Perfusion of the Rotator Cuff Tendon According to the Repair Configuration Using an Indocyanine Green Fluorescence Arthroscope: A Preliminary Report

Background: The disturbance of rotator cuff tendon perfusion has been connected with the suture-bridge configuration repair (SBCR) technique; however, in vivo assessments of the tendon blood supply have been problematic with other modalities. An evaluation of tissue perfusion by an indocyanine green (ICG) fluorescence arthroscope has been developed to counteract this difficulty. Purpose: To verify the hindrance of perfusion in SBCR, we used an ICG fluorescence camera to compare parallel-type transosseous repair (PTR) and SBCR in rabbits immediately and at 3 days after rotator cuff repair. Study Design: Controlled laboratory study. Methods: Acute rotator cuff repair was performed on the shoulders of 10 rabbits. Both shoulders were repaired using either PTR or SBCR. For PTR, simple repair was performed through 2 parallel transosseous tunnels created using a microdrill. For SBCR, 2 additional crisscross transosseous tunnels were added to mimic arthroscopic SBCR. Immediately after repair, ICG was injected through the ear vein, and images were recorded using an ICG fluorescence camera. Tendon perfusion was compared by measuring fluorescence intensity using ImageJ software in both methods. At 3 days after rotator cuff repair, a reassessment of ICG fluorescence was performed. In addition, as a subsidiary study, a comparison of each repair method and a healthy tendon was performed (PTR vs healthy tendon and SBCR vs healthy tendon). Six rabbits (3 for each comparison) were included. Results: Immediately after rotator cuff repair, the mean (±SD) grayscale intensity of ICG fluorescence was weaker in SBCR than PTR in 10 specimens (65.9 ± 47.6 vs 84.3 ± 53.4 per pixel, respectively; P = .003). At 3 days after repair, 8 specimens were included in the analysis because suture strands failed in 2 specimens in SBCR. The mean intensity of fluorescence was still weaker in SBCR compared with PTR (52.5 ± 13.7 vs 60.2 ± 22.7 per pixel, respectively; P = .077). The mean fluorescence intensity compared with a healthy tendon was 83.2% ± 9.5% in PTR and 63.2% ± 13.2% in SBCR. Conclusion: Our ICG fluorescence camera system was able to detect ICG fluorescence in an acute rabbit rotator cuff repair model. SBCR showed inferior tendon perfusion immediately after repair. At 3 days after repair, SBCR still showed inferior fluorescence intensity, although it did not reach statistical significance. Clinical Relevance: In this study, SBCR hindered perfusion at the tendon in the compressed area. This finding may affect rotator cuff tendon healing and failure mode.