Knee osteoarthritis involves cartilage changes that may lead to pain, stiffness, and reduced mobility, affecting daily activities like walking, climbing stairs, and standing from seated positions. Injection therapies deliver medication directly into the joint space, targeting inflammation or joint lubrication and aiming to provide pain relief when oral medications prove insufficient. Two commonly used injection types address osteoarthritis symptoms: corticosteroids, which may help reduce inflammation and pain in the short term, with many patients noticing improvement within the first one to two weeks, and hyaluronic acid, which supplements joint fluid and may provide more gradual symptom relief over several weeks, with onset typically later than corticosteroids.
Corticosteroids may help calm inflammatory activity within the joint, while hyaluronic acid aims to supplement the joint’s natural cushioning. Corticosteroid effects are typically short-term, and recommendations on hyaluronic acid differ between professional bodies. The choice depends on arthritis severity, previous treatment responses, and individual factors such as age, activity level, and other medical conditions.
Types of Knee Injections
Corticosteroid Injections
Corticosteroids such as triamcinolone or methylprednisolone are anti-inflammatory medications that may help reduce inflammation within the knee joint. Some patients experience improvement within a few days, although the duration of relief varies between individuals. Doctors generally limit the frequency of corticosteroid injections and assess the risks and benefits based on each patient’s condition.
During the procedure, the doctor cleanses the injection site with antiseptic solution, may apply topical anaesthetic, and uses anatomical landmarks or ultrasound guidance to help ensure accurate needle placement. The injection takes around 30 to 60 seconds, with most patients describing a pressure sensation rather than sharp pain.
Hyaluronic Acid Injections
Hyaluronic acid (viscosupplementation) aims to supplement the knee’s natural joint fluid, which may become less effective with osteoarthritis. Depending on the specific formulation, treatment may involve a single injection or a series of injections. These injections are intended to improve joint lubrication and cushioning, with outcomes varying between individuals.
Relief may develop gradually over several weeks after completing the injection series, with the duration of benefit varying between individuals. The effect relates to hyaluronic acid’s role in supporting joint lubrication rather than directly reducing inflammation. Some patients may experience temporary mild swelling or discomfort following the injection, which usually settles within a short period.
Before Your Injection
Pre-Procedure Preparation
Continue your current arthritis medications unless specifically instructed otherwise by your doctor. Inform your doctor about blood thinners, diabetes medications, or recent infections, as these may affect injection timing or technique.
Wear loose-fitting shorts or pants that easily roll above the knee. Arrange transportation if you have concerns about driving immediately post-procedure, though most patients are able to drive themselves home. Eat normally before the appointment unless receiving sedation for significant needle anxiety.
Medical History Review
Your orthopaedic surgeon will review previous imaging studies, including X-rays showing joint space narrowing, osteophyte formation, and subchondral changes. MRI findings, where available, help guide injection placement and type selection.
Documenting previous injection responses, including duration of relief and any adverse reactions, along with current pain levels, functional limitations, and previously tried treatments, helps your doctor set realistic expectations and select an appropriate injection type.
During the Procedure
Injection Process
The procedure typically begins with knee positioning, generally slight flexion at 20 to 30 degrees using a rolled towel under the knee. The doctor palpates anatomical landmarks, including the patella, joint line, and soft tissue depressions, to identify the injection site. Ultrasound guidance may help improve accuracy, particularly for patients with a higher body weight or significant joint changes.
After sterile preparation and draping, a fine needle enters the joint space through one of several standard approaches. Aspiration of existing joint fluid may occur before the injection, particularly if effusion is present. The injection itself takes around 30 to 60 seconds.
Immediate Sensations
Patients typically feel initial pressure as the needle enters the joint capsule, followed by a sensation of fullness as the medication enters the joint space. Corticosteroid injections rarely cause discomfort beyond the needle insertion. Hyaluronic acid may create temporary tightness due to the added volume.
💡 Did You Know?
The knee joint normally contains a small amount of synovial fluid, but injection volumes are generally well tolerated as the joint capsule stretches slightly to accommodate the additional fluid.
Immediate Post-Injection Period
First 24 to 48 Hours
Apply ice packs for 15 to 20 minutes every 2 to 3 hours to help manage injection site discomfort and swelling. Avoid excessive walking, standing, or strenuous activities for 48 hours to allow the medication to distribute throughout the joint. Continue regular daily activities but postpone exercise, sports, or physical therapy during this period.
Monitor for signs of infection, including increasing pain, warmth, redness, or fever above 38°C. These symptoms are rare but require prompt medical evaluation. Mild injection-site tenderness and slight swelling are common and typically resolve within a few days.
Activity Modifications
Resume normal walking after 48 hours, gradually increasing distance and duration. You can generally resume low-impact exercises like swimming or cycling after about a week.
Physical therapy may resume within the first week post-injection, focusing initially on range of motion and gentle strengthening. Avoid deep squats, lunges, or high-impact activities until pain relief stabilises. Your orthopaedic surgeon will provide a specific timeline based on your response.
Recovery Timeline
Week 1 to 2
Corticosteroid recipients often experience a meaningful reduction in pain by day 3 to 5, with peak effect around 7 to 14 days. Hyaluronic acid shows minimal early change as the medication integrates with existing joint fluid.
Tracking pain levels, stiffness duration, and functional changes using a daily log, along with activities that increase or decrease symptoms, can help guide future treatment decisions and identify an appropriate injection interval.
Week 3 to 4
Hyaluronic acid effects often become noticeable as joint lubrication improves and mechanical symptoms decrease for some patients. Patients report easier stair climbing, reduced start-up stiffness, and improved walking tolerance. Corticosteroid effects may remain stable or gradually decline, depending on the initial response.
Months 2 to 6
Monitoring injection duration helps plan any repeat treatment before symptoms fully return. Corticosteroid effects typically wane by month 3, while hyaluronic acid may provide relief through month 6 or longer for some patients. Maintaining exercise programmes and weight management may help support the benefits of injection therapy.
⚠️ Important Note:
A sudden loss of injection benefit with increased pain or swelling warrants medical evaluation to help rule out infection, crystal arthropathy, or a mechanical problem such as a meniscal tear.
Managing Side Effects
Common Reactions
A post-injection flare occurs in some patients, causing increased pain and swelling 6 to 24 hours after injection. This is thought to relate to crystallisation of corticosteroid particles or an inflammatory response to the injection volume. Management generally includes ice application, paracetamol, and activity restriction for 24 to 48 hours.
Hyaluronic acid may, rarely, cause a pseudoseptic reaction, with significant swelling and warmth that can resemble infection. Joint aspiration and fluid analysis can help distinguish this sterile inflammation from a true infection. Symptoms generally resolve with ice, rest, and anti-inflammatory medication as advised by your doctor.
When Complications Require Medical Attention
Seek prompt evaluation for fever above 38°C, severe pain preventing weight-bearing, or visible redness spreading beyond the injection site. Joint infections are rare but require prompt treatment. Persistent numbness, weakness, or colour changes should also be assessed promptly.
Optimising Injection Results
Physical Therapy Integration
A structured exercise programme may help support and prolong injection benefits through improved muscle strength, joint stability, and movement patterns. Quadriceps strengthening may help reduce patellofemoral stress and support shock absorption. Hip abductor exercises may help support alignment and reduce medial compartment loading.
Range of motion exercises may help maintain joint flexibility gained through injection pain relief. Manual therapy techniques may help address soft tissue restrictions and support joint mechanics. Your physiotherapist can coordinate treatment timing with your injection schedule.
Lifestyle Modifications
Weight management may help significantly reduce knee joint forces during walking for many patients. Low-impact exercises like swimming, water aerobics, and cycling may help maintain fitness without excessive joint stress. Proper footwear with cushioned soles and arch support may help support lower extremity alignment.
Dietary choices including omega-3 fatty acids, antioxidants, and adequate protein may support general joint health. Avoiding prolonged kneeling, squatting, or sitting in low chairs may help reduce strain on arthritic joints. Assistive devices like handrails and raised toilet seats may help reduce knee strain during daily activities.
✅ Quick Tip
Schedule injections to allow recovery time before important events or travel; planning procedures at least two weeks ahead of significant physical activities or long flights may help.
What Our Orthopaedic Surgeon Says
Injection timing matters as much as injection type. Early intervention, once oral medications become insufficient, may in some cases provide better, longer-lasting results than waiting until more advanced arthritis develops. I evaluate each patient’s activity goals, arthritis pattern, and previous treatment responses to help select an appropriate injection.
Many patients benefit from combining approaches: using corticosteroids for acute flares and hyaluronic acid for more sustained management. Success depends on realistic expectations, appropriate patient selection, and a comprehensive treatment plan that includes exercise and weight management. Injections may help buy time and support quality of life, but they work best as part of an integrated treatment approach.
Putting This Into Practice
- Schedule injections during periods of lower activity demands, allowing adequate recovery before important events or travel plans
- Keep a symptom diary documenting pain levels, functional abilities, and activity tolerance to help track injection effectiveness over time
- Develop a home exercise routine focusing on quadriceps strengthening, flexibility, and low-impact cardiovascular fitness
- Establish regular follow-up intervals to assess your response and help plan any repeat treatment before symptoms fully return
- Create environmental modifications at home and work to help reduce knee stress during daily activities
When to Seek Professional Help
- Knee pain limiting daily activities despite oral medications
- Morning stiffness lasting more than 30 minutes
- Difficulty with stairs, rising from chairs, or walking distances
- A previously effective injection now providing less relief
- Swelling that persists despite rest and elevation
- Mechanical symptoms like catching, locking, or giving way
- Night pain disturbing sleep quality
- Failed conservative treatments including physical therapy
Commonly Asked Questions
How painful is the injection itself?
Most patients rate injection discomfort as mild, broadly similar to a blood draw. The initial skin penetration may cause a brief sharp sensation, followed by a feeling of pressure as the medication enters the joint. A topical anaesthetic spray or ice may help reduce skin discomfort. The entire procedure typically takes a few minutes, including positioning and sterile preparation.
Can I drive myself home after the injection?
Most patients are able to drive themselves without difficulty. The injected knee may feel slightly different due to the added fluid volume, but this rarely affects driving ability. If you receive sedation for significant anxiety or have concerns about pedal control, arrange alternative transportation.
How do I know which injection type is right for me?
Your orthopaedic surgeon will consider arthritis severity on imaging, previous treatment responses, activity goals, and other medical conditions. Mild to moderate arthritis often responds well to hyaluronic acid, while inflammatory flares may be considered for corticosteroid injections. Your doctor can advise which option, if either, fits your specific situation.
What happens if injections stop working?
Decreasing injection effectiveness may indicate that arthritis has progressed, warranting a treatment review. Options may include trying a different injection type, adjusting the treatment plan, or discussing surgical options. Some patients maintain good function with regular injections for a considerable time before surgery becomes necessary.
Are there alternatives if I can’t have certain injections?
Medical conditions, allergies, or a poor response may limit some injection options. Alternatives that may be discussed include different medication approaches or, in some cases, surgical assessment. Your surgeon can discuss suitable options based on your individual circumstances.
Next Steps
Knee injections may offer pain relief and functional improvement for osteoarthritis when oral medications have proven insufficient. Good outcomes generally depend on selecting an appropriate injection type, timing treatment appropriately, and maintaining a broader arthritis management plan that includes exercise and lifestyle adjustments.
If you’re experiencing persistent knee pain, stiffness, or functional limitations from osteoarthritis, our accredited orthopaedic surgeon can evaluate your condition and discuss injection options tailored to your specific needs.
