2021-06-15, Müller, Sebastian, Schwenk, Tanja, de Wild, Michael, Dimitrou, Dimitris, Rosso, Claudio

Background: Cheese-wiring, the suture that cuts through the meniscus, is a well-known issue in meniscal repair. So far, contributing factors are neither fully understood nor sufficiently studied. Hypothesis/purpose: To investigate whether the construct stiffness of repair sutures and devices correlates with suture cut-through (cheese-wiring) during load-to-failure testing. Study design: Controlled laboratory study. Methods: In 131 porcine menisci, longitudinal bucket-handle tears were repaired using either inside-out sutures (n = 66; No. 0 Ultrabraid, 2-0 Orthocord, 2-0 FiberWire, and 2-0 Ethibond) or all-inside devices (n = 65; FastFix360, Omnispan, and Meniscal Cinch). After cyclic loading, load-to-failure testing was performed. The mode of failure and construct stiffness were recorded. A receiver operating characteristic curve analysis was performed to define the optimal stiffness threshold for predicting meniscal repair failure by cheese-wiring. The 2-tailed t test and analysis of variance were used to test significance. Results: Loss of suture fixation was the most common mode of failure in all specimens (58%), except for the Omnispan, which failed most commonly because of anchor pull-through. The Omnispan demonstrated the highest construct stiffness (30.8 ± 3.5 N/mm), whereas the Meniscal Cinch (18.0 ± 8.8 N/mm) and Ethibond (19.4 ± 7.8 N/mm) demonstrated the lowest construct stiffness. The Omnispan showed significantly higher stiffness compared with the Meniscal Cinch (P < .001) and Ethibond (P = .02), whereas the stiffness of the Meniscal Cinch was significantly lower compared with that of the FiberWire (P = .01), Ultrabraid (P = .04), and FastFix360 (P = .03). While meniscal repair with a high construct stiffness more often failed by cheese-wiring, meniscal repair with a lower stiffness failed by loss of suture fixation, knot slippage, or anchor pull-through. Meniscal repair with a stiffness >26.5 N/mm had a 3.6 times higher risk of failure due to cheese-wiring during load-to-failure testing (95% CI, 1.4-8.2; P < .0001). Conclusion: Meniscal repair using inside-out sutures and all-inside devices with a higher construct stiffness (>26.5 N/mm) was more likely to fail through suture cut-through (cheese-wiring) than that with a lower stiffness (≤26.5 N/mm). Clinical relevance: This is the first study investigating the impact of construct stiffness on meniscal repair failure by suture cut-through (cheese-wiring).

2015-05-07, de Wild, Michael, Molenberg, Aart, Amacher, Fabienne, Chris, Bradbury

Resorbable bone substitute materials are widely used for bone augmentation after tumor resection, parallel to implant placement, or in critical size bone defects. In this study, the structural dissolution of a biphasic calcium phosphate bone substitute material with a hydroxyapatite (HA)/tricalcium phosphate (ß-TCP) ratio of 60/40 was investigated by repeatedly placing porous blocks in EDTA solution at 37°C. At several time points, the blocks were investigated by SEM, µCT, and gravimetry. It was found that always complete 2–3 µm sized grains were removed from the structure and that the ß-TCP is dissolved more rapidly. This selective dissolution of the ß-TCP grains was confirmed by XRD measurements. The blocks were eroded from the outside toward the center. The structure remained mechanically stable because the central part showed a delayed degradation and because the slower dissolving HA grains preserved the integrity of the structure.