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 Table of Contents  
ORIGINAL ARTICLE
Year : 2014  |  Volume : 1  |  Issue : 3  |  Page : 164-169

A morphometric study of acromion process of scapula and its clinical significance


Department of Anatomy, Kasturba Medical College, Manipal University, Manipal, Karnataka, India

Date of Web Publication17-Aug-2014

Correspondence Address:
Chandni Gupta
Department of Anatomy, Kasturba Medical College, Manipal University, Manipal - 576 104, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2348-3334.138885

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  Abstract 

Objective: The acromion process is associated with a variety of ailments in the shoulder. Therefore, the aim of this study was to record and study all the morphometric values of the acromion process and its morphological features. Materials and Methods: The study was carried out on 50 unpaired dried scapulae. The length, width, and thickness of the acromion process were measured, and the length and width of scapula was also measured using vernier calipers. The acromiocoracoid and acromioglenoid distances were also measured. The shape, type of acromion process, and the presence of enthesophytes were noted and whether the anterior 2/3 rd of inferior surface of acromion process is rough or smooth was also noted. Results: The mean length, width, and thickness of acromion process were 4.21, 2.42, and 0.73 cm, respectively. The mean length and width of scapula were 13.93 and 10.14 cm, respectively. The mean acromiocoracoid distance and acromioglenoid distance were 3.09 and 2.47 cm, respectively. The most common shape of the acromion process noted was quadrangular in 40% of scapulae. In 90% of scapulae, the anterior 2/3 rd of inferior surface was rough and in 80% scapulae, enthesophytes were present. Conclusions: This study will help the clinicians in understanding and curing various shoulder joint disorders.

Keywords: Acromion, measurements, rotator cuff, shape, type


How to cite this article:
Gupta C, Priya A, Kalthur SG, D'Souza AS. A morphometric study of acromion process of scapula and its clinical significance. CHRISMED J Health Res 2014;1:164-9

How to cite this URL:
Gupta C, Priya A, Kalthur SG, D'Souza AS. A morphometric study of acromion process of scapula and its clinical significance. CHRISMED J Health Res [serial online] 2014 [cited 2019 Oct 21];1:164-9. Available from: http://www.cjhr.org/text.asp?2014/1/3/164/138885


  Introduction Top


The scapular spine, originating from the posterior surface of the scapula, is prolonged to a powerful and flattened process located on the boundary between the superior quadrant and the remaining quadrants of the scapula, forming the acromion process. The anterior third of the acromion process, the coracoacromial ligament, and the coracoid process form a familiar arch called the coracoacromial arch. This arch is fairly a non-elastic structure and it comprises of a subacromial space that is 1-1.5 cm wide and has the subacromial bursa, the myotendinous rotator cuff, and the tendon of the long head of the biceps muscle. [1]

Morphometry of the acromion process of the scapula is of significant importance, which is commonly involved in impingement syndrome of the shoulder joint. [2] Bigliani et al., studied 140 shoulders and categorized the acromial morphology into three types: Type I or flat, type II or convex, and type III or hooked. Since that time, the Bigliani-Morrison-April morphological classification has been the prevailing diagnostic tool for the impingement syndrome and rotator cuff tears. [1]

The variations of the acromion process must be kept in mind during surgery around the shoulder joint. [3] The knowledge regarding the shape and various distances of the acromion process might benefit the orthopedicians during surgical repair around the shoulder joint and the morphometric analysis of the acromion process should be used like a support to increase the knowledge about the disease that appears in this region. [2] Therefore, the aim of this study was to record the morphometric values and morphology of the acromion process of the scapula.


  Materials and Methods Top


The study was carried out on 50 dried, unpaired scapulae (21 right, 29 left). These scapulae did not have any external deformities. Ethical approval has been taken for the study from the local ethical committee. The following information was recorded: The type of the scapulae due to the shape of the acromion process according to the Bigliani-Morrison-April classification, Type I - flat acromion process, Type II - curved acromion process, and Type III - hook acromion process; the morphology of the inferior surface of the acromion process (whether smooth or rough); and the presence of enthesophytes (pulling osteophytes in the region of attachment of ligaments and tendons). We also looked for the different shapes of the acromion process and classified them into various types.

Several dimensions were measured, including the size of the scapula and the acromion process. The acromioglenoid and acromiocoracoid distances were also measured. These dimensions were measured using a vernier calipers.

The scapular measurements included the maximum longitudinal diameter between the superior medial and inferior angles, and the maximum transverse diameter between the medial border of the scapula, where the spine meets the body of the scapula and the anterior lip of the glenoid. The study of the dimensions of the acromion process included [Figure 1].
Figure 1: Showing measurements done on the scapula and acromion process. (a) Width of the acromion process, (b) Acromiocoracoid distance, (c) Acromioglenoid distance, (d) Length of the acromion, (e) Length of the scapula

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The anteroposterior length in the longitudinal axis.

The distance between the lateral and medial borders at the midpoint of the acromion process.

The thickness of the acromion process 1-cm posterior to the anterior border and 1 cm medial to the lateral border.

The acromiocoracoid distance was measured between the tip of the coracoid process and the tip of the acromion process, while the acromioglenoidal distance was measured as the distance between the supraglenoid tubercle and the tip of the acromion process [Figure 1].

Statistical analysis of the measured parameters was performed using Student's t-test as well as correlation tests for result analysis using SPSS 16 software.


  Results Top


The mean and range of all parameters on the right and left side scapulae are shown in [Table 1].
Table 1: Mean and range of parameters on the right side scapula

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The mean length and width of total scapulae were 13.93 and 10.14 cm, respectively. The mean length, width, and thickness of the acromian in all scapulae were 4.21, 2.42, and 0.73 cm, respectively. The acromiocoracoid distance and acromioglenoid distance in total scapulae were 3.09 and 2.47 cm, respectively. Different types of scapulae according to Bigliani et al., are shown in Graph 2 [Figure 2]. Various shapes of the acromion process are shown in Graph 1 [Figure 3] and [Figure 4]. Enthesophytes were seen in 80% of scapulae and more in type III (86.95%), and the inferior surface anterior 2/3 rd was rough in 90% of scapulae and that was also more in type III (100%) [Figure 2] and [Figure 5].
Figure 2: Showing types of scapulae and presence of enthesophytes. (a) Type I - fl at, (b) Type II - curved, (c) Type III - hook, (d) Presence of enthesophytes

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Figure 3: Showing different shapes of the acromion process. (a) Beak-shaped, (b) Rectangular, (c) Triangular, (d) Leaf-like, (e) Flask-shaped

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Figure 4: Showing different shapes of the acromion process. (a) Boot-shaped, (b) Quadrangular, (c) Square

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Figure 5: Showing inferior surface of the acromion process. (a) Smooth inferior
surface. (b) Rough inferior surface


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In our study, we also compares various parameters with each other and found that there was significant correlation between the length of the scapula and the length of the acromion process as well as between the width of scapula and the width of the acromion process as P value was 0.000 (<0.005). However, there was no significant correlation between the length of scapula, length of the acromion process, acromiocoracoid distance, and acromioglenoid distance as P > 0.005.


  Discussion Top


Measurements of the scapula and acromian process are vital since they vary in morphology, and when categorized in to various types, show connection to shoulder girdle pathologies. [3].

The clinical importance of this study rests on the contributory consequence of the shape of the anterior third of the acromion process in relation to the impingement syndrome as well as to rotator cuff tear. It is extensively believed that rotator cuff lesions are observed mostly in the hooked acromia (62-66% of the cases of rotator cuff tear involve the type III acromion process). [4],[5] This relationship is explained by the decrease in the sizes of the subacromial space in hooked acromia, which more frequently leads to impingement of the rotator cuff. [1]

Paraskevas et al., found the mean value of scapular height and width as 14.76 and 10.19 cm, respectively, whereas Singh et al., found the mean value to be 14.51 and 10.55 cm, respectively, which was almost similar to our study values of 13.93 and 10.14 cm, respectively. [1],[3]

Singh et al., found the mean value of scapular height and width as 14.57 and 10.65 cm, respectively, in left side scapulae and 14.46 and 10.46 cm, respectively, in right side scapulae. In our study, we obtained the values as 14.21 and 10.26 cm, respectively, in left side scapulae and 13.53 and 9.98 cm, respectively, in right side scapulae. [3]

Paraskevas et al., found the mean length, width, thickness of the acromion process as 4.61, 2.23, and 0.88 cm, respectively, and Singh J et al., found the values to be 4.61, 2.32, and 0.66 cm, respectively. The values were also similar to our study; we obtained the values as 4.21, 2.42 and 0.73 cm, respectively. The mean value of the acromiocoracoid distance and acromioglenoidal distance in their study was 2.81 and 1.77 cm, respectively, and 3.75 and 2.7 cm, respectively; in our study, the values were 3.09 and 2.47 cm, respectively. [1],[3]

Paraskevas et al., and Natsis et al., noticed the presence of enthesophytes in 21.5% and 15.6% of cases, respectively, while in our study the enthesophytes were present in 80% of cases. [1],[6]

Paraskevas et al., Natsis et al., and Getz et al., found the enthenophytes were present predominantly in the type III acromion process 75%, 37.7%, and 59%, respectively; in our study as well, enthenophytes were predominant in the type III acromion process 86.95%. [1],[4],[6]

Natsis et al., and Getz et al., found enthesophytes in 1 and 22 of type I acromion processes (2% and 24%), respectively; 19 and 115 of type II acromion processes (7.9% and 42.6%), respectively; and 46 and 20 of the type III acromion processes (37.7% and 59%), respectively. In our study, we found enthesophtyes in 11 of type I (68.7%), 9 of type II (81.8%), and 20 of type III (86.9%) acromion processes. [4],[6]

Paraskevas et al., and Singh et al., found the inferior surface of the anterior third of the acromion process was smooth in 37 and 72 cases (42% and 55.8%), respectively, and rough in 51 and 57 (57.9% and 44.2%), respectively, while in our study the inferior surface anterior 2/3 rd was smooth in 5 cases (10%) and rough in 45 cases (90%) of scapulae. [1],[3]

Paraskevas et al., found that the rough inferior surface was noted more in type III (13/16, 81.2%); in our study, it was more in type III (23/23, 100%). [1]

Mansur et al., and Singh et al., found the average length and breadth of the acromion process on the right scapulae as 4.64 cm and 2.66 cm and 4.64 cm and 2.34 cm, respectively, while in our study we obtained the values as 4.16 cm and 2.32 cm. Their values on left side were 4.55 cm and 2.72 cm and 4.58 cm and 2.3cm, respectively; however, in our study, the values were 4.25 and 2.49 cm, respectively. [2],[3]

Singh et al., found the average thickness of the acromion process on the right and left sides of the scapulae as 0.66 cm and 0.67 cm, respectively, while in our study we obtained the values as 0.73 cm and 0.74 cm. [3]

Mansur et al., and Singh et al., found the acromiocoracoid distance on the right and left sides in their study was 3.90 cm and 3.93 cm and 3.71 cm and 3.79 cm, respectively; in our study, we obtained almost the same values, as 3.18 cm and 3.03 cm. In their study, the acromioglenoid distance was 3.18 cm and 3.19 cm and 2.66 cm and 2.76 cm on the right and left sides, respectively, while in our study the values were 2.53 cm and 2.43 cm, respectively. [2],[3]

Mansur et al., classified the shape of the acromion process into 3 types as: Triangular - 36.76%, Quadrangular - 52.94%, and Tubular - 10.29%; in our study, we classified the shape of the acromion process into 9 types and we found triangular in 8% and quadrangular in 40% of cases. [2]

Nicholson et al., Singh et al., Natsis et al., and Getz et al., found the distribution of acromial morphologic types as type I (flat) 32%, 29%, 12.1%, and 22.8%, respectively; type II (curved) 42%, 38.8%, 56.5%, and 68.5%, respectively; and type III (hooked) 26%, 38.8%, 28.8%, and 8.6% of cases, respectively. In our study, we found the distribution to be type I - 32%, type II - 22%, and type III - 46% of cases. [3],[4],[6],[7]

Natsis et al., found that the enthesophytes were significantly more common in the type III acromion process, and this combination is particularly associated with subacromial impingement syndrome and rotator cuff tears, which we also found in our study. They also found that in type I and type IV acromion processes, the incidence of enthesophytes is very low. According to their other studies, rotator cuff tears are also rare in these two acromial process types. At any proportion, the enthesophytes are a significant reason for subacromial impingement syndrome and rotator cuff tears, either as the reason or as the outcome. [6]

There are additional macroscopic alterations in the anatomical features of the acromion process found in patients with rotator cuff lesions. These comprise thickening of the coracoacromial ligament and enthesophyte development. [5] The impingement of the supraspinatus tendon and usually of the elements of the great humeral tubercle takes place primarily at the acromial end of the coracoacromial ligament and the anterior border of the acromion process during flexion and internal rotation. The coracoacromial ligament is dragged by the great humeral tubercle, which is situated above it. This clarifies the enthesophyte development (pulling osteophytes) in the anterior third of the acromion process in patients with chronic impingement syndrome. [8]

Edelson and Taitz concluded that the slope and length of the acromion process and the height of the arch were utmost closely related with degenerative changes. Increased degenerative changes of both types were related with increased length of the acromion process and length was in turn connected to the shape of the acromion process. [5]

The anatomical features of the acromion process are associated with the pathology of the rotator cuff and its management. The acromion process plays a significant part in formation as well as in offering stability to the shoulder joint. Measurements of the scapula and acromion process are vital because these may be involved in various shoulder girdle pathologies. This study would be useful for surgeons while working on the shoulder joint.

 
  References Top

1.Paraskevas G, Tzaveas A, Papaziogas B, Kitsoulis P, Natsis K, Spanidou S. Morphological parameters of the acromion. Folia Morphol (Warsz) 2008;67:255-60.  Back to cited text no. 1
    
2.Mansur DI, Khanal K, Haque MK, Sharma K. Morphometry of acromion process of human scapulae and its clinical importance amongst Nepalese population. Kathmandu Univ Med J 2012;10:33-6.  Back to cited text no. 2
    
3.Singh J, Pahuja K, Agarwal R. Morphometric parameters of the acromion process in adult human scapulae. Indian J Basic Appl Med Res 2013;2:1165-70.  Back to cited text no. 3
    
4.Getz JD, Recht MP, Piraino DW, Schils JP, Latimer BM, Jellema LM, et al. Acromial morphology: Relation to sex, age, symmetry, and subacromial enthesophytes. Radiology 1996;199:737-42.  Back to cited text no. 4
    
5.Edelson JG, Taitz C. Anatomy of the coraco: Acromial arch. Relation to degeneration of the acromion. J Bone Joint Surg Br 1992;74:589-94.  Back to cited text no. 5
    
6.Natsis K, Tsikaras P, Totlis T, Gigis I, Skandalakis P, Appell HJ, et al. Correlation between the four types of acromion and the existence of enthesophytes: A study on 423 dried scapulas and review of the literature. Clin Anat 2007;20:267-72.  Back to cited text no. 6
    
7.Nicholson GP, Goodman DA, Flatow EL, Bigliani LU. The acromion: Morphologic condition and age-related changes. A study of 420 scapulas. J Shoulder Elbow Surg 1996;5:1-11.  Back to cited text no. 7
    
8.Burns WC 2 nd , Whipple TL. Anatomic relationships in the shoulder impingement syndrome. Clin Orthop Relat Res 1993;294:96-102.  Back to cited text no. 8
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1]


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