Osteoarthritis (OA), or degenerative joint disease, is the most common form of arthritis, affecting more than 32.5 million adults in the United States.1 Osteoarthritis results from damage to or breakdown of cartilage between bones, with the knee being the most common lower-limb joint affected by OA. The prevalence of knee osteoarthritis significantly increases with age.1
Risk Factors for Knee OA
Knee OA is a multifactorial disease, with many risk factors playing a role in symptomatic findings and disease progression. Risk factors for knee OA include obesity, physical stress at work, previous trauma or injury to the knee, genetics, and gender (occurs more commonly in women than men).1,2
Common knee surgeries, such as anterior cruciate ligament (ACL) repair and arthroscopic meniscal surgery, may increase a patient’s risk of developing OA,3 in part because of alterations in gait after surgery. Evidence also suggests that varus malalignment increases the risk of developing OA in the medial tibiofemoral aspect of the knee.4 In patients who are obese, increased compressive load on the medial compartment during weight-bearing activities can result in medial tibiofemoral OA.4
It is important for primary care providers to educate their patients about modifiable risk factors for knee OA, such as obesity, so that patients can incorporate changes into their daily routine to improve symptoms of knee pain.
Symptoms and Diagnosis of Knee Osteoarthritis
Chief complaints from patients with knee OA may include, but are not limited to, knee pain (including at night), loss of function, stiffness, swelling, decreased range of motion, limitations in activities of daily living, and disability.1
A thorough evaluation of a patient’s history can help identify risk factors or potential causes of knee OA. Clinical and physical examination findings also should be considered when diagnosing knee OA.1
Radiographs of the knee in patients with OA show cartilage loss and the resultant narrowing of the joint space and bone spurs around the joint (Figure).5 However, symptom severity in knee OA does not always correspond with radiologic findings.6 Pain is a subjective finding, making it difficult to determine why some people with OA are more symptomatic than others.
Once a diagnosis is made, it is important to identify the best treatment option for each patient.
Treatment Options for Knee Osteoarthritis
Osteoarthritis is a chronic, progressive disease, and treatment goals are targeted toward managing symptoms and slowing disease progression. A wide variety of conservative treatment options are available for knee OA.6-8
First-line pharmacologic treatment options for knee OA include topical or oral nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroid injections.8 However, these options may be limited by adverse effects and are not recommended for long-term use.8 Other recommended treatments include acetaminophen, duloxetine, topical capsaicin, and tramadol.8
Nonpharmacologic options such as lifestyle recommendations — exercise (walking, strength training, neuromuscular training, and aquatic exercise), tai chi, tibiofemoral knee braces, canes, and weight loss — are strongly recommended for people with knee OA. Alternative therapies that may reduce OA pain complaints include acupuncture, cognitive behavioral therapy, kinesiotaping, patellofemoral braces, radiofrequency ablation, thermal interventions, and yoga.8 The therapeutic effectiveness of these alternative therapies, however, has not been confirmed.7,8
When knee OA becomes refractory to conservative treatment measures and a patient’s quality of life is affected, surgical options should be considered. Several surgical options are considered curative treatments for knee OA. Common surgeries to treat knee OA include total knee replacement (TKR), unicompartmental knee replacement, osteotomy, arthroscopy, and cartilage repair.6
Multiple variables must be considered when determining which treatment option or surgical procedure is most appropriate for a patient. Weight management interventions are an important step, regardless of whether a patient undergoes conservative or surgical treatment for knee OA.