Exploring the level of association between rotator cuff tears and acromiohumeral distance: a systematic review.

Background: Rotator cuff tears (RCTs) are a prevalent cause of shoulder pain and dysfunction, often associated with narrowing of the acromiohumeral distance (AHD). AHD is commonly used as a valuable marker of rotator cuff integrity, yet its diagnostic and prognostic value remains debated. This systematic review aims to explore the relationship between AHD and RCTs, with consideration of tear type, imaging modality, and tendon involvement. Methods: A systematic search of PubMed, EMBASE, CINAHL, and Web of Science was conducted to identify comparative studies published between 2000 and 2024. Eligible studies included adults (≥18 years) with chronic or acute RCTs (partial or full-thickness) and healthy controls. Studies were required to report AHD measurements using magnetic resonance imaging, radiographs, or ultrasound in an upright, neutral shoulder position. Risk of bias was assessed using the Hoy et al tool. Eight studies met the inclusion criteria. Results: Across studies, AHD was consistently defined as the shortest distance between the acromion and humeral head. Imaging modalities varied, with magnetic resonance imaging most commonly used. While several studies reported significantly reduced AHD in RCTs, particularly full-thickness and multi-tendon tears, others found no significant differences compared to controls. Mean AHD values ranged from ∼5.9 mm in massive or multi-tendon tears to ∼9.7 mm in healthy controls. Multi-tendon involvement was consistently associated with greater AHD reduction than single-tendon tears. The reliability of AHD measurement was high across modalities. However, heterogeneity in sample size, imaging tools, and lack of control for confounding factors (eg, body mass index, activity level, muscle atrophy) limited comparability. Conclusion: AHD tends to decrease with increasing RCT severity, particularly in multi-tendon involvement, supporting its relevance in clinical assessment. However, inconsistencies across studies highlight the need for standardized imaging protocols and consideration of confounders. While AHD shows promise as a diagnostic and prognostic marker, it should not be used in isolation. Future longitudinal and dynamic imaging studies are recommended to better understand its clinical utility.