Cortisone Injections in Total Knee Replacements
Direct Answer
Cortisone injections can be administered to a replaced knee, but should be avoided in routine practice and only considered after strict screening for prosthetic infection in consultation with the orthopedic surgical team. 1
Key Clinical Decision Framework
When Injections May Be Considered
Cortisone injections into a prosthetic knee should only be performed after:
- Rigorous exclusion of prosthetic joint infection through clinical examination, laboratory analysis (inflammatory markers, aspiration if indicated), and radiographic evaluation 2
- Direct consultation with the orthopedic surgeon who performed the replacement 1
- Patient has failed other conservative management options and has persistent pain without identifiable surgical cause 2
Infection Risk Profile
The infection risk following cortisone injection into a prosthetic knee is 0.6% (1 in every 625 injections) based on a large retrospective review of 1,845 injections in 736 patients with total knee prostheses 1. However, a more recent systematic review suggests the risk may be as high as 2.1%, which is significantly higher than the 1.4% baseline infection rate in controls 3.
Critical timing consideration: One retrospective study of 184 patients with total knee prostheses showed no joint infections at minimum 1-year follow-up, though 31% received multiple injections 1.
Contraindications and High-Risk Scenarios
Absolute avoidance situations:
- Within 3 months before planned revision surgery due to significantly increased infection risk (0.5% to 1.0% vs baseline 1.04% to 2.5%) 1, 4
- Any clinical suspicion of prosthetic joint infection 2
- Patients who cannot undergo rigorous infection screening 1
Expected Efficacy in Prosthetic Joints
When appropriately selected patients receive cortisone injections into replaced knees 2:
- 76.6% reported decreased pain
- 57.9% reported increased motion
- 65.4% reported decreased swelling long-term
- 84.1% reported overall improvement (slight to great)
- 56.1% experienced benefit lasting greater than 1 month
The median time from index arthroplasty to injection in this cohort was 5.3 months 2.
Special Population Considerations
Diabetic patients require specific counseling:
- Monitor glucose levels closely for 1-3 days post-injection due to transient hyperglycemia risk 1
- Risk is highest in patients with suboptimal glycemic control 1
- No severe adverse events (hyperosmolar hyperglycemic state or ketoacidosis) have been reported in studies 1
Frequency Limitations
Limit to 3-4 injections per year maximum in the same prosthetic joint, following the same general principles as native joints 1. One study documented patients receiving up to 5 injections, though 30.8% of patients received more than one injection 2.
Post-Injection Care
Advise patients to avoid overuse of the injected joint for 24 hours, but immobilization is discouraged 1. Normal activity after 24 hours is appropriate 1.
Critical Clinical Pitfalls
The most important caveat: The EULAR guidelines explicitly state that intra-articular glucocorticoid injections in prosthetic joints "should be avoided in routine practice" and only considered after strict screening 1. This reflects the serious nature of prosthetic joint infection as a complication, even though the absolute risk appears relatively low in carefully selected patients.
Aseptic technique is mandatory with surgical gloves, skin preparation with alcohol or chlorhexidine, and consideration of changing needles between drawing and injecting 1.