Role of insole material in treatment of plantar fasciitis: a randomized clinical trial

Key points

1. 0135 adults with plantar fasciitis were randomly given one of three prefabricated insoles: carbon fiber, polyurethane, or foam.
2. 02Pain intensity (VAS) was similar across all three groups at baseline and at every follow-up, so no material clearly beat the others on raw pain.
3. 03Carbon fiber users showed a significant gain in quality of life (FAOS) at twelve weeks (p=0.047).
4. 04Foam users showed significant improvement on PROMIS pain intensity and pain interference at certain time points (p=0.0003 and p=0.036).
5. 05The authors suggest insole material may be linked to treatment effect and call for further gait-based and patient-specific research.

How it was conducted

Design

Randomized clinical trial at a tertiary foot and ankle research center in Massachusetts, per-protocol analysis

Participants

Adults diagnosed with plantar fasciitis who had not had injectable or surgical treatment

Groups

Carbon fiber insole (n=13), polyurethane insole (n=13), foam insole (n=9)

Outcomes

PROMIS 3a pain intensity, PROMIS 4a pain interference, FAOS, and VAS for pain

Time points

Baseline (T0) and 2, 6, and 12 weeks of insole use

Statistics

Kruskal Wallis and Friedman tests, significance set at p<0.05

What they found

• Mean age by group was 51.9 plus or minus 13.2, 51 plus or minus 12.5, and 47.9 plus or minus 13.5 years (p>0.05).
• Baseline weight by group was 211.6 plus or minus 32.7 lbs, 193.6 plus or minus 59.3 lbs, and 180.7 plus or minus 33 lbs (p>0.05).
• VAS pain intensity was similar across groups at baseline and all follow-up time points (p>0.05).
• Carbon fiber insole users had significant improvement in quality of life (FAOS) at twelve weeks (p=0.047).
• Foam insole users had significant pain relief on PROMIS pain intensity and pain interference (p=0.0003 and p=0.036).

Limitations

• Very small sample of 35 participants split across three groups, including only 9 in the foam group, limiting statistical power.
• Per-protocol analysis and short twelve-week follow-up mean longer-term and dropout effects are unknown.
• No active control or placebo insole, so improvement may partly reflect natural recovery over time.
• Reported as a conference meeting abstract with limited methodological detail and no full peer-reviewed write-up.

Why it matters

For patients

If you have heel pain from plantar fasciitis, the insole material may matter a little, but this small early study cannot tell you which one is clearly best for you.

For clinicians

Prefabricated insole material could be a variable worth considering, with carbon fiber linked to better twelve-week quality of life, though the small per-protocol sample warrants caution before changing practice.

For readers

This is a small, early-stage randomized trial reported as an abstract, so treat its findings as a hypothesis-generating signal rather than definitive evidence.