Knee Arthritis

Knee Arthritis is properly defined as inflammation of the knee joint. More specifically, arthritis is due to wear down of the smooth, critical cartilaginous surfaces of the knee. When the cartilage breaks down in the knee, the joint starts seeing increased stress during activity because it’s not as well protected. As a result, the joint lining, which is called the synovium, forms extra joint fluid to try to better lubricate the joint and bring in inflammation to the joint.

The classic symptoms of arthritis, which are knee pain that is exacerbated with activity, stiffness with limited range of motion especially when waking up in the morning and tends to get better with moving, swelling and warmth around the joint, difficulty with sitting or walking for long periods of time, and difficulty with stairs. Pain can be in several different areas of the knee depending on where the cartilage breakdown was seen, but can even be in the back of the knee in the form of a Baker’s cyst, which is due to excessive fluid accumulation from the knee joint in the back of the knee. Patients may also notice a sensation of crepitus which is a crunching or grinding sensation due to the irregular cartilage surface. You can think about this as a road which has potholes making driving along the road not as smooth as you would like.

There are several different causes of knee arthritis which include:

1. Traditional (idiopathic) osteoarthritis without a previous injury or an underlying disorder
2. Inflammatory arthritis secondary to rheumatologic causes such as rheumatoid arthritis or psoriatic arthritis
3. Post-traumatic arthritis after an injury such as a fracture about the knee
4. Crystal arthropathy which is due to patients having underlying conditions such as gout or pseudogout that forms irritating crystals in the joint
5. Septic arthritis due to an underlying infection of the joint, this represents an orthopedic emergency to thoroughly remove the infection.

For patients without a secondary reason for why they’re having their arthritis, most commonly this breakdown of the cartilage is due to the natural wear and tear on the cartilage over a lifetime of use. We know that genetics and family history is very important as many patients will remember that their parents or other family members dealt with similar issues of arthritis either in the knee or in a different joint. So the family history and just natural wear and tear are the most common presentation of this breakdown of the cartilage that we see as orthopedic surgeons. Additionally, increased body weight puts more load on the joint as well as repetitive stresses on the knee due to a patient’s occupation such as heavy manual labor or athletes with previous injuries to the knee ligaments, menisci, or cartilage.

If a patient is concerned about having knee arthritis, this is first confirmed on their history because many patients will have the symptoms that we have already outlined. A physical exam would confirm any focal versus generalized irritation of the cartilage surface as the knee will often have some swelling or even deformity depending on how severe the arthritis and cartilage breakdown is. Radiographs (x-rays) are essential to look at joint space narrowing due to the breakdown of the cartilage, osteophyte (bone spur) formation, and white sclerosis of the bone due to the increased stress on the bone. Radiographs also helps in deformity detection and planning such as bowing in or bowing out of the knee joint. Compared to other orthopedic conditions, many times an MRI or CT are not explicitly needed for diagnosis of the condition as high quality X-rays are often enough to tell the full story; nonetheless, CT can be utilized as part of preoperative planning when doing robotic or patient specific total knee replacement.