How long each shot may ease soreness

Cortisone can work quickly, but relief often fades

People in knee studies felt the most relief in the early weeks. By about three months the average change was small, and by six months it wasn’t clear.

That doesn’t mean every person feels the same amount of relief. Some notice little, while others walk or sleep more easily for a time.

Here’s what I’d watch closely. If each shot helps for less time, tell the clinician before you agree to another one.

PRP may take longer, and it doesn’t help everyone

PRP means platelet-rich plasma: your blood is spun into a small amount holding more platelets, the parts that help blood clot. A clinician then puts that prepared blood into the sore joint.

Some studies found people felt better months later. A large study found the prepared blood worked no better than a salt-water shot, which researchers used only for comparison.

QC Kinetix calls this kind of blood-based care biologic therapies and prepares it at the clinic. Studies disagree, so nobody can honestly say it usually helps or predict your relief.

The joint and the cause change the answer

Most timing studies looked at knees with arthritis. A sore shoulder tendon or a worn hip may not follow the same timing.

Your last response doesn’t prove what will happen next, but it gives the clinician useful facts. Bring the date and say how long the relief lasted.

A careful answer may be less exact than you’d like. Even so, it should fit the exam and the daily task you most want back.

Sources

1. The 2015 Cochrane review of 27 trials (1,767 participants) found intra-articular corticosteroid better than sham for knee OA pain (SMD -0.40, 95% CI -0.58 to -0.22; NNTB 8), but the benefit decayed with time: moderate at 1-2 weeks, small at 13 weeks, and no evidence of any effect at 26 weeks. All outcomes were graded LOW quality.

   Jüni P, et al. — Intra-articular corticosteroid for knee osteoarthritis.. Cochrane Database Syst Rev, 2015. DOI: 10.1002/14651858.CD005328.pub3.

2. A meta-analysis of eight RCTs found the pooled effect of intra-articular corticosteroid on knee pain was -0.58 SMD (95% CI -0.88 to -0.27; NNT 5.1), with the effect approaching statistical insignificance at four months and a non-significant pooled risk ratio for adverse effects of 0.95.

   Saltychev M, et al. — The Magnitude and Duration of the Effect of Intra-articular Corticosteroid Injections on Pain Severity in Knee Osteoarthritis: A Systematic Review and Meta-Analysis.. Am J Phys Med Rehabil, 2020. DOI: 10.1097/PHM.0000000000001384.

3. A meta-analysis of 7 trials (606 participants) mapped the crossover between the two commonest injections: corticosteroid is relatively more effective for pain from baseline to week 4, the two are equal at week 4, and beyond week 8 hyaluronic acid has the greater effect.

   Bannuru RR, et al. — Therapeutic trajectory of hyaluronic acid versus corticosteroids in the treatment of knee osteoarthritis: a systematic review and meta-analysis.. Arthritis Rheum, 2009. DOI: 10.1002/art.24925.

4. A 2022 BMJ systematic review and meta-analysis of 169 trials (21,163 participants) found viscosupplementation produced only a small pain reduction versus placebo (SMD -0.08, 95% CI -0.15 to -0.02; about -2.0 mm on a 100 mm VAS), below the minimal clinically important difference, and trial sequential analysis indicated conclusive evidence of clinical equivalence with placebo since 2009.

   Pereira TV, et al. — Viscosupplementation for knee osteoarthritis: systematic review and meta-analysis.. BMJ, 2022. DOI: 10.1136/bmj-2022-069722.

5. The RESTORE randomized trial (288 participants, leukocyte-poor PRP, 3 weekly injections) found no significant difference from saline placebo at 12 months in knee pain (-2.1 vs -1.8 points; difference -0.4, 95% CI -0.9 to 0.2) or in medial tibial cartilage volume (-1.4% vs -1.2%), with 29 of 31 secondary outcomes also showing no between-group difference.

   Bennell KL, et al. — Effect of Intra-articular Platelet-Rich Plasma vs Placebo Injection on Pain and Medial Tibial Cartilage Volume in Patients With Knee Osteoarthritis: The RESTORE Randomized Clinical Trial.. JAMA, 2021. DOI: 10.1001/jama.2021.19415.

6. A 2024 network meta-analysis of 48 studies (9,338 knees) at minimum 6-month follow-up ranked PRP first for pain and function (SUCRA 91.5), then BMAC (76.5) and hyaluronic acid (53.1), with corticosteroid (15.2) barely above placebo (13.7) at that time point.

   Jawanda H, et al. — Platelet-Rich Plasma, Bone Marrow Aspirate Concentrate, and Hyaluronic Acid Injections Outperform Corticosteroids in Pain and Function Scores at a Minimum of 6 Months as Intra-Articular Injections for Knee Osteoarthritis: A Systematic Review and Network Meta-analysis.. Arthroscopy, 2024. DOI: 10.1016/j.arthro.2024.01.037.

7. A meta-analysis of 14 placebo cohorts (1,076 patients) found intra-articular NORMAL SALINE alone produced statistically and clinically meaningful improvement in VAS pain and WOMAC scores lasting up to 6 months - meaning a large share of the improvement people attribute to an injection is not attributable to the drug in the syringe.

   Saltzman BM, et al. — The Therapeutic Effect of Intra-articular Normal Saline Injections for Knee Osteoarthritis: A Meta-analysis of Evidence Level 1 Studies.. Am J Sports Med, 2017. DOI: 10.1177/0363546516680607.

8. A systematic review of five small trials of intra-articular steroid injection in HIP osteoarthritis found a large treatment effect at one week that declined thereafter, a moderate effect persisting to eight weeks in two trials, and an odds ratio of 7.8 for meeting OMERACT-OARSI response criteria at eight weeks (NNT 2.4).

   McCabe PS, et al. — The efficacy of intra-articular steroids in hip osteoarthritis: a systematic review.. Osteoarthritis Cartilage, 2016. DOI: 10.1016/j.joca.2016.04.018.

9. FDA's HCT/P guidance sets out the minimal-manipulation and homologous-use criteria that decide whether a human cell or tissue product is regulated solely under 21 CFR Part 1271 (section 361) or requires a biologics licence; cell-based orthopaedic injections that fall outside those criteria are unapproved drugs and biological products, and no cell-based product is FDA-approved to treat osteoarthritis.

   U.S. Food and Drug Administration — Regulatory Considerations for Human Cells, Tissues, and Cellular and Tissue-Based Products: Minimal Manipulation and Homologous Use - Guidance for Industry and FDA Staff. U.S. Food and Drug Administration, 2020.