Institut für Medizintechnik und Medizininformatik
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Publikation Biomechanical evaluation of the interfacial strength of a chemically modified sandblasted and acid-etched titanium surface(Wiley, 06/2006) Ferguson, Stephen J.; Broggini, Nina; Wieland, Marco; de Wild, Michael; Rupp, Frank; Geis-Gerstorfer, Jürgen; Cochran, David L.; Buser, DanielThe functional capacity of osseointegrated dental implants to bear load is largely dependent on the quality of the interface between the bone and implant. Sandblasted and acid-etched (SLA) surfaces have been previously shown to enhance bone apposition. In this study, the SLA has been compared with a chemically modified SLA (modSLA) surface. The increased wettability of the modSLA surface in a protein solution was verified by dynamic contact angle analysis. Using a well-established animal model with a splitmouth experimental design, implant removal torque testing was performed to determine the biomechanical properties of the bone-implant interface. All implants had an identical cylindrical shape with a standard thread configuration. Removal torque testing was performed after 2, 4, and 8 weeks of bone healing (n = 9 animals per healing period, three implants per surface type per animal) to evaluate the interfacial shear strength of each surface type. Results showed that the modSLA surface was more effective in enhancing the interfacial shear strength of implants in comparison with the conventional SLA surface during early stages of bone healing. Removal torque values of the modSLA-surfaced implants were 8-21% higher than those of the SLA implants (p = 0.003). The mean removal torque values for the modSLA implants were 1.485 N m at 2 weeks, 1.709 N m at 4 weeks, and 1.345 N m at 8 weeks; and correspondingly, 1.231 N m, 1.585 N m, and 1.143 N m for the SLA implants. The bone-implant interfacial stiffness calculated from the torque-rotation curve was on average 9-14% higher for the modSLA implants when compared with the SLA implants (p = 0.038). It can be concluded that the modSLA surface achieves a better bone anchorage during early stages of bone healing than the SLA surface; chemical modification of the standard SLA surface likely enhances bone apposition and this has a beneficial effect on the interfacial shear strength.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation All-inside meniscal repair devices compared with their matched inside-out Vertical mattress suture repair. Introducing 10,000 and 100,000 loading cycles(SAGE, 01.09.2014) Rosso, Claudio; Müller, Sebastian; Buckland, Daniel M.; Schwenk, Tanja; Zimmermann, Simon; de Wild, Michael; Valderrabano, VictorAll-inside arthroscopic meniscal repairs are favored by most clinicians because of their lower complication rate and decreased morbidity compared with inside-out techniques. Until now, only 1000 cycles have been used for biomechanical testing. Hypothesis: All-inside meniscal repairs will show inferior biomechanical response to cyclic loading (up to 100,000 cycles) and load-to-failure testing compared with inside-out suture controls. Study Design: Controlled laboratory study. Methods: Bucket-handle tears in 72 porcine menisci were repaired using the Omnispan and Fast-Fix 360 (all-inside devices) and Orthocord 2-0 and Ultrabraid 2-0 sutures (matched controls). Initial displacement, displacement after cyclic loading (100, 500, 1000, 2000, 5000, 10,000, and 100,000 cycles) between 5 and 20 N, ultimate load to failure, and mode of failure were recorded, as well as stiffness. Results: Initial displacement and displacement after cyclic loading were not different between the groups. The Omnispan repair demonstrated the highest load-to-failure force (mean 6 SD, 151.3 6 21.5 N) and was significantly stronger than all the other constructs (Orthocord 2-0, 105.5 6 20.4 N; Ultrabraid 2-0, 93.4 6 22.5 N; Fast-Fix 360, 76.6 6 14.2 N) (P \ .0001 for all). The Orthocord vertical inside-out mattress repair was significantly stronger than the Fast-Fix 360 repair (P = .003). The Omnispan (30.8 6 3.5 N/mm) showed significantly higher stiffness compared with the Ultrabraid 2-0 (22.9 6 6.9 N/mm, P \ .0001) and Fast-Fix 360 (23.7 6 3.9 N/mm, P = .001). The predominant mode of failure was suture failure. Conclusion: All-inside meniscal devices show comparable biomechanical properties compared with inside-out suture repair in cyclic loading, even after 100,000 cycles. Clinical Relevance: Eight to 10 weeks of rehabilitation might not pose a problem for all repairs in this worst-case scenario.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation The new LassoLoop360° technique for biomechanically superior tissue grip(Springer, 2019) Müller, Sebastian; de Wild, MichaelPurposeSuprapectoral tenodesis is a frequently used technique for treating pathologies of the long head of the biceps bra-chii (LHBB) tendon. However, so far, no Gold Standard treatment exist. Hence, the arthroscopic LassoLoop360 (LL360) technique is introduced aiming to provide secure fixation and improved biomechanical properties. It was hypothesized, that the LL360 technique would show superior biomechanical response to cyclic loading and ultimate load-to-failure testing compared to the commonly used simple Lasso Loop (SLL).MethodsTwenty-two porcine superficial flexor digitorum tendons were prepared using a No. 2 suture according to either the SLL or the LL360 technique. Displacement after cyclic loading (1.000 cycles) between 5 and 30 N, ultimate load-to-failure (ULTF), mode of failure as well as the construct stiffness were tested.ResultsSignificantly less displacement was found in the LL360 group (SLL 2.25 ± 0.51 mm; LL360 1.67 ± 0.37 mm; p = 0.01). Ultimate Load to Failure was significantly higher in the LL360 (168.6 ± 29.6 N) as compared to the SLL (124.1 ± 25.8 N, p = 0.02). The LL360 also revealed a significant higher stiffness compared to the SLL (SLL 13.1 ± 0.9 N/mm vs. LL360 19.1 ± 1.0 N/mm, p < 0.001). The most common mode of failure was the suture cutting through the tendon, with a significantly less suture cutting through for the LL360 compared with the SLL (p < 0.05).ConclusionThe LassoLoop360-technique offers superior biomechanical characteristics regarding the tendon-suture-interface compared to the SLL. In the initial healing phase, the suture-tendon-interface is the most vulnerable part of the tendon-suture-anchor construct, the aim of this new technique is to reduce this weakest part of the chain (Ponce et al., Am J Sports Med 39:188–194, 2011). This technique may therefore be beneficial for arthroscopic suprapectoral biceps tenodesis at the entrance of the bicipital groove01A - Beitrag in wissenschaftlicher Zeitschrift