Osteoarthiritis
What is it?
Simply put arthritis is a degenerative process in joints, in the case of the knee the tibiofemoral and patellofemoral joints, which leads to loss of cartilage and pain. A good analogy would be when a tire loses its tread.
How does Arthritis happen?
A healthy knee has a host of factors that help the knee function normally. The major factors being ligaments which provide stability and help the knee to move the way it should. An inside (medial) and outside (lateral) meniscus that help to disperse forces between the tibia and femur and synovial fluid which provides nutrients and lubrication for the cartilage/knee, and the cartilage which helps provide smooth minimal friction movement. When one of these things get out of whack, it can start the process of arthritis. Loss of meniscus leads to inability to cushion the knee which leads to irregular wear on the cartilage. Injury to a ligament leads to abnormal motion which leads to abnormal force and subsequent wear. A traumatic injury from impact to cartilage can lead to a pothole or roughened area on the cartilage surface which again affects the motion and wear of the surround cartilage. Lastly changes to the synovial fluid in the knee, from infection, autoimmune disorders, or trauma, can all lead to damage to cartilage wear and arthritis.
What are Risk Factors?
You will start to sense a trend in regards to risk factors for knee injury. They are always lumped into modifiable and nonmodifiable, and many of these risk factors are risks for many different injuries/pathologies of the knee.
For Modifiable:
Bodyweight…1 pound of bodyweight=7 pounds of force through the knee. Simple 15 pounds one way or the other changes forces on your knee by Over 100 (105) pounds.
Muscle strength and tone. The reason physical therapy works is not because it REVERSES the disease, it instead helps to strengthen the dynamic stabilizers of the knee, your surrounding muscles. This helps to improve your overall gait (walking) biomechanics. Put more simplistically this helps you to walk normally, without a limp and in so doing helps your muscles to absorb more of the forces that your knee experiences when walking. Strong WELL BALANCED muscles protect the knee!
Intra-articular inflammatory state. This one is WAYYY too complicated to fully explain in just a few sentences, but in short, swelling and inflammation HURTS. Swelling and inflammation are produced by cells in the knee in response to an injury or in the case of arthritis in response to the chronic degeneration. We can’t undo the cause of the swelling, but we can help to diminish the swelling with oral (by mouth), topical (skin based) and intra-articular (shot) medications. Things like corticosteroids, non-steroidal anti-inflammatories (Advil, Aleve, Mobic, etc) and natural anti-inflammatories (omega-3, turmeric, ginger, etc) can all act to reduce inflammation, speaking to your physician regarding these options and which, if any, is best for you is important.
Bony Alignment. Patients who are knock kneed or bow legged end up loading their knee in a pathologic way which can lead to earlier wear and degeneration. Again this can be addressed with bracing to help offload the area of the knee that is overloaded. The brace in essence acts like a car jack, to “jack” open the area of the knee that is experiencing too much force and therefore pain. Surgery can definitively correct the issue.
Nonmodifiable
Post-Traumatic development of Osteoarthritis. Patients who have sustained a major knee injury in their life are at a significantly elevated risk of developing Arthritis later in life.
How common is Knee Osteoarthritis?
13% of women over 60 and 10% of men over 60 have symptomatic knee osteoarthritis.
Signs and Symptoms of Knee OA and what to do?
Knee arthritis can manifest in a number of ways, however commonly presents as progressive knee pain which first is primarily noticeable with high demand activities. This can then progress to knee pain with stairs, shorter walks and eventually aching and pain at night.
When the symptoms are bothersome enough and are affecting your quality of life you should present to your primary care provider to discuss symptoms and next steps of care.
Severity and Injury and Treatment options?
Knee osteoarthritis is commonly “graded” on xrays and MRI, however what matters the most is the patient, we treat patients not just images. So therefore some patients have debilitating pain with moderate X-ray reads while others have end stage arthritis on xrays but very little pain or disability. Because any kind of treatment comes with risks, the patient and the physician should always weight the risks and the potential reward of the proposed treatment to know what is the best option.
There are numerous treatment options however to just go over three main pathways.
Conservative (nonoperative) Management. This includes if applicable; bracing, injections, physical therapy, weight loss, medical management. From an injection standpoint again there are numerous but three common types you may hear about are; a) Corticosteroid injections which aim to decrease inflammatory response, b)Hyaluronic acid injections which also can decrease inflammation and concurrently increase lubrication in the joint, c) biologics which include stem cell injections, platelet rich plasma (PRP) injections as well as others. In the setting of arthritis the biologic agents are not acting so much to “regenerate” or regrow cartilage/reverse the arthritis, they are more acting to decrease the inflammatory state and improve pain.
Surgical management “joint preserving”. These types of procedures are aimed mainly to address malalignment. If a patient is severely knock kneed or bow legged and therefore their arthritis is isolated to one are of the knee, a surgery called an osteotomy can be performed. In an osteotomy the bone is cut and realigned to straighten out the knee joint and thereby offload the area of the knee that is painful. The osteotomy is more powerful and definitive than an “unloader brace” but acts by a similar principle, a “car jack” that can open up the damaged space. This option allows the patient to maintain their native joint. The main kinds are distal femoral osteotomy (cutting the lowest part of the femur) and proximal tibial osteotomy (cutting the highest or top part of the tibia).
Arthroplasty or joint replacement. This option includes replacing either a portion or the entirety of the knee joint with metal and plastic. In so doing the damaged cartilage surfaces of the knee and the arthritis are removed and therefore the pain causing agents are removed. However, it is a big procedure which requires extensive soft tissue manipulation so the surgery itself does cause pain at least for a period of time following the operation. The main kinds of arthroplasty are; a) patellofemoral arthroplasty, replacing the trochlea and the patella, b) medial or lateral unicompartmental arthroplasty, just replacing the inside or the outside portion of the knee, and a c)total knee arthroplasty, replacing all three compartments.