Effects of cassava wax immersion on pain, pressure pain threshold, and upper extremity function among patients with trigger finger.
Narongsak Khamnon, Vitsarut Buttagat, Sittiporn Punyanitya and 3 others
PMID 42688482WHAT IT FOUND
Ultrasound plus cassava wax immersion produced significantly greater pain relief than ultrasound alone in trigger finger, though both groups improved on all measures.
Small single-centre trial (38 patients, 4 weeks). Promising but not definitive.
Key findings
01Both groups showed significant pain reduction from baseline, but the experimental group (ultrasound + cassava wax) had significantly greater pain reduction than the control group (ultrasound alone) at every post-treatment time point.
02The experimental group showed significantly greater increases in pressure pain threshold than the control group at the immediate and short-term time points, while the control group's PPT improved significantly only at the short-term point.
03Both groups reduced the frequency of finger-locking episodes, but no significant between-group difference was found for this outcome.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only 38 participants (19 per group) at a single site in northern Thailand, limiting generalisability and statistical power for smaller effects. Follow-up was 1 month after a 4-week intervention; whether the added benefit of the wax bath persists beyond that is unknown. Single-blind design: patients knew whether they received the wax bath, which could bias self-reported outcomes such as VAS and DASH. The MCID thresholds used (VAS ≥ 2, DASH ≥ 10–15) are not specific to trigger finger, so the 'clinically meaningful' claim rests on borrowed cut-offs. The DASH items were re-grouped into five domains by the authors rather than using a validated subscale structure, so domain-level interpretation is tentative.
Declared interests
No conflicts of interest declared. The study was funded by Mae Fah Luang University, the institution where it was conducted.
The easy way to misread this
Do not read this as proof that cassava wax alone treats trigger finger. Both groups received ultrasound and both improved on every measure; the wax bath added a statistically significant extra benefit only for pain and pressure pain threshold, not for finger locking or (at all time points) DASH function. With 19 patients per arm, a single centre, and 1-month follow-up, the between-group differences could shrink or disappear in a larger, longer trial.