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NCT Number: NCT07674433

Investigation of the Relationship Between Pes Planus and Piriformis Syndrome: A Case-Control Study

The aim of this study is to investigate the relationship between Pes Planus and Piriformis Syndrome. The study will be conducted on individuals aged 18-65 years who are native Turkish speakers, have Turkish reading and writing skills, have been diagnosed with piriformis syndrome, and voluntarily agree to participate. Participants will consist of individuals who have not previously undergone lumbar, hip, or lower extremity surgery and have not received injection therapy (corticosteroids, PRP) or any other physiotherapy program within the last three months.

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Key information

Conditions

Piriformis Syndrome Congenital Abnormalities Congenital, Hereditary, and Neonatal Diseases and Abnormalities Flatfoot Foot Deformities Foot Deformities, Acquired Foot Deformities, Congenital Limb Deformities, Congenital Lower Extremity Deformities, Congenital Mononeuropathies Musculoskeletal Abnormalities Musculoskeletal Diseases Nerve Compression Syndromes Nervous System Diseases Neuralgia Neurologic Manifestations Neuromuscular Diseases Pain Pathological Conditions, Signs and Symptoms Pelvic Pain Peripheral Nervous System Diseases Pes Planus Piriformis Muscle Syndrome Sciatic Neuropathy Signs and Symptoms Talipes

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Kahramanmaraş Sütçü İmam Üniversitesi

Kahramanmaraş, onikişubat, 46100, Turkey (Türkiye)

About this study

In the literature, the effects of pes planus deformity on the lower extremity kinetic chain, especially its relationship with patellofemoral pain syndrome and non-specific low back pain, have been widely studied. However, case-control studies examining the direct relationship between increased tibial and femoral internal rotation caused by pes planus, the compensatory hypertrophy in the piriformis muscle which tries to stabilize the hip joint, and the resulting 'Piriformis Syndrome' are quite limited. This study aims to fill this gap in the literature by revealing the effect of foot postural disorders on deep gluteal region pathologies with clinical tests and to provide a biomechanical perspective to treatment protocols.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Piriformis group
  • 18-50 years old
  • Clinical diagnosis of piriformis syndrome
  • Positive FAIR test
  • Piriformis tenderness on palpation Control group
  • No piriformis syndrome
  • No hip or lower back pain
  • No neurological disease

Exclusion criteria

  • Herniated disc (L5-S1 radiculopathy),
  • previous hip surgery,
  • inflammatory joint diseases
  • neurological deficits…

Treatment and study plan

Primary outcomes

  1. Foot Posture Index (FPI-6)

    Time frame: Baseline

    To comprehensively assess the static foot posture of the participants, the Foot Posture Index, which has proven reliability in the literature, will be used. During the assessment, the participant will be fixed in a relaxed standing position with their arms at their sides and facing forward, distributing their weight equally on both feet.

  2. Navicular Drop Test(NDT)

    Time frame: Baseline

    In evaluating the foot posture of the participants, the Navicular Drop Test (NDT), which has proven reliability and validity in the literature, will be used (10). The Navicular Drop Test is a clinical measurement method used to evaluate the arch structure and dynamic stability of the foot.The measurement process consists of two stages: First, with the foot unloaded, the height of this marked point from the ground is measured with a millimeter ruler or caliper. Then, the participant is asked to stand up without changing the foot position and distribute their body weight evenly between both legs. In this loaded position, the distance of the navicular tubercle from the ground is measured again. Finally, the difference between the height in the seated position and the height in the standing position is calculated. This drop, recorded in millimeters, indicates how much the foot flexes or collapses under load.

Secondary outcomes

  1. Pain assessment

    Time frame: Baseline

    An algometer will be used to assess the pain threshold. The pressure-applying end of the algometric measuring device is blunt, not sharp, and has a diameter of 1 square centimeter. The pressure will be applied perpendicular to the midpoint of the muscle. Before the application, the individual will be informed and asked to report any pain felt while the pressure is gradually increased. The measurement will be taken while the individual is in a supine position. The value at which the individual first feels pain when pressure is applied will be recorded as the pain threshold. Three measurements will be taken at 1-minute intervals and their averages will be taken . The assessment will be made by applying pressure to the symphysis pubis.

  2. Demographic information

    Time frame: Baseline

    Demographic information of the individuals included in the study, such as age, height, body weight, body mass index, number of pregnancies, week of gestation, and the presence of any accompanying problems, will be recorded with a form.

Sponsors and collaborators

Lead sponsor

Kahramanmaras Sutcu Imam University

Other

Registry information

Acronym: Piriformis

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
Jun 29, 2026
Registry last updated
Jun 29, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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