Dr. Louis Rizio

PRP vs. Gel (HA) vs. Steroid injection for knee arthritis

Knee osteoarthritis (OA) causes pain and stiffness due to cartilage wear-and-tear. When exercise, weight loss, and pain medications aren’t enough, doctors often use injections to ease symptoms. Three common options are platelet-rich plasma (PRP), hyaluronic acid (HA), and corticosteroids. Recent randomized controlled trials (RCTs) in the last 5 years shed light on how these treatments compare in relieving pain, improving knee function, and how long their benefits last.

Platelet-Rich Plasma (PRP): PRP is made from the patient’s own blood – concentrating platelets and growth factors believed to reduce inflammation and promote healing. Hyaluronic Acid (HA): HA is a gel-like substance that lubricates the joint; it’s often called a “gel” or viscosupplement injection. Corticosteroids: Steroid injections (like triamcinolone, depo-medrol etc…) are powerful anti-inflammatories that provide quick pain relief.

Illustration of a normal knee (left) vs. a knee with osteoarthritis (right), showing how cartilage deterioration leads to bone-on-bone contact and joint inflammation .

Pain Relief and Functional Improvement

PRP provides greater pain relief and functional gain, especially long-term: Multiple recent RCTs and reviews report that PRP injections lead to significantly more pain reduction and better joint function than HA or steroids at mid- and long-term follow-ups . For example, in one trial a single PRP injection improved knee pain by ~52% after one year, compared to only ~14% improvement with a corticosteroid injection . Both PRP and steroid groups felt less pain in the first month, but by 3 to 6 months PRP patients had markedly better outcomes . PRP’s advantage extends to function: patients show higher scores on knee function tests (like WOMAC or IKDC) than those treated with HA or steroids in many studies . A 2025 meta-analysis of 42 RCTs concluded that PRP leads to lower pain scores and better function than HA across multiple studies . In short, PRP not only reduces pain more effectively, but the improvement in movement and daily activity tends to be greater and more sustained.

HA injections help, but not as much as PRP: Hyaluronic acid can modestly reduce pain and improve function, typically peaking a few months after a treatment cycle. Patients do report symptom relief – one review noted both PRP and HA injections help knee pain by 3 months, but PRP’s benefits were superior by 6 and 12 months . Some trials found no huge difference at early follow-ups, but by one year PRP-treated knees often feel better and work better than HA-treated ones . For instance, PRP patients had significantly lower pain scores at 6 and 12 months in many studies . That said, HA still provides relief for many patients. It may be a suitable option for those who prefer a well-established treatment, albeit with slightly less pronounced or shorter-lived improvements on average.

Steroid injections work fast but fade quickly: Corticosteroids (like cortisone shots) are known for rapid pain relief. RCTs show that steroid injections can sharply reduce knee pain within days to weeks, bringing quick comfort in flare-ups . In fact, one study reported steroids gave the best pain relief in the first 4–6 weeks compared to PRP or HA . However, this benefit is short-lived. Steroids do not improve underlying joint health, and their symptom relief often peaks around 1 month and then wanes . By 2–3 months after a steroid shot, patients tend to lose the pain reduction – in longer-term scores (6–12 months) steroid-treated knees usually fare no better than before and worse than knees treated with PRP or HA . For example, at one-year follow-up in an RCT, patients who got a steroid had no significant pain improvement from baseline, whereas PRP patients were still much better off . Thus, steroids are best for short-term relief, but they do not provide the lasting improvement seen with PRP (or even the moderate mid-term benefit of HA).

How Long Does Relief Last?

PRP’s relief lasts the longest: Patients who receive PRP injections often experience **pain relief that endures for 6 to 12 months on average . Many report meaningful improvement in pain and mobility for around a year before symptoms slowly start to return. In clinical studies, a single PRP injection provided sustained benefits through 6 months and even up to 1 year in mild-moderate OA . (In fact, some trials using two or three PRP injections show that top-up doses might extend the relief beyond a year .) This long duration makes PRP especially appealing for those looking to delay knee surgery. Keep in mind that results vary by individual – but overall, PRP’s therapeutic effect outlasts that of HA or steroids in comparable patient groups .

HA offers intermediate-duration relief: Hyaluronic acid injections typically relieve knee OA symptoms for about 4 to 6 months in patients who respond . Pain often starts improving ~4 weeks after the injections (since HA may need time to enhance the joint fluid) . Peak benefits are commonly reported around 2 to 3 months after a injection series . Many patients continue to feel improvement at 6 months, but by then some notice the pain creeping back. Studies indicate that roughly half of patients get significant pain relief for several months from HA, but the effect may diminish by 6–12 months . Some individuals do get longer relief (up to a year or more) – especially if they undergo repeat HA injection cycles . Overall, HA’s duration of benefit is moderate: longer than a one-time steroid shot, but generally shorter than PRP’s duration of effect.

Steroid relief is short-term: Corticosteroid injections act quickly but their pain-relieving effect usually lasts only a few weeks to a couple of months . Patients often feel significant relief within days, with the best improvement in the first 1–4 weeks. By about 8–12 weeks (2–3 months), however, the pain and stiffness tend to return as the steroid’s anti-inflammatory action wears off . Evidence from RCTs confirms that by 3–4 months after a steroid shot, there is often no remaining benefit over placebo or baseline in terms of pain scores . This short duration is why guidelines recommend limiting steroid injections to temporary symptom flares. Repeated frequent steroid shots are not advised (they can cause side effects or cartilage damage over time) . In summary, steroid injections shine in the short run but provide little to no lasting improvement in knee OA.

Randomized Controlled Trial Evidence Summary

Numerous RCTs in recent years have directly compared PRP, HA, and steroids in knee osteoarthritis. The overall findings can be summed up as follows:

PRP vs HA: PRP has a slight edge. Both treatments are safe and help reduce pain, but PRP-treated patients report greater pain relief and better function, especially noticeable at 6 months and beyond . For example, a network meta-analysis (2023) found PRP injections led to lower pain scores and better WOMAC function scores at 1 year than HA injections . Patients receiving PRP were also more likely to report meaningful improvement in symptoms. (One review noted ~60% of PRP patients had ≥50% pain improvement at 6 months, vs ~50% of HA patients .) PRP vs Steroid: PRP shows superior long-term efficacy. High-quality trials report that while steroids reduce pain faster in the first weeks, PRP’s benefits surpass steroids after 2–3 months and last much longer . At one-year follow-ups, PRP-treated knees consistently have less pain and better function than steroid-treated knees . For instance, one study found no pain improvement at 12 months with a single steroid shot, whereas PRP patients maintained significant pain relief through 1 year . These results suggest PRP addresses the underlying joint environment more effectively than a steroid’s temporary inflammation suppression . HA vs Steroid: Head-to-head trials are fewer, but the evidence indicates hyaluronic acid may not act as quickly as steroids for immediate pain relief, yet it potentially provides longer relief than steroids. Some comparisons show similar pain scores at 1–3 months between HA and steroid groups, but by ~6 months the steroid benefits fade while HA patients can still have reduced pain . In other words, steroids start strong then fizzle out, whereas HA has a slower, milder onset but can sustain moderate improvement a bit longer. By 6–12 months, neither may be very effective, but patients often prefer HA if they seek to avoid steroid side effects for a modest gain in duration of relief.

Finally, all three injections are generally considered safe when used properly. Side effects are usually mild for each – for PRP and HA the most common is temporary injection-site pain or swelling. PRP may cause a brief inflammatory reaction (e.g. mild flare-ups of knee swelling occurred in about 10–15% of patients in studies , which resolves within days). Steroid injections can sometimes cause a flare of pain shortly after injection and, if repeated too often, carry a small risk of cartilage or joint damage . In the reviewed RCTs, no severe adverse events were reported for PRP, HA, or steroids . All are non-surgical, outpatient treatments that can be administered in a doctor’s office.

Bottom Line: For knee osteoarthritis, PRP injections show the greatest and longest-lasting improvements in pain and function according to recent RCT evidence . PRP’s pain relief can last 6–12 months, significantly outperforming corticosteroids after the early weeks, and edging out hyaluronic acid at longer follow-ups . Hyaluronic acid injections do help a subset of patients, providing a few months of reduced pain and improved mobility, though results are not as pronounced or durable as PRP in many studies . Steroid injections remain a useful short-term option for flare-ups – they act fast, but their effects are fleeting (wearing off by about 2–3 months) . In summary, if the goal is swift, short-term pain relief, a steroid shot may be appropriate; for more sustained relief and functional improvement, PRP has emerged as an excellent choice (especially for mild-to-moderate OA), with HA as another middle-ground option . Always consult with a healthcare provider to determine the best treatment plan for your situation, but these findings from recent trials provide promising insight into what patients can expect from PRP, HA, or steroid knee injections.

Sources: Recent RCTs and reviews comparing PRP, hyaluronic acid, and steroids , including a 2023 network meta-analysis and a 2025 systematic review. These studies consistently show PRP’s superior pain and function outcomes at 6 and 12 months, versus the shorter-term benefits of HA and steroids. The above graphical summary illustrates these outcome differences in visual form.