Is radiation treatment effective for knee pain?

Radiation Treatment for Knee Pain: Effectiveness and Recommendations

Radiation treatment is not recommended for knee pain as it shows no substantial beneficial effect on symptoms compared to sham treatment and is not included in standard treatment guidelines for chronic knee pain. 1

Evidence Assessment for Radiation Treatment in Knee Pain

Current Guidelines and Recommendations

• The American College of Radiology (ACR) Appropriateness Criteria for chronic knee pain does not include radiation therapy as a recommended treatment option for knee pain 2
• Standard imaging recommendations for chronic knee pain include radiographs as initial assessment, followed by MRI or other modalities based on specific findings, with no mention of therapeutic radiation 2
• For patients with knee osteoarthritis (the most common cause of chronic knee pain), the ACR guidelines focus on diagnostic imaging rather than radiation as therapy 2

Research Evidence on Radiation Treatment

• A 2019 randomized, double-blinded, sham-controlled trial found that low-dose radiation therapy (LDRT) showed no substantial beneficial effect on symptoms or inflammatory signs in knee osteoarthritis compared to sham treatment 1
• The study concluded that based on this high-quality evidence, LDRT should not be recommended for knee osteoarthritis 1
• An older study from 1998 claimed efficacy for radiotherapy in degenerative joint disorders, but lacked the methodological rigor of more recent controlled trials 3

Alternative Evidence-Based Treatments for Knee Pain

Radiofrequency Treatments (Not to be confused with radiation therapy)

• Radiofrequency (RF) neurotomy of genicular nerves has shown significant pain reduction and functional improvement in elderly patients with chronic knee osteoarthritis pain 4
• A 2024 retrospective study on cooled radiofrequency ablation (c-RFA) demonstrated 65.5% average pain improvement with a duration of relief averaging 7.2 months 5
• These RF treatments target nerve pathways rather than using ionizing radiation to treat the joint directly 4, 5

Radiation Synovectomy (Different from External Beam Radiation)

• Radiation synovectomy using intra-articular radioactive isotopes like phosphorus-32 has shown some efficacy for inflammatory arthritis (specifically rheumatoid arthritis) 6
• This is a specialized procedure different from external beam radiation therapy and is primarily used for inflammatory rather than degenerative conditions 6

Clinical Decision Making Algorithm

1. Initial Assessment:

   • Begin with radiographs of the knee as the first-line imaging for chronic knee pain 2
   • Assess for common causes including osteoarthritis, meniscal tears, and other structural abnormalities 2

2. Follow-up Based on Radiographic Findings:

   • If radiographs show osteoarthritis: Consider standard treatments (analgesics, physical therapy, intra-articular injections) rather than radiation therapy 2, 1
   • If radiographs are normal or show joint effusion: MRI without contrast is usually appropriate 2

3. For Refractory Pain:

   • Consider radiofrequency treatments targeting genicular nerves rather than radiation therapy 4, 5
   • For inflammatory conditions like rheumatoid arthritis with monoarthritis, radiation synovectomy might be considered in specialized settings 6

Important Caveats and Pitfalls

• Do not confuse radiofrequency ablation (which uses thermal energy to target nerves) with radiation therapy (which uses ionizing radiation) 4, 5
• Older literature may suggest benefits of radiation therapy for knee pain, but more recent, high-quality randomized controlled trials do not support its use 3, 1
• Radiation therapy carries potential long-term risks including tissue damage and theoretical carcinogenic potential that must be weighed against limited evidence of benefit 1
• Standard treatment guidelines for knee osteoarthritis from major orthopedic and rheumatology organizations do not include radiation therapy in their recommendations 2