Nonoperative Management of Knee Osteoarthritis: A Review of the Evidence

A narrative review of the evidence
Shaun E. Chandran, MD – Chandran Orthopaedic Surgery, Torrance, California

Abstract

Background: Knee osteoarthritis (OA) affects hundreds of millions of people worldwide, and most patients are managed nonoperatively for years before, or instead of, total knee arthroplasty.

Methods: Narrative review of current AAOS, ACR, and OARSI guidelines and landmark randomized trials and meta-analyses of nonoperative knee OA treatment.

Results: Exercise, weight loss, and patient education are universally recommended core treatments. Topical and oral NSAIDs are the most effective analgesics; acetaminophen provides minimal benefit, and opioids, including tramadol, are not recommended. Intra-articular corticosteroids provide short-term relief, but repeated injections are associated with cartilage loss. Hyaluronic acid and platelet-rich plasma show inconsistent benefit, with the largest placebo-controlled PRP trial negative. Semaglutide produced substantial weight loss and pain reduction in the STEP 9 trial. Genicular nerve radiofrequency ablation outperformed corticosteroid and hyaluronic acid injection in active-comparator trials, whereas genicular artery embolization has conflicting sham-controlled results. Arthroscopic lavage and debridement, glucosamine, chondroitin, and lateral wedge insoles are not recommended.

Conclusions: Effective nonoperative care is layered: core interventions for all patients, NSAIDs for analgesia, judicious corticosteroid injection for flares, and selective use of newer therapies, with timely referral for arthroplasty when nonoperative care fails.

Introduction

Knee osteoarthritis (OA) is the most common cause of chronic knee pain in adults and a leading driver of disability worldwide. The Global Burden of Disease study estimated that roughly 595 million people had OA in 2020, with the knee the most frequently affected joint, and projects continued growth through 2050 as populations age and obesity rises [1].

Total knee arthroplasty (TKA) remains the definitive treatment for end-stage disease, but most patients spend years, often decades, in the nonoperative phase. Even among TKA candidates, a structured nonsurgical program produces clinically meaningful improvement in a substantial proportion of patients [5]. Nonoperative care is therefore not a delay tactic; it is the primary treatment for most of the disease course.

The nonoperative landscape has shifted considerably over the past decade. Major society guidelines from the American Academy of Orthopaedic Surgeons (AAOS), the American College of Rheumatology (ACR), and the Osteoarthritis Research Society International (OARSI) now converge on exercise, education, and weight management as core care, while downgrading or recommending against several widely used interventions [2-4]. At the same time, newer options, including GLP-1 receptor agonists, genicular nerve radiofrequency ablation, and genicular artery embolization, have entered practice with evidence of varying quality.

This review summarizes the current evidence for nonoperative treatment of knee OA, with emphasis on high-quality randomized trials and guideline recommendations, and offers a practical framework for the orthopaedic surgeon.

Methods

This is a narrative review, not a systematic review or meta-analysis. The primary sources were the current AAOS (2021), ACR/Arthritis Foundation (2019), and OARSI (2019) guidelines for knee OA [2-4], supplemented by landmark randomized controlled trials (RCTs), Cochrane reviews, and network meta-analyses addressing each treatment category.

Priority was given to sham- or placebo-controlled RCTs with patient-reported pain and function outcomes (WOMAC, KOOS, VAS) and follow-up of at least 6 months. Studies were selected for clinical relevance to an orthopaedic practice treating adults with symptomatic, radiographically confirmed tibiofemoral OA. Post-traumatic OA, inflammatory arthritis, and isolated patellofemoral disease were not specifically addressed.

Core First-Line Care

Exercise, weight management, and patient education form the foundation of treatment and are recommended by all three major guidelines regardless of disease severity [2-4]. They are low risk, inexpensive, and address both symptoms and modifiable drivers of progression.

Patient education and self-management. Education should cover the natural history of OA, the expected fluctuation of symptoms, the safety of activity, and realistic expectations for each treatment. Self-management programs improve pain and function modestly but consistently, and they improve adherence to the other core interventions [2,4].

Exercise and physical therapy. Land-based therapeutic exercise produces moderate improvements in pain and function, with effect sizes comparable to NSAIDs and a far better safety profile [6]. Benefits are seen with quadriceps and hip abductor strengthening, aerobic conditioning, and neuromuscular training; no single exercise type has proven clearly superior. Supervised programs outperform unsupervised home programs, particularly early.

Physical therapy compares favorably with injection-based care. In a randomized trial of 156 patients, a structured physical therapy program produced better WOMAC scores at 1 year than intra-articular glucocorticoid injection, with fewer repeat interventions [9]. Mind-body exercise also performs well: tai chi was as effective as standard physical therapy for knee OA over 12 weeks and improved secondary outcomes such as depression and quality of life [10].

Weight loss. Weight loss is among the most effective disease-modifying interventions available for patients with overweight or obesity. In the IDEA trial, combined diet and exercise achieving roughly 10% weight loss reduced pain and improved function more than either intervention alone and lowered compressive knee joint loads [7]. The WE-CAN trial confirmed that intensive diet plus exercise produced greater pain reduction at 18 months than an attention control, though the between-group difference was modest [8]. A practical target is at least 5% body weight loss, with greater benefit at 10% or more.

Pharmacologic Management

Topical and oral NSAIDs are the most effective analgesics for knee OA; most other oral agents offer small benefits or unfavorable risk profiles.

Topical NSAIDs. Topical diclofenac provides clinically meaningful pain relief in knee OA with minimal systemic exposure [11]. Because the knee is superficial, topical delivery is particularly effective here, and it is the preferred first pharmacologic option for patients aged 75 or older or those with gastrointestinal, renal, or cardiovascular risk [3].

Oral NSAIDs. Oral NSAIDs are strongly supported by all three guidelines [2-4]. A large network meta-analysis found diclofenac 150 mg/day and etoricoxib 60 mg/day most effective for pain, while acetaminophen at any dose did not reach the minimum clinically important difference [12]. Use the lowest effective dose for the shortest duration, consider a COX-2 selective agent or proton pump inhibitor in patients with GI risk, and avoid long-term use in patients with chronic kidney disease, heart failure, or established cardiovascular disease.

Acetaminophen. Acetaminophen has a small effect that is often clinically negligible [12]. It remains a reasonable option for short-term use in patients who cannot take NSAIDs, but it should not be presented as a meaningful standalone therapy.

Duloxetine. Duloxetine (typically 60 mg daily) produces modest improvements in pain and function and is conditionally recommended by ACR and OARSI [3,4]. It is most useful in patients with multisite pain, features of central sensitization, or comorbid depression.

Opioids and tramadol. Opioids, including tramadol, are not recommended for knee OA. AAOS recommends against oral narcotics given adverse events without meaningful efficacy [2]. In the SPACE trial, opioid therapy was not superior to nonopioid medications for chronic back, hip, or knee pain over 12 months and caused more adverse effects [13].

Glucosamine and chondroitin. The NIH-funded GAIT trial found no significant benefit of glucosamine, chondroitin, or their combination over placebo in the overall cohort [14]. ACR recommends against these supplements for knee OA [3]. They are generally harmless, so patients who already perceive benefit need not be forced to stop, but they should not be started as a recommended treatment.

Intra-Articular Injections

Corticosteroid injection provides reliable short-term relief; hyaluronic acid offers, at best, a small benefit that rarely exceeds the threshold for clinical importance.

Corticosteroids. Intra-articular corticosteroids reduce pain for roughly 2 to 6 weeks and are recommended for short-term relief of flares, particularly with effusion [2-4]. Repeated injection carries structural concerns. In a 2-year RCT, triamcinolone 40 mg every 3 months produced greater cartilage volume loss on MRI than saline, with no difference in pain [15]. A review in Radiology described four adverse joint findings observed after injection: accelerated OA progression, subchondral insufficiency fracture, complications of osteonecrosis, and rapid joint destruction [16].

Extended-release triamcinolone (TA-ER) prolongs intra-articular residence and produced greater pain relief than saline placebo at 12 weeks, but it was not significantly better than standard triamcinolone on the primary pain measures [17]. Cost limits routine use.

Practical guidance: limit injections to roughly 3 to 4 per year per knee, monitor glucose in diabetic patients, and avoid injection in the months before planned TKA. In a claims database of more than 83,000 TKAs, prior ipsilateral injection was associated with higher postoperative infection risk, and the odds remained elevated when injection occurred within about 6 months of surgery [18]. Many surgeons use a minimum 3-month interval, but these data suggest a longer window may be prudent.

Hyaluronic acid (viscosupplementation). Evidence for hyaluronic acid (HA) is contested. Earlier network meta-analyses suggested a benefit over oral placebo that is partly attributable to the intra-articular placebo effect [19]. A 2022 meta-analysis of 169 trials found that HA produced a small reduction in pain that fell below the clinically important threshold, with a higher risk of serious adverse events than placebo [20].

AAOS does not recommend HA for routine use, ACR conditionally recommends against it, and OARSI allows conditional use [2-4]. In practice, HA may be reasonable for selected patients with mild to moderate disease who cannot take NSAIDs or tolerate corticosteroids, provided expectations are set appropriately. Payer coverage for HA is increasingly restricted.

Orthobiologics

Platelet-rich plasma has mixed evidence, with the most rigorous placebo-controlled trial negative; cell-based injections remain investigational.

Platelet-rich plasma. Meta-analyses comparing PRP with HA suggest superior pain and function scores at 6 to 12 months, particularly with leukocyte-poor preparations [22]. However, these comparisons are limited by heterogeneous preparations, small trials, and an active comparator of uncertain efficacy.

The RESTORE trial, a double-blind RCT of 288 patients with medial knee OA, found no difference between leukocyte-poor PRP and saline in pain or MRI tibial cartilage volume at 12 months [21]. AAOS gives PRP a limited-strength recommendation, while ACR strongly recommends against it, citing lack of standardization [2,3]. PRP is reasonable to discuss with motivated patients with mild to moderate disease who understand it is generally self-pay and the evidence is inconsistent.

Cell-based therapies. Bone marrow aspirate concentrate, adipose-derived products, and culture-expanded mesenchymal cells lack high-quality evidence of benefit beyond placebo for knee OA. ACR strongly recommends against stem cell injections [3]. Culture-expanded cell products are not FDA approved for this indication, and patients should be cautioned about clinics marketing them as regenerative or cartilage-restoring.

Bracing, Orthoses, and Complementary Therapies

Unloader braces and canes are reasonable adjuncts in selected patients; lateral wedge insoles and acupuncture show little benefit over sham.

Bracing. Valgus unloader braces for medial compartment OA reduce pain in some patients and are recommended by ACR for tibiofemoral OA [3]. Benefit depends on fit, correctable alignment, and tolerance; long-term compliance is often poor. They are most useful in active patients with unicompartmental disease who wish to delay surgery. Patellofemoral braces and taping may help patients with predominantly anterior knee pain.

Footwear and insoles. Lateral wedge insoles were no better than neutral insoles for pain or structural progression in a 12-month RCT [23], and ACR conditionally recommends against them [3].

Assistive devices. A cane used in the contralateral hand reduces medial compartment load and is strongly recommended by ACR when ambulation is limited by pain [3].

Acupuncture and other modalities. In a sham-controlled trial, neither needle nor laser acupuncture outperformed sham for chronic knee pain in older adults [24]. Guidelines differ, with ACR giving acupuncture a conditional recommendation [3]. TENS lacks convincing evidence, and ACR recommends against it [3]. Thermal therapy is low risk and may be used for symptom relief.

Emerging Interventions

GLP-1 receptor agonists have the strongest new evidence; genicular nerve ablation is supported by active-comparator trials, and genicular artery embolization remains unproven against sham.

GLP-1 receptor agonists. In the STEP 9 trial, 407 adults with obesity and moderate knee OA received semaglutide 2.4 mg weekly or placebo for 68 weeks alongside diet and exercise counseling. Semaglutide produced about 13.7% body weight loss versus 3.2% with placebo and a significantly larger reduction in WOMAC pain [25]. This is the first pharmacologic agent with high-quality evidence of meaningful pain improvement in knee OA through weight reduction.

Practical considerations include cost, insurance coverage, gastrointestinal side effects, and loss of lean mass, which makes concurrent resistance exercise important. GLP-1 therapy may also help patients reach BMI thresholds for safe arthroplasty, though perioperative holding protocols should be followed.

Genicular nerve radiofrequency ablation. Radiofrequency ablation (RFA) of the superomedial, superolateral, and inferomedial genicular nerves targets articular sensory input without altering joint structure. Cooled RFA outperformed intra-articular corticosteroid at 6 months, with about three-quarters of RFA patients achieving at least 50% pain reduction [29], and outperformed a single HA injection in a separate RCT [30]. ACR gives RFA a conditional recommendation [3]. Sham-controlled data remain limited, and durability beyond 12 months is uncertain. RFA is best suited to patients who are poor surgical candidates or who wish to defer TKA.

Genicular artery embolization. Genicular artery embolization (GAE) targets synovial neovascularity believed to contribute to OA pain. Sham-controlled trials conflict. A small multicenter trial of 21 patients reported greater pain reduction with GAE than sham at 1 month [26]. In a 59-patient trial of Kellgren-Lawrence grade 2 knees, GAE showed benefit over sham only in the subgroup with complete embolization of all genicular arteries [27]. The largest double-blind trial, with 58 patients, found no difference in pain reduction between GAE and sham at 4 months, with more mild adverse events after GAE [28]. GAE should currently be regarded as investigational for knee OA.

Interventions Not Recommended

Arthroscopic lavage and debridement should not be used to treat knee OA. In a sham-controlled trial of 180 patients, arthroscopic lavage or debridement was no better than placebo surgery [31]. A subsequent RCT of 178 patients found that adding arthroscopic surgery to optimized physical and medical therapy provided no additional benefit at 2 years [32]. AAOS recommends against arthroscopy with lavage or debridement for patients with a primary diagnosis of knee OA [2]. Arthroscopy remains appropriate only for a distinct mechanical problem, such as a symptomatic loose body, in an otherwise mildly arthritic knee.

Other interventions with guideline recommendations against use in knee OA include opioids, including tramadol [2], glucosamine and chondroitin [3], lateral wedge insoles [3], TENS [3], stem cell injections [3], and systemic agents such as bisphosphonates, hydroxychloroquine, and methotrexate [3].

Practical Treatment Framework

Treatment should be layered rather than sequential: core care continues throughout, and adjuncts are added according to symptom severity, comorbidities, and patient goals.

1. All patients: education, structured exercise or supervised physical therapy, and weight loss of at least 5% to 10% when BMI is 25 or higher.
2. Analgesia: topical NSAID first, particularly in older or comorbid patients; oral NSAID at the lowest effective dose if needed; duloxetine for multisite pain or central sensitization.
3. Adjuncts for function: unloader brace for medial compartment disease with correctable alignment; cane for limited ambulation.
4. Flares or persistent pain: intra-articular corticosteroid, no more than 3 to 4 per year, and ideally none within 3 to 6 months of planned TKA.
5. Obesity with knee OA: consider GLP-1 receptor agonist therapy, coordinated with primary care.
6. Selected patients after counseling: HA or PRP for mild to moderate disease; genicular nerve RFA for patients who cannot or will not undergo surgery.
7. Failure of nonoperative care: refer for arthroplasty evaluation when pain and functional limitation persist despite an adequate trial and radiographic disease is advanced.

Conclusion

The most effective nonoperative treatments for knee OA are also the least glamorous: exercise, weight loss, and NSAIDs, preferably topical. Corticosteroid injections remain useful for short-term flares, but repeated use should be limited. Hyaluronic acid and PRP offer inconsistent benefit and require careful expectation-setting, while opioids, supplements, and arthroscopic debridement should be avoided.

GLP-1 receptor agonists represent the most significant recent advance, offering meaningful pain relief through weight loss. Genicular nerve RFA is a reasonable option for patients seeking to defer surgery, whereas genicular artery embolization requires further sham-controlled evidence. A layered, patient-centered approach allows most patients to manage symptoms for years and ensures that those who progress arrive at arthroplasty in optimal condition.

References

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This article is for educational purposes and does not replace individual medical advice. Chandran Orthopaedic Surgery, 4201 Torrance Blvd, Suite 310, Torrance, CA 90503. 310-644-1151.