Coracohumeral space and rotator cuff tears

Purpose of the study The anterior or subcoracoid impingement is often menti onned but remains unprecise as far as clinical, radiological or even anatom ical lesion are concerned. The purpose of our work was to study the differe nt factors influencing the subcoracoid space in case of cuff tear. Methods Our study was based on 206 shoulders operated for full-thickness ro tator cuff tear. The SubCoracoid Space (SPS), measured in millimeters on pr e-operative arthro-CT-scan, was defined by the shortest distance between th e coracoid process and the humeral head. Muscular statement of the rotator cuff componants was graded according to Goutallier's and Bemageau's classif ication. According to literature data, we chose "6 mm" value as an inferior limit for normality. Shoulders were dispatched into three groups: group 1 was composed of supraspinatus +/- infraspinatus tears (59 cases), group 2 w as composed of isolated lesions of the subscapularis (57 cases) and group 3 was composed of large cuff tears (supraspinatus +/- infraspinatus) involvi ng also the subscapularis (90 cases). Results There was a statistically significant relationship between SCS narr owing, duration of symptoms and the non-traumatic onset. When there was no subscapularis lesion (group 1) the mean SCS was 9 +/- 2 mm, in 3 cases the SCS was inferior to 6 mm. In group 2 (isolated lesion of the subscapularis) , the results were similar with 9 mm as an average and 3,5 p. 100 SCS infer ior to 6 mm. On the contrary, in group 3 we found the major percentage of S CS interior to 6 mm (27 p. 100) with an average of 7,7 +/- 3,5 mm. The long head of the biceps had no influence on the SCS. There was a strong statist ically significant relationship between SCS size and fatty degeneration of the subscapularis muscle (p < 10-4) and infraspinatus muscle (p = 0,0004). Eventually, there was a statistically significant correlation between the s ubcoracoid space and the sub acromial space. Discussion Measurements of the SCS in isolated lesions of the subscapularis show that the coracoid process is not the mechanical factor responsible fo r tendon rupture. SCS narrowing is the consequence of a large cuff tear inv olving both the subscapularis and the infraspinatus tendon. Subscapularis t ear is a necessary but not a sufficient condition by itself for SBS narrowi ng. Complete tear of the infraspinatus tendon and above ail the muscular de generation of the infraspinatus muscle is the other necessary condition for SCS narrowing. The horizontal control of the humeral head depends on subscapularis-infrasp inatus muscular balance control. According to Patte's hypothesis SCS narrow ing corresponds to an horizontal anterior translation of the humeral head d ue to fatty degeneration of subscapularis and Infraspinatus muscle.