A multicenter study to evaluate subscapularis muscle function using 5:30 o'clock portal for antero-inferior shoulder...

The purpose of this study was to compare the outcome after arthroscopic antero-inferior shoulder stabilization with and without using a 5:30 o'clock portal.

Sixty-two patients [age (mean ± SD), 28.05 ± 8.25 years] with a mean follow-up of 15.23 ± 5.02 months were included in this study. Thirty-one patients underwent arthroscopic antero-inferior shoulder stabilization using the 5:30 o'clock portal in center A (group I) and were compared to 31 matched patients managed with the 3 o'clock portal in center B (group II). Physical examination, standard shoulder scores, ultrasound assessment and subscapularis strength measurement were used to evaluate postoperative shoulder function.

Good to excellent results were seen in both groups. No significant differences were seen when comparing ASES, Constant and Rowe Score of both groups. Patients of group II achieved a significant higher score in the SST than patients of group I. (p < 0.05) Patients of group I had a significantly lesser loss of passive external rotation in 0° and 90° of abduction. (p = 0.04; p = 0.056) Ultrasound evaluation and strength measurement showed no significant differences in subscapularis muscle integrity or function neither between the involved and uninvolved shoulder nor between both groups.

Arthroscopic anterior-inferior shoulder stabilization results in excellent clinical results. When considering portal placement, the deep trans-subscapularis portal allows a more precise suture anchor placement at the inferior glenoid rim and capsular shift with a significant improved external rotation but does not negatively affect the subscapularis function in terms of internal rotation strength or structural integrity.

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