1 Introduction

Anterior dislocation of shoulder^1,2 joint is common among young males, as they are more prone for traumatic and sports injuries.³ Globally, the incidence of traumatic shoulder dislocation is 17–32 per 1,00,000 population per year (kroner K, Liavaag, Anne). And nearly 75% of anterior shoulder dislocations tend to recur.^4,5 During the first traumatic dislocation, there is disruption of anteroinferior glenoid labrum from glenoid margin. The structures that are put in stress during each dislocation are labrum and capsule. Hence it is not unusual to find variations in appearance of labrum and capsule in recurrent dislocators. Some common risk factors for recurrence^5,6 are male gender, young age, laxity, and participation in sports activity. The most common surgical technique to restore shoulder stability is arthroscopic bankart repair.^7,9 The technique of arthroscopic repair has evolved from transglenoid suturing⁸ to modern suture anchor type of fixations. Similarly, the outcome of arthroscopic bankart repair has shown to be almost equivalent to open bankart repair.¹⁰ Most of the studies have shown that the arthroscopic repair has a recurrence rate of 10% up to 3.6 years (Boileau, Carreira, Voos JE). But still the point of significance is that there is wide variation in the literature about the incidence of recurrence. The range varies from 5% to 33% in some series. Some of the operative risk factors are interval of more than six months between the dislocation and surgery, humeral head and glenoid defects and number of suture anchors used in arthroscopic surgery. (boileau, Kim SH, Porcellini G). As there is a greater number of dislocations, it is natural to expect repetitive damage to the labrum¹¹ and also the capsule.¹² The fact is also evident while performing arthroscopic repair from simple disruption of the labrum to complex damage of labrum and capsule. The purpose of our study is to describe the pattern of morphological changes that occur in the labrum and capsule as evident during arthroscopic assessment. We have classified the morphological pattern and have correlated with number of dislocations patient has sustained in the past.

2 Materials and methods

The patients who underwent arthroscopic anterior shoulder stabilisation over a period of 18 months during March 2014–September 2015 were selected for the study. The inclusion criteria were the patients with the first dislocation due to trauma irrespective of the age and gender. Those patients with multidirectional, ligamentous lax, revision cases, bony bankart and cases with associated shoulder pathology such as GT fracture, SLAP, rotator cuff tears, other labral tears were excluded from the study. The cases had undergone the standard operative procedure.

During the operative procedure the labrum is well liberated and delineated. The glenoid margin is freshened. Once the labrum floats to the level of the glenoid margin, the appearance of the glenoid and the capsule is noted and tabulated. The labrum is classified into three categories: If the labrum is seen as bulky then it is termed as Normal Labrum, If the labrum looks altered, but still definable as a discrete structure then it is called Desiccated Labrum. If the labrum is a thin structure with gross alteration in appearance then it is called as Shredded Labrum. Similarly, if the capsule appears to be stretched out due to plastic deformation then it called Damaged Capsule, otherwise it is called a Normal Capsule. And we have also found the extent of labral tear upto 5'o clock or beyond 5'o clock position. Based on findings and tabulated data, a comprehensive classification of morphology of labrum and capsule is done as follows.

The classification includes Normal Capsule and Normal Labrum (NN) [Fig. 1a], Normal Capsule and Desiccated Labrum (ND) [Fig. 1b], Normal Capsule and Shredded Labrum (NS) [Fig. 2a], Damaged Capsule and Normal Labrum (DN) [Fig. 2b], Damaged Capsule and Desiccated Labrum (DD) [Fig. 3a], Damaged Capsule and Shredded Labrum (DS) [Fig. 3b]. Convenience sampling method is used to collect the data. Data was entered into Microsoft Excel sheet and S.D analysed in SPSS ver.1.6.

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Fig. 1 a. Normal Labrum Normal Capsule b. Normal Capsule Desiccated Labrum.

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Fig. 2 a. Normal Capsule Shredded Labrum b. Damaged Capsule Normal Labrum.

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Fig. 3 a. Damaged Capsule Desiccated Labrum b. Damaged Capsule Shredded Labrum.

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Graph 1 Arthroscopic classification of Glenoid Labrum and Capsule in Shoulder Dislocation. NN: Normal capsule and Normal labrum, ND: Normal capsule and Desiccated labrum, NS: Normal capsule and Shredded labrum, DN: Damaged capsule and Normal labrum, DD: Damaged capsule and Desiccated labrum, DS: Damaged capsule and Shredded labrum.

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For continuous variables mean and S.D and for categorical variables frequency and percentage were calculated. Pearson chi-square test was applied to find the association between categorical variables.

3 Results

In Table 1, the characteristics of the patients with shoulder dislocation were shown. Only 2 patients (1.9%) were in the age group of less than 20 years of age. Maximum study participants (78.7%) were in the age group between 21 and 40 years and remaining were more than 40 years of age. 102 patients (94.4%) belonged to male gender. And 63% had right shoulder dislocation.

Table 2 and Graph 1 shows the arthroscopic classification of glenoid labrum and capsule in shoulder dislocation. Based on the arthroscopic findings the patients were classified as NN, ND, NS, DN, DD and DS which were 19 (17.6%), 13 (12%), 6 (5.6%), 2 (1.9%), 36 (33.3%) and 32 (29.6%) respectively.

Table 3, shows the relationship between arthroscopic classification of lesion and number of dislocations. Kruskal-wallis test was applied to find the association between the type of lesion and number of dislocations. In our study we found that the patient classified as DD and DS had higher number of dislocation when compared to NN, ND, NS and DN. This association was statistically significant as p value was 0.01. And chi-square test was applied to find the association between the type of dislocation and extent of lesion.

Table 4, shows that patients with damaged capsule, had a tendency towards lesion beyond 5'o clock position. But this association was not statistically significant.

4 Discussion

After index traumatic shoulder dislocation, usually the labrum and capsule gets dislodged from its attachment. When there is recurrence of dislocation, there is further injury to these structures. Objective of anterior stabilisation procedure is to identify the labrum and reattach it to original area. Mostly these labrum are stuck to the medial aspect of glenoid. Hence the most important step of the procedure is liberating the labrum from all the attachments and make it well delineated. Though the objective is to recreate the normal anatomy, it is difficult to restore the anatomy as the structure of labrum and capsule has changed due to multiple dislocations. Our classification is based on the appearance of the labrum and capsule after clear liberation and before approximating to the glenoid margin. It is also evident from our study, there are gross changes in appearance of labrum and capsule in recurrent dislocators. To our knowledge, so far there is no literature available to describe the morphology of labrum and capsule.

The mean age of the patients was 33.35 with S.D 6.83 and majority of them were males, 5.6% are females in our study population. This is because majority of shoulder labrum injury occurs among sportspersons who are in the age group between 20 and 40. This finding is similar with other studies which showed similar injuries among this age group. (Privetra, Park mj, Van de linde).

Totally there were 108 patients and majority of them had DS and DD which were 33.3% and 29.6% respectively. And the median number of times of dislocation among DD and DS were 6 (2–15) and 13 (3–30) whereas for NN, ND, NS and DN, the median was less than 5. From our study, we are able to comprehend that when number of dislocations increases the severity of the lesion also increases. Recurrent dislocators tend to have a labrum and the capsule that has lost its normal anatomy and capsule has plastically deformed. In this study, we have admitted patients for surgery based on who had symptoms and recurrent dislocation and the patients with NN, ND, NS were also underwent surgery because these patients want to continue their activities of daily living or sports activities without restriction (Lenart, Ricchetti). Our study findings were in consensus with other studies which were done by Privetra et al. and Van de linde. In our study we have also proved that majority (>90%) of the patients among DN, DD and DS category had the extent of lesion beyond 5'o clock position and this association was not statistically significant. This finding is similar to study findings found by Godin J et al. The extension of lesion is mainly because of the mechanism of injury due to the movement of the shoulder joint which in turn let the humerus to move anteriorly. Mainly the sports which are hand dominant (Tennis, badminton etc…) are prone for frequent shoulder dislocation (Dumont, Anakwenze). The DD and DS variety occurs as a result of heavy and lengthy first-time dislocation which has caused severe injury or it could be due to multiple dislocations in the past. Among these patients the possibility of re-dislocation is very high which caused them to restrict the daily activities. Hence, they might have decided to undergo surgery.

5 Conclusion

From this study we found that as the number of dislocations increases, the extent of destruction to the labrum and capsule becomes worse and reproducing the anatomy while doing the repair will not be possible. This also signifies the importance of early intervention in patients with recurrent shoulder dislocation as the chances of restoring anatomy will be much better if repair is done at an early stage.

Funding

The research did not receive any specific grant from funding agencies in public or non-profit sectors, and no material support of any kind was received.

Patient consent for publication

Not required.

Ethical approval

This is Level 3 observational study based on intra-operative findings, ethical committee approval was not required.