Therapy scout

1. Title and sponsor

Structured listening (audio frequency intervention) as an adjunct for postoperative pain and edema after elective foot and ankle surgery: a randomised, double-blind, sham-controlled trial.

Sponsor: [sponsor legal name]

Principal investigator: [investigator name, qualifications, institution]

Site: [hospital or clinic name and address]

2. Rationale and honest framing

Music and structured listening have randomised evidence for anxiety, distress and short-term pain as an adjunct to usual care. They have no established effect on swelling, and no tone has ever been shown to treat tissue injury.

This trial therefore tests an adjunct, not a treatment. The edema endpoint is included because it is the primary endpoint of the parallel PRFE pilot and is expected to be unchanged; a null edema result is a useful, publishable result and is stated as an expected outcome rather than a failure.

No participant-facing material will describe the audio as healing, curing or repairing anything.

3. Design

Randomised, double-blind, sham-controlled, parallel-group, single-site. 60 participants, 1:1 allocation (30 per arm).

Allocation is generated and held server-side by the app's existing randomisation service, in permuted blocks of four, concealed from participants, treating clinicians and outcome assessors.

Blinding is maintained because both arms receive an audio file of identical duration delivered through identical headphones on the same schedule; only the content differs.

4. Arms

Active arm: [the exact audio track, its source, sample rate, and the calibrated playback level in dB SPL at the ear]. Level is fixed by the study, not chosen by the participant.

Sham arm: an audio file of the same duration, same perceived loudness and same general character, constructed so that it carries no structured beat, tone pairing or spectral notch — for example low-level filtered pink noise matched to the active track's long-term spectrum.

Both files are labelled by allocation code only. Neither participant nor assessor can tell them apart by inspection of the player.

Usual postoperative care, including analgesia, elevation and any prescribed PRFE, continues identically in both arms and is recorded.

5. Population

Inclusion: adults 18–75 undergoing elective unilateral foot or ankle surgery; able to consent; able to use headphones; owns or is issued a compatible phone.

Exclusion: bilateral surgery; active implant of any kind (the app's screening lockout applies to any PRFE component of care); moderate or worse hearing loss, hyperacusis or bothersome tinnitus; current opioid use disorder; inability to complete the questionnaires.

Withdrawal for any reason is recorded with date and reason; no participant is replaced after randomisation.

6. Intervention schedule

Two listening sessions per day of 20 minutes each, morning and evening, from day 1 through day 14, seated or reclined with the operated limb elevated.

Adherence is captured automatically: each session is logged with allocation code, start time and completed minutes. A session shorter than 15 minutes counts as incomplete.

No participant may change the track, its level or its duration. The app exposes only start, pause and stop.

7. Endpoints (matched to the PRFE pilot)

Primary: ankle edema at day 7, figure-of-eight tape method at the marked landmark on both ankles, reported as the difference from the unoperated side. A between-arm difference smaller than 3 mm is within tape measurement noise and will be reported as no difference.

Secondary: NRS pain (0–10) at 1 hour, 24 hours, and days 3, 7, 14 and 30; analgesic consumption as oral morphine milligram equivalents per 24 hours; WOMAC pain subscale at days 7 and 30; wound photograph planimetry at days 7, 14 and 30 where a wound is present.

Additional for this trial only: STAI-6 anxiety and a single-item sleep-quality score at each visit, since anxiety and sleep are where audio has the strongest prior evidence.

Safety: all adverse events, plus specifically any new tinnitus, ear discomfort or headache attributed to listening.

8. Visit calendar

Baseline (pre-operative or day 0): consent, eligibility, tape landmarks marked and photographed, baseline edema both ankles, NRS, WOMAC, STAI-6, sleep.

Day 1, day 3, day 7, day 14, day 30: edema both ankles, NRS, analgesic diary review, STAI-6, sleep, adherence download, adverse events. WOMAC at days 7 and 30.

All readings are entered on the Swelling and Report pages, so the repeatability rule and the ±3 mm note apply unchanged.

9. Statistics

Analysis is by intention to treat. Primary endpoint compared by ANCOVA on day-7 side-to-side difference, adjusted for baseline difference and surgery type.

With 60 participants the trial can detect a between-arm difference of roughly 0.6 standard deviations at 80% power and two-sided alpha 0.05; smaller true effects will not be detected. Secondary endpoints are reported with 95% confidence intervals and are explicitly not adjusted for multiplicity — they are hypothesis-generating.

Blinding integrity is tested by asking each participant and assessor to guess the allocation at day 30 and reporting Bang's blinding index.

10. Governance

Ethics approval is required before any enrolment. This is a behavioural/adjunct intervention with a non-significant-risk profile and involves no investigational device output; if any PRFE component is under investigation, that device's own IRB approval and this protocol are submitted together.

Data are held in the app under row-level security; the analysis dataset carries study codes only, never names.

Registration on a public trials registry before first enrolment.

Data monitoring: [named monitor or committee]. Stopping rule: any serious adverse event judged related to listening stops enrolment pending review.

11. What this trial cannot do

It cannot show that a frequency cures a condition, and no result from it may be presented that way.

It cannot support a regulatory clearance: audio content is not the device, and this trial is not part of the 510(k) evidence for the applicator.

A positive anxiety or sleep result would support offering structured listening alongside care. A positive edema result would be surprising and would require independent replication before being believed.