Abstract
The transosseous equivalent/Suture Bridge or TOE/SB repair has received much attention in recent years as more shoulder surgeons transition to all arthroscopic rotator cuff repairs. The purpose of this study was to compare the biomechanical behaviour of several variants of the Suture Bridge repair performed by the authors.
Four different Suture Bridge constructs were performed six times on 24 sheep infraspinatus tendon humerus constructs. The first group was a standard Suture Bridge with two medial mattress stitches with knots (KSSB4). The second group had four medial mattress stitches with knots and was called KDSB8. The third group had two medial mattress stitches without knots and was called USBFT4. These first three repairs used two medial 5.5 mm Bio-Corkscrew FT Anchors and two lateral 3.5 mm PushLock Anchors (Arthrex). The fourth repair had two medial mattress stitches without knots and used all Pushlocks and was called USBP4.
The repairs were then analysed for failure force, cyclic creep and stiffnessafter. Cycling was performed from 10 to 100 N at 1 Hz for 500 cycles. Following cyclic testing a single cycle pull to failure at 33 mm/sec was performed. The constructs were also observed for failure mechanism and gap formation using digital video recording.
The KDSB8 repair with a mean failure force of 456.9N was significantly stronger than the USBP4 repair at 299.7N (P=0.023), the KSSB4 repair at 295.4N (P=0.019) and lastly the USBFT4 repair at 284.0N (P=0.011). There was no statistical difference between the measured failure force for the two mattress stitch KSSB4 repair with knots and the knotless two mattress stitch repairs USBFT4 and USBP4. There was not a statistical difference between any of the repairs for measured stiffness and cyclic creep. However, the KDSB8 repair showed no discernable gap formation or movement at the footprint during cyclic testing. The KSSB4, USBFT4 and USBP4 repairs demonstrated bursal sided gap formation in the range of 1 to 3 mm.
Based on the results of this study the transosseous equivalent/Suture Bridge repair with four stitches tied in the medial row and maximal lateral suture strand utilization (KDSB8 TOE/SB) is the strongest. The KDSB8 also appeared to show less bursal sided gap formation and greater footprint stability than the other Suture Bridge constructs tested.
