EUKINES Wearable Plantar-Pressure Insole System for Rehabilitation After Total Hip Arthroplasty

This is a prospective, randomized, partially blinded, multicenter clinical trial with a non-inferiority design conducted in patients undergoing primary total hip arthroplasty (THA) for advanced osteoarthritis. The study is embedded in the EUKINES project, which develops low-cost, printable pressure sensors and a wearable plantar-pressure insole system intended for scalable clinical rehabilitation and telerehabilitation use. The trial evaluates the clinical performance, safety, and usability of the EUKINES insole system as an adjunct to standard postoperative rehabilitation.

Adult patients scheduled for primary THA will be screened according to predefined inclusion and exclusion criteria and enrolled after providing written informed consent. A total of 200 participants will be randomized in blocks to one of four parallel rehabilitation arms: (1) EUKINES with real-time biofeedback, (2) EUKINES without biofeedback (data recording only), (3) a certified commercial reference gait-analysis system with biofeedback, or (4) standard rehabilitation without any gait-analysis device. All participants will follow the same structured 6-week rehabilitation program after surgery, including routine physiotherapy and six additional, approximately 3-hour gait-focused sessions. The content and duration of rehabilitation are equivalent across groups; only the use of gait-analysis devices and biofeedback differs between arms.

Outcome assessments will be performed at baseline and during postoperative follow-up. Primary endpoints include changes in plantar-pressure-derived gait parameters such as mean foot pressure and load asymmetry between the operated and non-operated limb, as well as changes in hip-related clinical scores (Harris Hip Score and the 12-item Hip Disability and Osteoarthritis Outcome Score, HOOS-12) and the incidence of adverse events and device-related complications. Secondary outcomes include extended spatiotemporal gait parameters, 10-Meter Walk Test performance, pain intensity and satisfaction with surgery and rehabilitation, and patient and therapist ratings of usability, comfort, and perceived usefulness of the EUKINES and reference systems. All plantar-pressure time-series data will be stored to allow post-hoc derivation of additional gait metrics and exploratory analyses.

The study is classified as a low-risk, add-on interventional trial that does not alter standard surgical procedures or baseline postoperative care. Device-assisted rehabilitation sessions are provided as an adjunct to routine practice. The trial is conducted in accordance with the Declaration of Helsinki and Good Clinical Practice, under the oversight of a bioethics committee. By directly comparing the EUKINES prototype with a certified commercial reference system and standard care, the study aims to demonstrate the feasibility and clinical usefulness of an affordable sensor-based gait-analysis platform and to provide a basis for future development of data-driven telerehabilitation and personalized rehabilitation strategies.

• Certified reference gait-analysis system (Device): Commercially available, certified plantar-pressure gait-analysis system used according to the manufacturer's recommendations to provide real-time biofeedback on gait parameters during rehabilitation sessions.
• EUKINES plantar-pressure insole system (Device): Wearable plantar-pressure insole system developed within the EUKINES project, consisting of thin-film printed pressure sensors, shoe-mounted electronic modules, and PC-based software for real-time gait data acquisition and visualization. In the biofeedback arm, real-time feedback on gait parameters is provided during rehabilitation sessions; in the non-biofeedback arm, data are recorded without feedback.
• Structured postoperative rehabilitation program (Other): Standard postoperative rehabilitation program after total hip arthroplasty, delivered according to local clinical protocols and including six additional approximately 3-hour gait-focused rehabilitation sessions over 6 weeks, with progressive gait training, balance and coordination exercises, and functional mobility tasks.

Primary outcomes

• Change in mean foot pressure (MFP) on the operated limb [Baseline (Week 0), Week 3, Week 6 after surgery]: Mean foot pressure (MFP) is defined as the average plantar pressure across all active sensing regions of the insole during the stance phase of gait, expressed in kilopascals. MFP will be recorded during standardized 10-meter walking trials using the EUKINES and/or reference insole systems, and session-level MFP will be calculated as the mean value across all valid steps. The primary analysis will compare changes in MFP on the operated limb over time and between rehabilitation arms.
• Change in load asymmetry between operated and non-operated limb [Baseline (Week 0), Week 3, Week 6 after surgery]: Load asymmetry will be quantified using plantar-pressure data from the EUKINES and/or reference insole systems as the difference or ratio between mean foot pressure on the operated and non-operated limb during standardized 10-meter walking trials. Reduced inter-limb asymmetry over time will be interpreted as improved functional load distribution after total hip arthroplasty.
• Change in Harris Hip Score (HHS) [Baseline (preoperative or immediate postoperative) and Week 6 after surgery]: The Harris Hip Score is a validated clinician-administered scale assessing pain, function, range of motion, and absence of deformity in patients after hip surgery. Total scores range from 0 to 100, with higher scores indicating better hip function. The primary analysis will compare changes in HHS from baseline to Week 6 between rehabilitation arms.
• Change in HOOS-12 total score [Baseline (preoperative or immediate postoperative) and Week 6 after surgery]: The HOOS-12 is a validated 12-item short form of the Hip Disability and Osteoarthritis Outcome Score that assesses pain, function, and quality of life in hip patients. Scores are transformed to a 0-100 scale, with higher scores indicating better outcomes. The main analysis will evaluate changes in HOOS-12 total score from baseline to Week 6, with reference to the minimal clinically important difference of approximately 9-12 points reported in the literature.
• Incidence of adverse events and device-related complications [From enrollment through Week 6 after surgery]: Safety will be assessed by recording all adverse events, device-related complications, skin irritation, falls, or other medical incidents potentially associated with device use or the supplementary rehabilitation sessions. Events will be classified by severity, relationship to the device or intervention, and outcome.

Secondary outcomes

• Preferred walking speed (10-Meter Walk Test) [Baseline, Week 3, Week 6]: Preferred walking speed over 10 meters will be measured in m/s during standardized 10-Meter Walk Tests; changes over time and between groups will be analyzed.
• Change in maximal walking speed (10-Meter Walk Test) [Baseline, Week 3, Week 6]: Maximal walking speed over 10 meters will be measured in m/s during standardized 10-Meter Walk Tests; changes over time and between groups will be analyzed.
• Change in spatiotemporal gait parameters derived from plantar-pressure insoles [Additional gait parameters (e.g., cadence, stance and swing phase duration, rollover time) will be derived from plantar-pressure time-series data and analyzed as exploratory secondary outcomes.]: Baseline, Week 3, Week 6
• Change in hip pain intensity (VAS) [Baseline, Week 3, Week 6]: Hip pain will be rated on a visual analogue scale (0-10), with higher scores indicating greater pain; changes over time and between groups will be compared.
• Change in patient satisfaction with surgery and rehabilitation measured with a Visual Analogue Scale (VAS) [Week 3 and Week 6]: Patient satisfaction with surgery and postoperative rehabilitation will be assessed using a 100-mm Visual Analogue Scale (VAS) ranging from 0 to 100, where 0 indicates "not satisfied at all" (worst possible satisfaction) and 100 indicates "extremely satisfied" (best possible satisfaction). The VAS score (points, 0-100; higher scores indicate better satisfaction) will be recorded at Week 3 and Week 6 after surgery, and changes over time and between study groups will be compared
• Patient-reported usability and comfort of the EUKINES and reference systems (study-specific 15-item Likert-scale questionnaire) [Week 3 and Week 6]: Patient-reported usability and comfort of the EUKINES system and the reference system will be assessed with a study-specific EUKINES Usability and Comfort Questionnaire developed by the investigators, consisting of 15 items rated on a 5-point Likert scale (0 = strongly disagree, 4 = strongly agree). For each system, an overall usability and comfort score will be calculated as the mean of all item scores and expressed in points (range 0-4; higher scores indicate better usability and greater comfort). Scores will be collected at Week 3 and Week 6 after surgery, and changes over time and between study groups will be compared.
• Therapist-reported usability and perceived usefulness of the EUKINES and reference systems (study-specific 12-item Likert-scale questionnaire) [Throughout the 6-week rehabilitation period]: Therapist-reported usability and perceived usefulness of the EUKINES system and the reference system will be assessed with a study-specific EUKINES Therapist Usability and Usefulness Questionnaire developed by the investigators, consisting of 12 items rated on a 5-point Likert scale (0 = strongly disagree, 4 = strongly agree). Two summary scores will be calculated for each system: a usability score and a perceived usefulness score, each expressed in points as the mean of the corresponding items (range 0-4; higher scores indicate better usability or greater perceived usefulness). Scores collected throughout the 6-week rehabilitation period will be analyzed as repeated measures and compared between systems and between study groups.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Age 18 years or older.
* Scheduled for primary total hip arthroplasty performed for advanced osteoarthritis or other degenerative hip disease.
* Willingness and ability to participate in the 6-week postoperative rehabilitation program and follow-up assessments.
* Ability to understand study information and provide written informed consent.

Exclusion Criteria:

* Coexisting medical conditions that may significantly affect rehabilitation outcomes or gait (e.g., severe neurological disorders, major lower-limb joint trauma, other significant musculoskeletal pathology).
* Cognitive impairment or psychiatric conditions that would preclude effective cooperation with the rehabilitation and research team.
* Any contraindication to participation in additional gait training sessions or use of the insole-based gait-analysis systems as judged by the treating physician.

• Andrzej Kotela, Principal investigator, Cardinal Stefan Wyszynski University in Warsaw