Tactile Incentiviser Improves Partial Weight Bearing After Lower-Limb Surgery

Summary

Background: After lower-limb surgery, many patients are instructed to walk with only a fraction of their body weight on the operated leg (partial weight bearing). Traditional teaching methods-verbal instructions or brief practice with a bathroom scale-often fail to maintain the load within a safe range, potentially increasing the risk of delayed bone healing or implant failure.

Purpose: This pilot study investigates whether a very low-cost, purely mechanical "tactile incentiviser" placed inside the shoe can assist participants in adhering to a 20% body-weight limit during the first two weeks of inpatient rehabilitation.

Design: Single-centre, parallel-group, randomised controlled trial. Thirty-four adults undergoing hip or knee arthroplasty, or surgery for femoral-shaft or pelvic fracture, were enrolled. Randomisation was performed using a computer-generated list in sealed envelopes. Outcome assessors were blinded.

Intervention: The device consists of four spring buttons embedded in a rubber insole that collapse and deliver a tactile cue when the 20% ± 1% load threshold is exceeded. Participants in the intervention group wore the insole during supervised walking sessions. Control participants received standard physiotherapy without feedback devices.

Primary Outcome: Absolute deviation (kg) between prescribed and actual load, assessed with a pressure sensor at baseline and discharge.

Secondary Outcomes: Pain intensity (NRS), Six-Minute Walk Test (6MWT) distance, and usability (System Usability Scale, SUS).

Note: No results or conclusions are included here. Results will be reported in the appropriate Results Section after the study is completed.

Conditions

• Femoral Fractures
• Pelvic Fractures
• Hip Fractures (ICD-10 72.01-72.2)
• Hip Arthroplasty
• Knee Arthroplasty
• Ankle Fractures

Interventions

DEVICE

mechanical feedback insole

A 3-mm rubber insole containing four 15-mm spring-steel snap buttons aligned along the heel-mid-foot axis. Each insole is statically calibrated on a hydraulic press so that the buttons collapse at 20 % ± 1 % of the individual's body weight, producing an unmistakable plantar cue when the load limit is exceeded. The device is purely mechanical, requires no batteries, and is fitted on postoperative day 1. Participants wear the insole during every supervised walking session until discharge (≈ 14 days).

PROCEDURE

Standard physiotherapy without feedback device

Routine inpatient physiotherapy consisting of verbal instruction to limit loading to 20 % body weight, initial bathroom-scale training, and assisted ambulation with walker or crutches. No tactile, visual, or electronic feedback device is provided. Session frequency, walking aids, analgesia, and discharge criteria are identical to the intervention arm; duration ≈ 14 days.

Sponsors & Collaborators

• Università degli Studi dell'Insubria

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

84 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2024-01-01

Primary Completion

2025-04-01

Completion

2025-04-25

Countries

• Italy

Study Locations