The results of this study suggest that only combined AC and CC reconstruction can adequately re-establish physiological horizontal ACJ stability. Therefore, it is likely that a combined surgical procedure with double suture-button devices and AC suture tape cerclage can adequately re-establish horizontal AC joint stability in case of an acute injury (≥type Rockwood IV and may allow superior clinical outcomes for patients, especially if early functional rehabilitation is intended).

BackgroundSutures colonized by bacteria represent a challenge in surgery due to their potential to cause surgical site infections. In order to reduce these type of infections antimicrobially coated surgical sutures are currently under development. In this study, we investigated the antimicrobial drug octenidine as a coating agent for surgical sutures. To achieve high antimicrobial efficacy and required biocompatibility for medical devices, we focused on optimizing octenidine coatings based on fatty acids. For this purpose, antimicrobial sutures were prepared with either octenidine-laurate or octenidine-palmitate at 11, 22, and 33 μg/cm drug concentration normalized per length of sutures. Octenidine containing sutures were compared to the commercial triclosan-coated suture Vicryl® Plus. The release of octenidine into aqueous solution was analyzed and long-term antimicrobial efficacy was assessed via agar diffusion tests using Staphylococcus aureus. For determining biocompatibility, cytotoxicity assays (WST-1) were performed using L-929 mouse fibroblasts.ResultsIn a 7 days elution experiment, octenidine-palmitate coated sutures demonstrated much slower drug release (11 μg/cm: 7 %; 22 μg/cm: 5 %; 33 μg/cm: 33 %) than octenidine-laurate sutures (11 μg/cm: 82 %; 22 μg/cm: 88 %; 33 μg/cm: 87 %). Furthermore sutures at 11 μg/cm drug content were associated with acceptable cytotoxicity according to ISO 10993–5 standard and showed, similar to Vicryl® Plus, relevant efficacy to inhibit surrounding bacterial growth for up to 9 days.ConclusionsOctenidine coated sutures with a concentration of 11 μg/cm revealed high antimicrobial efficacy and biocompatibility. Due to their delayed release, palmitate carriers should be preferred. Such coatings are candidates for clinical testing in regard to their safety and efficacy.

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Articular cartilage repair methods, in particular scaffold-based autologous chondrocyte implantation, are already in clinical use. In the coming years, the European guidelines on human cell-based medicinal products by the European Medical Agency (EMA) will extend today's quality control mechanisms by additional structural analyses. As articular cartilage has complex biphasic and viscoelastic mechanical properties, a high-performance material test system is required and has already been implemented. To characterize the recovery of cartilage and cartilage replacement materials, it is necessary to measure the dynamic recovery profile. A measurement system for an application like this requires an axis acceleration of more then 50 m/s(2). Furthermore, the test system needs custom-made components to fix the biological specimen while testing. A software package consisting of a graphical user interface and an axis controller leads to highly reproducible tests. The software makes use of a position and velocity controller as well as a force controller at kilohertz speed. While using the high performance force controller it is possible to apply static and dynamic loading profiles that are independent from position or speed set points and signals.

Resorbable polyglycolic acid (PGA) chondrocyte grafts are clinically established for human articular cartilage defects. Long-term implant performance was addressed in a standardized in vitro model. PGA implants (+/− bovine chondrocytes) were placed inside cartilage rings punched out of bovine femoral trochleas (outer Ø 6 mm; inner defect Ø 2 mm) and cultured for 84 days (12 weeks). Cartilage/PGA hybrids were subsequently analyzed by histology (hematoxylin/eosin; safranin O), immunohistochemistry (aggrecan, collagens 1 and 2), protein assays, quantitative real-time polymerase chain reactions, and implant push-out force measurements. Cartilage/PGA hybrids remained vital with intact matrix until 12 weeks, limited loss of proteoglycans from “host” cartilage or cartilage–PGA interface, and progressively diminishing release of proteoglycans into the supernatant. By contrast, the collagen 2 content in cartilage and cartilage–PGA interface remained approximately constant during culture (with only little collagen 1). Both implants (+/− cells) displayed implant colonization and progressively increased aggrecan and collagen 2 mRNA, but significantly decreased push-out forces over time. Cell-loaded PGA showed significantly accelerated cell colonization and significantly extended deposition of aggrecan. Augmented chondrogenic differentiation in PGA and cartilage/PGA-interface for up to 84 days suggests initial cartilage regeneration. Due to the PGA resorbability, however, the model exhibits limitations in assessing the “lateral implant bonding”.

Aims and Objectives:The purpose was to investigate biomechanical properties of different preparation techniques of tripled soft tissue ACL grafts to avoid early mechanical graft failure. It was hypothesized that 1) a graft with a quadrupled femoral portion results in higher load to failure and stiffness compared to a uniformly tripled graft, and 2) a Krackow stitch technique is superior to both baseball stitch and whipstitch technique.Materials and Methods:Forty-eight bovine flexor tendons (eight per group) with a final graft length of 8 cm were used for the present study and randomly assigned to the two graft configuration groups: A) quadrupled femoral portion with a tripled tibial portion, and B) uniformly tripled soft tissue graft. Within the two groups, three different stitching techniques were applied: 1) Whipstitch technique, 2) Krackow stitch, and 3) Baseball stitch. After preconditioning, the grafts were cyclically loaded for 1000 cycles between 50 and 200 N (1 Hz) with consecutive load to failure testing using a constant elongation of 30 mm/min. During biomechnical testing, graft elongation was evaluated with an optical tracking system. For statistical analysis a two-way analysis of variance with a post-hoc Holm-Sidak test was performed. To evaluate the failure mode the Fisher’s exact test was used. The significance level was set at p #CHR: lesslike# 0.05.Results:Considering load to failure, quadrupling the femoral portion of the graft significantly increased the load to failure (p = 0.003) while varying the stitching technique had no influence (p = 0.998). Additionally, graft elongation was lower in group A, but difference was not significant (p = 0.058). Lowest graft elongation was observed when a Krackow stitch was applied, followed by the baseball stitch, and the whipstitch technique (p = 0.035). In group A, all the constructs (graft including sutures) failed at the suture, whereas in group B the failure mode was a slippage of the free femoral graft strand in seven of eight grafts (p = 0.005).Conclusion:When using tripled ACL soft tissue grafts in combination with an extracortical fixation device, the femoral portion should be quadrupled whereas the stitching technique does not have a significant influence on the biomechanical properties. To achieve a higher load to failure with less graft elongation at time zero, the free femoral strand of the tendon graft should be wrapped around the femoral graft tendon loop. This could reduce early graft failure due to slippage of the third free femoral graft strand.

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