Preventing Knee Arthritis After Cartilage Injury with Platelet-Rich Plasma

Regenerative medicine is a relatively new term you may start hearing more about. It refers to finding ways to help the body heal itself at the cellular level. For example, tissue from an uninjured part of the knee cartilage can be used to grow more chondrocytes (cartilage cells). Platelet-rich plasma (PRP) is another form of regenerative medicine and the topic of this new study from the OASI Bioresearch Foundation in Milan, Italy.

Platelet-rich plasma (PRP) (also known as blood injection therapy) is a medical treatment being used for a wide range of musculoskeletal problems. PRP refers to a sample of serum (blood) plasma that has as much as four times more than the normal amount of platelets. This treatment enhances the body’s natural ability to heal itself and is used to improve healing and shorten recovery time from acute and chronic soft tissue injuries.

Using platelet-rich plasma to encourage tissue regeneration in the hyaline cartilage of the knee may be a new way to prevent or slow down the degenerative process that leads to osteoarthritis. Hyaline tissue is the type of cartilage that lines the inside of the knee joint.

The hyaline cartilage has many wonderful characteristics. It allows the knee joint to move without friction. It protects the bone underneath the cartilage from too much load and trauma. Hyaline cartilage also spreads out the forces placed on the knee joint during movement. But the one thing it does not have is a rich supply of blood. Injury or damage to the hyaline cartilage sets off a series of events that can lead to degeneration and osteoarthritis.

Who gets these kinds of knee injuries? And who can benefit from platelet-rich plasma injections to treat the problem? Many people of all ages who are physically active and especially participating in sports suffer from chondral injuries. And increasing age combined with chondral defects or injuries is a recipe for painful knee symptoms linked to osteoarthritis.

That's where platelet-rich plasma comes in. It has been used for years after plastic surgery and surgery on the mouth, jaw, and neck. It seems to promote and speed up healing. Anywhere from two to six times the number of platelets with their growth factors are released into the injured area.

Blood injection therapy of this type has been used for knee osteoarthritis, degenerative cartilage, spinal fusion, bone fractures that don’t heal, and poor wound healing. This treatment technique is fairly new in the sports medicine treatment of musculoskeletal problems, but gaining popularity quickly.

In this study, two groups of patients with osteoarthritis of the knee were given two injections of platelet-rich plasma (PRP). Conservative (nonoperative care) with anti-inflammatory medications had been tried for at least three months with no improvement in symptoms.

One group (25 patients) had previous surgery for the damaged knee cartilage (either a shaving procedure called debridement or a procedure called microfracture). Microfracture is the use of tiny holes drilled through the cartilage and bone to stimulate bleeding and healing. The other group (25 patients) did not have any knee surgery prior to the blood injection therapy.

Results for the two groups were compared by looking at pain, function, and quality of life. A variety of tests were used to collect information to measure these outcomes. All measures were taken before platelet-rich plasma injection (baseline), six months after the injections, and again one-year after injection therapy. Results were also compared between men and women to see if there was a sex-linked difference in treatment results.

They found no difference in results between the two groups or between the sexes. It seems everyone in the study benefitted and improved with this treatment approach. There was a positive effect of PRP in active patients with painful knee osteoarthritis. There were no differences between men and women and no adverse reactions or complications for anyone.

The post-operative program included the use of local ice held on the knee for 20 minutes every two to three hours for a 24-hour period. Patients were advised to tone down their level of activity and avoid vigorous use of the knee for at least 48 hours. They were allowed to put weight on the injected knee as tolerated (usually determined by pain levels).

In summary, using platelet-rich plasma (PRP) to stimulate the natural healing process and regenerate hyaline cartilage may be an acceptable way to treat damaged hyaline joint cartilage. This study provides some evidence that PRP can be used in active adults with cartilage lesions to prevent progression of osteoarthritis -- even for patients who have already had cartilage surgery (cartilage shaving or microfracture).

The authors point out that they used two PRP injections but there may be a more optimal number of injections required. Further research is needed to develop specific standardized treatment protocols. Likewise, studies are needed to find ways to predict how much PRP is needed for each type of tissue damage. Long-term studies (following patients for more than 12 months) are recommended.

Reference: Alberto Gobbi, MD, et al. Platelet-Rich Plasma Treatment in Symptomatic Patients with Knee Osteoarthritis: Preliminary Results in a Group of Active Patients. In Sports Health. March/April 2012. Vol. 4. No. 2. Pp. 162-172.

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