Effect of Foot Orthoses on Kneecap Position in Adults With Flexible Flatfoot

NCT07678840 | Not Yet Recruiting

• 1 other identifier: N-20260014
• Study Type: interventional
• Target: 10
• Locations: 1 country
• Sites: 1

Brief Summary

This study will look at whether correcting a flat foot position with foot orthoses, also called shoe inserts, can change the position of the kneecap during standing. Some people with flexible flatfoot have a foot position that may affect how the lower leg and knee are aligned. This may influence the way the kneecap sits or tilts in relation to the thigh bone. Foot orthoses are often used for knee and foot problems, but it is not clear whether they directly change kneecap position when a person is standing and bearing weight. The study will include adults with flexible flatfoot. Each participant will have low-dose, three-dimensional weight-bearing cone beam CT scans while standing in different foot positions: their natural foot position, with foot orthoses, and with foot orthoses inside a neutral running shoe. Scans will be performed with the knees straight and slightly bent. The main hypothesis is that correcting a pronated flat foot position with foot orthoses will reduce sideways tilt and outward shift of the kneecap compared with the participant's natural foot position. The study will also examine whether changes in foot position are accompanied by changes in lower-limb rotation. This study does not test whether foot orthoses reduce pain. Instead, it is designed to understand the immediate mechanical effect of foot correction on kneecap position.

Conditions

Patellofemoral Joint; Flatfoot

Keywords

Flatfoot; Foot pronation; Foot orthoses; Patellofemoral alignment; Patellar tilt; Kneecap position; Lower-limb alignment; Lower-limb rotation; Weight-bearing Imaging; Cone-Beam Computed Tomography

Outcome Measures

Primary Outcomes (2)

• Change in Lateral Patellar Tilt

  Lateral patellar tilt will be measured in degrees on standardized weight-bearing cone beam CT images. The measure describes the sideways tilt of the kneecap in relation to the thigh bone. It is defined as the angle between the transverse axis of the patella and the posterior condylar axis of the femur. Measurements will be performed for each foot posture condition: natural foot posture, barefoot correction with foot orthoses, and correction with foot orthoses inside a neutral running shoe. Measurements will be assessed at both 0 and 20 degrees of knee flexion. Change will be reported as the within-participant difference between foot posture conditions.

  During one imaging visit: natural foot posture, immediately after barefoot orthotic correction, and immediately after orthotic correction in a neutral running shoe, at 0 and 20 degrees of knee flexion

• Change in Bisect Offset

  Bisect offset will be measured as a percentage on standardized weight-bearing cone beam CT images. The measure describes the sideways position of the kneecap in relation to the groove of the thigh bone. It is defined as the percentage of lateral displacement of the midpoint of the patella from the midpoint of the trochlear groove. Higher percentages indicate greater lateral displacement of the kneecap. Measurements will be performed for each foot posture condition: natural foot posture, barefoot correction with foot orthoses, and correction with foot orthoses inside a neutral running shoe. Measurements will be assessed at both 0 and 20 degrees of knee flexion. Change will be reported as the within-participant difference between foot posture conditions.

  During one imaging visit: natural foot posture, immediately after barefoot orthotic correction, and immediately after orthotic correction in a neutral running shoe, at 0 and 20 degrees of knee flexion

Secondary Outcomes (5)

• Change in Tibial Tuberosity-Trochlear Groove Distance

  During one imaging visit: natural foot posture, immediately after barefoot orthotic correction, and immediately after orthotic correction in a neutral running shoe, at 0 and 20 degrees of knee flexion

• Change in Transmalleolar Rotation Across Foot Posture Conditions

  During one imaging visit: natural foot posture, immediately after barefoot orthotic correction, and immediately after orthotic correction in a neutral running shoe, at 0 and 20 degrees of knee flexion

• Change in Tibial Rotation Across Foot Posture Conditions

  During one imaging visit: natural foot posture, immediately after barefoot orthotic correction, and immediately after orthotic correction in a neutral running shoe, at 0 and 20 degrees of knee flexion

• Change in Femoral Rotation Across Foot Posture Conditions

  During one imaging visit: natural foot posture, immediately after barefoot orthotic correction, and immediately after orthotic correction in a neutral running shoe, at 0 and 20 degrees of knee flexion

• Change in Patellar Rotation Across Foot Posture Conditions

  During one imaging visit: natural foot posture, immediately after barefoot orthotic correction, and immediately after orthotic correction in a neutral running shoe, at 0 and 20 degrees of knee flexion

Other Outcomes (13)

• Change in Navicular Plantar Position Across Foot Posture Conditions

  During one imaging visit: natural foot posture, immediately after barefoot orthotic correction, and immediately after orthotic correction in a neutral running shoe, at 0 and 20 degrees of knee flexion

• Change in Navicular Medial Displacement Across Foot Posture Conditions

  During one imaging visit: natural foot posture, immediately after barefoot orthotic correction, and immediately after orthotic correction in a neutral running shoe, at 0 and 20 degrees of knee flexion.

• Change in Foot Axial Rotation Across Foot Posture Conditions

  During one imaging visit: natural foot posture, immediately after barefoot orthotic correction, and immediately after orthotic correction in a neutral running shoe, at 0 and 20 degrees of knee flexion

Study Arms (1)

Foot Posture Conditions

EXPERIMENTAL

Participants will undergo standardized weight-bearing cone beam CT scans under three foot posture conditions: natural foot posture, barefoot correction with foot orthoses, and correction with foot orthoses inside a standardized neutral running shoe. Each condition will be assessed with the knees fully extended and at 20 degrees of knee flexion. The foot orthosis will be selected for each participant to correct the rearfoot toward neutral alignment. If needed, an additional forefoot wedge may be used to achieve neutral alignment. The same orthotic correction will be maintained across the relevant scan conditions.

Device: Foot Orthoses

Interventions

Foot Orthoses DEVICE

Standardized prefabricated foot orthoses will be used to correct a pronated foot posture toward neutral rearfoot alignment during weight-bearing. Three orthosis configurations will be available, differing in medial arch height and degree of lateral calcaneal tilt. For each participant, the orthosis that best achieves neutral rearfoot alignment will be selected. If forefoot varus prevents neutral rearfoot alignment, an additional medial forefoot wedge may be applied under the first metatarsal. The selected orthotic configuration, including any forefoot wedge, will be kept unchanged during the relevant scan conditions. The intervention will be tested both barefoot and inside a standardized neutral running shoe.

Foot Posture Conditions

Eligibility Criteria

• Age: 18 Years - 35 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Age 18-35 years
• Pronated foot posture, defined as a Foot Posture Index (FPI) score of ≥ +6, including a calcaneal frontal plane position sub-score of +2. 25,26
• Flexible flatfoot deformity, defined as restoration of the medial longitudinal arch during lift of the first toe.

You may not qualify if:

• Knee pain during standing or at 20° knee flexion
• Clinical signs of tibiofemoral instability
• Previous knee or foot surgery
• History of patellar dislocation
• Neuromuscular disease
• Pregnancy
• Inability to perform full weight bearing during scans

Sponsors & Collaborators

• Regionshospital Nordjylland: lead
• Bispebjerg Hospital: collaborator
• Frederiksberg University Hospital: collaborator

Study Sites (1)

Sportsmedicinsk Center, Frederikshavn Sygehus

Frederikshavn, 9900, Denmark

Location

MeSH Terms

Conditions

Flatfoot

Interventions

Foot Orthoses

Condition Hierarchy (Ancestors)

Talipes; Foot Deformities, Acquired; Foot Deformities; Musculoskeletal Diseases; Foot Deformities, Congenital; Lower Extremity Deformities, Congenital; Limb Deformities, Congenital; Musculoskeletal Abnormalities; Congenital Abnormalities; Congenital, Hereditary, and Neonatal Diseases and Abnormalities

Intervention Hierarchy (Ancestors)

Orthotic Devices; Orthopedic Equipment; Surgical Equipment; Equipment and Supplies

Central Study Contacts

Mads K Hilligsøe, Doctor

CONTACT

+4542210433; m.hilligsoee@rn.dk

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER GOV
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: June 25, 2026
• First Posted: July 1, 2026
• Study Start: July 1, 2026
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): December 1, 2026
• Last Updated: July 28, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will not share

Locations

DK (1)