Knee Arthritis

Arthrosis, Degenerative Joint Disease


Arthritis is the inflammation or wear and tear of a joint. There are various types of arthritis that can affect the knee: osteoarthritis, rheumatoid arthritis, septic arthritis, dysplasias (which are generally genetic) and post-traumatic arthritis with or without prior scopes or surgeries.

  • Osteoarthritis is the most common type of arthritis and degeneration of the joint occurs over time with the normal aging process. This form of arthritis occurs when the protective coating on the ends of bones (articular cartilage) wears down over time and there is loss of cartilage at the knee.
  • Rheumatoid arthritis is an inflammatory form of arthritis that occurs at any age and can lead to a more rapid degeneration of the joint. Symptoms can occur at multiple joints.  This form of arthritis can cause painful swelling that can lead to bone erosion and deformity at a joint.
  • Septic arthritis is when there has been a previous infection that has destroyed the cartilage.
  • Post-traumatic arthritis begins after an injury has occurred that leads to the progression of degenerative changes in a given joint.  There may be history of a scope or cartilage procedure.


Typically there is a gradual increase of pain over time with weight bearing activities such as walking and standing.  Arthritic symptoms can also have episodic flares where symptoms worsen for a few days or weeks and then resolve. These symptoms may be worsened with inclines and declines and stairs. A patient can also experience stiffness and swelling at the involved joint. In addition, a patient can experience difficulty performing normal activities of daily living such as going up and down the stairs, cooking meals, and washing dishes as these activities all involve the patient bearing weight through the involved knee. Over time, the muscles in the leg can become weak and a patient can have a sensation of the knee buckling. 


  • A physical exam of the knee will be performed to evaluate the ligaments of the knee, range of motion of the knee, gait analysis (how you walk), status of the nerves around the knee, and will look for signs of swelling or tenderness on exam. 
  • Radiographic exam (x-ray) will be used to determine loss of cartilage and joint space in the knee.
  • Further exams including possible labs or MRI may be warranted based on exam findings. An MRI is usually not needed in cases where arthritis is seen on X-ray.


Typically starts with non-surgical treatments but may advance to surgical options.

  • Non-Surgical Options include:
    • Diet modification, weight loss
    • Activity modification, using an assistive device (cane, crutches, walker, trekking poles)
    • NSAIDS (non-steroidal anti-inflammatory drugs)
    • Injections - cortisone typically has a predictable result with improvement of pain from a few weeks to a few months. Viscosupplementation with hyaluronic acid formulations has worked in some people although the results have been more variable and less predictable.
    • Physical therapy or home exercises for strengthening the muscles of the leg. “Closed-Chain” exercises such as a low resistance bicycle can have excellent results and should be tried in most patients prior to considering injections or surgical intervention.
  • Replacement Surgical Options include:
    • Knee Replacement (tricompartmental) - A total knee replacement replaces the entire joint with a metal and plastic implant.
    • Partial Knee Replacement (unicompartmental or “UNI”) - A partial knee replacement or “uni” replaces only a portion of the joint. 
    • Arthroscopy or a “scope” typically does not provide long term relief for arthritis, but should be considered when there is sudden loss of motion and mechanical symptoms to suggest a torn cartilage.

Pre-Operative Care:  

The following non-operative measures may be recommended the majority of the time prior to considering surgical intervention:

  • Exercise to include daily bicycling to improve range of motion and strength
  • Weight loss through diet and restriction of empty calories (deserts, sweets, sugars, simple carbs) if above ideal body weight to decrease risk of infection and increase ability to perform surgery in a safe fashion, (Diabetics should consult with a physician before significantly modifying diet)
  • Medications such as anti-inflammatories to minimize inflammation and pain
  • Injections to also minimize inflammation and pain
  • Utilization of an assistive device while walking (cane, crutches, walker or trekking poles)
  • Physical therapy services
  • Bracing if warranted to unload to affected area
  • Modifying activities to reduce pain

Post-Operative Care

If there is evidence of significant degenerative changes (arthritis) and a patient has failed non-surgical treatment methods then the patient may be a candidate to undergo surgical intervention. 

  • Knee replacement (TKA) (tricompartmental): A total knee replacement replaces the entire joint with a metal and plastic implant. This is generally performed through less invasive techniques using modern instrumentation and components sized to the patient’s joint. Despite great care to perform the replacement precisely, a portion of patients up to 10-14% report residual discomfort and pain following a complete knee replacement. The TKA does a predictable job alleviating arthritic symptoms of activity related pain such as pain with walking. Pain in the front of the knee (Anterior knee pain) is relieved with less predictability as is pain when climbing stairs. If your symptoms are predominately in the front of the knee and your symptoms are mostly with stair climbing, discuss this in detail with your surgeon prior to considering complete knee replacement.
  • Partial (unicompartmental or “uni”)  knee replacement. A partial knee replacement replaces only a portion of the joint that is affected by arthritis. This is most commonly done for isolated medial (inside of the joint) arthritis and knee pain with activity. The ‘uni’ can typically be performed through a smaller incision and offers a faster recovery with many patients going home the day of surgery or the morning after surgery. To be candidate for this procedure, the patient should have pain isolated to the medial or inside of the knee with walking.  In addition the patient should have an intact, or not injured, anterior cruciate ligament and should have range of motion and a thin body habitus.   Contraindications or things which would limit the ability to perform a “UNI” would include obesity, contracture or stiffness, anterior knee pain (pain in the front of the knee) and an injured anterior cruciate ligament (ACL tear).

The goal of these procedures is to replace the involved arthritic bone in the joint with artificial parts to decrease pain and allow a patient to potentially return to some or all of their previous activities of daily living. If performed well, the replaced parts are durable and may provide decades of pain relief from arthritic activity related symptoms.

Risks of surgery include, but are not limited to: infection, bleeding, damage to nerves and blood vessels, soft tissue trauma, bruising, continued pain, stiffness, fracyture, decreased range of motion of knee, numbness or tingling, loosening or wear of prosthesis, need for further surgery. Risks of anesthesia include heart attack, blood clot, stroke, pulmonary embolism, and death.

Before surgery we encourage our patients to attend a two hour class (informational session) which explains what to expect before surgery, during your hospitalization, and throughout your post-operative recovery.

In order to decrease risk of blood clot in the legs which occurs in 5% of patients, blood thinning medication is recommended for one month after surgery. A walker, crutches, or cane would be used for a period of time as well during the recovery process.

There are typically several return visits for post-operative care within the first three months after surgery. In addition, patients return for evaluation one year post-operatively and five years post-operatively.

Condition:  Painful Total Knee Replacement

Most patients who have a knee replacement are very happy with the pain relief that comes after the surgery.  It is true that knee replacement surgery requires a period of difficult physical therapy after the surgery but most patients are feeling well enough to begin doing their activities of daily living before 3 months after surgery.  Occasionally, pain continues in the knee that had a replacement and continued exercising does not lead to relief of the pain.  This pain is often combined with limitation of motion of the knee such that a patient cannot do the activities that are necessary for daily life.

There are many reasons why a knee replacement surgery may not be as successful as the patient and the surgeon would like. Although rare, infection in the knee can cause pain and stiffness. Conditions such as fibromyalgia can also lead to an unsatisfactory result because of pain and stiffness.  In many cases we simply cannot find the reason why a replacement was not successful.

At the University of Michigan we are interested in trying to find the causes of pain and stiffness in knee replacement surgeries that appear from x-ray studies to be satisfactory.  To be sure, there are many cases in which we cannot find a reason for continued discomfort and stiffness. We are working with other specialists to provide help for patients who have painful total knees and to develop new techniques to prevent this type of pain from occurring after knee replacement.