Lesser tuberosity cysts and their relationship with subscapularis tears and subcoracoid impingement.

Background: We aimed to evaluate cysts in the lesser tuberosity of humeral head seen on magnetic resonance imaging (MRI) and their relationship with subcoracoid impingement and subscapularis tears evident on arthroscopic surgery videos. Our hypothesis was that the cysts would be more frequent with subscapularis tears and in the case of subcoracoid impingement.

Methods: Patients who underwent shoulder arthroscopy between January 2010 and January 2016 were retrieved to evaluate subscapularis tears on surgery videos and lesser tuberosity cysts (LTC), coracohumeral distances (CHD) on both sagittal oblique and transverse sections of MRI retrospectively. There were 137 patients meeting the study criteria with subscapularis tear evident on surgery video and having preoperatively studied magnetic resonance images. All the tears were classified according to the Lafosse's system. The control group was constituted with 121 patients who underwent shoulder arthroscopy and were diagnosed with no subscapularis tear. Then, any statistically significant relationship between these parameters was investigated by the use of statistics software.

Results: The mean age (57), gender distribution (female for 67.1%), and involved shoulder (right for 62.8%) rate of the groups were statistically similar. The existence rate of LTC was 55.5% and 19% for the study and control groups, respectively (P = .000). The study group was then evaluated in two groups regarding the existence of a cyst in the lesser tuberosity. There was no statistical difference between these two groups in terms of coracohumeral distances and tear type (P > .05). The study group was also divided into two depending on the transverse section CHD whether it was under 7 mm or not. There was still no statistical difference between these subgroups in terms of a cyst existence (P > .05). The supraspinatus tear rate and age distribution was also not differing in patients with and without LTC.

Conclusions: The LTCs were significantly associated with subscapularis tears, and could be used as an indicator in the interpretation of MRI scans. However, there was no relationship between the subcoracoid impingement and LTCs.