Custom insoles versus sham and GP-led usual care in patients with plantar heel pain: results of the STAP-study, a randomised controlled trial

Key points

1. 01Custom-made insoles were no better than sham (fake) insoles for pain or function at 12 weeks.
2. 02People in the GP-led usual care group reported slightly less pain and better function than the custom insole group.
3. 03Only the foot function difference favouring usual care reached a clinically important size.
4. 04Usual care patients used more co-treatments, including corticosteroid injections, which may explain part of their advantage.
5. 05Plantar heel pain often eases on its own, with most people recovering within 12 to 24 months.

How it was conducted

Design

Pragmatic three-armed, participant-blinded and assessor-blinded randomised controlled trial in primary care (the STAP-study, NTR5346)

Participants

185 adults aged 18 to 65 with plantar heel pain lasting 2 weeks to 2 years

Groups

Custom-made insole (n=70), sham insole (n=69), and GP-led usual care (n=46), all with an exercise information booklet; 2:3:3 allocation

Primary outcome

Pain at rest and during activity on an 11-point Numerical Rating Scale at 12 weeks

Secondary outcomes

First step pain, Foot Function Index (0 to 100), and self-reported recovery at 12 weeks

What they found

• Custom insole versus sham, pain during activity at 12 weeks: MD -0.05 (95% CI -0.58 to 0.49), p=0.87, no difference.
• Usual care versus custom insole, pain during activity: MD 0.94 (95% CI 0.23 to 1.65), p=0.01, favouring usual care.
• Usual care versus custom insole, first step pain: MD 1.48 (95% CI 0.65 to 2.31), p<0.001.
• Usual care versus custom insole, FFI pain subscale: MD 6.27 (95% CI 0.84 to 11.69); FFI function subscale: MD 7.37 (95% CI 1.27 to 13.46), exceeding the minimal clinically important difference of 7.21.
• Self-reported recovery at 12 weeks was similar across groups: custom 24/66 (36.4%), sham 25/69 (36.2%), usual care 15/41 (36.6%); usual care versus custom RR 0.48 (95% CI 0.24 to 0.96), p=0.04.
• Usual care patients reported more co-interventions: GP visits (46.2% vs 27.3%), heel cups or other biomechanical aids (41.0% vs 22.7%), and corticosteroid injections (15.4% vs 0%) versus the insole groups.
• Of 118 insole patients, only 68 (57.6%) reported wearing their insoles every day; 176 of 185 completed 12-week follow-up.

Limitations

• The usual care group received more co-interventions, including corticosteroid injections, which may have boosted their results.
• Only about 58% of insole patients reported wearing their insoles daily, so adherence was incomplete.
• Custom insoles were made at each podiatrist's discretion, so the intervention was not standardised.
• Follow-up was only 12 weeks for the primary comparison, so longer-term effects are unknown.

Why it matters

For patients

If you have plantar heel pain, a costly custom insole is unlikely to outperform standard GP care or even a fake insole over 3 months.

For clinicians

Routine referral to a podiatrist for custom insoles is not supported, so consider GP-led usual care and reserve insoles for selected cases.

For readers

This trial questions a common and expensive practice by showing custom insoles add no measurable benefit over sham or usual care.