Introduction

Understanding Knee Osteoarthritis

Knee osteoarthritis (OA) is one of the most common causes of chronic pain, stiffness and reduced mobility worldwide. It develops when the smooth cartilage that normally cushions the ends of the bones gradually deteriorates, resulting in increased joint stress, inflammation, stiffness and pain. Over time, changes can also occur in the underlying bone, synovial lining, ligaments and surrounding muscles, making osteoarthritis a complex whole-joint disease rather than simply a problem of worn cartilage.

Although osteoarthritis becomes more common with age, it is not an inevitable consequence of getting older. Previous injuries, excess body weight, repetitive joint loading, genetic factors and biomechanical abnormalities can all contribute to the development and progression of the condition. Symptoms often include pain during walking, climbing stairs, prolonged standing, rising from a chair, or after periods of inactivity. Many patients also experience stiffness, swelling, reduced confidence in the knee and a gradual decline in physical activity.

The good news is that there are now more treatment options available than ever before. Whilst osteoarthritis cannot currently be reversed, a wide range of non-surgical treatments can help reduce pain, improve function and quality of life, and in some patients delay the need for knee replacement surgery.

Why Symptoms and X-Rays Often Do Not Match

One of the most important concepts in knee osteoarthritis is that the severity of symptoms does not always correlate with the severity of changes seen on an X-ray. Some people with severe “bone-on-bone” osteoarthritis may report relatively little pain, while others with only mild structural changes can experience significant discomfort and disability.

This apparent mismatch occurs because pain arises from multiple structures within and around the joint. Inflammation of the synovial lining, irritation of the bone beneath the cartilage, muscle weakness, altered movement patterns and sensitisation of the nervous system can all contribute to the pain experience. Psychological factors, sleep quality, stress levels and general health can also influence how symptoms are perceived.

For this reason, treatment decisions should never be based solely on imaging findings. A patient’s symptoms, functional limitations, lifestyle, goals and expectations are often more important than the X-ray appearance alone when deciding which treatment is most appropriate.

Why Many Patients Want to Avoid or Delay Knee Replacement

Knee replacement surgery remains one of the most successful orthopaedic procedures available and can be life-changing for appropriately selected patients. However, not everyone wishes to proceed directly to surgery, and many patients seek effective alternatives before considering joint replacement.

Some individuals are simply not ready for surgery and wish to remain active while postponing a knee replacement. Others may have medical conditions that increase surgical risk, wish to continue working, participate in sport, or have personal reasons for preferring less invasive options. In addition, some patients may not yet have symptoms severe enough to justify major surgery despite significant osteoarthritic changes on imaging.

Over the past decade, several innovative non-surgical treatments have emerged. These range from established options such as corticosteroid injections and viscosupplementation, through to biologic therapies including platelet-rich plasma (PRP) and nSTRIDE, advanced interventional procedures such as genicular nerve radiofrequency ablation, and newer technologies such as Arthrosamid hydrogel injections.

The challenge for patients is that each treatment works in a different way, has different strengths and limitations, and is supported by varying levels of scientific evidence. The aim of this guide is to provide a balanced and evidence-based overview of the major non-surgical treatment options currently available for knee osteoarthritis, helping patients understand where each treatment may fit within their individual treatment journey.

What Happens Inside an Arthritic Knee?

Many people think osteoarthritis simply means that the cartilage has worn away due to ageing and years of use. Whilst cartilage damage is certainly an important part of the condition, modern research has shown that osteoarthritis affects the entire joint. The cartilage, bone, synovial lining, ligaments, muscles and even the nervous system can all contribute to symptoms. This helps explain why two people with similar X-rays may experience very different levels of pain and disability.

Understanding what is happening inside the knee also helps explain why different treatments work in different ways. Some treatments primarily target inflammation, others aim to improve the health of the joint environment, whilst procedures such as genicular nerve radiofrequency ablation reduce the transmission of pain signals without directly altering the arthritic process itself.

Cartilage Degeneration

Healthy cartilage provides a smooth, low-friction surface that allows the knee joint to move freely while distributing load across the joint. In osteoarthritis, this protective cartilage gradually becomes thinner, softer and less resilient. Small cracks may develop initially, followed by progressive loss of cartilage thickness over time.

As cartilage deteriorates, the ability of the joint to absorb shock becomes impaired. This leads to increased stress being transferred to the underlying bone and surrounding tissues. Patients often notice increasing stiffness, discomfort during weight-bearing activities and reduced tolerance for walking, climbing stairs or standing for prolonged periods.

Importantly, cartilage itself contains very few pain fibres. This means that cartilage loss alone does not fully explain the pain of osteoarthritis. Other structures within the joint often play a major role in symptom generation.

Synovial Inflammation

The synovium is the thin lining that surrounds the inside of the knee joint and produces the lubricating fluid that allows smooth movement. In many patients with osteoarthritis, this lining becomes inflamed, a process known as synovitis.

Synovial inflammation is increasingly recognised as one of the major drivers of pain in knee osteoarthritis. It contributes to swelling, warmth, stiffness and activity-related pain. Patients often notice that symptoms fluctuate over time, with periods of relative stability interrupted by painful inflammatory flares.

This inflammatory component helps explain why treatments such as corticosteroid injections can provide rapid symptom relief in selected patients and why newer biologic treatments such as PRP, nSTRIDE and Arthrosamid are thought to exert at least part of their effect through modification of the inflammatory environment within the joint.

Bone Changes

As cartilage loss progresses, the underlying bone is subjected to increasing mechanical stress. The bone may become thicker and denser in some areas, while new bony outgrowths known as osteophytes can develop around the margins of the joint.

In advanced osteoarthritis, narrowing of the joint space may eventually progress to so-called “bone-on-bone” disease. Although this term is commonly used, it is important to remember that not every patient with severe radiographic changes experiences severe pain. Likewise, some individuals with relatively modest X-ray changes can experience significant symptoms.

Changes within the bone beneath the cartilage are increasingly recognised as important contributors to pain generation and may partly explain why some patients experience deep aching pain even when there is relatively little visible inflammation.

Pain Mechanisms

Pain in osteoarthritis is complex and often arises from multiple sources simultaneously. The synovial lining, joint capsule, ligaments, surrounding muscles and the bone beneath the cartilage all contain pain-sensitive nerve endings capable of generating symptoms.

Over time, persistent pain can also alter the way the nervous system processes pain signals. This phenomenon, often referred to as sensitisation, may cause the knee to become more sensitive than would be expected based solely on the degree of structural damage. Patients may notice that pain becomes more widespread, more persistent or more easily triggered by everyday activities.

This understanding helps explain why treatments targeting pain transmission pathways, such as genicular nerve radiofrequency ablation, can provide meaningful symptom relief even though they do not directly alter the underlying osteoarthritic changes within the joint itself.

Why Osteoarthritis Is More Than “Wear and Tear”

The traditional view of osteoarthritis as a simple consequence of ageing and mechanical wear is now considered incomplete. Modern evidence suggests that osteoarthritis is a complex biological process involving mechanical stress, inflammation, changes in cartilage metabolism, alterations within the underlying bone and interactions with the nervous system.

This broader understanding is important because it explains why treatment approaches have evolved beyond simply managing symptoms. Some interventions aim to reduce inflammation, some seek to improve the joint environment, and others target the nerves responsible for transmitting pain signals. The increasing variety of available treatments reflects our growing understanding that osteoarthritis is not a single disease process but rather a combination of interacting mechanisms that vary from one patient to another.

How Knee Osteoarthritis is Graded

When discussing knee osteoarthritis, clinicians frequently refer to the Kellgren-Lawrence (KL) grading system. This is the most widely used radiographic classification system for describing the severity of osteoarthritis on plain X-rays. The grade provides an indication of the structural changes present within the joint and can help guide treatment discussions.

However, as discussed in the previous section, it is important to remember that osteoarthritis is far more complex than an X-ray image alone. While the KL grade provides useful information about structural disease severity, it does not always predict the amount of pain a person experiences or how much their daily activities are affected.

The Kellgren-Lawrence Grading System

Why Does the Grade Matter?

The severity of osteoarthritis can influence which treatments are most likely to be successful. Several of the treatments discussed later in this guide have been studied predominantly in patients with mild-to-moderate osteoarthritis (KL Grade 2–3), whilst others may still be considered in more advanced disease.

For example, the evidence summarised later in this article suggests that treatments such as PRP, nSTRIDE and genicular nerve radiofrequency ablation generally perform best in patients with Grade 2–3 osteoarthritis. Similarly, the available evidence for viscosupplementation (hyaluronic acid) is strongest in mild-to-moderate disease and is considerably less convincing in severe Grade 4 osteoarthritis.

In contrast, corticosteroid injections can be used across the full spectrum of disease severity, particularly when inflammation and swelling are prominent. More recently, treatments such as Arthrosamid have been studied in patients ranging from moderate to severe osteoarthritis, although the evidence base remains smaller than for some of the more established interventions.

Why Treatment Decisions Should Not Be Based on X-Rays Alone

One of the recurring themes throughout this article is that treatment decisions should never be based solely on imaging findings. The original studies discussed later repeatedly demonstrate that patient selection is often more important than the radiographic grade alone.

Some patients with severe Grade 4 osteoarthritis remain surprisingly active and manage their symptoms well with relatively simple measures. Conversely, some patients with only Grade 2 changes may experience significant pain due to inflammation, bone marrow irritation, muscle weakness or sensitisation of the nervous system.

For this reason, clinicians consider several factors when recommending treatment, including symptom severity, functional limitations, physical examination findings, the presence of inflammation, patient goals, overall health and previous response to treatment. The X-ray grade forms only one part of the overall clinical picture.

The Foundation of Treatment

Before considering injections or interventional procedures, it is important to recognise that every major international guideline recommends conservative management as the foundation of knee osteoarthritis treatment. In fact, one of the key messages from the evidence reviewed throughout this article is that no injection or procedure should be viewed as a substitute for maintaining joint health, muscle strength and physical activity.

The treatments discussed later in this guide can play an important role in reducing pain and improving function, but they are generally most effective when combined with appropriate exercise, weight management and rehabilitation strategies. Many patients achieve meaningful improvements without ever requiring invasive treatment, whilst others use injections or procedures to facilitate participation in rehabilitation that would otherwise be too painful.

Exercise — The Most Effective Non-Surgical Treatment

Exercise remains the single most consistently recommended treatment for knee osteoarthritis. Strong evidence demonstrates that regular, structured exercise can reduce pain, improve mobility, increase muscle strength and enhance overall quality of life.

Importantly, exercise does not need to be high-impact or excessively strenuous. Walking, cycling, swimming, resistance training and targeted strengthening exercises can all be beneficial. The goal is not simply to improve fitness but also to strengthen the muscles surrounding the knee, improve joint stability and reduce abnormal loading across the joint.

Many patients become less active because movement hurts, but reduced activity often leads to muscle weakness, reduced joint support and worsening symptoms over time. Breaking this cycle is one of the most important aspects of successful long-term management.

Weight Management

Excess body weight is one of the most important modifiable risk factors for knee osteoarthritis. Every step places several times body weight through the knee joint, meaning that even modest weight reduction can substantially decrease the mechanical load experienced by the joint throughout the day.

Weight loss can also reduce systemic inflammation, which may contribute to symptom improvement. Patients often underestimate how much difference a relatively small reduction in body weight can make to knee pain and function. For many individuals, weight management forms an essential component of any successful long-term treatment strategy.

Physiotherapy

Physiotherapy plays a central role in osteoarthritis management and is frequently recommended before considering injections or procedures. A physiotherapist can assess movement patterns, muscle weakness, flexibility deficits and biomechanical factors that may be contributing to symptoms.

Treatment often focuses on strengthening the quadriceps, improving hip and core stability, restoring flexibility and optimising gait mechanics. In addition to reducing pain, physiotherapy aims to improve confidence, balance and function, helping patients remain active and independent.

In many cases, injections are best viewed as tools that allow patients to engage more effectively with physiotherapy rather than as standalone treatments.

Bracing and Mechanical Support

Knee braces and walking aids can be useful in selected patients. Braces may help redistribute load away from the most affected compartment of the knee, improve stability and increase confidence during activity. Some patients report meaningful symptom improvement, particularly during walking and weight-bearing activities.

Walking poles, sticks and other assistive devices may also reduce stress on the joint and improve mobility. Whilst these interventions do not alter the underlying disease process, they can be valuable components of a comprehensive management plan.

Medications

A variety of medications may be used to help control symptoms. Topical anti-inflammatory gels are often recommended as a first-line option because they can provide local pain relief with fewer systemic side effects. Oral anti-inflammatory medications may also be effective for some patients, although they are not suitable for everyone and must be used with appropriate medical supervision.

Simple analgesics may have a role in selected patients, but long-term reliance on pain medication alone is rarely an ideal strategy. The goal should always be to improve function and quality of life rather than simply suppress symptoms.

Why Injections Should Not Replace Rehabilitation

One of the recurring themes throughout the treatments reviewed later in this article is that injections and procedures work best when incorporated into a broader rehabilitation programme. Even the most successful injection cannot restore muscle strength, improve balance, optimise biomechanics or address deconditioning caused by months or years of reduced activity.

Injections may reduce pain, control inflammation or improve function sufficiently to allow patients to exercise more effectively. They should therefore be viewed as part of a comprehensive treatment strategy rather than a replacement for exercise, physiotherapy and lifestyle modification.

This principle is particularly relevant when considering some of the more advanced treatments discussed later in this guide, including PRP, nSTRIDE, Arthrosamid and genicular nerve radiofrequency ablation. Whilst these interventions may provide significant symptom relief in selected patients, the best outcomes are generally achieved when patients continue to remain active and engaged in rehabilitation.

Overview of All Non-Surgical Treatment Options

Pain Spa offers a range of evidence-informed injection and interventional treatments for knee osteoarthritis. Each treatment works in a different way, has a different expected duration of benefit, and is suitable for different stages of osteoarthritis. The table below provides a practical comparison of the main options discussed in this guide.

Corticosteroid Injections

Corticosteroid injections are the most widely used and longest-established injection treatment for knee osteoarthritis. They have been used for decades and remain an important option for patients experiencing significant pain, swelling and inflammation within the knee joint. As highlighted in the comparison table earlier, corticosteroid injections are one of the few treatments that can be considered across the full spectrum of osteoarthritis severity, from relatively mild disease through to advanced Grade 4 osteoarthritis.

Although they do not repair cartilage, reverse osteoarthritis or alter the long-term progression of the condition, they can provide meaningful short-term pain relief and may help patients regain mobility, participate in physiotherapy and improve their quality of life during painful flare-ups.

How Do Corticosteroid Injections Work?

As discussed in Section 2, inflammation of the synovial lining (synovitis) is an important contributor to pain in many patients with knee osteoarthritis. Corticosteroids work by suppressing this inflammatory process within the joint. By reducing the production of inflammatory chemicals, they can decrease swelling, improve joint movement and reduce pain.

The medication is injected directly into the knee joint, allowing a high concentration to reach the target tissues whilst minimising exposure elsewhere in the body. Relief often occurs relatively quickly, making corticosteroid injections particularly useful when symptoms have deteriorated suddenly or when inflammation is clearly contributing to the patient’s pain.

What Does the Evidence Show?

The evidence summarised in the original Pain Spa review demonstrates that corticosteroid injections provide reliable short-term pain relief for many patients with knee osteoarthritis. Their greatest benefit occurs during the first few weeks following treatment, particularly in patients with active inflammation and swelling.

The available evidence consistently shows that the benefits tend to diminish over time. Whilst many patients experience meaningful improvement initially, the average effect gradually declines over subsequent months. This contrasts with some of the newer treatments discussed later in this guide, such as PRP, nSTRIDE, Arthrosamid and genicular nerve radiofrequency ablation, which are often selected specifically because they may offer longer-lasting symptom relief.

The review article also highlights an important consideration regarding repeated steroid injections. Studies evaluating frequent injections over prolonged periods have raised concerns regarding accelerated cartilage thinning. For this reason, corticosteroid injections are generally viewed as a short- to medium-term symptom management tool rather than a long-term disease-modifying treatment.

Potential Benefits

For appropriately selected patients, corticosteroid injections can provide several important benefits:

• Rapid reduction in pain and inflammation.
• Improved mobility and walking tolerance.
• Reduced swelling and joint stiffness.
• Facilitation of physiotherapy and rehabilitation.
• Useful symptom control during acute flare-ups.
• Can provide temporary relief whilst awaiting surgery or another intervention.
• Applicable across all Kellgren-Lawrence grades of osteoarthritis.

Many patients report that the greatest benefit is not simply pain reduction, but the ability to become more active again. This reinforces the principle discussed in Section 4 that injections should ideally support rehabilitation rather than replace it.

Risks and Limitations

Although corticosteroid injections are generally considered safe when used appropriately, no medical treatment is entirely without risk. The most common limitation is that symptom relief is often temporary. Unlike some biologic therapies or radiofrequency procedures, corticosteroids are not usually expected to provide benefit for many months or years.

Potential risks include:

• Temporary increase in blood glucose levels in patients with diabetes.
• Post-injection flare with transient worsening of pain.
• Small risk of infection.
• Occasional skin or soft-tissue changes around the injection site.
• Potential cartilage damage with repeated frequent injections over prolonged periods.

For this reason, most clinicians avoid repeated injections at very frequent intervals and generally regard corticosteroid treatment as part of a broader management strategy rather than a treatment that should be repeated indefinitely.

Who Are the Best Candidates?

Based on the evidence reviewed in the Pain Spa article, corticosteroid injections are most useful in patients with:

• Painful inflammatory flare-ups of knee osteoarthritis.
• Visible swelling or evidence of synovitis.
• Acute deterioration in symptoms.
• Pain that is preventing participation in physiotherapy.
• A need for short-term symptom relief whilst considering other treatment options.
• Any Kellgren-Lawrence grade of osteoarthritis.

In contrast, patients seeking prolonged symptom relief over many months or years may ultimately be better candidates for some of the alternative treatments discussed later in this guide, including PRP, nSTRIDE, Arthrosamid or genicular nerve radiofrequency ablation, depending on their osteoarthritis grade and overall clinical circumstances.

Hyaluronic Acid (Viscosupplementation)

Viscosupplementation, commonly known as hyaluronic acid (HA) injection therapy, has been used for many years as a non-surgical treatment for knee osteoarthritis. Hyaluronic acid is a naturally occurring substance found within healthy synovial fluid, where it contributes to lubrication, shock absorption and smooth joint movement. In osteoarthritic knees, both the concentration and quality of hyaluronic acid are reduced, leading to less effective joint lubrication and cushioning.

The principle behind viscosupplementation is simple: by injecting hyaluronic acid directly into the knee joint, it may be possible to temporarily improve the properties of the joint fluid and reduce symptoms. However, as discussed in the original Pain Spa review, viscosupplementation remains one of the most debated treatments in knee osteoarthritis and continues to generate considerable discussion within the medical community.

How Does Hyaluronic Acid Work?

Hyaluronic acid acts as a lubricant and shock absorber within the joint. In theory, restoring the viscoelastic properties of the synovial fluid may reduce friction between joint surfaces, improve movement and reduce mechanical irritation within the knee.

In addition to its mechanical effects, hyaluronic acid may also exert mild anti-inflammatory actions within the joint environment. Although the injected material itself is gradually absorbed over time, some patients continue to experience symptom improvement for several months after treatment.

As highlighted in Section 2, inflammation of the synovial lining is an important contributor to pain in many patients with osteoarthritis. One proposed mechanism is that viscosupplementation may improve the joint environment sufficiently to reduce some of these inflammatory processes.

Why Does the Evidence Remain Controversial?

Few treatments in knee osteoarthritis have generated as much debate as viscosupplementation. The original Pain Spa review highlights that some of the largest and most rigorous analyses have concluded that the average benefit of hyaluronic acid over placebo is relatively small and may not be clinically meaningful for many patients.

However, other analyses of the same evidence have reported statistically significant improvements in pain and function. This has resulted in differing recommendations between international organisations and explains why opinions on viscosupplementation remain divided.

The American Academy of Orthopaedic Surgeons (AAOS) and the American College of Rheumatology (ACR) do not recommend routine use of hyaluronic acid injections for knee osteoarthritis. In contrast, several European organisations continue to support selective use in appropriately chosen patients, particularly those with mild-to-moderate osteoarthritis who may not be suitable candidates for other treatments.

The practical conclusion from the evidence is that viscosupplementation appears to work well for some patients, poorly for others, and it remains difficult to predict who will respond. This variability is one of the major reasons for the ongoing controversy.

Potential Advantages

Despite the debate surrounding the evidence, viscosupplementation continues to have several potential advantages:

• Generally well tolerated.
• Can be performed as an outpatient procedure.
• May provide symptom relief for several months in responders.
• Suitable for patients unable to tolerate oral anti-inflammatory medication.
• May offer longer-lasting benefit than corticosteroid injections in some patients.
• Can be repeated if effective.

For some patients, particularly those with mild-to-moderate osteoarthritis, viscosupplementation may provide a useful intermediate option between simple conservative measures and more advanced interventions.

Limitations and Drawbacks

The principal limitation of viscosupplementation is uncertainty regarding effectiveness. Whilst some patients experience meaningful improvement, others notice little or no benefit.

The original Pain Spa review also notes that outcomes are considerably less favourable in advanced Grade 4 osteoarthritis, where significant cartilage loss and structural joint damage are already present. For this reason, many clinicians reserve viscosupplementation primarily for patients with mild-to-moderate disease.

Additional limitations include:

• Variable response rates between patients.
• Evidence remains conflicting and controversial.
• Benefit is generally temporary rather than permanent.
• Less effective in advanced bone-on-bone osteoarthritis.
• May require repeat treatment courses.
• Not suitable for patients with a knee replacement.

Who Are the Ideal Candidates?

Based on the evidence reviewed in the original article, the patients most likely to benefit from viscosupplementation include:

• Kellgren-Lawrence Grade 2–3 osteoarthritis.
• Mild-to-moderate symptomatic disease.
• Patients who cannot tolerate oral anti-inflammatory medication.
• Those seeking an option that may last longer than a corticosteroid injection.
• Patients who are not yet ready for more advanced procedures.
• Individuals who understand that outcomes can be unpredictable.

In contrast, patients with severe Grade 4 osteoarthritis may derive greater benefit from alternative options discussed later in this guide, such as genicular nerve radiofrequency ablation, Arthrosamid or, in some circumstances, consideration of knee replacement surgery.

Genicular Nerve Radiofrequency Ablation (RFA / Cooled RFA)

Genicular nerve radiofrequency ablation (RFA) represents one of the most evidence-supported interventional treatments currently available for painful knee osteoarthritis. Unlike corticosteroids, hyaluronic acid, PRP, nSTRIDE or Arthrosamid, which aim to influence the joint environment itself, genicular nerve treatment targets the pain pathways transmitting signals from the arthritic knee to the brain.

This distinction is important. Whilst biologic and injectable therapies attempt to modify inflammation, lubrication or tissue biology within the joint, genicular nerve procedures focus on reducing pain transmission. For many patients this can result in substantial improvements in pain, mobility and quality of life, even when significant structural osteoarthritis remains present.

Understanding the Knee Pain Nerves

Pain arising from the knee joint is transmitted through several small sensory nerves known collectively as the genicular nerves. These nerves carry pain information from structures such as the synovium, joint capsule, ligaments and subchondral bone.

Importantly, these are sensory nerves rather than motor nerves. They are involved in transmitting pain signals but do not control muscle strength, movement or stability of the knee. The aim of treatment is therefore to reduce pain whilst preserving normal function.

The Importance of Diagnostic Genicular Nerve Blocks

One of the major advantages of genicular nerve treatment is the ability to test the concept before committing to radiofrequency ablation. This is achieved through diagnostic genicular nerve blocks.

A small volume of local anaesthetic is placed around the target genicular nerves under image guidance. If the patient’s pain improves significantly during the local anaesthetic phase, this suggests that the genicular nerves are an important contributor to their symptoms and that radiofrequency treatment is likely to be beneficial.

This diagnostic step is a major strength of the procedure and helps improve patient selection, allowing treatment to be directed towards those most likely to respond.

Evidence Perspective: Amongst the interventional treatments discussed in this article, cooled genicular nerve radiofrequency ablation currently possesses one of the strongest evidence bases, including sham-controlled randomised studies.

Pain Spa Perspective: Genicular nerve radiofrequency ablation is one of the most important non-surgical interventions available for knee osteoarthritis. The combination of diagnostic nerve blocks, careful patient selection and image-guided radiofrequency treatment allows a precision-medicine approach that is difficult to replicate with other therapies. Importantly, it remains one of the few treatments that can be offered both before and after knee replacement surgery, making it a particularly valuable option for patients seeking meaningful pain relief without immediate surgery.

Platelet-Rich Plasma (PRP) Therapy

Platelet-rich plasma, commonly known as PRP, is one of the most widely discussed biologic treatments for knee osteoarthritis. It is produced from a sample of the patient’s own blood. The blood is spun in a centrifuge to separate and concentrate the platelets, which are then injected into the knee joint.

Platelets contain growth factors and signalling proteins that may help influence inflammation, cartilage cell activity and the health of the joint lining. PRP should not be described as a cartilage-regenerating cure. Its role is better understood as an attempt to improve the biological environment within the arthritic knee.

Why PRP Remains Controversial

The evidence for PRP is large but genuinely mixed. The RESTORE trial, one of the most rigorous individual studies, compared PRP with saline injection and found no significant difference in pain or cartilage volume at 12 months. In that study, the PRP group also showed more areas of cartilage thinning.

However, when multiple trials are analysed together, the picture becomes more favourable, particularly for higher-quality PRP preparations with higher platelet concentrations. This is why PRP cannot be judged as one uniform treatment. The key issue is not simply whether PRP works, but what type of PRP is being used.

Why Preparation Matters So Much

The most important message from the evidence is that not all PRP preparations are equal. A low-quality or poorly concentrated preparation may be biologically weak and may behave very differently from a high-platelet, freshly prepared and appropriately activated PRP product.

High-Platelet vs Low-Platelet PRP

Platelet concentration appears to be one of the most important variables. Your article highlights that high-platelet PRP exceeded the threshold for clinically meaningful improvement at three, six and twelve months in a large analysis of placebo-controlled trials, whereas low-platelet PRP did not reach this threshold.

This means that negative PRP studies should not automatically be interpreted as proving that all PRP is ineffective. Some may instead show that a particular preparation protocol was not strong enough, not optimised, or not delivered in the most effective way.

Leukocyte-Rich vs Leukocyte-Poor PRP

Leukocytes are white blood cells. Some PRP preparations retain them, producing leukocyte-rich PRP, while others remove most of them, producing leukocyte-poor PRP. Theoretical arguments exist on both sides: leukocyte-poor PRP may be less inflammatory, while leukocyte-rich PRP may contain additional immune and signalling factors.

However, the evidence summarised in your article indicates that neither formulation has been shown to be clearly superior overall. Two large RCTs found no major difference between leukocyte-rich and leukocyte-poor PRP. Therefore, either formulation may be reasonable, but the overall preparation quality remains crucial.

Single Injection vs Three-Injection Course

Another important practical issue is the number of injections. Some clinics offer a single PRP injection, but your article highlights that three injections at weekly intervals appear to provide more consistent outcomes.

This is particularly important when counselling patients. PRP should not always be presented as a one-off injection. For knee osteoarthritis, the best-supported protocol is often a course of three injections, especially when using high-platelet, activated and freshly prepared PRP.

What Does the Evidence Show?

The most balanced interpretation is that PRP has promise, but the evidence remains inconsistent. The American Academy of Orthopaedic Surgeons gives PRP a limited recommendation, reflecting the fact that results are encouraging in some studies but not uniform across the literature.

Meta-analyses tend to favour PRP, especially high-platelet formulations, while the RESTORE trial remains an important caution because it showed no meaningful advantage over saline. This tension is exactly why preparation quality and patient selection are so important.

With an optimised preparation, symptom relief may last around six to twelve months in responders, and treatment courses can be repeated where appropriate.

Advantages of PRP

• Uses the patient’s own blood.
• Avoids corticosteroids.
• May provide longer-lasting benefit than steroid injections in selected patients.
• Biologically active treatment aimed at improving the joint environment.
• Best evidence in mild-to-moderate osteoarthritis.
• Can be repeated if effective.

Limitations of PRP

• Evidence remains mixed.
• Preparation protocol matters enormously.
• Low-platelet or poorly prepared PRP may be ineffective.
• Single injection may be less consistent than a three-injection course.
• Post-injection flare with temporary pain and swelling can occur.
• Benefit is less predictable in severe Grade 4 osteoarthritis.
• Not suitable for patients with a knee replacement.

Who Benefits Most?

Based on your article, the strongest evidence for PRP is in patients with Kellgren-Lawrence Grade 2–3 knee osteoarthritis. Patients with very severe Grade 4 disease have less predictable outcomes, and PRP should not be presented as a substitute for knee replacement when the joint is already severely damaged.

nSTRIDE (Autologous Protein Solution)

nSTRIDE, also known as Autologous Protein Solution (APS), is a next-generation blood-derived treatment designed specifically to target inflammation within the osteoarthritic knee. Like PRP, it uses the patient’s own blood. However, nSTRIDE employs a more sophisticated processing system aimed at concentrating anti-inflammatory proteins as well as growth factors.

The concept is attractive. Rather than simply delivering platelets and growth factors, nSTRIDE attempts to increase the concentration of the body’s own natural anti-inflammatory molecules that oppose some of the key inflammatory pathways involved in osteoarthritis. However, despite this promising biological rationale, the current clinical evidence remains limited and somewhat contradictory.

How Does nSTRIDE Work?

Approximately 55 mL of blood is drawn from the patient. A first centrifugation step concentrates platelets and white blood cells. This material is then passed through a specialised chamber containing polyacrylamide beads. These beads remove water from the plasma, concentrating proteins and cytokines within the final solution.

The resulting APS contains high concentrations of anti-inflammatory proteins including interleukin-1 receptor antagonist (IL-1Ra) and soluble TNF receptors. These are natural molecules produced by the body that help counteract inflammatory pathways believed to contribute to osteoarthritis progression and symptoms.

How Is nSTRIDE Different From PRP?

Why Concentrating Anti-Inflammatory Proteins Matters

Modern osteoarthritis is increasingly recognised as more than a simple “wear and tear” condition. Inflammation within the synovium and joint environment plays an important role in driving symptoms and disease progression.

The rationale behind nSTRIDE is therefore biologically appealing. By concentrating molecules such as IL-1Ra and soluble TNF receptors, the treatment aims to oppose some of the inflammatory pathways that contribute to pain and joint dysfunction. Whether this translates into superior clinical outcomes remains uncertain and is the focus of ongoing research.

What Does the Evidence Show?

The evidence base for nSTRIDE is currently small and contradictory. Only two randomised controlled trials have been completed, involving 46 and 40 patients respectively. These studies reached opposite conclusions.

The first study reported meaningful improvement in pain at 12 months compared with saline injection. However, the second study found no significant benefit at any timepoint, and patients receiving nSTRIDE reported worse pain scores at 12 months.

Longer-term follow-up data suggest that some patients may experience durable benefit, but the available evidence remains insufficient to draw firm conclusions. Importantly, these studies are considerably smaller than the evidence base available for corticosteroids, hyaluronic acid, PRP or genicular nerve radiofrequency ablation.

How Long Does It Last?

Open-label follow-up data suggest that symptom improvement may persist for up to three years following a single injection. However, these durability claims require confirmation through larger independent studies.

One follow-up study found that approximately one in four patients required further treatment or surgery within three years, indicating that long-term outcomes remain variable.

Advantages of nSTRIDE

• Uses the patient’s own blood.
• Specifically designed to concentrate anti-inflammatory proteins.
• Single-injection treatment.
• Potentially longer duration than standard PRP.
• Biologically plausible mechanism targeting inflammatory pathways.
• Avoids corticosteroids.

Limitations of nSTRIDE

• Only two small randomised trials currently available.
• Conflicting clinical results.
• Not included in any major international guideline.
• Long-term durability requires independent validation.
• Reduced response rates in severe Grade 4 osteoarthritis.
• Cannot be used in patients with a knee replacement.

Who Might Benefit Most?

The article suggests that the most suitable candidates are patients with mild-to-moderate osteoarthritis who continue to experience symptoms despite conventional treatments and who are interested in emerging biologic therapies. Outcomes appear less favourable in advanced Grade 4 disease.

Arthrosamid

Arthrosamid is one of the newer non-surgical injection treatments for knee osteoarthritis. It is very different from corticosteroid injections, hyaluronic acid, PRP and nSTRIDE. It is not a steroid, not a blood-derived biologic treatment and not a temporary lubricant. Arthrosamid is a non-absorbable hydrogel designed to remain within the knee joint and integrate into the synovial tissue.

It is best understood as a long-lasting intra-articular hydrogel treatment that aims to improve the joint environment and reduce symptoms from a single injection. This makes it an attractive option for selected patients who are seeking longer-lasting relief and who are not ready for knee replacement surgery.

What Is Arthrosamid?

Arthrosamid is a polyacrylamide hydrogel composed of 97.5% water and 2.5% cross-linked polyacrylamide. It is administered as a single 6 mL injection into the knee joint.

Unlike hyaluronic acid, which is gradually absorbed, Arthrosamid is non-degradable and is designed to remain within the joint. Unlike PRP and nSTRIDE, it is not produced from the patient’s own blood. Its proposed benefit comes from its physical integration into the joint lining and its effect on the local joint environment.

How Does Arthrosamid Integrate Into Synovial Tissue?

After injection, Arthrosamid becomes incorporated into the synovial tissue, which is the soft lining inside the knee joint. Rather than remaining as a free-floating fluid, the hydrogel forms a stable layer within the synovial lining. Histological and imaging studies suggest that this integration begins within approximately 10–14 days.

This is one of the most important differences between Arthrosamid and viscosupplementation. Hyaluronic acid acts more like a temporary lubricant, whereas Arthrosamid is designed to become part of the joint lining and remain there for a prolonged period.

Proposed Mechanism of Action

The exact mechanism by which Arthrosamid improves symptoms is still being studied. The proposed effects include mechanical cushioning, improved synovial support, reduction in irritation within the joint and possible anti-inflammatory effects.

Biomarker studies have suggested an increase in anti-inflammatory mediators following treatment, raising the possibility that Arthrosamid may do more than simply provide mechanical support. However, this potential immunomodulatory effect requires further research.

What Does the Current Evidence Show?

The evidence for Arthrosamid is promising but still developing. A randomised controlled trial comparing Arthrosamid with hyaluronic acid showed that Arthrosamid was non-inferior to hyaluronic acid for pain reduction at 26 weeks. This means that Arthrosamid performed at least as well as hyaluronic acid in that study, but it was not clearly superior across all outcomes.

Several open-label and observational studies have reported improvements in pain, stiffness and physical function. These improvements appear to be maintained in a proportion of patients over longer follow-up periods. However, much of the long-term evidence comes from open-label extension studies, which means there was no ongoing placebo or active comparison group in later years.

This is important when counselling patients. Arthrosamid has encouraging durability data, but the overall evidence base remains smaller than for more established treatments such as corticosteroids, hyaluronic acid, PRP and genicular nerve radiofrequency ablation.

Long-Term Follow-Up Data

The most distinctive feature of Arthrosamid is the possibility of sustained benefit from a single injection. Follow-up data have reported ongoing improvement at one, three and five years in selected patients.

Advantages of Arthrosamid

• Single 6 mL intra-articular injection.
• Non-absorbable hydrogel designed to remain within the joint.
• Integrates into the synovial lining rather than acting as a temporary lubricant.
• Potential for several years of symptom relief in responders.
• Not a steroid and not derived from blood.
• Studied in patients with moderate to severe osteoarthritis, including KL Grade 2–4.
• May be attractive for patients wishing to delay knee replacement surgery.

Limitations and Uncertainties

• Evidence base remains smaller than for several established treatments.
• No placebo-controlled Arthrosamid trial has yet confirmed superiority over placebo response.
• The main randomised trial showed non-inferiority to hyaluronic acid, not clear superiority.
• Long-term data are mainly open-label extension studies.
• Some long-term follow-up includes attrition, which may favour patients who responded well.
• Not currently included in major osteoarthritis guidelines.
• Cannot be used in patients with a knee replacement.

Who Might Benefit Most?

Arthrosamid may be considered in selected patients with symptomatic knee osteoarthritis who are seeking a longer-lasting single-injection option and who are not yet ready for knee replacement surgery. It has been studied in KL Grade 2–4 osteoarthritis, although careful patient selection remains important.

Comparing All Treatments Side-by-Side

The non-surgical treatment options for knee osteoarthritis differ considerably in how they work, how long they last, which osteoarthritis grades they suit best, how strong the evidence is, whether they can be repeated, and whether they remain suitable after knee replacement surgery. There is no single “best” treatment for every patient.

The most appropriate option depends on the patient’s Kellgren-Lawrence grade, symptom pattern, presence of inflammation, previous treatment response, medical history, cost considerations, personal goals and whether knee replacement surgery is being considered.

Comprehensive Clinical Comparison

Practical Considerations

Main Advantages and Limitations

Evidence Strength at a Glance

Key Clinical Differences

Which Treatment Is Right for Me?

Choosing the right treatment for knee osteoarthritis depends on several factors. Whilst the Kellgren-Lawrence grade provides a useful framework, it is only one part of the decision-making process. Symptoms, function, swelling, previous treatment response, general health, surgical plans and individual goals are often more important than the X-ray itself.

The table below provides a practical guide to where the various non-surgical treatment options fit within the osteoarthritis pathway. It reflects the evidence and treatment positioning discussed throughout this article and should be viewed as a clinical guide rather than a rigid set of rules.

Treatment Options by Osteoarthritis Grade

Treatment Pathway in Practical Terms

When Should Knee Replacement Be Considered?

One of the most important questions in knee osteoarthritis management is knowing when non-surgical treatments have reached their limits and when knee replacement surgery should be discussed. Contrary to popular belief, the decision is not based solely on X-ray findings. Some patients with severe radiographic osteoarthritis function surprisingly well, while others with more modest structural changes experience profound pain and disability.

Modern treatment decisions are increasingly centred around symptoms, function, quality of life and treatment response rather than imaging alone. The goal is not necessarily to avoid surgery at all costs, but to ensure that surgery is considered at the right time and for the right reasons.

When Should Knee Replacement Be Discussed?

Knee replacement should generally be considered when osteoarthritis continues to have a major impact on quality of life despite appropriate non-surgical management. This may include persistent pain, progressive loss of function, reduced mobility, difficulty sleeping, inability to participate in valued activities or increasing dependence on pain medication.

When Are Injections Unlikely to Help Sufficiently?

No treatment works equally well for every patient. As osteoarthritis progresses, the likelihood of meaningful benefit from some injection therapies decreases. This is particularly true in end-stage Grade 4 osteoarthritis, where substantial structural damage, deformity and loss of joint space may limit the effectiveness of biologic and viscosupplementation treatments.

Can Interventional Treatments Delay Surgery?

For many patients, the answer is yes. A major role of modern interventional pain management is to reduce pain, improve function and maintain quality of life while delaying the need for knee replacement surgery. This can be particularly valuable for younger patients, patients with medical comorbidities, those wishing to remain active, or individuals who are simply not ready for surgery.

However, delaying surgery is not the same as avoiding surgery. Some patients ultimately progress to knee replacement despite receiving excellent symptom relief from injections or radiofrequency procedures. In these situations, interventional treatments should be viewed as part of the overall management pathway rather than a cure for osteoarthritis.

Pain Spa Expert Perspective & Treatments Offered

One of the most important messages from this article is that there is no single “best” treatment for knee osteoarthritis. The most appropriate intervention depends on the stage of osteoarthritis, symptom severity, functional limitations, previous treatment response and whether knee replacement surgery is being considered.

The evidence reviewed throughout this article demonstrates that different treatments occupy different positions within the osteoarthritis pathway. Some treatments appear most effective in earlier disease, whilst others remain valuable even in advanced osteoarthritis or following knee replacement surgery. Successful treatment therefore depends not only on selecting the right intervention but also on selecting it at the right stage of disease.

Dr Krishna’s Approach to Knee Osteoarthritis

Why Ultrasound-Guided Precision Matters

Many of the treatments discussed in this article are highly dependent on accurate placement. Ultrasound guidance allows real-time visualisation of soft tissues, blood vessels, nerves and joint structures, helping ensure treatment is delivered precisely where intended.

This is particularly important for biologic therapies, hydrogel injections and genicular nerve procedures, where treatment success depends not only on the treatment itself but also on accurate technique and careful patient selection.

Treatments Offered at Pain Spa

Frequently Asked Questions

Which injection lasts the longest?

Arthrosamid has the longest published follow-up data, with open-label studies reporting benefit for several years after a single injection. However, this does not mean it is automatically the best treatment for every patient. Genicular nerve RFA can also provide long-lasting pain relief, often 12–24 months in responders, and has a stronger interventional evidence base.

Is Arthrosamid better than PRP?

They are very different treatments. PRP is a blood-derived biologic treatment that depends heavily on preparation quality, platelet concentration and injection protocol. Arthrosamid is a non-absorbable hydrogel that integrates into the synovial lining. Arthrosamid has promising long-term single-injection data, while PRP has a broader but mixed evidence base. The best choice depends on OA grade, goals, cost, expectations and clinical assessment.

Is PRP worth the extra cost?

PRP may be worthwhile in carefully selected patients, particularly those with Grade 2–3 knee osteoarthritis who want a biologic option and understand that preparation quality matters. The best evidence supports high-platelet, fresh, preferably activated PRP, often delivered as a three-injection course. It is less predictable in severe Grade 4 OA.

Does genicular RFA damage nerves permanently?

No. Genicular RFA targets sensory nerves that transmit pain from the knee. It does not damage the main nerves controlling leg movement or muscle strength. The treated pain fibres can recover over time, which is why the benefit may wear off and the procedure can be repeated if it was successful.

Can these treatments delay knee replacement?

Yes, in selected patients. Treatments such as PRP, Arthrosamid and genicular RFA may reduce pain and improve function enough to delay knee replacement. However, delaying surgery is not the same as avoiding it permanently. If pain, stiffness and disability remain severe despite treatment, knee replacement should be discussed.

Which treatment is best for Grade 4 osteoarthritis?

In end-stage Grade 4 osteoarthritis, many injections become less predictable. Steroid injections may help inflammatory flares, and genicular RFA may help pain control or act as a bridge to surgery. Arthrosamid may be considered in selected patients with realistic expectations. Hyaluronic acid, PRP and nSTRIDE are usually less reliable in severe end-stage disease. Knee replacement should be discussed where symptoms and disability are significant.

Key Clinical Take-Home Messages

Knee osteoarthritis management has evolved considerably over the past decade. Patients now have access to a range of non-surgical treatment options that extend far beyond traditional steroid injections and knee replacement surgery. However, understanding where each treatment fits within the osteoarthritis pathway is essential to achieving the best outcomes.

References

The following references informed the evidence summaries and treatment comparisons discussed throughout this article. Particular emphasis has been placed on major international guidelines, randomised controlled trials, systematic reviews, meta-analyses and long-term follow-up studies relevant to contemporary non-surgical management of knee osteoarthritis.

Major Clinical Guidelines

1. Kolasinski SL, Neogi T, Hochberg MC, et al. 2019 American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip and Knee. Arthritis Care & Research. 2020;72(2):149–162.
2. American Academy of Orthopaedic Surgeons (AAOS). Management of Osteoarthritis of the Knee (Non-Arthroplasty), Clinical Practice Guideline. Updated Evidence-Based Guideline.
3. Bruyère O, Honvo G, Veronese N, et al. An updated algorithm recommendation for the management of knee osteoarthritis from the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO).
4. RACGP Guideline for the Management of Knee and Hip Osteoarthritis.

Corticosteroid Injection References

5. Jüni P, Hari R, Rutjes AWS, et al. Intra-articular corticosteroid for knee osteoarthritis: systematic review and meta-analysis of randomised controlled trials.
6. McAlindon TE, LaValley MP, Harvey WF, et al. Effect of Intra-articular Triamcinolone versus Saline on Knee Cartilage Volume and Pain in Patients with Knee Osteoarthritis. JAMA. 2017;317(19):1967–1975.

Viscosupplementation (Hyaluronic Acid) References

7. Rutjes AWS, Jüni P, da Costa BR, et al. Viscosupplementation for Osteoarthritis of the Knee: A Systematic Review and Meta-analysis.
8. Bannuru RR, Osani MC, Vaysbrot EE, et al. Comparative effectiveness of pharmacologic interventions for knee osteoarthritis.
9. ESCEO Working Group recommendations regarding selective use of hyaluronic acid in knee osteoarthritis.

Genicular Nerve Radiofrequency Ablation References

10. Choi WJ, Hwang SJ, Song JG, et al. Radiofrequency treatment of genicular nerves for chronic knee osteoarthritis pain: a randomised controlled trial.
11. Chen AF, Mullen K, Casambre F, et al. Thermal nerve radiofrequency ablation compared with hyaluronic acid injection for chronic knee osteoarthritis pain.
12. Systematic reviews and meta-analyses of sham-controlled genicular nerve radiofrequency studies evaluating pain reduction and functional outcomes in knee osteoarthritis.

Platelet-Rich Plasma (PRP) References

13. Bennell KL, Paterson KL, Metcalf BR, et al. Effect of Intra-articular Platelet-Rich Plasma vs Placebo Injection on Pain and Medial Tibial Cartilage Volume in Patients With Knee Osteoarthritis: The RESTORE Randomized Clinical Trial. JAMA. 2021;326(20):2021–2030.
14. Meta-analyses of placebo-controlled PRP trials demonstrating superior outcomes with high-platelet preparations compared with low-platelet PRP.
15. American Academy of Orthopaedic Surgeons (AAOS) evidence review regarding platelet-rich plasma therapy for knee osteoarthritis.

nSTRIDE (Autologous Protein Solution) References

16. Kon E, Filardo G, Di Matteo B, et al. Early clinical investigations of Autologous Protein Solution (APS) for knee osteoarthritis.
17. Placebo-controlled APS clinical trials evaluating pain and functional outcomes in knee osteoarthritis.
18. Long-term observational studies examining durability and progression to surgery following APS treatment.

Arthrosamid (Polyacrylamide Hydrogel) References

19. Henriksen M, Overgaard A, Hartkopp A, Bliddal H. Intra-articular 2.5% polyacrylamide hydrogel for the treatment of knee osteoarthritis: proof-of-concept and early clinical outcomes. Clinical and Experimental Rheumatology. 2018.
20. Bliddal H, Beier J, Hartkopp A, Conaghan PG, Henriksen M. Polyacrylamide hydrogel versus hyaluronic acid for knee osteoarthritis: randomised controlled trial. Clinical and Experimental Rheumatology. 2024.
21. Bliddal H, Beier J, Hartkopp A, Conaghan PG, Henriksen M. Three-year follow-up of a single intra-articular polyacrylamide hydrogel injection for knee osteoarthritis. Clinical and Experimental Rheumatology. 2026.
22. Bliddal H, Beier J, Hartkopp A, Conaghan PG, Henriksen M. Five-year outcomes following a single Arthrosamid injection in knee osteoarthritis. Clinical and Experimental Rheumatology. 2026.
23. Aykaç B, Dinç M, Nar ÖO, Karasu R, Bayrak HÇ. Comparative efficacy of polyacrylamide hydrogel versus hyaluronic acid and corticosteroid injections in knee osteoarthritis. Medicine. 2025.
24. Farhan-Alanie MM, Brown S, Wright K, Snow M. Efficacy and safety of polyacrylamide hydrogel injections for knee osteoarthritis: systematic review. The Knee. 2026.
25. Christensen L, Camitz L, Illigen KE, et al. Synovial incorporation of polyacrylamide hydrogel following intra-articular injection in normal and osteoarthritic joints. Osteoarthritis and Cartilage. 2016.

Additional Osteoarthritis References

26. Hunter DJ, Bierma-Zeinstra S. Osteoarthritis. Lancet. 2019;393:1745–1759.
27. Kraus VB, Blanco FJ, Englund M, Karsdal MA, Lohmander LS. Call for standardized definitions of osteoarthritis and risk stratification.
28. Loeser RF, Goldring SR, Scanzello CR, Goldring MB. Osteoarthritis: a disease of the joint as an organ. Arthritis & Rheumatism.
29. Conaghan PG, Kloppenburg M, Schett G, Bijlsma JWJ. Osteoarthritis research priorities and future directions.