Why can soreness change from one day to the next?

Does a better day prove that care worked?

One good day can follow rest, lighter work, or better sleep. The ache may also change without a clear reason.

That’s why one person’s report can’t prove what caused relief. It tells what happened to that person, which still may matter.

Research compares groups to see whether a treatment adds help. Even then, the result may not match every sore joint.

Watch whether you can walk, reach, or sleep more easily. Those changes give the clinic more useful details than praise alone.

Does PRP work the same in every joint?

Joints and tendons don’t all bear the same kind of strain. Care that helps one sore area may do less for another.

The way PRP is prepared can also differ between offices. That makes broad claims hard to use for your own choice.

Ask which body part the research covered and how people were checked. You’ll get more from a clear answer than a promise.

Can reviews prove that a treatment will help?

Public comments can describe kindness, clear bills, and calls returned. They can’t show whether a treatment caused less soreness.

A review may leave out the exam, other care, and recovery time. It may also cover a service that has nothing to do with joints.

Use the comment for the facts it gives you. Ask clinic staff about the care being offered and its limits.

Your own doctor or nurse can help weigh those answers. Bring up past care and any health issue that may matter.

Evidence sources

1. In the RESTORE trial - the largest placebo-controlled PRP trial in knee osteoarthritis - 288 adults aged 50+ with symptomatic Kellgren-Lawrence grade 2-3 medial knee OA received three weekly intra-articular injections of leukocyte-poor PRP from a commercial system or saline placebo. At 12 months the mean change in knee pain was -2.1 points with PRP versus -1.8 with saline (difference -0.4; 95% CI -0.9 to 0.2; P=.17) against a minimum clinically important difference of 1.8, and the change in medial tibial cartilage volume was -1.4% versus -1.2% (difference -0.2%; 95% CI -1.9% to 1.5%; P=.81). Twenty-nine of 31 prespecified secondary outcomes showed no significant between-group difference. The authors concluded the findings do not support use of PRP for knee OA.

   Bennell KL, Paterson KL, Metcalf BR, 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.

2. A Bayesian network meta-analysis restricted to LARGE randomized trials (at least 100 patients per group; 57 trials, 22,795 participants, 18 intra-articular interventions) found treatment effects were larger in the 35 high-risk-of-bias trials than in the 22 low/unclear-risk trials. Excluding high-risk trials, the effects of 16 of the 18 intra-articular interventions in knee or hip OA were smaller than the minimal clinically important difference and most were consistent with placebo effects; triamcinolone had the highest probability of exceeding the MID at weeks 2-6.

   Pereira TV, Saadat P, Bobos P, et al. — Effectiveness and safety of intra-articular interventions for knee and hip osteoarthritis based on large randomized trials: A systematic review and network meta-analysis. Osteoarthritis and Cartilage, 2025.

3. A meta-analysis of 73 articles covering 5,895 patients quantified the PLACEBO response to intra-articular injection in knee osteoarthritis: statistically and clinically significant improvements in pain, function and quality of life at 1, 3 and 6 months, with responder rates above 50% at each of those points, declining by 12 months. The placebo response was stronger in trials with more female participants and in more recently published trials. This is why an uncontrolled 'our patients improved' figure carries almost no information.

   Previtali D, Boffa A, Di Laura Frattura G, et al. — Placebo response to intra-articular injections in knee osteoarthritis: magnitude, evolution over time, and influencing factors. A systematic review and meta-analysis with meta-regression. EFORT Open Reviews, 2025.

4. An updated meta-analysis of six randomized trials (422 patients) found no benefit of PRP over placebo for Achilles tendinopathy on VISA-A at 3 months (mean difference 1.7; 95% CI -1.8 to 5.2), 6 months (0.5; 95% CI -8.5 to 9.3) or 1 year (-7.9; 95% CI -27.3 to 11.6), nor on VAS pain at 3 months. Funnel-plot asymmetry suggested publication bias inflating apparent benefits. The authors wrote that PRP should not be used to treat Achilles tendinopathy until high-quality trials show a clear clinical benefit.

   Barreto ESR, Antunes Junior CR, Silva IC, et al. — Is Platelet-rich Plasma Effective in Treating Achilles Tendinopathy? A Meta-analysis of Randomized Clinical Trials. Clinical Orthopaedics and Related Research, 2025.

5. A network meta-analysis of 11 randomized trials (1353 patients) with HIP osteoarthritis found that for both pain and function, at 2-4 months and at 6 months, NO intervention - corticosteroid, hyaluronic acid or PRP - significantly outperformed an intra-articular saline placebo injection.

   Gazendam A, Ekhtiari S, Bozzo A, et al. — Intra-articular saline injection is as effective as corticosteroids, platelet-rich plasma and hyaluronic acid for hip osteoarthritis pain: a systematic review and network meta-analysis of randomised controlled trials. British Journal of Sports Medicine, 2021.

6. A systematic review and meta-analysis with best-worst case analysis found statistically NON-significant evidence that PRP with or without physical therapy reduced mean time to return to play or reinjury rates for hamstring injuries compared with no treatment or physical therapy alone, in short-term follow-up. Complication rates (postinjection discomfort, pain or sciatic nerve irritation) averaged 5.2% +/- 2.9%. The pooled picture does not support the single positive trial.

   Seow D, Shimozono Y, Tengku Yusof TNB, et al. — Platelet-Rich Plasma Injection for the Treatment of Hamstring Injuries: A Systematic Review and Meta-analysis With Best-Worst Case Analysis. American Journal of Sports Medicine, 2021.

7. The Cochrane review of platelet-rich therapies for musculoskeletal soft-tissue injuries concluded there is currently insufficient evidence to support the use of platelet-rich therapy for treating musculoskeletal soft tissue injuries, overall and for individual conditions - including pooled data from six trials of PRP applied during rotator cuff repair surgery, which showed no statistically or clinically significant long-term functional difference. The review ended with an explicit call for standardisation of PRP preparation methods.

   Moraes VY, Lenza M, Tamaoki MJ, et al. — Platelet-rich therapies for musculoskeletal soft tissue injuries. Cochrane Database of Systematic Reviews, 2014.

8. In a 2-year double-blind randomized trial, intra-articular triamcinolone every 12 weeks produced significantly greater cartilage volume loss than saline (mean change in index compartment cartilage thickness -0.21 mm versus -0.10 mm; between-group difference -0.11 mm; 95% CI -0.20 to -0.03) and no significant difference in knee pain (-1.2 versus -1.9). The authors concluded the findings do not support this treatment for symptomatic knee osteoarthritis - which is the honest reason a patient may want an alternative to repeat steroid shots.

   McAlindon TE, LaValley MP, Harvey WF, et al. — Effect of Intra-articular Triamcinolone vs Saline on Knee Cartilage Volume and Pain in Patients With Knee Osteoarthritis: A Randomized Clinical Trial. JAMA, 2017.

9. A systematic review and meta-analysis in the BMJ concluded that strong conclusive evidence indicates viscosupplementation (hyaluronic acid) leads to only a small reduction in knee osteoarthritis pain compared with placebo - less than the minimal clinically important between-group difference - and that based on 15 large placebo-controlled trials in 6462 participants it is associated with a statistically significant higher risk of serious adverse events (relative risk 1.49; 95% CI 1.12-1.98). The findings do not support broad use of viscosupplementation.

   Pereira TV, Juni P, Saadat P, et al. — Viscosupplementation for knee osteoarthritis: systematic review and meta-analysis. BMJ, 2022.

10. A study training predictive models on imaging features found that neither radiographic grading (IRF) nor MRI-based MOAKS scoring predicted patient pain or symptoms in knee osteoarthritis - the best model reached an R-squared of only 0.28, and predictive performance got WORSE as symptoms got more severe. An X-ray grade is not a prediction of how much someone hurts, and it is not on its own a reason to treat or not treat.

    Hill BG, Eble S, Moschetti WE, et al. — The Discordance Between Pain and Imaging in Knee Osteoarthritis. Journal of the American Academy of Orthopaedic Surgeons, 2025.