Clinico-Radiological Correlation of Subcoracoid Impingement with Reduced Coracohumeral Interval and its Relation to Subscapularis Tears in Indian Patients.

Abstract

Clinically, subcoracoid impingement is characterized by pain at the anterior aspect of the shoulder that is induced by adduction, internal rotation and forward flexion. This position leads to narrowing of the Coraco-Humeral Interval (CHI)-that is, the space between the coracoid process and the lesser tuberosity of the humerus. Structures in the rotator interval are at greatest risk for impingement which includes the Subscorapularis tendon, tendon of the long head of the biceps, and the middle gleno-humeral ligament. This may result in Rotator interval pathologies such as subscapularis tear and long head of biceps tendon subluxation or fraying. To study the prevalence of radiological evidence of reduced Coraco-Humeral Interval (CHI) in patients with clinically evident Subcoracoid impingement and to examine the presence of Subscapularis tears in these patients. Twenty four patients (6 males, 18 females, average age 52.83 years) were included in this prospective study who were diagnosed to have rotator cuff tears clinically. Nine of these patients were clinically found to have concomitant subcracoid impingement. All patients were subjected to MRI of shoulder. Measurement of the CHI was done in images with humerus in maximal internal rotation. Presence of subscapularis tear was examined intraoperatively. Statistical evaluation of the data was performed using Student's t-test and Fisher's exact test and the results were applied to two cohorts of patients. One cohort consisted of patients who had a CHI value of less than 5.5mm and the other cohort had a CHI value greater than 5.5mm. Average CHI values in patients with and without a subscapularis tear were determined. Nine patients who had clinical subcoracoid impingement were found to have an average CHI of 5.33mm. All nine of them had an associated tear of subscapularis with long head of Biceps tendon subluxation and/or fraying. Remaining 15 patients had an average CHI of 10.48 and they did not have either signs of Subcracoid impingement or subscapularis tear but had a tear elsewhere (Supraspinatus or Infraspinatus). Difference between these two groups was found highly significant (p-value<0.001). All patients with a CHI value of equal to, or less than 5.5mm had a subscapularis tear, whereas only 11% of patients with a CHI value more than 5.5mm had a tear (p-value<0.001, highly significant). Reduction in the CHI has a significant association with rotator interval pathologies such as subscapularis tears and subluxation or fraying of long head of biceps tendon. Treatment of such patients should include modalities such as coracoplasty or anterior shoulder stabilisation. We recommend that clinical evidence of subcoracoid impingement should lead to further Investigation in the form of MRI and estimation of CHI. A CHI of less than 5.5 mm may indicate subscapulais tear in Indian patients.