الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
The GH joint is an anatomically complex joint with the widest range of motion (ROM) of all joints in the body. The stability of this joint results from the balance of both static and dynamic stabilizers acting in numerous ways. The bony structures of the glenoid & humeral head, the glenoid labrum, the joint capsule, as well as the glenohumeral ligaments are static stabilizers whose anatomy is crucial to compensate the relative instability of the joint. While, the dynamic stabilizers include the rotator cuff muscles and, to a lesser degree, the long head of the biceps [LHB] and the deltoid.
GH instability remains a very complex and sometimes challenging diagnostic problem. There are potential lesions of the capsule and labroligamentous structures that could occur in association with shoulder instability, and also the clinical history and physical findings don’t seem to be always sufficient to achieve an accurate diagnosis. Therefore, it’s important to be oriented by the anatomy, pathology, history, physical examination, and classification systems to diagnose these patients correctly.
Reliable diagnostic imaging is mandatory not only for establishing an accurate diagnosis but also for evaluation when different treatment options are considered. Imaging is incredibly important when clinical findings are contradictory or sparse. Several imaging modalities are available including conventional radiography, ultrasonography, CT arthrography, conventional MRI and MR arthrography. Lately, MR arthrography was increasingly recognized as the gold standard examination in assessment of glenohumeral instability . The injection of paramagnetic contrast agent into the joint allows for capsule distension and better visualization of intraarticular structures such as the glenoid labrum and glenohumeral ligaments, and providing demarcation of complex anatomic structures of the joint, along with excellent delineation of associated intra-articular lesions.
The purpose of this study was to prospectively evaluate the diagnostic performance of MRA in evaluating shoulder lesions, by performing MRA employing a paramagnetic contrast agent, with arthroscopic correlation.
This study was performed on 50 patients, with mean age 34 years with a clinical diagnosis of shoulder instability. All patients were subjected to MRA of the shoulder. Then patients subsequently underwent arthroscopic surgery. Detailed arthroscopic findings were reported and compared with MRA findings. In the current series, injection of contrast into the glenohumeral joint was performed using US guided techniques “using either anterior rotator interval approach or the posterior approach” and revealed high success rates from the 1st attempt of injection, with the posterior approach noticed to be less painful and more tolerable by the patients, besides, it causes no injuries to the anterior stabilizers.
Arthroscopic examination confirmed 74 pathological findings in 50 patients included within the current study. Patients frequently presented with multiple lesions, however, patients equal or younger than 34 years showed high incidence of labral lesions while those above 34 years had higher incidence of rotator cuff tears (RCTs). In our study, MR arthrography showed labral tears with greater sensitivity besides to what it afforded in imaging capsuloligamentous, cartilaginous injuries as well as small partial or complete tears of the RC tendons. Although it nicely revealed the labroligamentous injuries in our population, MRA also showed some limitations regarding assessment of cortical bone.
In the present study, MR arthrography had 94% sensitivity and specificity reaching about 84% for the detection of labral lesions based on an arthroscopic reference standard.
Drawbacks of MR arthrography include the invasive nature of the procedure. Additional drawbacks include the expense, also the use of MRA is restricted by general contraindications to MR imaging, such as claustrophobia, the presence of MRI-incompatible implanted medical devices. Rarely, diagnostic problems arise from the utilization of MR arthrography like the injection of air mimicking a loose body or extra-articular leak
In conclusion, our results recommend that MRA should be increasingly used, especially when the labral or capsular tear isn’t obvious from the clinical investigation and also to assess the joint capsule itself, and also the size of the ligament-labral injury.
Clinical scenarios and their recommended method of evaluation by:
• Plain X-ray is required to exclude major fractures in post-traumatic
Cases.
• Conventional MRI
- Trauma (older than 40 years)
- Instability in patients older than 40 years (Shoulder stabilization transfers from the labrum to the rotator cuff with advancing years, limiting the value of arthrography in older patients).
• Direct MR arthrography
- Athletes with chronic shoulder injuries (younger than 40 years).
- Instability (younger than 40 years).
- Labral lesions.
- Capsular lesions.
- Biceps anchor.
- chronic recurrent instability.