Anatomical and morphological study of the subcoracoacromial canal.
Many clinical anatomy studies have looked into how variations in the acromion, coracoacromial ligament (CAL) and subacromial space are associated with rotator cuff injuries. However, no study up to now had defined anatomically the fibro-osseous canal that confines the supraspinatus muscle in the subcoracoacromial space. Through an anatomical study of the scapula, we defined the bone-related parameters of this canal and its anatomical variations.



This study on dry bones involved 71 scapulas. With standardised photographs in two orthogonal views (superior and lateral), the surface area of the subcoracoacromial canal and the anatomical parameters making up this canal were defined and measured using image analysis software. The primary analysis evaluated the anatomical parameters of the canal as a function of three canal surface area groups; the secondary analysis looked into how variations in the canal surface area were related to the type of acromion according to the Bigliani classification.



Relative to glenoid width, the group with a large canal surface area (L) had significantly less lateral overhang of the acromion than the group with a small canal surface area (S), with ratios of 0.41±0.23 and 0.58±0.3, respectively (P=0.04). The mean length of the CAL was 46±8mm in the L group and 39±9mm in the S group (P=0.003). The coracoacromial arch angle was 38°±11° in the L group and 34°±9° in the S group; the canal surface area was smaller in specimens with a smaller coracoacromial arch angle (P=0.20).



Apart from acromial morphology, there could be innate anatomical features of the scapula that predispose people to extrinsic lesions to the supraspinatus tendon (lateral overhang, coracoacromial arch angle) by reducing the subcoracoacromial canal's surface area.



Anatomical descriptive study.
Orthopedics Department, Pontchaillou University Hospital, 2, rue Henri-Le-Guilloux, 35000 Rennes, France. Electronic address: olivier.le.reun@chu-rennes.fr.
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O
Le Reun
Orthopedics Department, Pontchaillou University Hospital, 2, rue Henri-Le-Guilloux, 35000 Rennes, France. Electronic address: jonathan.lebhar@chu-rennes.fr.
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J
Lebhar
Anaesthesiology Department, Pontchaillou University Hospital, 2, rue Henri-Le-Guilloux, 35000 Rennes, France. Electronic address: francois.mateos@chu-rennes.fr.
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F
Mateos
Département de Préhistoire, Muséum National d'Histoire Naturelle, UMR 7194, USM 103/CNRS, 1, rue René-Panhard, 75013 Paris, France; UMR 7268, Aix-Marseille université, faculté de Médecine-Secteur Nord, boulevard Pierre-Dramard, 13344 Marseille cedex 15, France. Electronic address: jeanlucvoisin2004@yahoo.fr.
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JL
Voisin
Orthopedics Department, Pontchaillou University Hospital, 2, rue Henri-Le-Guilloux, 35000 Rennes, France. Electronic address: herve.thomazeau@chu-rennes.fr.
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H
Thomazeau
Orthopedics Department, Pontchaillou University Hospital, 2, rue Henri-Le-Guilloux, 35000 Rennes, France; Mouvement Sport Santé (M2S lab), University Rennes 2 - ENS Rennes - UEB, avenue Robert-Schuman, Campus de Ker Lann, 35170 Bruz, France. Electronic address: mickael.ropars@chu-rennes.fr.
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Ropars
D000174:Acromion / Q000033:anatomy & histology*; D000070597:Coracoid Process / Q000033:anatomy & histology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008023:Ligaments, Articular / Q000033:anatomy & histology
Anatomical study; Impingement syndrome; Rotator cuff tear; Scapula