Tips for Diagnosis and Management of Knee Osteoarthritis (OA)

Download PDF of below Clinicians Tips for the Diagnosis and Management of Knee Osteoarthritis (OA)

Diagnosis of Knee Osteoarthritis (OA)

Risk factors and History

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Risk Factors

  • The main risk factors associated with knee OA are age, female sex, and obesity.
  • Ask about prior knee injuries or surgeries. Up to 50% of individuals with an ACL rupture will develop knee OA within 10–20 years.
  • Genetics are also relevant, ask about a family history of total knee replacement for OA in a biologic parent or sibling.
  • Occupations that involve sustained kneeling or squatting or heavy manual work (e.g., farming, construction) are associated with knee OA.
  • Some local mechanical factors are also relevant such as knee malalignment and quadriceps muscle weakness.
  • Recreational running is not associated with an increased risk of knee OA.
  • The presence of Heberden's nodes (hard soft tissue or bony swellings at DIP joints) are associated with an increased incidence and progression of knee OA.

Clinical Features

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  • Diagnosis is primarily based on patient history and physical examination. Knee OA can be diagnosed clinically without imaging in patients aged ≥45 years presenting with activity-related joint pain and with no or less than 30 min of morning stiffness (NICE guidelines, 2022)
  • Other international guidelines for knee OA specify the presence of one or more clinical features on clinical exam (crepitus, restricted ROM, bony enlargement).
  • Symptoms usually start gradually with a prolonged history of discomfort, interspersed with self-limited flare-ups.
  • Pain is typically related to weight-bearing activity (prolonged standing, walking, stairs) that worsens with activity and improves with rest. Ask about symptoms like stiffness, particularly after long periods of inactivity.
  • Three out of four patients with knee OA report some symptoms of knee instability or ‘giving way’. Changes in neuromuscular control (impaired proprioceptive feedback and altered motor patterns) is one of the principle reasons for these ‘giving way’ episodes.
  • Mechanical symptoms like (clicking, pseudo-locking, catching) are commonly reported in knee OA and associated with articular cartilage changes.
  • Clinical features of more advanced OA presentation are a knee flexion contracture, restricted knee flexion, bony enlargement (or a thickened knee joint) and crepitus.
  • Changes in knee joint alignment is also associated with more advanced disease. Varus (bow-legged) deformity due to cartilage loss in the medial compartment, and valgus (knock-knee) deformity occurs due to joint space narrowing in the lateral compartment.

Differential Diagnosis

  • In a study of primary care radiographs of knee OA, only 0.5% (5/1,334) revealed conditions needing further investigation or specific treatment (osteonecrosis, osteochondral lesion, fracture and subluxation).
  • Suspect rheumatoid arthritis with a swollen red tender joint, greater than 30 minutes morning stiffness and raised inflammatory markers.
  • Suspect gout in a person with a history of gout, if the onset is sudden and unexplained (often at nighttime), and pain is very acute and severe.
  • Suspect septic arthritis in the presence of fever and acute onset of pain and redness. Joint aspiration may be needed to rule this out.
  • Suspect subchondral insufficiency fractures (previously known as spontaneous osteonecrosis) in older females with low bone density with acute onset of severe pain and progressive difficultly weight-bearing or deteriorating gait.

Imaging

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  • Imaging is not necessary to diagnose knee OA, this can be done based on history and physical exam. Neither is imaging necessary to guide non-surgical management.
  • In the presence of severe pain, if non-surgical treatment is ineffective, plain film x-rays, may be helpful to guide referral to an orthopedic surgeon. These are usually performed in standing to reveal the extent of joint space narrowing of the tibiofemoral joint.
  • Imaging is indicated when the clinical assessment cannot rule out serious pathology. For example, when there is a rapid deterioration in pain and function or clinical characteristics are inconsistent with OA (constant unremitting pain, difficultly weight-bearing etc).
  • Utilisation of MRI is not recommended for knee pain in middle-aged and older adults with no history of significant trauma.
  • Early access to MRI for knee symptoms is associated with higher health care utilisation without superior health outcomes.

Management of Knee OA

Education

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  • Educate patients by discussing their diagnosis, prognosis and treatment options (See Tiers of Treatment below). Teach them about load management, monitoring their pain response to exercise and what measures they can take to improve their long-term knee health.

  • Modern explanations of OA take the emphasis off a “wear and tear” disease. Instead conceptualise it as a maladaptive repair response and describe OA as an “imbalance between joint tissue breakdown and repair”. Use language with patients that communicates positive expectations and reassures people that they can live well with knee OA.
  • Educate patients about likely prognosis. The condition does not always worsen over time, but symptoms typically fluctuate. Patients who believe a knee replacement is inevitable can perceive that non-surgical management is futile
  • Studies of 5-year pain trajectories for knee OA found the majority of participants fluctuated symptomatically but did not deteriorate. This is reflected in a radiographic study where knee OA structural changes remained relatively stable over 8 years for 85% of people.
  • It is reassuring for patients to know that pain flares are a normal part of OA symptom behaviour, and do not necessarily represent a deterioration in their overall condition.
  • Pain is a sign of tissue sensitivity rather than a direct measure of tissue damage. Structural changes are important but other factors also influence the amount of pain experienced.
  • Symptoms such as pain, locking, catching and ‘giving way’ can make patients fearful of being active. Educating patients that these that are typical of knee OA can help de-threaten them.
  • Emphasise the modifiable aspects of joint health; that joint tissues are living and adaptable, that articular cartilage responds well to loading, and physical activity makes it healthier.
  • Educate about maintaining a healthy lifestyle as far as possible. Systemic inflammation associated with obesity and metabolic conditions can drive disease progression.
  • Educate patients about optimal load for a healthy knee joint. Sustained and excessive loading (like some elite level sports) can drive cartilage breakdown, but too little loading (a sedentary lifestyle) will cause cartilage thinning. Physical activity and exercise at a moderate level is considered protective.
  • Explore and address other wider factors beyond the knee that influence knee health - poor sleep, elevated stress, pain-related fear of movement and sedentarism.

Exercise

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  • The effects of exercise on pain are small to moderate (equivalent to an oral NSAIDs) in short term studies. Longer term exercise adherence is likely to have important benefits for mood, comorbidities, systemic inflammation, BMI, muscle strength and other factors that can determine the progression of the condition.
  • Structured exercise interventions that typically focus on strengthening of lower extremity muscles offer improvements in pain and function and should be carried out at least twice per week.
  • Aerobic exercise is also important. If starting from 0 minutes of activity, a daily 10-minute walk is a good starting point. Build to 30-minutes of activity on at least 5 days per week. Discuss with the patient which activities they enjoy as they are more likely to adhere to the programme. Social motivation also increases adherence so encourage family and friend support.
  • It is reassuring for patients to know that pain flares are a normal experience with an increase in activity. This does not mean that the activity is causing harm or joint damage. The body’s response to increased activity will settle after a period of time and they can expect pain to reduce to baseline again.
  • Approach a discussion on exercise like a ‘behavioural change conversation’ rather than an education session. Explore with the patient any potential barriers. Use goal setting and action planning tools (see Resources section) to support these conversations.
  • Determine the patient’s current level of activity, ability and confidence to exercise and prescribe exercise or refer appropriately based on this. Follow the Physical Activity Pathway in Healthcare in Ireland model. Some patients may need referral to a physiotherapist while others may benefit from a brief intervention and signposting to programmes or activities available in the community (e.g. Local Sports Partnerships, walking groups). Additional information on community initiatives can be found here.
  • Consider social prescribing as a means of referring people to a range of non-clinical community supports, it may help people with comorbid conditions and poor social support. https://www.hse.ie/eng/about/who/healthwellbeing/our-priority-programmes/mental-health-and-wellbeing/social-prescribing/

Weight Management

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  • Weight gain is associated with accelerated structural disease progression (decrease in cartilage volume, synovitis, bone marrow lesions) in knee OA, compared to those with a stable weight. Weight loss, however, does not reverse these structural changes, therefore raising patient awareness about avoiding weight gain is important.

  • International clinical guidelines recommend weight loss for knee OA in people with overweight or obesity.
  • In trials of weight loss to treat knee OA, a 10% reduction in body weight is associated with a 50% reduction in knee symptoms.
  • Weight loss trials in knee OA have involved intensive interventions with very low calorie diets. Follow-up studies indicates that improvements from these interventions are difficult to maintain in the longer term.
  • People with obesity or who are overweight should be supported to lose weight. While there is a dose response in symptom reduction, any amount of weight reduction is beneficial.
  • New evidence has emerged on the use of GLP1-Agonists from the STEP 9 trial. Once weekly semaglutide was compared to placebo in people with obesity and moderate knee OA. At 68 weeks, improvements in pain were significantly better in the semaglutide group than in the placebo group (decrease of 42 vs. 28 points, from a mean baseline of 71/100 points). Drop-out rate in the semaglutide group was higher due to gastrointestinal side effects.
  • There is no particular diet recommended for people with OA. Following the national healthy eating guidelines is generally recommended, along with avoiding high alcohol intake and ultra-processed (high fat, sugar, salt) foods.

Medications, Injections and Other Treatments

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  • Currently no disease modifying drugs exist for knee OA. Medications and injections are considered second line treatments after the core treatments of exercise and weight management.
  • Topical NSAIDs are recommended above oral NSAIDs due to a better safety profile.
  • Oral NSAIDs can be effective in reducing pain in knee OA, however due to their risk of adverse events they should be used with caution especially in older patients and people with multiple comorbidities. They are generally not considered safe for long term use.
  • NSAID risk should be mitigated by regularly monitoring for adverse reactions, minimising dose and keeping treatment duration brief.
  • Paracetamol is no longer recommended due to limited efficacy and safety considerations connected to its long-term use (such as liver toxicity).
  • Weak opioids (e.g codeine) have limited efficacy for knee OA and are only recommended if a patient cannot take NSAIDs. Strong opioids should not be used to treat OA pain as the risks outweigh the benefits.
  • Corticosteroid injections are recommended by NICE guidelines for their short-term efficacy (moderate quality evidence). Long-term use is not supported by current evidence and repeat injections may cause cartilage damage.
  • NICE recommends against hyaluronic acid (low quality evidence) as second-line treatment.
  • Platelet rich plasma (PRP). In the RESTORE trial, adults with mild to moderate knee OA who received PRP injections (x 3) did not have less knee pain or less disease progression compared to saline injections at 12-month follow-up. PRP is not currently recommended by the NICE guidelines.
  • There is currently a lack of evidence for stem cell therapy and clinical guidelines do not support their use.
  • Supplements like glucosamine and chondroitin have not been shown to be helpful.
  • There is no good evidence that electrotherapy such as a TENS machines, acupuncture, insoles or special footwear are helpful for knee OA.

Surgery

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  • Total knee arthroplasty (TKA) is indicated when weight bearing x-rays indicates advanced OA (minimal or no joint space) and the patient reports severe functional limitations and persistent/severe pain disrupting sleep, despite optimal non-surgical management.
  • About 80% of patients undergoing TKA report substantial improvements in pain; however up to one-third report unfavourable outcomes between 3 months and 5 years post-op.
  • Arthroscopic lavage and debridement are not recommended for knee osteoarthritis. There is substantial evidence to suggest this procedure has no clinically meaningful benefit over placebo.
  • How long does a knee replacement last? A review using national joint registry data found approximately 82% of TKAs and 70% of unicondylar knee replacements last 25 years.
  • Data from the NHS suggests two-thirds of patients (65.6%) achieved a clinically meaningful improvement in joint function after elective revision of TKA. Almost half of patients reported one or more adverse events.
  • An online decision-making tool from the U.K. National Joint Registry can be used with the patient. It provides the benefits and risks of surgery.

Download Tips for Diagnosis and Management of Knee Osteoarthritis (OA) PDF
SOURCES OF INFORMATION

The information in this website page was informed by the following sources/references:

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  • Bliddal, H, et al. Once-Weekly Semaglutide in Persons with Obesity and Knee Osteoarthritis
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