The most common presentation of osteoarthritis of the knee (OAK) is involvement of the tibiofemoral joint, the space between the femur (upper leg bone) and the tibia (the larger of the two lower leg bones.)
These are the two surface areas that contain the largest amount of hyaline cartilage inside the knee.
As mentioned earlier, hyaline cartilage is the “harder” of the two type of cartilage within the knee. Hyaline cartilage caps the ends of the long bones inside the joint while fibrocartilage, a softer more pliable cartilage is represented by the medial and lateral menisci of the knee. These are semicircular piece of cartilage that give added protection to the hyaline cartilage when it comes to shock absorption, gliding, and rotation.
Symptoms of OAK typically consist of stiffness, swelling, buildup of joint fluid, and tenderness along the joint line. Over time the ability to bend and straighten the knee will be compromised as well. While one compartment, either the medial (inside) or lateral (outside) compartment of the knee may be affected more than the other, often both compartments are affected. This causes diffuse pain.
The diagnosis can be suspected clinically by history and physical examination. It can be confirmed by positive changes seen on standing knee x-rays. Magnetic resonance imaging (MRI) is much more sensitive to changes of OAK which will consist of cartilage defects, bone edema (swelling), and fluid.
The typical treatment regimen is aimed at pain relief and maintenance of function.
If the patient is overweight, weight loss is a must. Regular exercise consisting of low impact aerobic exercise, resistance exercise, and stretching are components of a common-sense program for a patient with OAK.
Addition of non-steroidal-anti-inflammatory drugs taken either orally or given as a topical agent may also be used.
Removal of excessive joint fluid followed by Injections of glucocorticoids (“cortisone”) are helpful for symptomatic relief. Glucocorticoids have a deleterious effect on articular cartilage and should be used sparingly, no more often than three times per year in a given joint.
The patient may also benefit from viscosupplement injections. These are substances consisting of hyaluronic acid which mimics the characteristics of normal joint fluid. These injections can also help provide symptomatic relief.
All injections need to be administered using ultrasound guidance to ensure accuracy.
Surgery is defined as being cartilage sparing or cartilage sacrificing. Cartilage sparing procedures involve osteotomy- removing a wedge of bone in order to line the knee joint straighter. This is used in young active adults to buy time. Cartilage sacrificing procedures refer top joint replacement. The trend recently has been for patients to get these operations done at a younger age. The downside is that these surgeries are associated with a small but real risk of severe complications including infection, blood clots, and death.
An option that is being proven to be an alternative is the use of autologous stem cells, a patient’s own stem cells to help sustain and possibly regrow cartilage in an osteoarthritis knee.
(Wei N, et al. Guided Mesenchymal Stem Cell Layering Technique for Treatment of Osteoarthritis of the Knee. J Applied Res. 2011; 11: 44-48)