Establishing MRI-based Normative Acromiohumeral Distance and its Demographic Associations: A Cross-sectional Study from Puducherry, India

Introduction: Acromiohumeral Distance (AHD) is a crucial imaging parameter that reflects the width of the subacromial space. Narrowing of the AHD is associated with shoulder impingement and rotator cuff pathology. Magnetic Resonance Imaging (MRI) offers multiplanar imaging with high soft tissue resolution, but normative MRI-based AHD data in asymptomatic shoulders are limited. Aim: To determine MRI-based AHD in patients with normal supraspinatus and infraspinatus tendons, and to compare values across gender and side in Puducherry, India. Materials and Methods: This hospital-based cross-sectional study was conducted at the Department of Radiodiagnosis, Sri Venkateshwaraa Medical College Hospital and Research Centre, Puducherry, India, from February 2020 and March 2024, comprising 64 retrospective and 30 prospective cases, totalling 94 participants. The MRI shoulder scans of 94 participants aged 18-60 years with no shoulder pathology were analysed. AHD was measured in coronal and sagittal planes as: (a) humeral cortex to acromion; and (b) humeral cartilage to acromion. Mean values and standard deviations were calculated. An Independent t-test was used to assess differences by gender and side. A p-value 0.05). Conclusion: The MRI-based normative AHD values are provided for intact supraspinatus and infraspinatus tendons. These reference values can aid in accurate assessment of subacromial pathologies and planning of surgical or conservative management.