A cortisone injection into the knee joint is a common medical procedure designed to deliver anti-inflammatory medication directly to the site of pain and swelling. The primary component, a corticosteroid, mimics hormones naturally produced by the body and works to suppress the local immune response that drives inflammation. This targeted approach aims to reduce discomfort and improve function, often providing pain relief that can last for weeks to months. Proper post-procedure care, particularly regarding physical activity, must be carefully managed to ensure the drug remains effective and the joint is protected.
Immediate Post-Injection Protocol
Following the procedure, a mandatory period of restriction spans the first 24 to 48 hours. During this time, strictly limit heavy weight-bearing activities on the treated knee to allow the injection site to seal and prevent the medication from being prematurely flushed out. Patients should keep the knee joint relatively still and avoid strenuous exercise, heavy lifting, or high-impact movements.
Applying ice or a cold pack can help manage temporary soreness or swelling at the injection site. This initial rest is also important because some patients experience a “cortisone flare,” a temporary increase in pain and inflammation that typically resolves within two days. The injection site should also be kept clean and dry for the first day to minimize the risk of introducing bacteria into the joint capsule.
Understanding the Cortisone Effect and Timing
The immediate pain relief felt after the injection is usually due to the local anesthetic, such as lidocaine, which is often mixed with the steroid, not the cortisone itself. This numbing agent wears off within a few hours, which is why the joint may feel sore again before the cortisone takes effect. The steroid medication requires time to migrate and bind to receptors within the joint tissues to begin its anti-inflammatory action.
This delayed onset is known as the “cortisone lag time,” and significant therapeutic benefit typically begins three to seven days following the procedure. During this period, vigorous physical activity can increase blood flow and fluid circulation within the joint capsule. This elevated pressure may cause the steroid molecules to be prematurely dispersed into the systemic bloodstream, potentially reducing the anti-inflammatory effect. Waiting for the drug to settle maximizes the therapeutic window.
Phased Return to Activity Guidelines
The return to exercise should be a slow, phased progression that respects the body’s healing process and the drug’s mechanism of action. After the initial 48-hour period of strict rest, the first phase involves introducing gentle movement. This includes light walking around the house and non-weight-bearing range-of-motion exercises, such as slow knee bends while seated, which help prevent stiffness without stressing the joint.
Phase two, beginning around days four through seven, allows for the cautious reintroduction of low-impact activities. Excellent options at this stage include swimming, water aerobics, or using a stationary bicycle with low resistance. These activities promote cardiovascular health without subjecting the knee to impact loading. During this week, it remains important to avoid any activity that involves jumping, twisting, or quick lateral movements.
Once the initial week has passed and the cortisone pain relief is noticeable and stable, the patient can progress to phase three. This involves a gradual return to moderate strengthening exercises, such as leg lifts and gentle closed-chain exercises like mini-squats. The focus should be on building stability around the knee without inducing pain, and increased activity must be dictated by how the joint responds.
Returning to high-impact activities, such as running, jogging, or plyometrics, constitutes phase four and requires the longest delay. Guidelines suggest waiting at least two weeks, and often longer, until pain relief is substantial and the joint has fully settled. High-impact sports should only be attempted after consulting with the treating physician, as resuming them too soon can reduce the cortisone’s effectiveness and potentially cause further joint damage.
Warning Signs and When to Seek Medical Advice
While cortisone injections are generally safe, patients must monitor for specific symptoms that indicate a potential complication. A sudden and severe increase in knee pain that goes beyond the expected post-injection soreness should prompt immediate medical contact, as this intense pain can signal a problem.
Signs of infection require urgent medical attention. These symptoms include:
- A fever or chills.
- Significant and increasing warmth around the knee.
- Excessive redness.
- Pus draining from the injection site.
Any unexpected neurological changes, such as numbness, tingling, or sudden muscle weakness in the leg or foot, also warrant immediate consultation with a healthcare professional.