Incidence and clinical impact of cystic changes in interpositional grafts following arthroscopy-assisted lower trapezius tendon transfer: A retrospective comparative clinical study.

Abstract

Cystic changes within interpositional grafts used for arthroscopy-assisted lower trapezius tendon transfer (aLTT) are occasionally detected on postoperative magnetic resonance imaging (MRI); however, their clinical significance remains unclear. This study aimed to investigate the incidence, clinical relevance, and biological implications of cystic changes in interpositional grafts. We retrospectively reviewed 176 patients who underwent aLTT for posterosuperior irreparable rotator cuff tears with a minimum follow-up of 2 years. Patients were classified into an intact group (n = 150) or a cystic group (n = 26) based on postoperative MRI findings. Clinical outcomes were evaluated by assessing shoulder pain, patient-reported outcome measures (PROMs), active range of motion (aROM), and shoulder muscle strength. Radiologic outcomes included acromiohumeral distance (AHD), Hamada grade, and graft integrity. Cystic changes were identified in 14.7% of patients at a mean of 12.4 ± 9.3 months (range, 6-48 months) postoperatively. Achilles tendon allografts were associated with a higher incidence of cystic changes than fascia lata autografts (p = 0.035). The mean cyst diameter showed no significant change from initial identification (34.2 ± 13.2 mm, range 12.3-55.9 mm) to final follow-up (31.7 ± 11.7 mm, range 6.8-43.9 mm, p = 0.856). No significant differences were observed between groups in clinical outcomes, including PROMs, aROM, shoulder muscle strength, or graft retear rates (intact group, 18.5% vs. cystic group, 26.9%; p = 0.423). However, postoperative AHD increased significantly in the intact group but decreased significantly in the cystic group, with the intact group demonstrating a significantly greater postoperative AHD (8.9 ± 1.7 mm vs. 7.7 ± 1.9 mm, p < 0.001). Cystic changes in interpositional grafts after aLTT were not associated with inferior clinical outcomes or higher graft failure rates. These findings suggest that such changes likely represent benign rather than indicators of graft failure. Recognizing this distinction is important to avoid unnecessary revision surgery based solely on MRI appearance. Level III, retrospective comparative study.