Smith Geoffrey C S, Liu Victor K, Bonar S Fiona, Lam Patrick Hong
University of New South Wales, Sydney, New South Wales, Australia.
St George Orthopaedic Department, Sydney, New South Wales, Australia.
Arthrosc Sports Med Rehabil. 2020 Sep 3;2(5):e547-e552. doi: 10.1016/j.asmr.2020.06.014. eCollection 2020 Oct.
The aim of this study was to assess the nature of the middle deltoid muscle insertion onto the lateral acromion by macroscopic, MRI and histologic examination and to, therefore, assess the potential impact of a vertical lateral acromioplasty on the deltoid origin.
We assessed the acromial origin of the deltoid in 6 cadaver shoulders by macroscopic, MRI and histologic examination. The cadavers were scanned with T1 and proton density-weighted sequences. H&E- and Masson trichrome-stained histologic sections through the acromion were taken and visualized under polarized microscopy.
The enthesis of the deltoid muscle consisted of dense birefringent bundles of collagen that blended with the bony endplate of the acromion at all points on its lateral wall. A prominent band of collagen was seen on both MRI and histologic slices, traversing the superior surface of the acromion. It was continuous with the deltoid origin and blended with the superficial fascia of the deltoid laterally.
The middle deltoid muscle occupies the entire lateral acromion.
A high critical shoulder angle is associated with rotator cuff tears. A lateral acromioplasty resects the lateral acromion and aims to normalize the critical shoulder angle. However, a vertical lateral acromioplasty may release the middle deltoid origin from the lateral acromion. The superior band of collagen may anchor the middle deltoid to the superior acromion and prevent retraction.
本研究旨在通过宏观、MRI和组织学检查评估三角肌中束在肩峰外侧的附着性质，从而评估垂直外侧肩峰成形术对三角肌起点的潜在影响。
我们通过宏观、MRI和组织学检查评估了6具尸体肩部三角肌的肩峰起点。尸体采用T1加权和质子密度加权序列进行扫描。取穿过肩峰的苏木精-伊红染色和马松三色染色组织切片，并在偏光显微镜下观察。
三角肌的附着点由致密的双折射胶原束组成，这些胶原束在其侧壁的所有点都与肩峰的骨终板融合。在MRI和组织学切片上均可见一条突出的胶原带，横贯肩峰的上表面。它与三角肌起点连续，并在外侧与三角肌的浅筋膜融合。
三角肌中束占据整个肩峰外侧。
高临界肩峰角与肩袖撕裂相关。外侧肩峰成形术切除肩峰外侧，旨在使临界肩峰角正常化。然而，垂直外侧肩峰成形术可能会使三角肌中束起点从肩峰外侧松解。上方的胶原带可能将三角肌中束固定于肩峰上方并防止其回缩。
