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.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
10
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.
Sportsmedicinsk Center, Frederikshavn Sygehus
Frederikshavn, Denmark
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.
Time frame: 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.
Time frame: 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 Tuberosity-Trochlear Groove Distance
Tibial tuberosity-trochlear groove distance will be measured on standardized weight-bearing cone beam CT images and reported in millimeters. The measure describes the side-to-side distance between the tibial tuberosity, where the patellar tendon attaches on the shin bone, and the center of the trochlear groove of the thigh bone, where the kneecap moves. 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.
Time frame: 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
Transmalleolar rotation will be measured in degrees on standardized weight-bearing cone beam CT images. The measure describes the rotation of the ankle axis in relation to the long axis of the foot. The ankle axis is defined as a line through the medial and lateral malleoli. The foot axis is defined by an adjusted sagittal foot reference plane derived from calcaneal and metatarsal head landmarks on cone beam CT. Transmalleolar rotation is calculated as the angle between the malleolar line and this foot axis. Positive values indicate external rotation relative to the foot axis, and negative values indicate internal rotation. Measurements will be performed for each foot posture condition at 0 and 20 degrees of knee flexion.
Time frame: 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
Tibial rotation will be measured in degrees on standardized weight-bearing cone beam CT images. The measure describes the rotation of the shin bone in relation to the long axis of the foot. It is defined as the angle between a line tangent to the posterior surface of the proximal tibia and the foot axial rotation reference. The foot axial rotation reference is an adjusted sagittal foot plane derived from calcaneal and metatarsal head landmarks on cone beam CT. Positive values indicate external rotation relative to the foot axis, and negative values indicate internal rotation. Measurements will be performed for each foot posture condition at 0 and 20 degrees of knee flexion. Change will be reported as the within-participant difference between foot posture conditions.
Time frame: 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
Femoral rotation will be measured in degrees on standardized weight-bearing cone beam CT images. The measure describes the rotation of the thigh bone in relation to the long axis of the foot. It is defined as the angle between a line tangent to the posterior femoral condyles and the foot axial rotation reference. The foot axial rotation reference is an adjusted sagittal foot plane derived from calcaneal and metatarsal head landmarks on cone beam CT. Positive values indicate external rotation relative to the foot axis, and negative values indicate internal rotation. Measurements will be performed for each foot posture condition at 0 and 20 degrees of knee flexion. Change will be reported as the within-participant difference between foot posture conditions.
Time frame: 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
Patellar rotation will be measured in degrees on standardized weight-bearing cone beam CT images. The measure describes the rotation of the kneecap in relation to the long axis of the foot. It is defined as the angle between the transverse axis of the patella and the foot axial rotation reference. The foot axial rotation reference is an adjusted sagittal foot plane derived from calcaneal and metatarsal head landmarks on cone beam CT. Positive values indicate external rotation relative to the foot axis, and negative values indicate internal rotation. Measurements will be performed for each foot posture condition at 0 and 20 degrees of knee flexion. Change will be reported as the within-participant difference between foot posture conditions.
Time frame: 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
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.