Post-stroke immobilization and reduced weight-bearing frequently lead to significant regional bone mineral density loss and asymmetry, particularly in the paretic upper extremity, which increases fracture risks. While Dual-Energy X-ray Absorptiometry (DXA) is the gold standard for evaluating systemic bone loss, it primarily focuses on axial or lower extremity sites and lacks universal accessibility. Since routine shoulder radiographs offer an opportunistic screening tool to evaluate regional bone quality without additional radiation , this study aims to compare proximal humerus cortical bone thickness between the paretic and non-paretic sides in stroke patients and assess its correlation with systemic DXA values to determine its clinical utility.

This cross-sectional, observational study involves a retrospective data analysis of patients aged 18 and older who experienced a single unilateral stroke at least 6 months prior and present with clinical hemiparesis. Eligible participants must have concurrent standard anteroposterior shoulder radiographs and DXA measurements available from their routine clinical follow-ups. Patient demographic data, stroke characteristics, Brunnstrom stages, and systemic DXA measurements (femoral neck and lumbar spine T-scores and bone mineral density values) are systematically recorded for analysis.

Cortical bone thickness measurements are performed using ImageJ software on standard radiographs at points 10 cm and 12 cm distal to the highest point of the humerus. To ensure reliability, measurements for both the paretic and non-paretic sides are conducted independently by two researchers who are completely blinded to the DXA results. Statistical analyses, including paired t-tests or Wilcoxon tests and Pearson or Spearman correlations, will be used to compare the sides and evaluate the relationship between radiographic cortical thickness and systemic bone density.

Background Post-stroke immobilization and reduced weight-bearing often lead to significant regional bone mineral density (BMD) loss and asymmetry, particularly in the paretic upper extremity, which increases fracture risks. While Dual-Energy X-ray Absorptiometry (DXA) is the gold standard for evaluating systemic bone loss, it primarily targets axial or lower extremity sites and may not be universally accessible in every clinical setting. Routine clinical imaging, such as standard shoulder radiographs, presents a valuable opportunistic screening tool to assess regional cortical bone quality without exposing patients to additional radiation.

Objective The primary objective of this cross-sectional, observational study is to compare proximal humerus cortical bone thickness between the paretic and non-paretic sides in patients with stroke. Additionally, the study aims to evaluate the correlation between radiographic cortical thickness measurements and systemic DXA values to determine the clinical utility of standard X-rays in identifying post-stroke regional bone loss.

Study Design and Methods This retrospective data analysis will include patients aged 18 and older with a history of a single unilateral stroke occurring at least 6 months prior, and presenting with clinical hemiparesis. Eligible participants must have concurrent standard anteroposterior shoulder radiographs and DXA measurements.

Measurement Protocol: Cortical bone thickness (CBT) will be measured at 10 cm and 12 cm distal to the highest point of the humerus using standard radiographs via ImageJ software.

Blinding: Measurements will be independently performed by two separate researchers who are completely blinded to the patients' DXA results.

Comparison: The radiographic cortical thickness values from both paretic and non-paretic sides will be correlated and compared against femoral neck and lumbar spine (L1-L4) DXA T-scores and BMD values.

Inclusion Criteria:

• Patients aged 18 years and older.
• A documented history of a single unilateral stroke that occurred at least 6 months prior to evaluation.
• Presence of clinical hemiparesis.
• Availability of concurrent standard anteroposterior (AP) shoulder radiographs taken within 6 months post-stroke alongside systemic DXA measurements.

Exclusion Criteria:

• History of surgical intervention in either shoulder. History of a proximal humerus fracture.
• Co-existing metabolic bone diseases, such as primary hyperparathyroidism or osteomalacia.
• History of malignancy.
• Documented history of corticosteroid use.
• Imaging artifacts that compromise the accuracy of DXA measurements.
• History of a secondary stroke.

Adults aged 18 years and older recruited from the clinics of Istanbul Physical Medicine and Rehabilitation Training and Research Hospital. Participants will include hemiparetic individuals with a history of a single unilateral stroke occurring at least 6 months prior, who possess concurrent standard shoulder radiographs and systemic dual-energy X-ray absorptiometry measurements.