Creatine

Creatine's mechanism has nothing to do with cartilage, and this entry won't pretend otherwise. Phosphocreatine buffering raises training quality, which augments resistance-training gains in lean mass and strength — and quadriceps strength is a known protective factor for knee-OA symptoms and function. Any joint benefit runs through muscle.

The direct knee-OA trials

Neves 2011 (n=24 postmenopausal women with knee OA, 20 g/day for a week then 5 g/day, 12 weeks, both arms doing supervised lower-limb resistance training): physical function improved only with creatine — timed-stands went from 15.7 to 18.1 reps versus no change on placebo (P=0.004) — along with WOMAC function and stiffness subscales, lower-limb lean mass, and quality of life. The asterisk: pain improved in both groups. That was the training working, not the creatine.

Osama 2025 (n=40, creatine plus physical therapy versus placebo plus identical therapy, 4 weeks): greater improvements in VAS pain, overall KOOS, isometric strength and fall risk with creatine. Three measures did not separate — the KOOS quality-of-life subscale, knee range of motion, and the five-repetition sit-to-stand, where both arms improved at the same rate. Short, small, multiple co-interventions, not yet replicated.

That is the entire direct evidence base: 64 randomized participants across two single-centre trials.

The null trials

The pattern across the null results is instructive. Around total knee arthroplasty (n=37, dosed before and after surgery), creatine produced no benefit for body composition, strength, or recovery — a catabolic peri-operative window likely swamps any supplement. In rheumatoid arthritis without a training program (n=40), creatine added half a kilogram of appendicular lean mass but no knee-extensor strength, no grip strength and nothing on any objective function test. Both arms improved equally on those tests, which the authors read as practice rather than treatment. The lean mass arrived with a litre of extra body water and receded with it after supplementation stopped.

The consistent reading: creatine helps when paired with progressive resistance training and does little without it.

The indirect base

The meta-analysis behind the "stronger muscle protects the joint" logic pooled 22 randomised trials (n=721 older adults): creatine during resistance training added about 1.37 kg of lean tissue and modestly more upper- and lower-body strength than training alone. Ten of the 22 found nothing on their own. Fifteen were in healthy older adults and one was in osteoarthritis; the rest covered frailty and other chronic illness, and dropping all of those leaves 1.26 kg. No joint outcomes were measured in any of them — it anchors the mechanism, not the OA claim.

Dose & practical notes

Trial-tested regimens: 20 g/day loading for 5–7 days then 3–5 g/day, or simply 3–5 g/day throughout. Expect roughly 1–2 kg of scale-weight gain from intramuscular water. If you are not doing progressive resistance work, the trial record gives you little reason to expect anything.

Safety

Creatine monohydrate at 3–5 g/day has an unusually deep safety record; controlled data do not support kidney-damage claims in healthy users, including older adults — though the ISSN position stand making that case has authors with industry consulting ties. Use medical supervision with pre-existing renal disease. Serum creatinine rises benignly (it is a creatine metabolite) and can be misread on blood panels; GI upset occurs at large single doses.

What I take from it

Creatine is the rare supplement here whose best evidence is explicit about its route: it makes rehab and strength training work better, and strength is one of the few interventions with real evidence for painful knees. Take it as a training adjunct or not at all.