ABSTRACT

Corresponding Author:
Dr. Susmita Saha,
Flat No. 8C, pkt 10B, Blk. 7,
Jasola-110025, New Delhi, India.
E-mail: drsusmita.sh@gmail.com

ABSTRACT

BACKGROUND

Suprascapular notch is a depression located in the superior border of the scapula near its lateral part, close to the root of the coracoid process. It is bridged by the superior transverse scapular ligament & serves as a path for the suprascapular nerve. The notch is commonly seen in all the scapulae with variable morphology. Sometimes, it is associated with ossified transverse scapular ligament which plays an important role for the suprascapular neuropathies which has been suggested in many previous literatures. But, its absence can also be a reason for nerve entrapment which has been mentioned less frequently. The purpose of this study was to find out the incidence of completely absent suprascapular notch among dry scapulae of north India, especially Gurugram region along with a morphometric evaluation of superior border of scapular where the notch is situated.

METHODS

One hundred & ten adult dry scapulae of unknown sex from the osteology museum of SGT Medical College, Gurugram, were obtained for evaluation of absence of suprascapular notch in the superior border of the scapulae near the root of the coracoid process by subjective evaluation (visual inspection). We have also done a morphometric evaluation (length) of the superior border of all the scapulae irrespective of the suprascapular notch. Our observations were compared with other osteological studies performed on other population groups.

RESULTS

Of the 110 scapulae studied, 43 belonged to right side & 67 scapulae of left side. By visual inspection, 13 scapulae (11.8%) were devoid of suprascapular notch on the upper border & rest 88 scapulae (88.81%) had different variety of suprascapular notch. Among the 13 scapulae without suprascapular notch, 8 scapulae (61.5%) were of right side and 5 scapulae (38.46%) were of left sided bone. Apart from this, the average length of the superior border of the scapulae was 42.73 mm.

CONCLUSIONS

Incidence of completely absent suprascapular notch in our study is 11.8% which will act as a reference point among Gurugram population in north India. Clinicians should keep in mind about complete absence of suprascapular notch which can be a probable reason for the suprascapular nerve entrapment.

KEY WORDS

Scapula, Superior Border, Suprascapular Notch, Absent Suprascapular Notch, Morphology, Entrapment Neuropathy

BACKGROUND

Scapulae is a triangular flat bone which lies on the posterolateral aspect of the chest wall extending from second to seventh rib and articulates with the clavicle & the head of the humerus with many soft tissue attachments.⁽¹⁾ Numerous major clinical conditions are related to this bone like impingement syndrome, entrapment neuropathies & glenohumeral dislocations with disabilities.⁽¹⁾ The bone is also known as shoulder blade; two in either sides of the thoracic wall which link the appendicular skeleton of the upper limb with the axial skeleton with the help of the clavicle.⁽²⁾ The bone is having a body with 2 surfaces; costal or subscapular fossa and a dorsal surface which is further divided into supraspinous & infraspinous fossa as it contains a spinous process. It also bears 3 angles, superior; inferior & lateral which actually possess the glenoid cavity to form the shoulder joint.⁽²⁾ So, scapula plays an important role in the movements of the glenohumeral joint.⁽³⁾ Scapula also contains three borders; superior, medial & lateral. Among the three borders, the superior one is the thinnest & shortest which extending from the root of the coracoid process to the superior angle of the scapula.⁽⁴⁾ The superior border is mostly interrupted by the presence of suprascapular notch near the junction of medial two third & lateral one third very close to the coracoid process.⁽⁵⁾ Normally the suprascapular notch of different variety is located in the lateral part of the superior border.^(5,6) Sometimes the notch is bridged by the ossified superior transverse scapular ligament converting the notch into a foramen.⁽⁴⁾ The suprascapular nerve arising from the upper trunk of the brachial plexus traverses under the superior transverse scapular ligament to supply the supraspinatus muscle, then runs along the lateral border in the spinoglenoid notch to enter into the infraspinous fossa to innervate the infraspinatus muscle.⁽⁴⁾ So, entrapment of the nerve is very common whenever there is ossified superior transverse scapular ligament leading to a foramen & this condition was first described by Koppel & Thompson.⁽⁷⁾ The morphological variation regarding the suprascapular notch is one of the causative factors for suprascapular neuropathies which is seen mostly in athletes.⁽⁸⁾ Most frequent clinical manifestations are inability to abduct the arm not only in athletes but also fencers, dancers, hunters & individual performing lot of overhead abduction as a part of their occupation.^(9,10,11) The most popular classifications for suprascapular notch is the one by Rengachary et al. described in 1979 where six types of suprascapular notches were defined.^(12,13) Among the six types, the first variety of scapulae showed small indentation or no notch near the coracoid process of scapula.⁽¹²⁾ Ticker et al. categorized the suprascapular notch of scapulae into ‘U’ & ‘V’ shaped variety.⁽¹³⁾ But, other authors have also described the morphological variations of the notch according to their shape like U shaped; V shaped; foramen or absent notch means totally straight superior border.^(14,15,16) Though normally the notch is present in the scapula with various morphological features with many clinical implications, but its absence is also seen in some of the scapulae.⁽¹⁷⁾ So, complete absence of suprascapular notch is also thought to be a reason for nerve entrapment as compression of the suprascapular nerve is possible by the superior transverse scapular ligament characterized by diffuse pain in the posterolateral aspect of the shoulder causing weak abduction.⁽¹⁸⁾ Very few studies have been performed to determine the incidence of absent suprascapular notch in Indian population, so keeping this in mind the study have been undertaken among the dry scapulae of north Indian zone.

METHODS

In the present anatomical study, 110 adult dry scapulae (this was the sample size available in the department; was more than 30 which is the minimum no for the sample size in any osteological study) of unknown sex obtained from the osteology museum of Department of Anatomy, SGT Medical College, Gurugram were evaluated for the incidence of absent suprascapular notch. Scapulae were segregated & broken scapulae especially the superior border was excluded for the evaluation. General morphological parameter like the side of the bone was also mentioned. Each bone was studied for the presence or absence of any types of notch in the superior border near the root of the coracoid process like U shaped; V shaped, ossified suprascapular ligament which convert the notch into foramen by subjective evaluation (visual inspection). Then the incidence of completely absent suprascapular notch was calculated according to the side of the scapulae. Apart from this, we have also measured the length of the superior border of all the scapulae irrespective to the presence or absence of notch by a digital vernier caliper in mm which extends from the root of the coracoid process to the superior angle of the scapula. Scapulae with absent suprascapular notch were segregated for photography & proper documentation was done. We have also done photography for ‘U’ shaped notch & scapula with suprascapular foramen for the differentiation of absent notch in the superior border.

Statistical Analysis

All the data obtained were tabulated in Microsoft excel 2007 version & maximum; minimum; mean & standard deviation was calculated. Though it was a descriptive type of analysis, so test of significance was not applied.

RESULTS

In the present osteological evaluation, 110 adult dry intact scapulae were examined for the incidence of absent suprascapular notch on the superior border of the scapulae by visual inspection. Out of the 110 scapulae studied, 43 belonged to right side and 67 belonged to left side. By subjective evaluation (visual inspection) method we have obtained 13 scapulae (11.8%) were devoid of suprascapular notch on the superior border of scapulae; rest 88 scapulae (88.81%) with different types of notches like little indentation, U shaped, V shaped or suprascapular foramen on the superior border of scapulae which has been displayed in the Table/ Fig 1 along with the graphical representation in Table/ Fig 2. It was also observed that, among the 13 scapulae with absent suprascapular notch, 8 scapulae (61.5 %) were belonged to the right side & 5 scapulae (38.46%) were of the left side. The incidence of morphological evaluation of absence suprascapular notch according to the side has been displayed in Table 1. Among all the dry specimens where suprascapular notch was absent, it was observed that there was no lateral confluent near the root of the coracoid process thus to confirm its absence. Mostly the superior border was straight in our observation among the scapulae with absent suprascapular notch.

Along with this, the morphometric evaluation (Length) of the superior border of all scapulae was also measured. We observed the mean length of superior border of scapula was 57.83 mm irrespective to the side or presence or absence of the notch. The minimum, maximum, mean and standard deviation of the length is shown in Table 2. Though the results are of descriptive statistics type, so application of test for significance was not required.

Photograph of the 3 scapulae without suprascapular notch in the superior border containing a straight superior border has been demonstrated in Fig 1. Photographs of 2 adult scapulae with a ‘U’ shaped notch as well as a suprascapular foramen have been also displaying in Fig 2 for well differentiation of scapulae devoid of notch and containing notch in the superior border.

 DISCUSSION

In the present osteological evaluation, 110 adult dry intact scapulae were examined for the incidence of absent suprascapular notch on the superior border of the scapulae by visual inspection. Out of the 110 scapulae studied, 43 belonged to right side and 67 belonged to left side. By subjective evaluation (visual inspection) method we have obtained 13 scapulae (11.8%) were devoid of suprascapular notch on the superior border of scapulae; rest 88 scapulae (88.81%) with different types of notches like little indentation, U shaped, V shaped or suprascapular foramen on the superior border of scapulae which has been displayed in the Table/ Fig 1 along with the graphical representation in Table/ Fig 2. It was also observed that, among the 13 scapulae with absent suprascapular notch, 8 scapulae (61.5 %) were belonged to the right side & 5 scapulae (38.46%) were of the left side. The incidence of morphological evaluation of absence suprascapular notch according to the side has been displayed in Table 1. Among all the dry specimens where suprascapular notch was absent, it was observed that there was no lateral confluent near the root of the coracoid process thus to confirm its absence. Mostly the superior border was straight in our observation among the scapulae with absent suprascapular notch.

Along with this, the morphometric evaluation (Length) of the superior border of all scapulae was also measured. We observed the mean length of superior border of scapula was 57.83 mm irrespective to the side or presence or absence of the notch. The minimum, maximum, mean and standard deviation of the length is shown in Table 2. Though the results are of descriptive statistics type, so application of test for significance was not required.

Photograph of the 3 scapulae without suprascapular notch in the superior border containing a straight superior border has been demonstrated in Fig 1. Photographs of 2 adult scapulae with a ‘U’ shaped notch as well as a suprascapular foramen have been also displaying in Fig 2 for well differentiation of scapulae devoid of notch and containing notch in the superior border.

 CONCLUSION

Suprascapular notch shows remarkable variations in the scapula which has been reported by many authors among different population groups with different sample sizes. But, very few studies have been undertaken to evaluate the frequency of complete absence of suprascapular notch among Indian population especially north zone. Complete absence of suprascapular notch is an important cause of suprascapular nerve entrapment syndrome. Apart from this, morphological data regarding completely absent suprascapular notch will provide an anatomical baseline to correlate the radiologic findings with clinical presentations which is expected to be of great help to the orthopaedic surgeon to devise appropriate surgical interventions to restore the normal function of the shoulder joint.

 ACKNOWLEDGEMENT

The authors thank Dr. Neelam Vasudeva, Director Professor, Department of Anatomy, Maulana Azad Medical College, for her constant inspiration.