What are the potential side effects of steroid knee injections?

Steroid Knee Injection Side Effects

Corticosteroid knee injections are generally safe with predominantly minor, self-limited side effects, though serious complications including infection, tendon rupture, and accelerated cartilage damage can occur rarely.

Common Local Side Effects

Immediate Reactions (Within Days)

• Post-injection pain flare occurs commonly, with injection-site soreness reported in approximately 9% of patients (17 of 191 injections) 1
• Vasovagal reactions occur in approximately 2.5% of patients, manifesting as dizziness, lightheadedness, or syncope 1
• Facial flushing and sweating are steroid-specific side effects occurring in approximately 1.6% of patients (3 of 191 injections), typically resolving within 24-48 hours 1, 2, 3

Delayed Local Complications

• Skin changes including hypopigmentation, cutaneous atrophy, and thin fragile skin can develop at injection sites 2, 3, 4
• Post-injection flare with increased pain, swelling, and joint stiffness may occur following intra-articular administration 2, 3
• Infection risk ranges from 1 in 3,000 injections in general populations, though this may be substantially higher in immunocompromised patients 5

Serious Musculoskeletal Complications

Joint and Cartilage Effects

• Accelerated osteoarthritis progression and cartilage damage have been reported with repeated injections, though one 2-year randomized trial found no radiographic progression difference between steroid and saline injections 4, 6
• Charcot-like arthropathy can develop with repeated intra-articular injections 2, 3
• Aseptic necrosis of the femoral head has been reported as a rare complication 2, 3

Tendon and Soft Tissue

• Tendon rupture is a recognized complication, particularly with peritendinous injections 2, 3, 4
• Calcinosis may occur following intra-articular or intralesional steroid use 2, 3

Infection Risk Considerations

Pre-Surgical Timing

• Increased deep infection risk after total knee replacement has been reported when steroids are administered within 3 months before surgery, with all three deep infections in one study occurring in patients who received pre-operative injections 7, 8
• However, a larger matched cohort study of 302 patients found no significant increase in infection rates when injections were given within 12 months before total knee arthroplasty 9
• Both injections should be avoided within 3 months prior to knee replacement surgery due to potential infection risk 7

General Infection Risk

• Septic arthritis is rare but serious, requiring immediate antimicrobial therapy if suspected 2
• Injection into infected sites is contraindicated and appropriate joint fluid examination should exclude septic processes before injection 2, 4

Systemic Side Effects

Metabolic and Endocrine

• Transient hyperglycemia occurs commonly in diabetic patients, requiring glucose monitoring for 1-3 days post-injection 7, 2, 3
• Adrenal suppression can develop with repeated injections, particularly problematic during physiologic stress 2, 3
• Cushingoid features may develop with chronic use, including moon face, weight gain, and abnormal fat deposits 2, 3

Cardiovascular

• Hypertension and fluid retention can occur due to sodium retention and potassium loss 2, 3
• Congestive heart failure may be precipitated in susceptible patients 2, 3

Bone Health

• Osteoporosis can develop with repeated injections through decreased bone formation and increased resorption 2, 4
• Vertebral compression fractures and pathologic fractures of long bones are recognized complications 2, 3

Neuropsychiatric Effects

• Mood disturbances ranging from euphoria and insomnia to severe depression and frank psychotic manifestations can occur 2, 3
• Personality changes and emotional instability may develop or be aggravated by corticosteroids 2, 3

Ophthalmic Complications

• Increased intraocular pressure can develop, requiring monitoring if steroid therapy continues beyond 6 weeks 2
• Posterior subcapsular cataracts and glaucoma are recognized complications with repeated use 2, 3

Critical Safety Considerations

Contraindications

• Absolute contraindications include superficial or deep infection, fracture, or presence of a prosthetic joint 4
• Injection into unstable joints is generally not recommended 2

High-Risk Populations

• Immunosuppressed patients face substantially elevated infection risks, including rare cases of epidural abscess, meningitis, and endocarditis 1
• Diabetic patients require specific counseling about hyperglycemia and glucose monitoring 7
• Postmenopausal women warrant special consideration due to increased osteoporosis risk 2

Duration and Frequency Considerations

• Short-term efficacy is well-established, with significant pain relief lasting 1-4 weeks, though some patients experience benefits up to 12 weeks 1, 7
• Medicare typically limits injections to no more frequently than every 3 months for the same joint 7
• Long-term safety appears acceptable based on a 2-year randomized trial showing no deleterious anatomical effects with injections every 3 months 6