. The surface consists of transplanted hyaline cartilage and fibrocartilage. The fibrocartilage is thought to act as a grout between the individual autografts. OCG can be performed as an open procedure or arthroscopically.
In autologous chondrocyte implantation, a small piece of hyaline cartilage is removed from another,
less weight bearing section of the joint, and approximately 10,000 cartilage cells are
isolated from the piece. These chondrocytes are then grown in vitro where they multiply until there are about 50-60 million
cells. A second, often open, procedure is then performed where the cartilage cells
are injected into a special matrix material that has been placed where
the cartilage was worn away. The cells continue to grow into the bone
and form a new cartilage covering. A slower clinical response has been observed after autologous chondrocyte implantation as compared with osteochondral autograft, however OCG has been limited by a higher incidence of donor-site morbidity.
With all three procedures, patient progress of cartilage growth and durability are followed using MRI imaging.
A September 2010 review article by Harris et.al in , entitled "Autologous Chondrocyte Implantation: A Systematic Review" looked at these different procedures to see if the current literature supported the choice of using ACI over the other cartilage repair/regeneration procedures. They conducted a systematic review of 13 studies that included over 900 patients who had undergone one of the procedures. All the techniques demonstrated improvement in the patients when compared to the preoperative state.
They concluded that their analysis demonstrated "a trend toward autologous chondrocyte implantation having improved outcomes as compared with microfracture but do not allow us to conclude that there is any difference between autologous chondrocyte implantation and osteochondral autograft transplant. ... Additional long-term follow-up with high-level evidence will be required to determine the degree of difference between autologous chondrocyte implantation and microfracture."
The study had also looked into whether certain patient-specific and defect-specific factors influenced outcomes after ACI. Not surprisingly, the authors suggest that ACI may be the"best option for large defects in young, active people a short duration of symptoms and no previous cartilage surgery."