Picture 1 - The Shoulder Joint
Source - wikipedia
The Acromion is an anatomical feature on the scapula (the shoulder blade). It is a lateral of extension of the spine on the scapula, forming the highest point on the shoulder and is triangular in shape. It occurs along with the coracoids process over the shoulder joint.
The acromion may also be called the acromion process. This acromion process, an extension of the scapular spine, extends laterally over the shoulder joint. The acromion process and the clavicle together make up the acriomioclavicular joint.
Acromion shoulder is the lateral extension of the spine of the scapula. Scapula is the scientific name for the shoulder blade. The spine leads to a ‘head’ and here it bears two processes – the acromion process and the carocoid process. The acromion process, when joins the clavicle, together with it provides the attachments for muscle of the arm and the chest.
The superior surface of the acromion bone is convex shaped and is directed to all three sides – upwards, laterally and backwards. The surface is rough, so as to provide for the attachment of the Deltoideus fibres. The inferior surface is smooth and concave, whereas the superior one is rough and convex.
On the basis of the lateral and medial borders, we can explain the anatomy of the acromion process in a slightly different manner. The lateral border of the acromion is thick and irregular, lined by 3-4 tubercles. The medial one is concave, and comparatively shorter in length. To this medial border, we also find a part of the trapezius attached.
The acromion fractures can be of many kinds –Type 1, Type 2, Type 3 and the Stress fractures. They may be further sub-divided into Type 1a, 2a, 2b etc. The Types of Acromion are described in detail below.
Type 1 Acromion
This class of fracture is known as Flat Acromion. This kind of fracture records a comparatively low number of impingement cases. It is subdivided into type 1A and type 1B. Type 1A requires less time for healing. This kind of bone fracture is mainly caused due to tearing and pushing actions. So it is also known as Avulsion fractures. Type 1B is the kind in which the displacement of the bone is not much. The primary cause behind this type is trauma.
Type 2 Acromion
This is the curved kind of Acromion, also called the curved acromion, which records cases with a high impingement injury. This acromion appears on the occurrence of many kinds too many displacements in the bone, which may be lateral or anterior. There may or may not be the reduction in the subacromial space. The patient can recover within 6 weeks without any surgical or operative treatment.
Type 3 Acromion
This is the Hooked Acromion or the beaked acromion. This kind of fracture is the most commonly occurring one. It results into a kind of inferior displacement. The pain caused by this fracture is greater than the other two. It may either be an anatomical feature, or degenerative. This fracture cannot be cured without surgical treatment. Surgery is indispensable if the acromion is a degenerative one.
Type 4 Acromion
This is the most recent classification of acromion process. In this type of acromion, the undersurface is convex near the distal end. The frequency of this acromion is increasing in the present day.
One of the most important factors which are related to rotator cuff pathology is Acromion morphology. The surgeons who are performing angioplasty based on preoperative radiographs, base their surgery on this important rationale of acromion morphology. Variation of this moprphology has been related with the pathogenesis syndrome also.
Written by Simran Goyal
on April 28th, 2011. The article was last updated on July 19th, 2011