When and how much does the muscle strength recover after arthroscopic superior capsular reconstruction?

Abstract

Recently, arthroscopic superior capsular reconstruction (SCR) has been performed for irreparable large to massive rotator cuff tears and its excellent clinical results have also been reported. Although the muscle strength was reported to recover, it is not clarified yet when and how much it recovers. The purpose of this study was to determine the recovery pattern of muscle strength after SCR. Thirty-five patients (mean age: 65 years) who met the following inclusion criteria were retrospectively reviewed: 1) those with large to massive, irreparable tears of the rotator cuff including the supraspinatus and infraspinatus tendons; 2) those with severe muscle atrophy and fatty change; 3) those with their muscle quality and strength assessed by MRI and a dynamometer at 6 months, 1 year, and 2 years; 4) those with a minimum follow-up of 2 years; and 5) those without severe osteoarthritis. The isometric muscle strength of scaption, internal and external rotation in adduction was measured twice for each motion by a dynamometer. Relative to the muscle strength of the uninvolved side, the involved side showed 61 ± 21% in scaption, 63 ± 20% in external rotation, and 103 ± 29% in internal rotation at 2 years after surgery. Whereas no significant differences were observed between 1-year and 2-year follow-ups, there was a significant difference in muscle strength of scaption between 6-months and 1-year (P = 0.0174). Graft retear was seen in 5 cases (14%). There was a trend that the muscle strength of scaption and external rotation in the no retear group was greater than that in the retear group despite no significant difference (P = 0.0717, P = 0.0824, respectively). The recovery of the muscle strength after SCR was observed until 1 year after surgery and the muscle strength of scaption and external rotation returned to 60% of the uninvolved side at 2 years.