A cortisone shot can reduce pain from a torn ligament, but it won’t heal the tear itself. In fact, cortisone actively works against the biological process your body uses to repair damaged tissue. Whether the shot makes sense for you depends heavily on the severity of your tear and what you’re trying to achieve: short-term pain relief or long-term recovery.
What Cortisone Does to Injured Tissue
Cortisone is a powerful anti-inflammatory. When injected near a torn ligament, it suppresses the swelling, redness, and pain that come with the injury. That sounds like a good thing, but inflammation is also how your body starts rebuilding damaged tissue. It’s the signal that calls repair cells to the injury site.
Cortisone disrupts this process at a fundamental level. It delays the arrival of inflammatory cells and fibroblasts (the cells responsible for laying down new collagen), slows the deposit of collagen itself, and reduces the growth factors that drive tissue repair. The decrease in collagen production happens because cortisone lowers the genetic instructions cells use to manufacture new collagen fibers. So while the pain drops, the structural repair of your ligament slows down or stalls.
Where Cortisone Shots Actually Help
The clearest benefit is for partial tears, specifically Grade 1 and Grade 2 injuries, where the ligament is stretched or partially torn but still intact. In these cases, a cortisone shot can break a cycle of chronic pain and inflammation that’s preventing you from doing rehab exercises or returning to normal activity.
One study on MCL (inner knee ligament) injuries found that patients with Grade 1 and Grade 2 tears who received a cortisone injection experienced immediate symptom relief, and 80% were able to return to sport afterward. That’s a strong result, but the key context is that these were partial tears in a ligament with good blood supply, which heals relatively well on its own.
For complete tears (Grade 3), cortisone is rarely recommended. The ligament is fully disrupted, and the priority is either surgical repair or bracing to allow the ends to reconnect. Suppressing inflammation and collagen production in a fully torn ligament works against recovery. Many orthopedic providers actively discourage steroid injections near areas where tissue is already ruptured.
How Quickly It Works and How Long It Lasts
Most people notice pain relief within a few days to a week. Complete pain relief typically takes about a week, with the full effect settling in around the three-week mark. Pain tends to improve faster than mechanical symptoms like stiffness or instability.
The relief is temporary. Cortisone doesn’t change the underlying structure of your ligament. Depending on the severity of the injury, the effect may last weeks to a few months before pain returns. This is why cortisone is best understood as a window of opportunity: it buys you reduced pain so you can do the rehab work that actually strengthens and stabilizes the joint.
The Risk of Making Things Worse
Cortisone injections carry a real risk of weakening the tissue they’re meant to help. A cohort study of shoulder patients found that those who received steroid injections had a 9.8% rate of tendon tears, compared to just 1.2% in patients who didn’t get injections. After adjusting for other factors, the injections were associated with a 7.4 times higher risk of tendon rupture, with the average time to onset around 39 months.
While that study looked at tendons rather than ligaments, the underlying biology is the same: cortisone weakens collagen-based connective tissue. The risk is highest when injections are repeated or given directly into a structure that’s already compromised. The American Academy of Orthopaedic Surgeons notes that most providers set a practical limit of three to four cortisone shots per year to any one area. Beyond that, the diminishing returns on pain relief and the rising risk of complications like tears and infection make surgery a better option.
What to Do After the Injection
Rest the affected joint for one to two days after the shot. The first 24 hours should involve minimal stress on the area to allow the medication to absorb and to watch for any adverse reactions. For a knee or ankle injection, you can begin light activity like stationary cycling or bodyweight exercises 24 to 48 hours afterward, then gradually increase intensity based on how you feel.
The most important step is starting or continuing physical therapy once the pain window opens up. The cortisone reduces your symptoms, but it’s the progressive loading, strengthening, and stability work in rehab that actually helps the ligament recover and protects you from reinjury. Skipping rehab and simply relying on the shot for pain relief is where patients run into trouble, because the underlying tear hasn’t changed.
How Cortisone Compares to PRP
Platelet-rich plasma (PRP) injections use concentrated growth factors from your own blood to promote tissue repair, essentially the opposite approach from cortisone. In the short term, cortisone and PRP perform about the same for pain relief. Over longer follow-up periods, PRP shows a trend toward better functional recovery, though the difference hasn’t reached statistical significance in most studies.
The trade-off is practical. Cortisone is cheaper, widely available, and covered by most insurance plans. PRP is often out of pocket and costs several hundred dollars per injection. For someone with a partial ligament tear who needs quick pain relief to start rehab, cortisone is a reasonable first step. For someone concerned about long-term tissue quality, or who has already had multiple cortisone shots, PRP may be worth discussing with an orthopedic provider.
Which Ligaments Respond Best
Ligaments with good blood supply tend to respond better to any treatment, including cortisone. The MCL on the inner side of the knee is a good example: it has a rich blood supply, heals well without surgery, and the research on cortisone injections for chronic MCL pain is encouraging. The lateral ankle ligaments, which are the most commonly sprained ligaments in the body, also fall into this category for partial tears.
The ACL, by contrast, sits inside the knee joint in an environment with poor blood supply. It doesn’t heal well on its own, and cortisone injections into the joint won’t change that. For a complete ACL tear, the conversation is about surgical reconstruction or learning to live without the ligament, not about cortisone. A cortisone shot into the knee joint after an ACL tear might temporarily reduce swelling and pain, but it has no role in repairing the ligament itself.