Continuing Medical Education: Understanding Osteoarthritis.

Edited By: Gregory C. Gardner, M.D.
Last updated Friday, January 07, 2005

Introduction

Joint anatomy

• Articulating surfaces covered by hyaline cartilage
• Joint enclosed by fibrous capsule
• Synovial membrane lines capsule and provides lubricating joint fluid and nutrients for the articular cartilage

Articular cartilage

Chondrocytes produce type II collagen, proteoglycan matrix, and enzymes such as collagenase and hyaluronidase that repair and remodel the cartilage.

Type II collagen produces the tensile strength and structure of the cartilage. The collagen bundles are arranged at 90 degrees to the joint surface.

The proteoglycan matrix are composed of huge macromolecular structures are negatively charged and are extensively hydrated and when a load is applied to the cartilage, water is displaced and is reimbibed when the load is removed helping the cartilage to maintain shape and help cushion the load.

Cartilage in osteoarthritis

Early changes include an increase in water content of the cartilage, changes in the quality and quantity of the proteoglycan matrix, and increased collage extractability.

Later changes include fibrillation of the cartilage, loss of cartilage substance, osteophyte formation, and increased bone density below the area of cartilage loss.

Chondrocytes actually work overtime initially to try to keep up with repair demands but eventually fall behind. Cytokines such as IL-1 may play a role in controlling the activity of degradative enzymes.

Causes

• Aging - Most important "cause" of OA
• Genetics - Recently, abnormal type II collagen gene recognized as a cause of OA in certain families
• Weight - Excess weight has been found to be a factor in OA of the knee in particular. At the hip and knee, 4 time body weight is concentrated across weight bearing surfaces
• Trauma - This is recognized as a cause of OA in usual and unusual joint areas
• Metabolic Abnormalities - Chondrocalcinosis may be a marker for diseases such as hemochromatosis, hypothyroidism, hyperparathyroidism, hypomagnesemia

Natural history

• Nonlinear Progression - Progression difficult to predict
• Radiographic vs Clinical Disease - Many people may have evidence of degenerative changes on X-ray but will not have any pain or disability from such

Risk factors For progression

• Joint Trauma - This will further injure damaged cartilage
• Excess Weight - Also a factor for further cartilage damage
• Abnormal Joint Alignment - Once a joint such as the knee has developed a valgus or varus deformity, the progression is more rapid

Joint areas involved in primary osteoarthritis

• DIPs
• PIPs
• 1st CMC
• Hips
• Knees
• 1st MTP
• Cervical Spine
• Lumbar Spine

If other areas involved think history of trauma or one of the metabolic causes of OA such as hemachromatosis or CPPD.

Clinical characteristics of osteoarthritis

• Mild morning stiffness (<15 minutes)
• Pain with use
• Swelling (synovial fluid is noninflammatory)
• Gelling (stiffness after rest)
• Boney deformity (Heberden's and Bouchard's nodes)

Radiographic features

• Non-uniform joint space narrowing
• Subchondral sclerosis
• Subchondral cysts
• Osteophytes

Basic differential diagnosis

• Rheumatoid arthritis
• Psoriatic arthritis
• Tophaceous urate gout
• Calcium pyrophosphate deposition disease

Patient role in the management of osteoarthritis

• Avoid joint trauma
• Lifestyle modification if necessary
• Lose weight if needed
• Exercise as directed
• Use assistive devices/orthotics as requested
• Take medications as directed
• Be aware of potential medication side effects

Physician role in the management of osteoarthritis

• Educate patient
  1. In-office discussions
  2. Provide educational material (The Arthritis Foundation is an excellent source for materials)
• Decide on appropriate therapy and discuss options with patient
• Administer and monitor therapy

Is exercise important?

Range of motion and isometrics

1. Instruction - I find that many of the joint specific exercises can be taught in the office or with a single visit to a physical therapist with perhaps a monitoring follow up visit. It is important to emphasize the patient's role in this therapy and one can even resort to giving the patient a personal prescription for the therapy. The importance of maintaining strong peri-joint musculature cannot be over emphasized!
2. Review - At each visit, review the patient's program and encourage continued exercise and increase in exercise intensity if necessary.

Aerobic conditioning

1. Instruction - This can be taught in a similar way to the ROM/Isometric exercise program. I "offer" the patient swimming, walking, or exercise bicycle as options. Water aerobics has the advantage of reducing impact to affected weight bearing joints and if the patient has paid for a program they may be more likely to go! The Arthritis Foundation can be contacted for locations of water programs that may be specifically designed for people with arthritis. It is best if aerobic conditioning be done 2-3 times per week and be progressive. Have the patient start off slow and increase the activity gradually. Aerobic conditioning has been shown to improve such things as the overall level of physicalactivity, reduce pain scores, and reduce levels of anxiety and depression associated with osteoarthritis.
2. Review - At each visit the patients program should be reviewed and should be encouraged to continue the activity. Studies have not shown any exacerbation of joint pain from such programs.

Ambulatory aids

• Canes - Utilized in the opposite hand of the affected joint. Can off load 20-30% of the weight on the joint and provide a sense of stability. Important to give the patient a brief course of cane training and to make sure the cane is the correct height. Can be done in office or by therapist
• Forearm Crutches - For more serious joint off loading in patient who may not be a surgical candidate
• Walkers - Useful for frail patient for in home or level ground walking for those who are not surgical candidates.
• Braces - Knee Sleeves can give some patients a sense of stability and reduce pain by simple contact. Firm Knee Braces can be customized to off load either the medial or lateral compartment of the knee but are expensive (try 500 dollars and cannot be returned). I have had luck in a few patients with off the shelf models without modification. Short Opponens Splint can be useful to decrease the pressure on the 1st CMC joint of the hand
• Lateral Heel Wedges - Up to 50% of patients have a good to excellent result in terms of pain reduction by putting a lateral heel wedge insert into the shoe of a patient with medial knee osteoarthritis. Best for mild disease

Household assistance

• Tub Seats/Shower Seats - As above with reference to tub or shower
• Elevated Chairs - Allows patient with knee OA to get out of chair easier especially if there is patellofemoral compartment involvement
• Kitchen/Household Utensils - There are a variety of objects that can be used by patients with hand involvement to make life easier. Often best done with consultation with occupational therapist

Analgesics

• Acetaminophen - Recent study found that 4000 mg of acetaminophen was as effective as 1200 mg of ibuprofen in OA. A definite consideration in all patients but especially in those with risk factors for NSAID toxicity. Can be added in prn doses to NSAIDs.
• Propoxyphene/Codeine - Can be used in patients without other options but in limited amounts. I usually give small monthly amount ie #15 and will not refill before the month is over. Avoid stronger, more potentially addictive opiates.
• Capsaicin Cream - Inhibits activity of substance P. Recent study of hand OA found reduction of pain by 40% and stiffness by 30% when applied QID for4 weeks at the 0.075% strength compared to placebo.
• Tricyclics - Several studies have demonstrated the usefulness of low dose TCAs in improving sleep and pain in patients with OA. It is always useful to address sleep quality as we may be able to provide an improvement in pain by improving sleep quality. Some of the pain reliving qualities may be on the basis of their effects on serotonin.

Analgesics and antiinflammatories

• NSAIDs - The mainstay of medication therapy for OA. May interfere with the production of cartilage proteoglycans and therefore may have an adverse effect on OA (controversial). Patients over age 60 at greater risk for NSAID toxicity. Nonacetylated salicylates may be useful in patients at risk for NSAID toxicity but need something stronger than acetominphen. Several different NSAIDs can be tried before one gives up on these. Remember that medications should only be part of the total program of treatment.
• Injectable Corticosteroids - Useful as an adjunct to overall program. Some patients have several months of benefit. Should not be used more than 3-4 times per year and no more than 10 injections total into any weight bearing joint. May work by inhibiting production IL-1 and its subsequent effect on the production of proteolytic enzymes.

Knee arthroscopy in osteoarthritis

Conditions that make arthroscopy useful

• Meniscal tear - Symptoms that suggest a meniscal tear include: recent onset of pain and swelling on top of previous OA symptoms, localized joint line tenderness, relatively normal X-rays for the amount of pain, locking, or joint giveway. The degenerative meniscus may be more likely to tear with less trauma. MRI can confirm the tear
• Loose body - Symptoms are usually knee locking and possibly giveway. If loose body is calcified, may be visible on X-rays

Conditions that make arthroscopy less useful

• Severe OA
• Varus or valgus deformity
• Chondrocalcinosis
• Previous meniscectomy

Total joint arthroplasty

Information to discuss with patient

• Cost of surgery is about $25,000 with expenses not completely covered by medicare and supplemental. Need to get cost estimate from surgeon's office
• Hospital 3-7 days without complications; protected ambulation and therapy for 6 weeks; return to full activities may take 6 months. There is a limitation to activity level as well.
• Complications include risks of anesthesia, DVT/PE, infection, and later loosening of the prosthesis.

Good candidates for TJA

• Uncontrolled pain - This is the main reason for considering TJA. If medical Rx in not satisfactory and the patient is willing to go through the risks and hassels of surgery, then >80% of patients will have good to excellent pain relief
• Immobility - Less important to pain in my mind but also a factor
• Age over 70 - Patients at this age are easier on prostheses and few require revision due to wear and tear
• Slender build - Easier on the prostheses
• Good health
• Sedentary lifestyle - Easier on prostheses and will find permitted activities acceptable

Conclusion

As a resident in internal medicine, I was taught to treat OA with NSAIDs and if this did not help, with a referral to an orthopaedist or rheumatologist. In this lecture, I have tried to point out the variety of therapeutic options available to every physician who takes care of patients with OA. The treatment of OA is a "program" in which the physician and patient each have their responsibilities with the goal of improving the quality of life for the patient with OA.

References

1. Brandt KD. Osteoarthritis. Clin Geriatr Med 1988;4:279-293.

   The most important theories concerning the pathogenesis of osteoarthritis.

2. Davis MA. Epidemiology of osteoarthritis. Clin Geriatr Med 1988;4:241-255.

   Risk factors for and the natural history of osteoarthritis.

3. Hammerman D. The biology of osteoarthritis. N Engl J Med 1989;320:1322-1330.

   Biology of normal articular cartilage and the changes that occur with osteoarthritis.

4. Furst DE, Paulus HE. Aspirin and other nonsteroidal antiinflammatory drugs. In McCarty D, Ed. Arthritis and Allied Conditions. 12th Edition, Lea & Febiger, Philadelphia,1993, pp. 507-543.

   Outlines the mechanism of action of NSAIDs and discusses each NSAID individually, detailing their reported adverse reactions.

5. Bradley JD, Brandt KD, Katz BP, Kalasinski LA. Comparison of an intiinflammatory dose of ibuprofen, an anlagesic dose of ibuprofen, and acetaminophen in the treatment of patients with osteoarthritis of the knee. N-Engl- Med 1991;325:87-91.

   Controlled trial of ibuprofen in 2 doses compared to acetaminophen for knee osteoarthritis with no difference of significance noted although several trends favored the ibuprofen. The authors suggest that acetaminophen is more appropriate therapy in most patients with osteoarthritis due to its favorable safety profile.

6. McCarthy GM, McCarty DJ. Effect of topical capsaicin in the therapy of painful osteoarthritis of the hands. J Rheumatol 1992;19:604-607

   Controlled trial of capsaicin cream in osteoarthritis of the hand. Discussed in the text.

Surgery for arthritis at the University of Washington