Patients undergoing total hip arthroplasty (THA) may experience objective or perceived leg length discrepancy (LLD/PLLD), which can negatively affect gait, pelvic balance, and patient satisfaction.

The iliotibial band (ITB) plays a critical role in lateral thigh tension transmission, and alterations in its stiffness may influence the perception of limb length discrepancy.

Shear-wave elastography (SWE) is a noninvasive ultrasound-based technique that enables quantitative assessment of soft tissue stiffness.

This cross-sectional observational study aims to investigate the relationship between ITB stiffness measured by SWE and both radiographic and perceived leg length discrepancy in adult patients who underwent unilateral primary THA at least 12 months previously.

This study will include adult patients aged 18-90 years who underwent unilateral primary total hip arthroplasty at least 12 months prior to enrollment.

Patients will undergo clinical evaluation, functional scoring, radiographic assessment, and bilateral ITB stiffness measurement using shear-wave elastography.

Radiographic leg length discrepancy will be assessed using previously obtained pelvis AP and full-leg length radiographs without additional imaging exposure.

Perceived leg length discrepancy will be evaluated using a block test during standing examination.

ITB stiffness will be measured bilaterally at standardized anatomical landmarks using SWE by two experienced radiologists.

The primary aim is to assess correlations between ITB stiffness and radiographic LLD, as well as perceived LLD. Secondary analyses will evaluate whether ITB stiffness predicts PLLD independently of radiographic LLD.

Inclusion Criteria:

Age between 18 and 90 years History of unilateral primary TKA, with no prior revision surgery At least 12 months after surgery and returned to functional weight-bearing No use of walking aids, or use of a cane only for outdoor ambulation

Exclusion Criteria:

Bilateral TKA or severe osteoarthritis in the contralateral hip History of femoral, tibial, or hip surgery resulting in limb length-altering deformity Significant scoliosis (>20° Cobb angle) or pelvic obliquity >5° Neurological disorders (e.g., severe polyneuropathy, hemiparesis) History of lateral thigh surgery (e.g., IT band release, TFL surgery) Body mass index (BMI) >40 (may reduce the reliability of SWE measurements) Suspected prosthetic joint infection or implant instability

Patients who underwent total hip arthroplasty and had a minimum follow-up of at least 1 year were included in the study.

Individual participant data will not be shared.