Knee Arthritis

The Basics

  • Knee arthritis is a degenerative disease of the knee joint that causes progressive loss of articular cartilage under the patella(kneecap) and between the tibia(shin bone) and femur (thigh bone)

  • The knee joint is made up of three compartments. The patellofemoral compartment is the joint where the patella (knee cap) glides on the femur(thigh bone). The femoral tibial joint (between the thigh bone and shin bone) is divided into the medial (inside) and the lateral (outside) compartment. Arthritis of all three joints is called tricompartmental arthritis.

  • Patients will often complain of knee pain and stiffness. The stiffness may lead to loss of extension or flexion as the disease progresses. Activity may result in increased swelling. Night pain or pain at rest is common as the disease progresses. Patients may have instability, locking, or catching as the joint destruction advances.

  • There are many factors that can contribute to knee arthritis, some of which can include:
    1) Previous injury to the articular cartilage resulting in what is known as post-traumatic arthritis
    2) Previous injury to the stabilizing ligaments of the knee joint (anterior cruciate, posterior cruciate, medial collateral, or lateral collateral ligaments are the main ligaments) can result in instability that causes greater wear on the joint cartilage
    3) Surgically removing the meniscus due to tears will result in worsening arthritis with time. To combat this, the surgeon will leave as much functional meniscus as possible
    4) There are many possible genetic links to knee arthritis but many if not all of these can be modified or controlled with lifestyle changes. Metabolic syndrome which results in abdominal obesity, dyslipidemia ( high triglycerides and low-density lipoproteins) , high blood pressure, and diabetes is associated with knee arthritis.

  • Patients will often have an effusion (fluid in the knee) or a Baker’s cyst (fluid behind the knee). They may have tenderness along the joint line. The examiner may feel crepitus (grating or grinding sensation) in the joint with range of motion. As the disease progresses the patient will lose motion and this may result in walking with a limp. Medial compartment arthritis will result in a varus or bow legged deformity. Lateral compartment arthritis will result in a valgus or knock kneed deformity.

  • 1) The best test to evaluate knee arthritis is weightbearing X-Rays. The joint space is filled with cartilage and as the cartilage thins it will appear as joint space narrowing. When there is no joint space it is called bone on bone arthritis because there is no cartilage left. The X-rays will not show the articular cartilage but it will show the bone changes that result from cartilage loss. With loss of cartilage the bone develops bone cysts, sclerotic changes, and peripheral osteophytes (bone spurs).

    2) An MRI is less useful than X-ray when evaluating for knee arthritis. When a patient has mild arthritic changes on X-Ray an MRI might be ordered to evaluate for meniscus tears if conservative treatment fails. The MRI is usually ordered as a preoperative test to see if knee arthroscopy to remove the torn meniscus would benefit the patient. When the X-ray shows moderate or severe arthritis an MRI does not affect the treatment plan because removing a torn meniscus would not benefit the patient.

  • 1) Pain relievers are often used to treat arthritis pain. Tylenol (acetaminophen) is likely the safest arthritis medicine as long as the patient does not have liver issues or a history of heavy drinking. Tramadol is a non narcotic pain reliever that can help with arthritis pain but it is not recommended for routine use. Narcotic medicines are not recommended for arthritis pain.

    2) Non-Steroidal anti-inflammatory drugs are effective to treat arthritis. In past generations putting every patient on 800mg of Motrin/Ibuprofen/Advil was routine but this is not healthy for most patients' kidneys, stomach lining, or heart/blood pressure. Healthy patients can tolerate this dose but their PCP should be aware they are taking it. Most patients only take Motrin for an arthritis flare for a few days or weeks. Naprosyn/Naproxen/Aleve are a twice a day option. Meloxicam/ Mobic and Celebrex are once a day options. They all have similar side effects to Motrin but these side effects can be minimized with controlled dosing. Regardless you should not take them if you have been advised against it by your PCP, if you are on blood thinners, or you are taking another NSAID. In some patients a non steroidal anti-inflammatory cream is a better option.

    3) Supplements- there are many anti- inflammatory supplements such as Glucosamine/ Chondroitin and Turmeric that have benefited patients. Others have found relief or a decrease in symptoms from an anti-inflammatory diet.

  • A weak or stiff joint will be a painful joint. The physical therapist will use modalities to decrease pain and swelling in the joint while working to improve range of motion and build up strength in the quadriceps and hamstrings. Therapy will not cure the arthritis but it can decrease pain and increase function. It is important to continue these exercises at home a few times a week.

  • An improved diet and low impact exercise will decrease the inflammation in the joint and overall pressure on the joint.

  • 1) Steroid/cortisone injections are highly effective in decreasing the inflammation in the joint and therefore decrease the pain. They usually begin working 3-4 days after the injection. Too many injections will weaken the healthy cartilage so this is avoided. In general patients with severe arthritis can have 2-3 injections a year which is an injection every 4-6 months. For this reason we consider a successful shot one that gives several months of pain relief. With younger patients or patients with mild arthritis we try to limit these injections.

    2) Viscoelastic joint injections / Artificial joint fluid / gel shots- These shots can be useful in many patients. The success rate is less than cortisone injections but they often last longer when they work. It could take several weeks until pain relief but it is not uncommon to get some relief for 6-12 months. These injections require insurance approval which usually takes a few weeks. The injections can be one shot or a series of 3 shots. There are many different brands and your insurance company will determine what shot you get. They all have hyaluronic acid which is a main component of normal joint fluid. There is no evidence that one brand is superior to another.

    3) Stem cell and Protein Rich Plasma injections- These injections have many growth factors which do not replace cartilage but they may help heal damaged cartilage. Insurance does not cover these injections and they can be expensive. There are minimal drawbacks from trying these injections besides the cost and the disappointment if they do not work.

  • 1) Arthroscopic debridement - arthroscopic debridement has limited indications for treating moderate to severe arthritis and is not often indicated. Patients who have loose bodies causing catching or locking in the joint may get relief of mechanical symptoms but should not expect relief from their arthritis pain. Patients with mild arthritis will usually get relief from debriding large meniscus tears. Surgeons will often say they “ shaved away the arthritis when they were in there” which means they shaved away the unstable cartilage. When a patient has relief from this type of procedure it is usually due to removing the torn meniscus. There is a diagnostic component to these procedures. The torn meniscus is probed and when it is large or unstable ( moving into the joint ) the patient is more likely to benefit from removal. It is not uncommon for the articular cartilage to be more damaged than expected or the meniscus to be less damaged than expected from the X-rays and MRI and these patients do not usually get relief from the procedure.

    2) Knee arthroplasty / Knee replacement - This is the treatment for severe arthritis when conservative care has failed. Surgery is indicated for patients who can no longer perform ADLs and low impact activities they enjoy. It involves replacing the joint surfaces. When the medial and lateral joints are replaced +/- the patellar joint it is called a total joint arthroplasty. When arthritis is limited to one compartment the patient may be a candidate for unicompartmental arthroplasty. Although most patients get relief after surgery up to 20% have continued pain after surgery. Although the joint surface is replaced the tendons, muscles, ligaments, nerves and skin are still yours and all these can still produce pain. Therapy is critical to regain motion and strength after surgery. A stiff and weak knee will still be a painful knee even after a joint replacement. Waiting for the swelling, bruising, and pain to subside before working on your knee motion will often result in a stiff painful knee.

    Additional Considerations:
    1) Anesthesia- the surgery is now often an outpatient surgery with patients going home the same day and starting outpatient therapy within 1-2 days. The patient will have a regional anesthesia to help with post-operative pain control along with general anesthesia. The patient will need pre-operative clearance from their PCP and possibly their cardiologist. They will need to refrain from eating or drinking after midnight the evening before the surgery. They will need a ride home from the surgery and will usually need assistance at home for several days or weeks. Many patients will be unable to drive for 6 weeks after surgery so they will need rides to and from therapy appointments. Some patients will have surgery at the hospital and may stay for 1-2 days after. Occasionally older patients with no help at home will need to go to a rehabilitation center after surgery.

    2) Recovery - most patients will take 3-6 months to recover. Some patients are already significantly better and returned to full activity at 2 weeks. This is a reasonable goal but should not be expected as far as planning return to work, vacations, etc.. Some patients may take up to two years to fully recover.

    3) Outcome - Most patients are satisfied with their knee replacement. The most common problem after surgery is stiffness which could require prolonged therapy or a manipulation under anesthesia to break up adhesions. Loosening, malalignment, or fracture around the implant could require a revision procedure. A revision is more complicated with less predictable results. An infection will require a surgical washout which could result in removal of the implants. This can lead to multiple surgeries. Infections are a rare but sometimes a life altering complication. Medical complications such as cardiac, pulmonary, or neurologic issues can result in death. Your physicians will assess your risk during your pre-operative clearance.

    4) Appropriate age- patients with lower impact lifestyles and occupations will do better after surgery. As technology has advanced patients are getting joint replacements at a younger age. The goal is to maintain the joint your entire life to avoid a difficult revision procedure. This means avoiding activities that lead to significant impact on the joint such as running , jumping down from ladders, etc..

    5) Antibiotics - You will need antibiotics before any surgery or dental procedure to avoid bacteria spreading to the joint and resulting in an infection. Routine dental cleaning does not need antibiotics.

    6) Weight - heavier patients have a higher complication rate and less satisfaction after knee replacement. Recent reports have criticized using Body Mass Index as an inaccurate tool in medicine however at the extreme levels of obesity it is still useful for discussion. Patients with a BMI < 30 will do much better with surgery. In general most surgeons recommend avoiding surgery with a BMI > 40. Heavier patients are advised to discuss this with your PCP and a nutritionist. Maintaining an ideal weight will not only increase your chances of having a successful surgery but you may be able to avoid surgery completely

Treatment

Prevention

Knee arthritis is one of the most common reasons to see an orthopedic surgeon. After examining thousands of patients and looking at thousands of X-rays and MRIs we know that the amount of arthritis does not correlate with the amount of pain. I will frequently say “ there are people out there running marathons with knees that look like yours.” We know that lighter patients who maintain strong and flexible knees tolerate arthritis well and prevent the arthritis from progressing. Ultimately arthritis is a disease of chronic inflammation. If you decrease your chronic inflammation you will decrease your arthritis pain. An anti-inflammatory diet can significantly decrease your arthritis pain and many doctors encourage you to try it before proceeding with a knee replacement. Improving your overall fitness will improve your arthritis pain. Improving sleep and stress levels will as well. We will frequently see patients with bone on bone arthritis who require minimal treatment because they have controlled their chronic inflammation. Some of these patients fell into this lifestyle while others consciously chose to pursue a healthier way to approach life.