Learn why the joint aches and what can help

What to notice when soreness starts

Joint wear often feels stiff at first, eases with motion, then aches after use. A sore tendon usually hurts when the nearby muscle pulls against it.

A recent twist or fall can cause a fresh injury. Tell the clinician if the joint swelled, locked, gave way or changed shape.

What to try during a lighter day

Do less of the exact movement that brought on soreness. A short, flat walk may feel better than long standing or sharp turns.

Don't keep repeating a movement just to test the joint. Note whether rest, easy motion or a cool pack calms the ache.

What to take to the joint exam

Write down when the soreness began and the exact place it hurts. Include swelling, night aching, weakness, catching or trouble with stairs.

Bring a medicine list and any old X-ray report. The exam can separate joint wear from a sore muscle cord or fresh injury.

When to get care without waiting

Fever with a joint that feels hot or looks swollen needs prompt care. New weakness, numbness or a limb that won't hold weight also can't wait.

Soreness that stays steady can begin with a regular visit. Seek faster help when swelling grows quickly or you feel ill.

Sources

1. The ESSKA-ORBIT European consensus on blood-derived orthobiologics graded 28 question-statement sets; only 9 of 28 had high-level scientific support. Three statements reached grade A: that there is enough preclinical and clinical evidence to support PRP use in knee OA; that clinical evidence shows effectiveness in MILD TO MODERATE knee OA (KL grade 3 or lower); and that PRP provides a longer effect than the short-term effect of corticosteroid with a safer profile. The panel regarded PRP as a valid and possible first-line injectable option for KL grades 1-3.

   Laver L, et al. — The use of injectable orthobiologics for knee osteoarthritis: A European ESSKA-ORBIT consensus. Part 1-Blood-derived products (platelet-rich plasma).. Knee Surgery, Sports Traumatology, Arthroscopy, 2024. DOI: 10.1002/ksa.12077.

2. The 2025 Cochrane review of stem cell injections for knee osteoarthritis pooled 25 randomised trials (1,341 participants) and found that, compared with placebo injection, stem cell injection MAY slightly improve pain (1.2 points better on a 0-10 scale, 7 studies, 445 participants) and function (14.2 points better on a 0-100 scale, 7 studies, 432 participants) up to six months - both rated LOW-certainty evidence, downgraded for indirectness (cell source, preparation and dose varied across studies) and suspected publication bias, since up to three larger RCTs were conducted and withdrawn before reporting results. Radiographic progression was not assessed in any included study.

   Whittle SL, et al. — Stem cell injections for osteoarthritis of the knee.. Cochrane Database of Systematic Reviews, 2025. DOI: 10.1002/14651858.CD013342.pub2.

3. FDA states verbatim of stem cell products, stromal vascular fraction (adipose-derived cells), umbilical cord blood, Wharton's jelly, amniotic fluid and exosome products: 'None of these products have been approved for the treatment of any orthopedic condition, such as osteoarthritis, tendonitis, disc disease, tennis elbow, back pain, hip pain, knee pain, neck pain, or shoulder pain.' The only FDA-approved stem cell products in the United States are blood-forming (hematopoietic progenitor) cells derived from umbilical cord blood, approved only for disorders of blood production, and there are currently NO FDA-approved exosome products.

   U.S. Food and Drug Administration — Consumer Alert on Regenerative Medicine Products Including Stem Cells and Exosomes. FDA (Center for Biologics Evaluation and Research), 2020.

4. A systematic review of 32 studies comparing leukocyte-poor and leukocyte-rich PRP in knee OA found both formulations improved pain and function above the MCID with no significant difference between them at 3, 6 or 12 months - but leukocyte-RICH PRP carried significantly higher odds of post-injection pain (OR 1.64; 95% CI 1.29-2.10) and swelling (OR 1.56; 95% CI 1.22-1.99).

   Kim JH, et al. — Adverse Reactions and Clinical Outcomes for Leukocyte-Poor Versus Leukocyte-Rich Platelet-Rich Plasma in Knee Osteoarthritis: A Systematic Review and Meta-analysis.. Orthopaedic Journal of Sports Medicine, 2021. DOI: 10.1177/23259671211011948.