Written by the Nuvirox Research Team
Key Points
- A 2021 meta-analysis of 13 randomized trials (1,086 patients) found orthopedic insoles produced a statistically significant, but small, reduction in knee osteoarthritis pain.
- The most common type studied — lateral wedge insoles for medial knee osteoarthritis — has genuinely mixed results: some well-run 12-month trials found real benefit, others found insoles worked no better than a flat control insole.
- Insoles are cheap, low-risk, and easy to try, which is probably why they remain a first-line recommendation even though the average effect size across trials is modest.
Short answer: modestly yes for some people, with a research record that is genuinely mixed rather than a clean win. Orthotic insoles — particularly lateral wedge insoles, which tilt the outside of the foot slightly upward to shift load away from the inner knee — are one of the most-studied non-drug interventions for knee osteoarthritis. Pooled across 13 randomized trials and over a thousand patients, they produce a statistically significant pain reduction. But “statistically significant” and “life-changing” are different things, and several individual high-quality trials have found insoles perform no better than a flat placebo insole.
What are orthotic insoles supposed to do, mechanically?
They’re designed to change how much force passes through the inner (medial) versus outer (lateral) compartment of the knee with every step. Most people with knee osteoarthritis have it worse on the inner side of the joint, and that side also happens to carry more load during normal walking due to typical leg alignment. A lateral wedge insole tilts the sole of the foot so the outer edge sits slightly higher, which theoretically shifts load toward the outer knee compartment and away from the more arthritic inner side. This measurable load shift is called the knee adduction moment (KAM), and it’s the biomechanical variable most insole trials actually track, alongside patient-reported pain.
What do the actual trials show?
The pooled evidence leans positive but modest; the individual trials are all over the map. A 2021 systematic review and meta-analysis of 15 studies from 13 randomized controlled trials, covering 1,086 participants, found orthopedic insoles produced a statistically significant reduction in WOMAC pain scores compared to controls — though the effect size was modest and heterogeneity across studies was high, meaning individual trials disagreed substantially with each other.
Look at the individual trials and you can see why. A well-designed 12-month randomized trial of lateral wedge insoles for medial knee osteoarthritis, tracking both symptoms and structural cartilage volume on MRI, was built specifically to test whether insoles could slow disease progression, not just mask pain. A separate randomized crossover trial found insoles improved function and reduced discomfort similarly to a more rigid ankle-foot orthosis. But a Brazilian randomized trial comparing a lateral wedge insole with subtalar strapping against a neutral control insole found that both groups improved on WOMAC scores over 24 weeks, with no statistically significant difference between the wedge and the neutral insole — a genuine null result for the “wedge” part of the intervention specifically. And a randomized trial comparing insoles against knee braces found no differences in pain or WOMAC scores between the two, with only about 17% of patients meeting formal responder criteria.
Why do the results disagree so much?
Individual biomechanics, insole design, and how consistently people actually wear them all vary a lot between trials — and between people. Insoles that measurably reduce the knee adduction moment in a gait lab don’t always translate into less pain in daily life, and vice versa. Compliance also matters: one trial noted that patients in the insole group complied better with wearing their assigned device than patients using a brace, which can itself inflate an insole’s apparent effectiveness independent of biomechanics.
What orthotic insoles won’t do
They won’t reverse existing cartilage loss, and a flat, unfitted insole from a drugstore rack is not the same intervention that’s been tested in these trials. Most of the positive trials used custom-fit or specifically-angled wedge insoles, not generic cushioned inserts. If you have significant knee malalignment (notably bow-leggedness), some evidence suggests wedge insoles may be less consistently helpful than for more neutral alignments. See a doctor or podiatrist before investing in custom orthotics if your pain is new, worsening, or accompanied by visible joint swelling or instability.
How does this compare to other joint-loading approaches?
Insoles are one of several approaches researchers have tested for shifting mechanical load away from an arthritic knee, and they tend to sit in the middle of the pack — more evidence than trekking poles, less consistent than a well-fitted brace for some patients. A randomized crossover trial comparing lateral wedge insoles, an ankle-foot orthosis, and the combination of both found that a valgus knee brace produced more pain and knee-adduction-moment benefit than the insole alone, though combining the two didn’t meaningfully outperform the brace by itself. This kind of head-to-head comparison is useful precisely because it tests these assistive devices against each other rather than each in isolation against a placebo, which is closer to the real-world decision most people with knee osteoarthritis actually face: not “insole or nothing,” but “insole, brace, or both.”
Frequently asked questions
Do I need custom orthotics, or will over-the-counter insoles work? Most of the positive trial results used a specific lateral wedge angle (commonly around 5 degrees), which is closer to what a podiatrist fits than a generic drugstore insole — though some trials did use simpler off-the-shelf wedge designs.
How long before I’d notice a difference? Trials generally assessed outcomes at multiple points from a few weeks out to 12 months, with the clearest signal typically building over the first 2–3 months of consistent daily wear.
Are insoles better than knee braces? The direct comparison trial found no meaningful difference between the two for pain or function, so this often comes down to comfort and which one you’ll actually wear consistently.
Can insoles replace exercise or weight management for knee osteoarthritis? No — insoles are best thought of as one modest piece of a broader plan; see our review of exercise for arthritic joints for the bigger picture.
FROM NUVIROX
Why we formulated Joint+ Restore
Joint+ Restore isn't built around a single trendy ingredient — it's built around a formula philosophy: pair the compounds with the most consistent published research behind them, skip the ones that only look good in a marketing bullet point, and back the whole thing with a guarantee long enough to actually judge it. We're currently reformulating Joint+ Restore, so rather than list ingredients that may change, here's what won't change: every version is dosed at levels drawn from the human trial literature, not proprietary-blend guesswork, and it's covered by our 60-day money-back guarantee — long enough to actually evaluate it the way the research says you should.
The bottom line
Orthotic insoles are a low-risk, inexpensive intervention with real but modest supporting evidence — worth trying, not worth expecting a dramatic result from. If insoles alone aren’t enough, it’s worth reading how they compare to other assistive approaches, including our look at whether trekking poles reduce knee joint load and our earlier coverage of knee braces for osteoarthritis.
References
- Effects of orthopedic insoles on patients with knee osteoarthritis: A meta-analysis and systematic review. PMID: 33904586.
- Bennell KL, et al. Lateral wedge shoe insoles for medial knee osteoarthritis: a 12-month randomised controlled trial. PMC3102980.
- Lateral wedge insole for knee osteoarthritis: randomized clinical trial. PMC10496616.
- Medial Knee Osteoarthritis Treated by Insoles or Braces: A Randomized Trial. Clin Orthop Relat Res. 2010.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for professional medical advice.