Why does joint soreness come and go?

Why might the joint improve before care begins?

People often make an appointment when the ache is worse than usual. That sore spell may ease with time, lighter activity or better sleep before care begins. This is why some studies use saline, which is clean salt water. One group gets salt water as a joint shot, while the other receives the care being tested during an otherwise similar visit with the same attention and aftercare from the clinic team. Doctors can then see whether the tested care brought more relief than the salt-water shot. The salt water isn’t offered to soothe the joint; doctors use it only for a fair study.

Relief still matters to you.

What is worth writing down?

You might note whether walking, stairs, reaching, yard work or sitting came first. Add how long the soreness lasted and whether rest, heat, cold or slow movement helped. These details may guide the exam and help your doctor decide whether an X-ray or another scan could explain wear or an old injury. Meanwhile, smaller chores and easy motion may hold down stiffness. Any calendar in the house will work, and you don’t need special equipment. If the notes become a burden, stop; remembering one troublesome activity is still helpful.

You’ll arrive with useful facts.

Sources

1. A meta-analysis of the PLACEBO arms of 73 double-blind trials (5,895 patients) quantified what a saline knee injection alone achieves: statistically and clinically significant improvement in pain, function and quality of life at 1, 3 and 6 months, with responder rates exceeding 50% at all three time points, peaking around 4-8 months and declining by 12 months. Placebo response was stronger in trials with more female participants and in more recently published trials.

   Previtali D, 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. DOI: 10.1530/EOR-2025-0022.

2. RESTORE, the largest and most rigorously blinded placebo-controlled PRP trial in knee OA (n=288, participant-, injector- and assessor-blinded), gave three weekly injections of a commercial leukocyte-poor PRP or saline. At 12 months the change in knee pain was -2.1 vs -1.8 points (difference -0.4; 95% CI -0.9 to 0.2; P=.17) and the change in medial tibial cartilage volume was -1.4% vs -1.2% (difference -0.2%; P=.81). Twenty-nine of 31 prespecified secondary outcomes showed no between-group difference. The authors concluded the findings do not support the use of PRP for knee OA.

   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.

3. In a within-patient placebo-controlled trial, 25 people with BILATERAL knee osteoarthritis received bone marrow aspirate concentrate in one knee and saline in the other, acting as their own controls. Pain scores fell significantly from baseline in BOTH knees at 1 week, 3 months and 6 months, and the relief - described by the authors as dramatic - did not differ significantly between the BMAC knee and the saline knee.

   Shapiro SA, et al. — A Prospective, Single-Blind, Placebo-Controlled Trial of Bone Marrow Aspirate Concentrate for Knee Osteoarthritis.. American Journal of Sports Medicine, 2017. DOI: 10.1177/0363546516662455.

4. 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.

5. A meta-analysis of 50 studies (4,076 patients) quantified the placebo effect of knee injections as significant and long-lasting, with functional improvements persisting even longer than the improvements in pain perception, and warned that the size of this effect should not be overlooked when interpreting trials or counselling patients.

   Previtali D, et al. — The Long-Lasting Effects of "Placebo Injections" in Knee Osteoarthritis: A Meta-Analysis.. Cartilage, 2021. DOI: 10.1177/1947603520906597.

6. A network meta-analysis of pharmacologic knee OA treatments found intra-articular treatments were superior to oral NSAIDs, and the authors attributed this at least partly to the integrated placebo effect of the injection itself rather than to the injected substance.

   Bannuru RR, et al. — Comparative effectiveness of pharmacologic interventions for knee osteoarthritis: a systematic review and network meta-analysis.. Ann Intern Med, 2015. DOI: 10.7326/M14-1231.