The goal of this clinical trial is to learn whether personalized weight-bearing prescriptions using Smart Crutch Tips™ can improve recovery after surgery for tibial shaft fractures. The study will also assess how safe and practical this approach is in daily outpatient use.

Can a personalized weight-bearing program based on CT and finite element analysis help the fracture heal faster? Can it help patients return to full weight-bearing sooner? Can it reduce the fear of movement during recovery? Does iterative walking in the early postoperative period support faster or better bone healing? Researchers will compare standard rehabilitation to different types of personalized weight-bearing programs to see which leads to faster healing, earlier mobility, and better outcomes.

Participants will:

Use Smart Crutch Tips™ during walking for up to 24 weeks; Follow a personalized weight-bearing prescription based on CT scans and biomechanical modeling; Follow a specific walking plan with real-time audio and visual feedback; Attend six follow-up visits over 36 weeks for clinical exams, x-rays, and CT scans; Complete online questionnaires about pain, activity, and fear of movement.

This is a pilot multicenter clinical trial designed to explore the impact of individual weight-bearing and iterative walking regimens on the healing of tibial shaft fractures. The study will enroll 30 adult participants (aged 18 to 80) with closed tibial shaft fractures (AO/OTA 42-A, 42-B, or 42-C) treated by intramedullary nailing and/or plate fixation. Participants will be allocated into three parallel groups (ten participants per group), two of whom will receive personalized weight-bearing protocols based on finite element analysis (FEA) performed using individual CT scan data.

The goal of the study is to determine whether providing precise, data-driven weight-bearing recommendations-delivered through Smart Crutch Tips™ with real-time visual and auditory feedback-can enhance fracture healing by promoting safe interfragmentary motion.

Group 1 (control - standard practice) will use Smart Crutch Tips™ for load data collection only, without feedback, and follow AO Foundation guidelines, progressing weight-bearing based on pain tolerance.

Group 2 (controlled mechanical stimulation) will receive personalized FEA-based load prescriptions for optimal interfragmentary motion, with real-time audio/visual feedback from Smart Crutch Tips™. They will perform iterative walking sessions (minimum two-hour rest between), gradually increasing steps per their plan, plus prescribed lower limb strengthening exercises.

Group 3 (optimized stimulation per Claes-Heigele theory) will receive FEA-based prescriptions targeting maximum fracture-zone voxel optimization, with real-time feedback. They will follow the same walking and exercise protocol as Group 2.

Participants will use ComeBack Mobility Smart Crutch Tips™ all the time they use crutches in an outpatient setting for up to 24 weeks, depending on their healing progress. These devices provide real-time guidance to help users stay within their prescribed weight-bearing range and transmit data to a centralized monitoring platform.

Participants will attend seven in-person follow-up visits: screening (Day 0-7), and then at 6, 12, 16, 20, 24, and 36 weeks after surgery. Аt each follow-up visit starting from Visit 1 (6 weeks) Radiographic assessments (X-ray) will be performed to monitor fracture healing, Computed tomography (CT) scans will be conducted only at specific time points: during the screening period (0-7 days post-surgery), and prior to Visit 1 (6 weeks), Visit 2 (12 weeks), and optional prior to Visit 3 (16 weeks) to adjust weight-bearing prescription and assess consolidation dynamics. Clinical data will be collected via the ComeBack Mobility app and electronic case report forms (eCRFs).

Before each follow-up visit, participants will complete an online diary that includes validated questionnaires such as the Tampa Scale for Kinesiophobia (TSK-17) and the Lower Extremity Functional (LEFS). At Visit 1, participants will also complete the System Usability Scale (SUS) to assess their experience using the device.

All study procedures will be conducted according to a standardized research protocol across multiple orthopedic hospitals and trauma centers in Ukraine, ensuring consistency in surgical technique, data collection, and follow-up.

Inclusion Criteria:

1. Signed informed consent was provided after being fully informed about participation in the study.
2. Age: 18 to 80 years for both males and females (pre-menopausal).
3. Body weight between 40 and 120 kg.
4. Body Mass Index (BMI) between 18.5 and 29.9 kg/m².
5. Diagnosed with a closed tibial shaft fracture (AO/OTA classification: 42-A, 42-B, or 42-C) requiring surgical treatment.
6. Fracture treated exclusively with intramedullary nailing and/or plate fixation
7. No diabetes or well-controlled diabetes (HbA1c ≤ 7.0%).
8. Ability to use crutches without losing balance and medically cleared for partial weight-bearing on the operated limb.
9. Willingness to adhere to the prescribed weight-bearing protocol using the Smart Crutch Tips™ device.
10. Enrollment within 48 hours following surgical intervention.
11. Alcohol consumption (up to 2-3 times per week) within acceptable limits.
12. Willingness to comply with all study procedures, including follow-up visits at weeks 1, 6, 12, 16, 20, 24 and 36 after surgery.
13. Patients with fractures extending into the articular surface of the distal tibial epiphysis may be included, provided that the fracture is deemed stable

Exclusion Criteria:

1. Presence of open or high-energy fractures, multiple lower-limb fractures, or use of bone grafts.
2. Fractures classified as 43-B or 43-C according to AO/OTA.
3. Chronic alcoholism (defined as >14 standard drinks per week for men or >7 for women).
4. Presence of metabolic disorders, including uncontrolled thyroid dysfunction, severe renal or hepatic pathology.
5. Pathological fractures associated with osteoporosis, osteomyelitis, tumors, metastases, or rickets.
6. Lower-limb contractures with functional impairment of grade II or higher.
7. Pregnancy or intention to conceive during the study period.
8. Psychiatric, cognitive, or neurological disorders that may interfere with adherence to the rehabilitation protocol or effective communication with the study team.
9. Clinically significant heart failure (including chronic or acute, with an ejection fraction <40% or with symptoms such as edema, dyspnea at rest, or orthopnea).
10. Pulmonary insufficiency of any origin, accompanied by chronic hypoxemia (PaO₂ < 60 mmHg) or hypercapnia (PaCO₂ > 45 mmHg), requiring oxygen support or significantly limiting physical activity.
11. Clinically significant neurological disorders that may affect motor function, coordination, or physical activity (e.g., stroke with residual deficits, Parkinson's disease, multiple sclerosis, cerebral palsy).
12. Diagnosed epilepsy or other seizure disorders not fully controlled by medication.
13. Progressive neurodegenerative diseases (e.g., amyotrophic lateral sclerosis, Huntington's disease, dementia).
14. Any sensory, balance, or vestibular disorders that may impair safe use of the investigational device.
15. Participation in another clinical study within the past 6 months that could affect the results of the current study.
16. Ongoing or planned use of medications known to affect bone healing.

Time to radiographic fracture union (primary endpoint)

mRUST scores at predefined time points

Compliance data on axial loading collected by Smart Crutch Tips™

Functional recovery outcomes (LEFS, TSK-17 questionnaire responses)

Pain level assessments (VAS)

Adverse event data, including AEs, SAEs, ADEs, SADEs, and device deficiencies

Gait adherence metrics derived from the CBM mobile app

Baseline demographic and clinical information relevant to fracture type and healing (e.g., fracture classification, BMI, CT-derived FEA data)

IPD and supporting documentation will be made available six months after the publication of the primary results. Data will remain accessible for at least 3 years from that date.

Access to IPD will be granted to qualified researchers affiliated with academic, clinical, or non-profit institutions conducting methodologically sound analyses that align with the objectives of the original study or explore related hypotheses. Requests must include a research proposal, analysis plan, and ethical approval if applicable. All requests will be reviewed by the study's principal investigator and sponsor team based on scientific merit and compliance with data privacy standards.

Data analysts, FEA specialists and radiologists will also be blinded to group allocation until the database lock