Journal of Orthopaedic Science · Nov 4, 2026

CT-derived Hounsfield units of the acromion and scapular spine: Age- and sex-related associations and measurement reliability in adults

By Kurisu Y, Yukata K, Saeki Y et al.

Background Acromial and scapular spine fractures are important complications after reverse total shoulder arthroplasty (rTSA). Although CT-derived Hounsfield units (HU) permit site-specific assessment of regional bone quality, reproducible measurement sites remain uncertain. We examined associations of acromial and scapular spine HU with age and sex and assessed measurement reliability. Methods This retrospective study included 210 shoulders from 201 adults who underwent shoulder CT between 2014 and 2023. Trabecular HU was measured at the acromion and three scapular spine sites; two measurements incorporating cortical bone were assessed separately. Observer reliability was evaluated using intraclass correlation coefficients. Age and sex associations were examined in models adjusted for diagnostic category and within-patient correlation. Results Trabecular HU was lower in women than men at all four sites in unadjusted comparisons. After adjustment, HU was negatively associated with age at all four sites, with estimated differences per decade of −12.3 HU at the acromion and −42.2, −28.0, and −29.2 HU at the lateral 6-mm, medial 6-mm, and medial 12-mm scapular spine, respectively. Age associations persisted at the three scapular spine sites among adults aged ≥50 and ≥ 60 years. The adjusted sex association remained significant at the medial 6-mm site. Observer reliability was high at both medial spine sites. Conclusions Regional trabecular HU was negatively associated with age, particularly at scapular spine sites in older adults. The medial scapular spine showed strong age associations and reproducible measurements, supporting further evaluation of this region in studies of fracture risk after rTSA.

doi.org/10.1016/j.jos.2026.10.008Open accessPubMed 42982669Biomarkers