Journal of Marine Medical Society

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 21  |  Issue : 1  |  Page : 15--18

Accuracy of magnetic resonance imaging of the shoulder in evaluation of anterior shoulder instability


Yogesh Sharma1, Mohammed Schezan Iqbal2, Ajay Deep Sud2, Pankaj Sharma2, Mohit Thapa Magar3,  
1 Command Medical Officer, WNC, Mumbai, India
2 Department of Orthopaedics, AFMC, Pune, Maharashtra, India
3 Department of Radiodiagnosis, AFMC, Pune, Maharashtra, India

Correspondence Address:
Surg Lt Cdr Mohammed Schezan Iqbal
Department of Orthopaedics, AFMC, Pune - 411 040, Maharashtra
India

Abstract

Background: Shoulder arthroscopy is currently considered the gold standard in diagnosing shoulder pathologies. Although magnetic resonance imaging (MRI) has an established accuracy in determining labral injuries following glenohumeral instability, the opinions of surgeons and radiologists regarding MRIs are still inconsistent till date. The aim of this study was to carry out a diagnostic evaluation of MRI vis-a-vis shoulder arthroscopy for the assessment of Bankart and Hill-Sachs lesions in subjects of anterior shoulder instability. Subjects and Methods: This was a diagnostic evaluation study, estimating the accuracy of MRI in diagnosing lesions encountered in shoulder dislocations vis-a-vis shoulder arthroscopy. Ninety participants of anterior shoulder dislocation were evaluated preoperatively with a shoulder MRI. The study participants were later subjected to a diagnostic shoulder arthroscopy and managed operatively on a case-to-case basis. Results: The sensitivity and specificity of MRI to diagnose a Bankart lesion were 90.78% and 85%, respectively. The positive predictive value (PPV) and negative predictive value (NPV) were 97% and 63% for the same. The sensitivity and specificity of MRI to diagnose a Hill–Sachs lesion were 92.68% and 85.71%, respectively. The PPV and NPV were 84.44% and 93.33% for the same. The diagnostic accuracy for MRI detection of Bankart lesion was 91% and of Hill–Sachs lesion was 88.89%. Conclusions: MRI is a very sensitive and specific tool in the detection of lesions commonly associated with shoulder instability, namely Bankart and Hill–Sachs lesions.



How to cite this article:
Sharma Y, Iqbal MS, Sud AD, Sharma P, Magar MT. Accuracy of magnetic resonance imaging of the shoulder in evaluation of anterior shoulder instability.J Mar Med Soc 2019;21:15-18


How to cite this URL:
Sharma Y, Iqbal MS, Sud AD, Sharma P, Magar MT. Accuracy of magnetic resonance imaging of the shoulder in evaluation of anterior shoulder instability. J Mar Med Soc [serial online] 2019 [cited 2019 Sep 22 ];21:15-18
Available from: http://www.marinemedicalsociety.in/text.asp?2019/21/1/15/260673


Full Text



 Introduction



Human shoulder is the most mobile joint in the body. This mobility provides the upper extremity with tremendous range of motion. This wide range of motion also makes the shoulder joint unstable and prone to injury, both acute and repetitive.

Glenohumeral dislocation is a common clinical entity, with a reported prevalence of about 2% and anterior instability being the most common.[1] It is defined as the dissociation between the glenoid and the humeral head.[2] Despite reduction and immobilization following the first dislocation, a patient can present with recurrent instability with a resultant decrease in the functionality of the shoulder, thus restricting occupational and athletic activities alike.[3]

The most common lesion associated with a traumatic anterior dislocation of the shoulder is a tear of the anteroinferior labrum known as the “Bankart lesion” or its variations, which are being increasingly recognized.[2] The Bankart “essential lesion” is an avulsion of the labrum from the anterior inferior glenoid with an associated tear in the labrum.[4] Its corresponding lesion in the humeral head, namely the Hill–Sachs lesion, is frequently associated with the Bankart lesion, and its extent modifies the type of intervention routinely performed for the management of isolated Bankart lesions.

Arriving at diagnosis is the key to planning the treatment and rehabilitation protocol. Remarkable and impressive developments in the fields of arthroscopy and magnetic resonance imaging (MRI) accomplished over the past three decades have resulted in higher accuracy of diagnosis of shoulder pathologies.[5]

Arthroscopy is currently considered the gold standard in diagnosing shoulder pathologies. It allows direct visualization of the intra-articular structures under a magnification of almost ×20.[6] However, the procedure is invasive and thus carries the risks of complications, such as infection, damage to adjacent structures (e.g., musculocutaneous nerve or articular cartilage), and fluid extravasation, in addition to observational errors and anesthetic risks as well.

MRI has an established accuracy in determining labral injuries following glenohumeral instability using noncontrast-enhanced, nonionizing imaging techniques for diagnostic assessment of lesions of shoulder instability.[5] However, the opinions of surgeons and radiologists regarding MRIs are still inconsistent till date.[7]

This study was undertaken with the aim of diagnostic evaluation of MRI vis-a-vis shoulder arthroscopy, which is the present-day gold standard, for the assessment of Bankart and Hill–Sachs lesions in participants of shoulder instability.

 Subjects and Methods



This is a diagnostic evaluation study, which compares the accuracy of MRI in diagnosing lesions encountered in shoulder dislocations vis-a-vis shoulder arthroscopy, which is considered the gold standard for the same. The present study was conducted in a tertiary care hospital in the Department of Orthopaedics, in consultation with the Department of Radiodiagnosis, over a 1½-year period from January 2017 to June 2018. Ethical clearance was obtained from the institutional ethics committee before the start of the study. The inclusion criteria for our study were age >18 years, history of anterior shoulder dislocation (single or recurrent), and no previous shoulder surgery. Exclusion criteria were associated proximal humeral fractures, including isolated fracture of the greater tuberosity, history of posterior shoulder dislocation, clinical diagnosis of multidirectional shoulder instability, and osteoarthritis of the glenohumeral joint. The sample size was calculated presuming a 95% confidence interval for the sensitivity of MRI versus arthroscopic findings of Bankart lesion in the shoulder joint, referencing the work of Joshi and Puri,[8] with a 6% absolute margin of error. The sample size worked out to be 87, assuming sensitivity to be 91%.[8] However, 90 participants were studied for the present diagnostic evaluation. The sampling done in our study was a nonprobability sampling.

All eligible participants (90 participants) were evaluated preoperatively with history and clinical examination, followed by plain radiography (standard anteroposterior and axillary lateral views of the affected shoulder). Patients who provided written informed consent to be a part of our study were subjected to a shoulder MRI (Siemens; MAGNETOM Symphony®, 1.5T). MRI study was performed using a variety of imaging sequences (T1-weighted, T2-weighted, and short-tau inversion recovery images), and a single, independent radiologist evaluated the MRIs. All MRI reports were documented by the same radiologist.

The study participants were later subjected to a diagnostic shoulder arthroscopy, which was performed by a single orthopedic surgeon using standard anterior and posterior arthroscopic portals. Arthroscopic examination consisted of evaluation of the glenohumeral joint, glenohumeral capsule, glenoid labrum, subacromial space, rotator interval, biceps tendon, and rotator cuff tendons on both subacromial and glenohumeral surfaces. The management of identified lesions, as evidenced in the arthroscopy, was done appropriately in the same setting. Operative findings were documented in the operative notes.

The MRI reports and operative notes for all 90 participants were reviewed. Shoulder arthroscopy was designated to be the gold standard for the diagnosis of shoulder pathology, and MRI findings were compared with arthroscopic findings for determining its sensitivity, specificity, negative predictive value (NPV), and diagnostic accuracy, using appropriate statistical tests.

 Results



All participants who were part of the study were males. Of the 90 participants who consented to be a part of the study, majority of the study population (76.6%) were in the active age group of 21–40 years. The mean age of the study population was 27.23 ± 7.05 years. Based on the participants' history on the mechanism of injury, shoulder dislocation was common in traumatic events such as road traffic accidents, falls while climbing or jumping, and sports which require abduction and external rotation of the shoulder joint such as swimming, volleyball, and kabaddi. The frequency of various injury mechanisms varied across the age groups, with the younger population suffering from injury during sporting activities while the older population suffering from traumatic injuries.

The hallmark of a shoulder dislocation, the Bankart lesion, was reported positive in the MRI of 71 participants, of whom 69 were confirmed on arthroscopy. Of the 19 participants who were diagnosed to not have a Bankart lesion on MRI, 12 were confirmed to not having the same on arthroscopy [Table 1].{Table 1}

The Hill–Sachs lesion, a commonly associated lesion in shoulder instability, was reported to be positive in 45 MRI reports, 38 of which were seen to be present on shoulder arthroscopy. Of the remaining 45 participants who were reported as not having a Hill–Sachs lesion on MRI findings, 42 were eventually shown to be negative for associated Hill–Sachs lesion on arthroscopy as well [Table 2].{Table 2}

The sensitivity of MRI to diagnose a Bankart lesion was 90.78%, and its specificity was 85%. The positive predictive value (PPV) was 97% and NPV was 63% for the same. The sensitivity of MRI to diagnose a Hill–Sachs lesion was 92.68% and its specificity was 85.71%. The PPV was 84.44% and NPV was 93.33% for the same. The diagnostic accuracy for MRI detection of Bankart lesion was 91% and Hill–Sachs lesion was 88.89%, which was assessed using Chi-square test [Table 3].{Table 3}

No complications were encountered during MRI or arthroscopic surgery in the study population during the study.

 Discussion



Shoulder dislocation is a problem commonly seen in emergency departments. Before the introduction of MRI, only invasive tests such as arthrography, double-contrast computed tomographic arthrography, and arthroscopy were the means available for the assessment of intra-articular pathology associated with this condition.[9]

MRI has been in use for the diagnosis of shoulder pathologies since the 1980s, but the diagnostic accuracy of MRI for the detection of pathognomonic lesions of shoulder instability, as evidenced in the literature of that era, was not great. However, with the advent of new technology and better equipment, newer imaging sequences, and improved technical know-how, the preoperative detection of lesions predictive of recurrent shoulder instability along with associated shoulder disorders has improved dramatically, as shown by Kirkley et al.[10] MRI has also been shown to be sensitive in diagnosing Hill–Sachs lesions,[11] capsular and glenoid labral tears,[12] and rotator cuff tears, all of which may play a role in recurrent shoulder dislocations.

MRI has been shown to be an effective and accurate modality for preoperative evaluation of lesions associated with shoulder instability. The percentage of Bankart lesions found to be positive in our study was 78.8% versus 83%–100%, while that of Hill–Sachs lesions present on MRI was 50% versus 47%–100%.[13] Hayes et al.,[14] in their study of 87 patients with shoulder instability, determined the sensitivity and specificity of MRI in detecting Bankart lesion to be 98.4% and 95.2%, respectively. Bhatnagar et al.[15] found MRI to be highly sensitive and specific in detecting Bankart lesion, showing sensitivity of 80%, specificity of 100%, PPV of 100%, and NPV of 89%.

The agreement of MRI and arthroscopy showing the presence or absence of a Bankart lesion and a Hill–Sachs lesion demonstrated perfect agreement (k = 1.0) for both lesions in the study carried out by Kirkley et al.[10] Joshi et al.[8] in their prospective study among 30 patients with shoulder instability found sensitivity of 91.3%, specificity of 85.71%, and diagnostic accuracy of 90% in detecting a Bankart lesion by preoperative MRI. These studies and their data support our study findings of various measures of diagnostic evaluation.

Workman et al.[11] performed an MRI for the detection of Hill–Sachs lesion in shoulder instability participants. They demonstrated a sensitivity of 97%, specificity of 91%, and a diagnostic accuracy of 94% for detecting Hill–Sachs lesion and concluded that MRI can be a valuable tool in diagnosing the Hill–Sachs lesion preoperatively. Our study supports their findings with the sensitivity of MRI to diagnose a Hill–Sachs lesion being 92.68% and its specificity of 85.71%.

There are some limitations of our study. First, although our inclusion criteria had males as well as females who could have been a part of our study, our study population ultimately consisted of only male participants. Hence, no gender-specific analyses of various parameters could be carried out. Second, we have not determined the frequency of generalized ligamentous laxity in our study population using various scoring systems such as the Beighton score, which may play a role in the observed rates of the lesions of shoulder instability on MRI as well as arthroscopy.

 Conclusions



MRI is a very sensitive and specific tool in the detection of lesions commonly associated with shoulder instability, namely Bankart and Hill–Sachs lesions. MRI is noninvasive, which combines the soft-tissue contrast with tomographic possibilities, without using ionizing radiation. It is also useful in demonstrating both, the superficial and deep structures, and can differentiate bone, cartilage, and ligaments with precision. It provides the orthopedic surgeon a view to the possible hurdles he/she might face during surgery, by also showing lesions which are not commonly thought to accompany shoulder instability. It assists in classification and preoperative assessment of the pathology. In patients whom a diagnosis is doubtful, MRI has a definite role in the diagnosis and possible prevention of an unneeded surgical intervention. Arthroscopic techniques, which are a gold standard, remain a leading surgical option because they are minimally invasive and require less operative time and shorter hospitalization but are offset by the fact that they need anesthesia and are associated with surgical and anesthetic complications, which preclude their routine use in the diagnostic domain.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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