Which joints can be treated with low dose radiation therapy (LDRT)?

Low-Dose Radiation Therapy for Joint Treatment

Low-dose radiation therapy (LDRT) can be used to treat painful bone metastases in any weight-bearing or non-weight-bearing bones, vertebral bodies with impending compression or cord compression, and sacroiliac joints in cancer patients, but is NOT recommended for primary osteoarthritis or degenerative joint disease due to significant cancer risk. 1

Cancer-Related Bone Disease (Appropriate Indications)

Multiple Myeloma and Bone Metastases

LDRT (10-30 Gy) is indicated for palliative treatment of:

• Uncontrolled pain from bone lesions 1
• Impending pathologic fractures in any bone 1
• Impending spinal cord compression 1
• Weight-bearing bones with structural compromise 1
• Vertebral compression requiring pain control 1

Technical Considerations for Cancer Treatment

• Limited involved fields should be used to preserve stem cell harvest potential in transplant candidates 1
• Single-fraction radiotherapy (8 Gy) is as effective as multiple fractions (30 Gy in 10 fractions) for bone metastases, with 66% overall response rate 1
• Orthopedic consultation is mandatory for actual or impending long-bone fractures 1

Ankylosing Spondylitis (Historical Use - NOT Recommended)

Spine and Sacroiliac Joints

• Local irradiation to the spine and sacroiliac joints was historically effective for pain relief up to 12 months in ankylosing spondylitis 1
• This treatment is contraindicated due to unacceptable cancer risk: relative risk of 2.74 for leukemia (95% CI 2.10-3.53) and 1.26 for cancers at irradiated sites (95% CI 1.19-1.32) 1

Degenerative Joint Disease (NOT Standard of Care)

Critical Safety Warning

Radiation therapy for osteoarthritis carries significant malignancy risk and is NOT included in American College of Rheumatology treatment algorithms. 2, 3

Research Data (Not Guideline-Supported)

While research studies report treatment of the following joints, these are not guideline-recommended approaches:

• Finger joints (proximal/distal interphalangeal): 70% pain improvement reported with 0.5 Gy single dose 4, 5
• Thumb (rhizarthrosis): 53% response rate in retrospective series 6
• Knee (gonarthrosis): 64-67% response rate 6, 7
• Shoulder (omarthrosis): 59% improvement in Constant-Murley score 6
• Hip: 71% improvement in Harris hip score 6
• Heel (calcaneodynia) and Achilles tendon: studied in elderly patients ≥70 years 7
• Trochanteric bursitis: included in prospective trials 7

Clinical Algorithm for Decision-Making

Step 1: Identify the Underlying Condition

• If cancer-related bone disease (myeloma, metastases): LDRT is appropriate and guideline-supported 1
• If ankylosing spondylitis: LDRT is contraindicated due to cancer risk; use TNF inhibitors instead 1
• If osteoarthritis/degenerative disease: LDRT is NOT standard of care; proceed to Step 2 2, 3

Step 2: For Osteoarthritis - Exhaust Standard Therapies First

• Non-pharmacological: exercise, weight management 2, 3
• Pharmacological: NSAIDs, acetaminophen 2, 3
• Intra-articular corticosteroid injections 3
• Physical therapy 3
• Orthopedic evaluation for joint replacement surgery 2, 3

Step 3: LDRT Consideration Only After All Standard Options Failed

If considering LDRT for osteoarthritis (off-guideline), patient must meet ALL criteria:

• Age ≥60 years 3
• Documented failure of pharmacologic therapies 3
• Evaluated by orthopedic surgeon and deemed medically inoperable 3
• Fully informed of 1.26-fold increased cancer risk at irradiated sites 1, 2

Common Pitfalls to Avoid

• Never use LDRT as first-line treatment for osteoarthritis - the cancer risk (RR 1.26 for site-specific cancers, RR 2.74 for leukemia) outweighs benefits in non-malignant conditions 1, 2
• Do not confuse palliative cancer treatment with degenerative disease treatment - these have completely different risk-benefit profiles 1, 2
• Avoid treating ankylosing spondylitis with radiation - TNF inhibitors are far safer and more effective 1
• Do not irradiate large fields in potential transplant candidates - this compromises stem cell harvest 1