Treatment for Damage to the Knee Cartilage: Repair or Reconstruct?What's the best way to treat damage in the knee joint articular cartilage? In this report, surgeons from the Netherlands summarize the current evidence for repair versus restorative procedures. The articular cartilage is a smooth, fibrous covering over the two bones that form a joint. If you were to look at this structure on a chicken leg, it is the equivalent of the gristle at the end of the drumstick.
The purpose of the articular cartilage is to protect the bone while making it possible for the knee joint to slide and glide as it bends and straightens. Damage to this part of the joint can create cracks and even holes called defects that must be treated to prevent erosion of the underlying bone. Without treatment, the eventual outcome is painful knee osteoarthritis.
Don't confuse the articular cartilage with the meniscus. Torn meniscus is a common injury among sports athletes. The meniscus is a C-shaped disc of dense cartilage that also protects the joint, helps create smooth movement, and transmits load placed on the joint. The focus of this report remains just on the articular cartilage, which lies underneath the meniscus (between the meniscus and the bone itself).
There has been some suggestion that surgeons treat articular defects based on their training, not based on the evidence. That's why a systematic review of this type is important -- it helps surgeons see what works best and when to use a variety of techniques. With this information, they can seek additional training and provide best practice (evidence-based) procedures to all their patients.
To perform a systematic review, it is necessary to search for all studies published on a single topic. Each study must be carefully reviewed for research methods and quality. Small studies with only a few patients or case studies featuring only one patient are not included. Finding studies that measure the same things in order to compare the results is always a challenge in a systematic review. Finding studies that follow patients for the same (or similar) lengths of time is also important.
As part of this systematic review process, articles had to be in English, French, German, or Dutch (languages the researchers could read or translate) and compare at least two of the three techniques listed. Studies were limited to those that included patients with articular cartilage lesions that had not yet progressed to damage to the bone and defects that did not include damage to the meniscus.
In this case, the authors were able to find 865 articles on the treatment of articular cartilage lesions. But only four were randomized controlled trials (RCTs) that would qualify as sufficient evidence on this condition. Randomized means the patients were assigned to their treatment group based on computer selection, not based on any particular characteristic such as age, activity level, or type of damage. Three treatment techniques were included: osteochondral autologous transplantation (OAT), microfracture (MF), and autologous chondrocyte implantation (ACI).
Microfracture is a way to repair the defect. The surgeon drills tiny holes through the articular cartilage into the bone. This causes bleeding and the formation of tiny blood clots to fill the defect. The body then sets up a healing response that releases growth factors and causes new chondrocytes (cartilage cells) to form. Transplantation and implantation are restorative techniques. The surgeon uses a plug of cartilage and bone taken from a healthy area of the patient's own knee for the transplantation procedure or the patient's own normal, healthy cartilage for implantation procedures to fill in the hole.
After analyzing all the data and comparing results, the authors made the following observations:
The authors concluded that patient factors such as age, activity level, and size of the defect are important to consider when choosing the best treatment approach. The surgeon should also review patient size (body mass index), the location of the defect, and the actual size of the defect once the area around it was debrided (cleaned up in preparation for the procedure).
For future studies, there is a need to evaluate the durability of each procedure. How long do the results last? Do some techniques hold up better than others? If so, why? What patient factors or types and sizes of defects affect the final outcomes? Although this systematic review focused on treatment based on defect size, in general, there is still a need for solid evidence to support one treatment technique over another for all patient characteristics.
Joris E. Bekkers, MD, et al. Treatment Selection in Articular Cartilage Lesions of the Knee. A Systematic Review. In The American Journal of Sports Medicine. November 2009. Vol. 37. Suppl. 1. Pp. 148S-155S.
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