Osteoarthritis medial knee

by Nathan Wei, MD, FACP, FACR

Nathan Wei is a nationally known board-certified rheumatologist and author of the Second Opinion Arthritis Treatment Kit. It's available exclusively at this website... not available in stores.

Click here: Second Opinion Arthritis Treatment Kit

Osteoarthritis of the knee is a common problem.

It is a major cause of pain and disability and can impose significant financial costs on society. Osteoarthritis of the knee often has a significant impact on patient functioning and activities of daily living.

The estimated population prevalence varies from 4% to 30% depending on age, gender, and disease definition. The risk of osteoarthritis of the knee is comparable in men and women up to about 50 years of age.

Osteoarthritis is a disease of articular cartilage, which is composed mainly of water, collagen, and proteoglycans. Chondroitin sulfate and keratin sulfate are attached to a protein core forming proteoglycans. These in turn bind with hyaluronic acid and proteins. This gives cartilage its stability and strength. Collagens, especially type II (the major type in hyaline cartilage), also play a major role in the structural integrity and functional capabilities of cartilage.

The first manifestation of osteoarthritis is cartilage irregularity. This is followed by erosion of the cartilage surface and then, by cartilage loss, which can leads to bone-on-bone contact within the joint.

Microscopically, fibrillation (irregularity) occurs in the early stages, before the eventual depletion of glycosaminoglycans. This leads to the development of fissures and clefts and loss of cartilage. Inflammatory cells proliferate.

As a result of the depletion of glycosaminoglycans, the water content of cartilage increases. There is also an increase in matrix metalloproteinase enzymes, which play a major role in the degradation of cartilage.

Cells called chondrocytes multiply and produce increased quantities of various enzymes and growth factors. This results in an imbalance between the degradation and the synthesis of the cartilage matrix. When this imbalance occurs, osteoarthritic changes develop.

Crystal deposition has also been implicated as a cause of osteoarthritis. Calcium pyrophosphate or hydroxyapatite crystals have been seen to accumulate in the joint fluid. This leads to release of enzymes (collagenases, stromelysin, and other proteases) and other factors (prostaglandin E2) that can increase cartilage degeneration.

Progression of the disease is accompanied by a change in cartilage architecture, which alters the mechanical stresses within the joint. This leads to further joint damage and degradation. Mechanical stress seems to be the inciting event, leading to changes in chondrocyte metabolism and matrix properties as well as increased amounts of proteolytic enzymes. Multiple microfractures eventually lead to degradation and loss of articular cartilage, which alters joint architecture and promotes osteophyte (spur) production.

Periostitis (inflammation of the thin membrane that covers bone) may develop at sites of bone remodeling leading to pain. Other pain generators include microfractures of underlying bone, irritation of sensory nerve endings in the synovium from osteophytes, periarticular muscle spasm, and bone "angina" from diminished blood flow and elevated pressure inside bone. Synovial inflammation with associated release of prostaglandins, leukotrienes, and various cytokines can also cause pain.

Osteoarthritis of the knee is a caused by multiple factors, including genetic, metabolic, biochemical, enzymatic, and biomechanical.

In women, osteoarthritis tends to have a stronger association with obesity and is frequently bilateral; in men it tends to be related to prior trauma or injury and is often unilateral. Risk factors include older age, female sex, osteoarthritis at other sites, obesity, and previous injury or surgery. Obesity and previous injury seem to have a greater impact on the development of osteoarthritis rather than on progression.

Factors such as ligamentous instability and abnormal motion may also contribute to premature osteoarthritis of the knee. Running is a good example. Despite the evidence that a moderate amount of running does not seem to cause the development of osteoarthritis of the knee in most people, it has a different effect on people who have sustained previous trauma or injury or have joints with significant anatomical abnormalities. Low-impact activities do not seem to promote an increased risk of osteoarthritis of the knee, but high-impact or high-intensity activities do.

Controlled joint loading and motion may actually stimulate repair of diseased cartilage and promote maintenance of the normal synovial joint function. This is evident after a prolonged decrease in joint use (ie, after injury or trauma), when cartilage changes frequently occur.

Prolonged immobilization of the joints eventually causes irreversible damage to articular cartilage.

Up to a certain level, this increased loading and motion of the joint may increase matrix synthesis relative to matrix degeneration and promote healthier cartilage. Above this threshold, activities may become harmful, possibly because of repetitive subthreshold injuries.

Another constant risk factor for osteoarthritis of the knee is obesity, especially in middle-aged or older women compared with men. Body weight and BMI (body mass index) are good predictors of osteoarthritis of the knee.

Age plays a critical role in the prevalence and incidence as well as the progression of osteoarthritis of the knee. However, multiple studies have shown that osteoarthritis is a specific process and not simply a normal part of aging.

Reduced quadriceps muscle strength relative to body weight may be a risk factor for osteoarthritis of the knee for women.

Gradual progression of pain is usually the initial symptom of osteoarthritis, but patients may remain asymptomatic. It is often aggravated by weight-bearing or increased use (walking or other exercise). Patients may also complain of anterior knee pain that is worse with prolonged sitting (theater sign), climbing stairs, jumping, squatting, or kneeling. Initially, the pain improves with rest, but with disease progression, the pain may occur both at rest and at night. Weather changes tend to alter the level of pain in osteoarthritis of the knee. People often note increased pain with damp, cool, or rainy conditions. This is probably caused by a change in intra-articular pressure associated with changes in atmospheric pressure.

Other symptoms include stiffness and limitation of function, with or without crepitus (crunching). Morning stiffness associated with osteoarthritis usually lasts for 15 to 20 minutes or less. Patients also have "gelling" (stiffness with rest and inactivity) that resolves within a few minutes of activity.

As osteoarthritis of the knee progresses, patients complain of instability with giveway and diminished range of motion. Patients may even report locking or catching of the knee. Patients may also note a deformity (often a varus or bowleg deformity). Patients with severe osteoarthritis of the knee can develop a limp or report episodes of falling. Soft-tissue swelling and joint effusion can develop with disease progression.

In osteoarthritis of the knee, involvement is more likely to be unicompartmental (one compartment). Medial compartment osteoarthritis (OA) is more frequent than lateral compartment OA, the medial meniscus being more vulnerable to injury than the lateral meniscus.

OA of medial or lateral compartment may also follow an injury. For example, injury to the cartilage surface or untreated cruciate ligament damage may cause joint instability and joint surface and meniscal damage - leading to OA.

A variety of treatment options exist for patients with isolated medial compartment arthritis of the knee. Non-surgical interventions include the use of canes, non-steroidal anti-inflammatories, lateral shoe wedges, cortisone, viscosupplements, and a variety of knee braces. Surgical options include arthroscopic debridement, high tibial osteotomy, or a unicondylar or total knee replacement.

Knee immobilizers can be used during the acute inflammation phase of knee arthritis. Most of the pain associated with knee osteoarthritis is worsened with weight-bearing and load across the knee rather than with joint motion. However, the immobilizers can help reduce the hamstring spasms and flexion contractures that occur with the acute flare-ups of arthritis. Several authors have shown that proprioception is decreased in patients with osteoarthritis of the knee. It has also been demonstrated that a neoprene sleeve or elastic bandage can improve the proprioception in these patients. Since these sleeves provide very little support, it is believed that the feelings of improved stability and pain reduction are due to the improvement in joint proprioception. The neoprene sleeves are relatively inexpensive and reasonably comfortable.

Valgus unloader braces were designed to provide medial compartment pain relief by reducing the load on that compartment. Several studies investigating the clinical efficacy of valgus bracing have reported that patients experience significant pain relief and improvement in physical function while wearing the brace. Valgus bracing can affect the biomechanics of the gait pattern.

The most common braces used for the treatment of knee arthritis include the knee immobilizer, the unloader brace, and the neoprene sleeve. The immobilizer may be useful to rest the acutely inflamed arthritic knee. However, motion should be started as soon as possible to prevent flexion contractures and subsequent weakness.

Although it provides little or no mechanical support, the neoprene sleeve may improve proprioception, pain, and the disease-specific quality of life. The unloader brace has been shown to affect gait parameters, including the medial compartment load and the varus and adduction moments. The unloader brace showed a significant reduction in pain and improvement of function when compared to medical management alone and the neoprene sleeve.

Finally, another study demonstrated the efficacy of lateral wedged insoles for treatment of medial OA.

Laterally elevated wedged insoles in the treatment of medial knee osteoarthritis. A two-year prospective randomized controlled study.

Pham T, Maillefert JF, Hudry C, Kieffert P, Bourgeois P, Lechevalier D, Dougados M.

Rene Descartes University, Cochin Hospital, Paris, France.

OBJECTIVE: To compare the clinical effects of laterally wedged insoles and neutrally wedged insoles (used as control) in patients with medial femoro-tibial knee osteoarthritis. METHODS: Study design: 24-month prospective randomized controlled study. Patients: Outpatients with painful medial femoro-tibial knee osteoarthritis. Outcome measures: Patient's overall assessment of disease activity (5 grade scale), WOMAC index subscales and concomitant treatments. Statistical analysis: Performed as an intention-to-treat analysis, with the last observation carried forward (LOCF). Main symptomatic criterion: Improvement in the patient's assessment of activity (defined as a reduction of one grade or more at the end of the study as compared to baseline, and no intra-articular injection or lavage during the 6 months previous to the last visit). Secondary criteria for assessment: (a) Changes in the WOMAC subscales at month 24, and (b) concomitant therapies (analgesics, NSAIDs and intra-articular injections or lavages). Structural criterion: Joint space width (JSW) at the narrowest point. Non-compliance was defined as intermittent or lack of insole fitting at two consecutive visits. Compliance within groups was compared by using a life table analysis technique (Log-Rank). RESULTS: The baseline characteristics of the 156 recruited patients (41 males, 115 females, mean age 64.8 years) were not different in the 2 treatment groups. At year 2, there was no statistically significant difference between the 2 groups concerning the percentages of patients with improvement in both global assessment of disease activity and in WOMAC subscales (pain, stiffness, function). The number of days with NSAIDs intake was lower in the group with laterally wedged insoles than in the neutrally wedged group (71+/-173 days vs. 127+/-193 days, P=0.003, Mann-Whitney test). The mean joint space narrowing rate did not differ between the two groups: 0.21+/-0.59 mm/year in the laterally wedged group vs 0.12+/-0.32 mm/year in the neutrally wedged group. Compliance and tolerance were satisfactory. Compliance was different between the 2 groups at month 24, with a greater frequency of patients who wore insoles permanently in the laterally wedged insole group than in the other group (85.8% vs 71.9%, P=0.023). CONCLUSION: This study failed to demonstrate a relevant symptomatic and/or structural effect of laterally-wedged insoles in medial femoro-tibial OA. However, the reduced NSAIDs intake and the better compliance in the treatment group are in favor of a beneficial effect of laterally-wedged insoles in medial femoro-tibial OA.

For patients who fail conservative measures, more invasive treatments are often required.

Arthroscopy is a surgical procedure that uses small incisions and miniature instruments. A tiny telescope (arthroscope) is inserted into the joint space, which is then filled with fluids so the surgeon can clearly see the components of the joint. This enables the surgeon to look directly at the bone surfaces and to determine how advanced your arthritis is.

Using tiny instruments, the surgeon can trim damaged cartilage, remove any loose particles or debris from the joint (a procedure called debridement).

More recently, there have been at least two major double-blind studies that have cast doubt on the efficacy of arthroscopic debridement for osteoarthritis.

There is a new procedure using autologous stem cells (stem cells harvested from the hip of the patient). The stem cells and platelet rich plasma (obtained from the whole blood of the patient- platelets are cells rich in growth and healing factors) are injected into the knee using ultrasound guidance. This procedure is done under local anesthesia and preliminary results are very promising.

For more information, go to

Stem cell treatment for osteoarthritis Discussion of the use of stem cells to treat osteoarthritis.

An osteotomy may be recommended if damage to the knee cartilage is primarily unicompartamental. The surgeon repositions the joint to move the mechanical axis of weight-bearing for the limb away from the damaged area. This shifts weight-bearing stresses from the damaged section to a healthier part of the knee. This is done by removing a wedge of bone to align the femur and tibia. An osteotomy can restore knee function and reduce osteoarthritis pain. It may even stimulate the growth of new cartilage. The results deteriorate over time. Many people who have an osteotomy will eventually need a total knee replacement (arthroplasty).

An arthroplasty is a joint replacement procedure. If the arthritis is localized to one side of the knee, the orthopaedic surgeon may recommend a unicompartmental knee arthroplasty. If both sides of the knee are affected, a total joint replacement may be more appropriate. The replacement parts are made of cobalt-chrome or titanium metals and smooth, wear-resistant plastic (polyethylene).

The results of total joint replacement are generally good. Patients experience significant pain relief and improved physical functioning. There are risks to the surgery, and full rehabilitation may take three to six months. In addition, the prosthesis (artificial joint) may eventually loosen or wear out so that a second surgery is needed. However, at the 10-year mark, the success rate with most prostheses today is about 90 percent.

A complication of osteoarthritis of the medial knee is anserine bursitis. Pain here may be confused with the pain that accompanies OA. It is often seen in middle aged, over-weight women. It is often due to direct trauma or overuse injury.

In addition to medial knee pain, a patient may also have skin numbness below the patella.

There is tenderness over the pes anserine bursa which is a bursa that is located distal to the medial joint line (below tibial plateau) and sandwiched between ligament and tendon on medial knee. Important adjacent structures include the medial collateral ligament beneath bursa and medial thigh tendons from the sartorius muscle, gracilis muscle, and semitendinosus muscle.

Medial OA pain must be differentiated from anserine bursal pain as well as pain related to medial meniscus injury and medial collateral ligament strain. Treatment measures include:

B. Local ice therapy
C. Modify activities
D. Pes Anserine Injection

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