A new rigid biodegradable anchor for meniscus refixation: biomechanical evaluation

Abstract

All-inside repair devices have been developed to overcome the disadvantages of conventional suture techniques (such as vein and nerve damage and increased OR time). The Contour Meniscus Arrow is a second generation of the first biodegradable all-inside implant, the Meniscus Arrow. The aim of this study was to compare the biomechanical properties of the Contour Meniscus Arrow to the first-generation Meniscus Arrow and vertical or horizontal suture techniques. In fresh frozen bovine menisci, initial fixation strength, stiffness and failure mode of four different meniscus refixation techniques (Meniscus Arrow, Contour Meniscus Arrow, vertical and horizontal 2-0 Ethibond suture techniques) were evaluated in a computer-based material-testing machine at a rate of 12.5 mm/s. Vertical meniscus sutures showed the highest initial fixation strength, followed by the horizontal suture technique and the Contour Arrow. The Meniscus Arrow showed inferior pull-out strength. Subjecting the different refixation techniques to cyclic testing decreased the fixation strength in all groups. The modified Meniscus Anchor (Contour Arrow) provides biomechanical properties that are superior (pull-out strength) or similar (stiffness) compared to the first biodegradable all-inside implant, the Meniscus Arrow. The pull-out strength of the Contour Arrow was comparable to the pull-out strength reported for horizontal meniscus sutures in the literature. These biomechanical characteristics of this new implant justify clinical use.

Elongation and Structural Properties of Meniscal Repair Using Suture Techniques in Distraction and Shear Force Scenarios

“…Another reason for the higher load to failure of horizontal sutures might be that the current study used a cross-head speed of 12.5 mm/min, which has been reported to be reflective of rapid loading forces. 4,14,[42][43][44] This rapid loading might prohibit the suture from cutting through the fibers, as has been reported in earlier publications.…”

“…Although biomechanical studies have investigated the structural properties of suture techniques, rigid anchors, and flexible anchors in a distraction force scenario, this test setup might replicate the in vivo situation a meniscal repair is subjected to only in part. 4244 Injuries to the menisci have been reported to occur most commonly in response to a twisting force combined with an axial load, subjecting the meniscal tissue to shear forces as well as compressive loads. 20 During movement of the knee, the occurring shear forces are considerably important for the intermediate part of the meniscus.…”

“…This number is consistent with previous publications. 4,14,42–45 Animals were obtained from the same abattoir and were especially grown for slaughter. The menisci were dissected free, leaving the adhering capsule intact and stored at –20°C until 5 hours before testing.…”

“…This displacement rate is consistent with that used in prior studies evaluating the ultimate pull-out strength of sutures and suture anchors and is reflective of rapid loading forces. 4,14,42–44 Load and elongation were recorded continuously using the software of the testing machine. The resulting load elongation curve was documented, as well as the ultimate failure load and the mode of failure.…”

Biomechanical comparison of vertical suture techniques for repairing radial meniscus tear

“…After a preload of 2 N was applied to the specimen, cyclic loading from 5 to 20 N was performed at a frequency of 1 Hz and a crosshead velocity of 12.5 mm/s [ 6 , 24 , 35 , 39 , 41 ]. The load and frequency were chosen based on previous studies and reflective of in vivo post-operational rehabilitation [ 5 , 6 , 9 , 12 , 28 , 29 , 35 , 37 , 45 , 46 ]. Specimens underwent 900 submaximal loading cycles and the Instron device was programed to pause 45 s at 0, 100, 300, 500 cycles to enable data collection and normal saline was sprayed to keep the specimens moist.…”