The Effect Subtalar Joint Pronation on Postural Stability and Lower Extremity Alignment
Condition: Postural Stability; Dynamic Knee Valgus; Injury Prevention
Study type: Interventional

Summary: 
      The lower extremity consists of sequent columns. The deviation of one segment from its normal
      alignment in the lower extremity also affects the alignment of the other segments. The
      alignment of the parts of the foot during weight bearing is called foot posture. Foot posture
      is divided into neutral, pronation, and supination. Foot posture varies significantly from
      person to person, and deviations from normal foot posture are associated with lower extremity
      injuries. Increased or prolonged pronation has been identified as both a risk factor and
      etiologic factor for increased navicular drop, a lower extremity malalignment pattern. In
      pronation posture, the foot may not adequately adapt to the ground, and there is increased
      movement of the lower extremity in the frontal plane. As a result, the person's postural
      stability is compromised. The fact that the foot is the most distal segment of the lower
      extremity chain indicates that even small biomechanical changes in the bearing surface can
      significantly affect postural control strategies. There are studies in the literature that
      examine the effect of foot pronation on dynamic balance and postural stability in individuals
      with different foot postures. However, to our knowledge, there is no study that examines
      differences in postural stabilization and lower extremity alignment by classifying
      individuals with varying degrees of subtalar joint pronation into pronation and hyper
      pronation groups.
    

Detailed description: 
      Examination of the biomechanics of the foot and ankle is an important aspect in the
      evaluation of human movement. The purpose of this study is to divide healthy subjects into
      pronation and hyperpronation foot postures and investigate the effects of differences
      subtalar pronation amounts in lower extremity alignment and postural stabilization. The part
      of the foot where the subtalar joint is located is called the hindfoot. The anatomy and
      alignment of the hindfoot is a critical factor in the biomechanics of the lower extremities
      and the function of human locomotion. Pronation of the foot causes tibial internal rotation
      and femoral internal rotation through the mechanism of the kinetic chain, resulting in valgus
      alignment of the knee when the foot is on the ground. The valgus alignment changes the
      position of the pelvis. Alternations in pelvic position increases the tension on the hip and
      pelvic muscles because it changes the force lever. In addition, increased femoral internal
      rotation of the lower extremity relative to the tibia has been shown to increase stress on
      the weight-bearing tissues of the tibio-femoral compartments and increase tibial internal
      rotation in individuals with pronated foot posture. Normal pronation motion is necessary for
      proper foot function, but increased and excessive pronation of the subtalar joint is a
      condition that should be investigated because it presents several problems with lower
      extremity alignment. The fact that foot pronation is important for the lower extremity
      kinetic chain during dynamic tasks prompts us to investigate foot pronation by measuring it
      in various ways. The purpose of this study is to divide healthy subjects into pronators and
      hyper pronators and to investigate the effects of differences in lower extremity kinetic
      chain alignment and postural stabilization and in healthy subjects.
    

Intervention name(s): Postural stability assessment; Frontal plan prjection angle; Foot and Ankle Ability Measure; Navicular Drop Test; Calcaneotibial Angle Measurement; Tibial Torsion Angle; Femoral internal and external rotation measurement
Intervention type(s): Other; Other; Other; Other; Other; Other; Other
Intervention description(s): The Biodex Balance System SD (BDS) (Biodex Medical Systems Inc., Shirley, New York, USA) assesses postural stability (PS). Both static PS (SPS) and dynamic PS (DPS) will be assessed. In the DPS assessment, the platform can be tilted 20° in any direction. For static measurement, participants will be asked to stand barefoot on the platform, stand on one leg, keep the knees in 20-30° flexion. Meanwhile the contralateral knee will be asked to keep in 90° flexion, and stabilize their feet until the end of the test. Upon completion of the SPS assessment, the DPS assessment will be performed. The difficulty level of the DPS test will accepted as 4. For both SPS and the DPS assessment, the test consists of 3 trials of 20 seconds each with a 10-second break between trials.; Frontal Plan Projection Angle (FPPA) is calculated as the angle between the thigh segment and the trunk segment based on the postural image, considering the position of the thigh and tibia. The FPPA will be evaluated using the Spark motion Pro™ application (2D). Before measurement, markers will be placed bilaterally at the SIAS, at the midpoint of the femoral condyles, and at the midpoint of the ankle bones. Participants will stand on the floor barefoot and arms crossed over the chest. Subjects will be asked to squat in a controlled manner and perform a 60° knee bend without losing balance before returning to the starting position. Test will be performed by using single leg squat test. The one-legged squat will be performed for 5 seconds at a standard pace with the researcher acting as the counter. Degrees smaller than 165 will be accepted as increase in knee valgus.; The Foot and Ankle Ailability Measure (FAAM) is used to assess the self-reported overall functional level of patients with leg, foot, and ankle musculoskeletal injuries and conditions. It consists of 1) activities of daily living [ADL] and 2) sports [S] and can be scored from 0 to 100%. In the FAAM, there are 29 items that are scored from 0 to 4. There are 21 items related to various functional activities under the subtitle activities of daily living, and 8 items related to various activities related to participation in sports under the subtitle sports. Standardized response options are answered on five-point likert scales ranging from 0 (I cannot) to 4 (no difficulty). Point totals between 0 and 84 for the ADL subtitle and between 0 and 32 for the Sports subtitle are converted to percentage points.; The navicular drop test (NDT) is a clinical method for assessing the mobility of the medial longitudinal arch (MLA). The extent of navicular subsidence is assessed to determine the flexibility of the MLA and the position of the navicular with and without transfer of body weight. To assess navicular drop, the subtalar joint will be positioned in neutral position and the height of the navicular will be measured in non-weight bearing position. Then the measurement will be repeated in weightbearing position. The height difference between the two measurements in sitting and standing is recorded as the NDT value. Values more than 10mm is accepted as pathological.; Measurement of the calcaneotibial angle (CTA) is one of the methods used in the evaluation of the foot and ankle. By measuring this angle, it is assessed whether the ankle problems are related to the hindfoot. In the CTA measurement, the angle between the vertical axis of the calcaneus and the longitudinal axis of the achilles tendon is measured in the standing and prone positions, and the differences will be recorded. Values more than 8 degrees is accepted as calcaneal valgus.; Tibial torsion is a rotational deformity which can be measured between the long axis of the tibia and the transmalleolar axes. This measurement can be used to determine the extent to foot malalignment is due to bone torsion. Measurement will be done by a goniometer. Participants will be asked to lie prone and will be positioned with the knee joint in 90° flexion and the ankle joint in a neutral position. Normal alignment is 20 degrees external rotation. Any increase or decrease accepted as pathological.; Accurate assessment of hip joint range of motion (ROM) is an important component in the overall clinical evaluation of lower extremity injuries, particularly those of the hip and groin. The expected hip rotational range of motion for internal rotation (IR) is 45°, and for external rotation (ER) is 0° to 45°. In this study, a smartphone-based inclinometer will be used to measure femoral IR and ER. The inclinometer will be placed vertically so that the top edge is just below the tibial tuberosity and the bottom edge is pointed at the midpoint of the medial and lateral malleoli.
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Intervention model description: Participants will be selected from healthy individuals aged 18-40 years. According to the foot posture index, participants who has a value between 6 and 9 will be added to pronation group and participants who has a value between 10 and 12 will be added to hyper pronation group. Then measurement will be done by the same physiotherapist. Only one measurement will be done.
Masking: None (Open Label)
Primary purpose: Screening
Keywords: Foot posture; Balance; Tibial torsion; Calcaneal valgus; Frontal plan projection angle