Guidelines on Knee Pain Therapies From the American Society of Pain and Neuroscience

The American Society of Pain and Neuroscience has released consensus guidelines on interventional therapies for knee pain in the Journal of Pain Research.

Among Americans aged 55 years and older, an estimated 25% experience chronic knee pain, and 1 in 5 Americans aged 50 years and older report severe difficulties with physical function due to knee pain.

To evaluate a patient with knee pain, a physical examination is the first crucial step. Clinicians should assess for swelling and skin changes. Evidence of swelling should trigger an assessment for pathologies associated with swelling, such as osteoarthritis, Baker cyst, and soft tissue injury, among others. Skin changes may suggest complex regional pain syndrome (CRPS) or infection.

Imaging modalities should follow the cursory physical examination. The American College of Radiology recommends that radiography should be the initial imaging modality. Radiographs allow for evaluation of the joint space and identification of osteophytes and subchondral cysts. If soft tissue damage is suspected, magnetic resonance imaging (MRI) can be used. In the case of contraindications for MRI, computed tomography (CT) is a suitable alternative imaging modality.

Clinicians should be scrutinizing patients for the most common causes of knee pain, specifically sprains, meniscal injuries, tendinopathy, bursitis, osteoarthritis, CRPS, chondromalacia, and postsurgical pain.

To manage knee pain, conservative care in the form of nonsteroidal anti-inflammatory drugs (NSAIDs) is recommended. Current evidence suggests that NSAIDs are moderately effective at controlling moderate to severe knee pain, including among patients with osteoarthritis and those having undergone total knee arthroplasty. The guideline authors recommend topical treatments (diclofenac 70-81 mg/d) over oral NSAIDs to decreased risk for systemic toxicity.

The use of chronic opioids is currently being scrutinized due to the opioid epidemic in the United States. A systematic review and meta-analysis failed to find evidence to support the use of opioids in patients with knee pain, and a randomized controlled trial did not find significant differences in pain experienced among patients receiving treatment with opioids vs those receiving NSAIDs. The guideline authors recommended against opioid use due to the high risk for adverse effects coupled with the lack of efficacy for knee pain.

Patients with symptomatic osteoarthritis may experience short-term pain relief with intra-articular corticosteroid injections; however, the authors report that there remains debate about the efficacy of these injections in this setting.

Genicular nerve ablation is a safe and effective therapeutic option for patients with osteoarthritis-associated pain or pain associated with total knee arthroplasty. Peripheral nerve or dorsal root ganglion stimulation are safe and effective therapeutic options for chronic postsurgical pain or neuropathic pain.

Other alternative modalities recommended for pain associated with osteoarthritis are intra-articular platelet-rich plasma injection or mesenchymal stem cell infusion. The statement authors pointed out, however, that as not all platelet-rich plasma injections are equivalent and there is much variation in treatment protocols, outcomes may vary. Similarly, there is great heterogeneity in mesenchymal stem cell therapies, and the authors rate their recommendation about this treatment with only moderate confidence.

Nonpharmacologic approaches to the management of knee pain may be effective for some patients. Physical therapy is recommended for patients with osteoarthritis and soft tissue injuries, and this approach may be effective for some patients with CRPS and patellofemoral pain syndrome. Durable medical equipment is recommended for knee pain in general; depending on the diagnosis, this may take the form of a lateral shoe wedge, patella strap, cane, walker, or crutches.

For patients who do not experience pain relief from pharmacologic and nonpharmacologic analgesics and are good candidates for surgery, knee arthroscopy is safe and effective for the repair of soft tissue injury and minor bony pathologies and may be effective for some patients with knee osteoarthritis. The subset of patients with symptomatic osteoarthritis who have experienced failure of conservative treatment may be candidates for knee joint arthroplasty.

Guideline authors concluded, “The diagnosis and care of knee pain is an evolving area of medicine that is rife with innovation and emerging treatments. Considering the commonality of this malady in the aging and injured population, it is imperative to have a consistent treatment algorithm that is recognized and followed across the various specialties of medicine that encounter these patients. While the current paradigm still emphasizes palliative treatments as a means of prolonging or avoiding the need for surgical intervention, there is no consistency or clear agreement on which treatments should be provided at the various stages in the patient journey.”