A biomechanical and histological comparison of the suture bridge and conventional double-row techniques of the repair of full-thickness rotator cuff tears in a rabbit model

The suture bridge (SB) technique and conventional double-row (DR) are both effective in repair of full-thickness rotator cuff tears . However, increasing numbers of scholars believe that the SB technique produces better results than conventional DR because of the higher bone-tendon contact area and pressure. However, The clinical outcomes have been mixed and little direct evidence has been supplied in vivo. This study was designed using the SB and DR techniques to determine which is the better technique.

Sixty-four New Zealand white rabbits were randomly divided into 2 groups, the SB group and DR group. SB and DR were then used to repair their rotator cuff tears. Rabbits were then sacrificed at the 2^nd, 4^th, or 8^th week after surgery and a histological comparison was made. The biomechanical comparison was made at the 8^th week.

The load to failure of the SB group was 134.59 ± 17.69 N at the 8^th postoperative week, and that was significantly higher than in the DR group (103.83 ± 6.62, P = 0.001), but both repair groups remained lower than in the control group (199.25 ± 14.81). Histological evaluation showed that both the SB and DR groups healed at the bone-tendon interface. But there were subtle differences between the two groups in the structure and morphology of collagen fibers and cartilage cells at bone-tendon interface. In general, the collagen fibers of the SB group were more compact than those of the DR group at all times tested. At the 4^th and 8^th weeks, the collagen fibers and cartilage cells in the SB group were arranged in a column modality, but those in the DR group were distributed horizontally.

The SB technique facilitated healing more effectively than the conventional DR technique. The difference in morphology of collagen fibers and cartilage cells may be related to the difference in bone-tendon contact pressure.