Osteoarthritis medial knee

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 substantial impact on 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. However, after 50 years of age, the incidence and prevalence of osteoarthritis of the knee increases more rapidly in women than in men.

Osteoarthritis is predominantly a disease of articular cartilage, which is composed mainly of water, collagens, and proteoglycans. Chondroitin sulfate and keratin sulfate (glycosaminoglycan side chains) are attached to a protein core forming proteoglycans. These in turn bind with hyaluronic acid (glycosaminoglycan) and proteins, contributing to cartilage stability and strength. Collagens, especially type II (the major type in hyaline cartilage), also play a key 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 ultimately, by cartilage loss, which can result in bone-to-bone contact within the joint.

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

As a result of the depletion of glycosaminoglycans, the water content of cartilage increases. There is also an increase in matrix metalloproteinase enzyme activity, which plays a major role in the degradation of the extracellular matrix of cartilage and facilitates the breakdown of both proteoglycans and collagen.

Cells called chondrocytes proliferate 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 in the pathogenesis of osteoarthritis. The progression of osteoarthritis is often parallel with calcium phosphate crystal, calcium pyrophosphate, or hydroxyapatite accumulation in the joint fluid. This leads to release of enzymes (collagenases, stromelysin, and other proteases) and other factors (prostaglandin E2) that can augment cartilage degeneration.

Progression of the disease is inevitably 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 alterations in chondrocyte metabolism and matrix properties as well as increased production of proteolytic enzymes. It appears that multiple microfractures eventually lead to degradation and gradual loss of the 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 with resultant pain. Other pain generators include subchondral microfractures, irritation of sensory nerve endings in the synovium from osteophytes, periarticular muscle spasm, and bone angina from diminished blood flow and elevated intraosseous pressure. 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 (which may account for up to 40% to 60% of osteoarthritis), metabolic, biochemical, enzymatic, and biomechanical properties, as well as environmental factors. The pathogenesis of osteoarthritis of the knee is different between men and women. 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. Established 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 initiation than on progression. There is also evidence that a certain level of physical activity may have the same effect.

Some studies have demonstrated a strong association with heavy physical activity and the incidence of osteoarthritis of the knee, especially in elderly patients. This may be related to physiologic impairment (muscle weakness, proprioceptive defects, meniscal degeneration, or ligamentous tears) in the skeletal response to physical activity in older people. These biomechanical stresses may permit transmission of an increased load across affected osteoarthritic joints, leading to accelerated joint damage. Biomechanical and biochemical factors, age, sex, characteristics of the playing surface, duration and intensity of the sport, and history of joint injury or trauma (sudden or repetitive) are risk factors that most physicians would consider important in the development of exercise-related osteoarthritis of the knee.

Factors such as ligamentous instability and abnormal motion may also contribute to premature osteoarthritis of the knee. Running is a good example of these concepts. Despite the evidence that a moderate amount of running does not seem to augment 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 variances. 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 damaged cartilage and promote maintenance of the normal synovial joint structure, composition, and function. This is evident after a prolonged decrease in joint use (ie, after injury or trauma), when cartilage changes frequently occur. Protracted immobilization of the joints eventually causes irreversible damage to articular cartilage. This often includes contracture of periarticular dense fibrous tissues, muscles that act across the joint, articular cartilage loss, and infiltration of fibrofatty tissue into the joint cavity.

Up to a certain threshold, 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 deleterious, possibly because of repetitive subclinical injuries.

Another consistent 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 consistent 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.

Gender is another critical factor for osteoarthritis of the knee. An increase in body weight has been associated with osteoarthritis of the knee in women but not statistically significant in men. Reduced quadriceps muscle strength relative to body weight may be a risk factor for osteoarthritis of the knee in women. Quadriceps strength was found to be about 15% to 18% less among women with radiographic evidence of osteoarthritis of the knee compared with normal subjects. This relationship did not hold true for men.

Estrogen deficiency may also play a role in the development of osteoarthritis in women. Postmenopausal estrogen replacement therapy may have a moderately protective effect on the incidence and progression of radiographic osteoarthritis of the knee in elderly women.

The insidious onset with gradual progression of aching pain is usually the initial symptom of osteoarthritis, but patients may remain asymptomatic. The pain may be localized to the knee or radiate widely. 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, which may indicate patellofemoral joint involvement. Initially, the pain improves with rest, but with disease progression, the pain may occur both at rest and at night. Weather patterns 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 a sensation of crepitus. Compared with rheumatoid arthritis, morning stiffness associated with osteoarthritis usually lasts for 15 to 20 minutes or less. Patients also describe the "gel phenomenon" (stiffness with rest and inactivity) that resolves within a few minutes of activity. As osteoarthritis of the knee progresses, patients complain of sensations of instability with buckling or giving out and diminished range of motion. Patients may even report locking or catching of the knee secondary to intra-articular loose bodies from degenerative pieces of cartilage shed into the joint. 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. Medial compartment osteoarthritis (OA) is more frequent than lateral compartment OA and commonly follows damage to the meniscus ('knee cartilages'), the medial meniscus being more vulnerable to injury than the lateral meniscus. Take out the whole meniscus on the medial side ('total meniscectomy') and the altered forces will eventually result in medial compartment OA, the joint space on that side will collapse, the bone will try to heal things by pushing out bridges of bone, further distorting the anatomy, the cartilage will become under stress and eventually break down.

The same think may happen on the lateral side, but this is less common due to biomechanical factors in the menisci. Take out the whole meniscus on the lateral (outer) side and eventually lateral compartment osteoarthritis will develop, with the leg will become knock-kneed - the opposite of medial compartment OA.

OA of medial or lateral compartment may also follow an injury, where a chondral defect may have occurred - a chunk of joint surface knocked off into the joint, leaving a crater in the joint surface and a 'loose body' in the joint cavity. Or untreated cruciate ligament damage may cause joint instability and joint surface and meniscal damage - leading to OA.

The pathologic changes of synovial fluid hyaluronic acid, with its decreased molecular weight and concentration, led to the concept of viscosupplementation. The exact mechanism of action of viscosupplementation is unclear. Although restoration of the elastoviscous properties of synovial fluid seems to be the most logical explanation, other mechanisms must exist. The actual period that the injected hyaluronic acid product stays within the joint space is on the order of hours to days, but the time of clinical efficacy is often on the order of months. Other postulated mechanisms to explain the long-lasting effect of viscosupplementation include possible anti-inflammatory and antinociceptive properties, or stimulation of in

Multiple studies have been conducted to evaluate the efficacy of intra-articular hyaluronan injections. Initial studies in the 1970s and 1980s demonstrated benefits for hyaluronan-injected knees.

In contrast to some trials which demonstrated no or minimal beneficial effects from intra-articular hyaluronan, other randomized controlled studies suggest overall beneficial effects of hyaluronan over placebo.

In a meta-analysis of eight hyaluronan trials involving 971 patients, outcomes in patients treated with hyaluronan were superior to outcomes in patients treated with placebo at the end of the treatment cycles and after six months.

Clinical studies have been conducted using cross-linked hylan in the treatment of knee osteoarthritis. These have demonstrated statistically significant benefits. In addition, findings from a clinical practice confirm these results. In most of the trials of hyaluronan and hylan, rates of adverse reactions have been low (generally zero to 3 percent). No systemic reactions were attributed to hyaluronic acid. Most of the reported adverse reactions consisted of minor localized pain or effusion, which was almost always resolved within one to three days. No long-term side effects have been reported.

The ideal candidate for intra-articular hyaluronic acid has yet to be defined. Studies are inconclusive regarding the best responders with respect to age, level of osteoarthritis as defined radiographically, level of symptoms and level of physical activity. Intra-articular hyaluronic acid injections should be considered in patients with significantly symptomatic osteoarthritis who have not responded adequately to standard nonpharmacologic and pharmacologic treatments or are intolerant of these therapies (e.g., gastrointestinal problems related to anti-inflammatory medications). Patients who are not candidates for total knee replacement or who have failed previous knee surgery for their arthritis, such as arthroscopic debridement, may also be candidates for viscosupplementation. Total knee replacement in younger patients may be delayed with the use of hyaluronic acid.

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A variety of other 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 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 exacerbated 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 markedly 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 by reducing the varus thrust and moment, medial compartment load, and the adduction moment.

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) and clean the joint (a process called "lavage" or "irrigation"). If other problems are discovered, such as a torn meniscus (a C-shaped piece of cushioning in the knee) or a damaged ligament, they can be corrected during the same surgery.

Arthroscopy can be helpful if your joint pain results from a tear in the cartilage or meniscus, or if bits of debris are causing problems in bending or straightening the joint. In people under age 55, arthroscopic surgery may help delay the need for more serious surgery such as a joint replacement. As with any surgery, there are some risks due to the use of anesthesia and the possibility of infection. Other complications may include damage to nerves or blood vessels, the development of blood clots in veins and scarring.

Arthroscopy is not the best option for everyone. Although the puncture wounds are small and pain is minimal, it takes several weeks for the joint to recover fully. Your physician will prescribe a specific activity and rehabilitation program to encourage recovery and protect future function of the joint.

An osteotomy may be recommended if damage to your knee cartilage is primarily in one section (compartment) of the knee. The inside (medial) compartment, where the inner knob of the thighbone (femoral condyle) meets the top of the shinbone (tibia), is most commonly involved. An osteotomy also may be recommended if a broken knee does not heal properly. This procedure involves reshaping the bones to improve knee alignment. The surgeon repositions the joint to move the mechanical axis of weightbearing for the limb away from the damaged area. This shifts weightbearing stresses from the damaged section to a healthier part of the knee. An osteotomy can restore knee function and diminish osteoarthritis pain. It may even stimulate the growth of new cartilage. Although an osteotomy can decrease pain and improve function, the results often deteriorate over the long term. Many people who have an osteotomy will eventually need a total knee replacement (arthroplasty). As with all surgeries, there is a slight possibility of infection, complications from the anesthesia or other surgical complications such as blood clots, nerve damage and circulation problems. There will be a cosmetic difference between the surgically-treated knee and the untreated knee.

An arthroplasty is a joint replacement procedure. If your OA Knee pain is severe and significantly limits your movement, your physician may recommend that the diseased bone and tissue be replaced by an artificial joint. If your 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 replacment parts are made of cobalt-chrome or titanium metals and smooth, wear-resistant plastic (polyethylene).

The results of total joint replacement are generally excellent. Patients experience significant pain relief and improved physical functioning. There are some 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.

The orthopaedic surgeon should discuss the type of knee replacement, the type of surgery (minimal incision or standard incision), the potential risks and the rehabilitation protocol with you before you make your decision.

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:

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

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