Background For the reconstruction of acromioclavicular (AC) joint separation, several operative procedures have been described; however, the anatomic reconstruction of both coracoclavicular ligaments has rarely been reported. Purpose The aim of this biomechanical study is to describe a new procedure for anatomic reconstruction of the AC joint. Study Design Controlled laboratory study. Materials and Methods Forty fresh-frozen cadaveric shoulders were tested. Cyclic loading and a load-to-failure protocol was performed in vertical (native, n = 10; reconstructed, n = 10) and anterior directions (native, n = 10; reconstructed, n = 10) on 20 AC joints and repeated after anatomic reconstruction. Reconstruction of conoid and trapezoid ligaments was achieved by 2 TightRope devices (Arthrex, Naples, Florida). Dynamic, cyclic, and static loading until failure in vertical (n = 5) and horizontal (n = 5) directions were tested in native as well as reconstructed joints in a standardized setting. Results The native coracoclavicular ligaments in static load for vertical force measured 598 N (range, 409–687), elongation 10 mm (range, 6–14), and stiffness 99 N/mm (range, 67–130); static load for anterior force was 338 N (range, 186–561), elongation 4 mm (range, 3–7), and stiffness 140 N/mm (range, 70–210). The mean maximum static load until failure in reconstruction for vertical force was 982 N (range, 584–1330) ( P = .001), elongation 4 mm (range, 3–6) ( P < .001), and stiffness 80 N/mm (range, 66.6–105) ( P = .091); and for anterior static force 627 N (range, 364–973) ( P < .001), elongation 6.5 mm (range, 4–10) ( P = .023), and stiffness 78 N/mm (range, 46–120) ( P = .009). During dynamic testing of the native coracoclavicular ligaments, the mean amount of repetitions (100 repetitions per stage, stage 0–100 N, 100–200 N, 200–300 N, etc, and a frequency of 1.5 Hz) in native vertical direction was 593 repetitions (range, 426–683) and an average of 552 N (range, 452–683) load until failure. In vertical reconstructed testing, there were 742 repetitions (range, 488–893) ( P = .222; with a load until failure of 768 N (range, 486–900) ( P = .095). In the anterior direction load, the native ligament failed after an average of 365 repetitions (range, 330–475) and an average load of 360 N (range, 307–411), while reconstructed joints ended in 549 repetitions (range, 498–566) (P = .008J with a load until failure of 547 N (range, 490–585) ( P = .008). In all testing procedures, a preload of 5 N was performed. Conclusion The anatomic reconstruction of the AC joint using TightRope is a stable and functional anatomic reconstruction procedure. The reconstruction technique led to favorable in vitro results with equal or even higher forces than native ligaments. Clinical Relevance Through anatomic repair, stable function of the AC joint can be achieved in an anatomic manner.
This paper describes an adaptive fuzzy control algorithm that may be used for the automation of medical devices. The automation system consists of a set of controllers containing the expertise of the physician and a main fuzzy controller that creates new rules based on this knowledge plus additional information about the patient. An adaptive mechanism evaluates the performance of the controller by using reference models and modifies its rules when needed. As a test case the automation of an extra-corporeal support system is presented, where a centrifugal pump speed is adjusted based on desired pressures and flow values.
Abstract Background: Mechanical properties and biocompatibility make zirconia ceramics suitable implant material. The characteristics of tooth‐color like, the ability to be machined and the low plaque affinity make zirconia especially suitable as a dental implant material. The influence of surface modification on the osseointegration of this material has not been extensively investigated. Purpose: Long‐term investigations with titanium implants have shown superior biomechanical results with the sandblasted acid‐etched (SLA) surface, demonstrating a high bone–implant interaction. The objective of this study was to compare two different zirconia surface topographies biomechanically and histologically with the well‐documented titanium SLA surface. Material and methods: Zirconia implants with either a machined (ZrO 2 m) or a sandblasted (rough, ZrO 2 r) surface were manufactured with the exact same cylindrical shape with a standard ITI thread configuration as the SLA titanium implants. The incisors 2 and 3 were removed from both sides of the maxillae of 13 adult miniature pigs and the tissues left to heal for 6 months. After this time period the animals received a total of 78 implants using a randomized scheme, with the titanium SLA implant used as an only individual reference. After healing periods of 4, 8, and 12 weeks 20, 24, and 25 implants, respectively, were subjected to removal torque tests (RTQ) as the main biomechanical analysis of the of the study. A fewer number was resected on bloc, embedded in methylmethacrylat and analyzed for their direct bone apposition under a light microscope. Results: Surface analysis revealed the highest surface roughness for the SLA‐implant, followed by ZrO 2 r and ZrO 2 m. The turned ZrO 2 m implants showed statistically significant lower RTQ values than the other two implants types after 8 and 12 weeks, while the SLA implant showed significantly higher RTQs values than ZrO 2 r surface after 8 weeks. Differences in the bone apposition were observed in the histomorphometric analysis using light microscopy for all surfaces at any time point. Conclusion: The findings suggest that ZrO 2 r implants can achieve a higher stability in bone than ZrO 2 m implants. Roughening the turned zirconia implants enhances bone apposition and has a beneficial effect on the interfacial shear strength.
The endoluminal VAC-therapy is already used successfully in the management of upper gastrointestinal leaks and perforations. In the ENT area the use of VAC-therapy is known in pharyngocutanous fistulas. We now report on an application in a pharyngo-prevertebral fistula. The patient has had a panendoscopy with samplings from the hypopharynx because of a complex tumor history (State after laryngopharyngectomy and reconstruction with myofascial flap, State after radiochemotherapy) four weeks prior. He now reported about a pronounced odynophagia. At the examination, we discovered a lot of saliva in the hypopharyngeal funnel. A broad spectrum antibiotic therapy was started and a CT scan of the neck and a Gastrografin swallow was performed. The CT scan showed a defect in the right hypopharynx with an inflammatory fluid pathway emanating from it and extending dorsally to the prevertebral fascia. A contrast medium depot in the form of a hypopharyngeal right fistula was found in the swallow. Based on the findings we performed a panendoscopy and collected samples. Additionally we placed a gastric tube. During the surgery we saw a hypopharyngeal fistula on the right side into the carotid sheath reaching till prevertebral. The biopsy showed no malignancy. Due to the difficult soft tissue conditions without healing tendency under conservative therapy we decided to start an endoluminal retrogradely transnasally placed VAC-therapy as off-label use. Therefore we used the Eso-SPONGE®-system with a VAC-pump from the company KCI. The system was placed for 16 days, with regular changes every 4 days. Among this, a clear granulation of the fistula pocket with improvement of symptoms was observed. The system was tolerated without problems and oral nutrition was possible again afterwards.
The purpose of the present study was to investigate the osseointegration of microstructured zirconia implants in comparison with sandblasted and acid-etched (SLA) titanium implants in a biomechanical study.Zirconia implants (4.1 mm in diameter, 10 mm in length) were produced using a new low pressure injection molding technique. After that the implants were acid-etched with hydrofluoric acid. Standard Ti-SLA implants of the exact same shape served as controls. Six months after extraction of incisors 2 and 3, 16 adult pigs received a total of 64 implants in the maxillae. After 4, 8, and 12 weeks the animals were sacrificed, and 59 implants could be analyzed to removal torque (RTQ) testing.The mean RTQ values for zirconia implants were 42.4 Ncm at 4 weeks, 69.6 Ncm at 8 weeks, and 69.3 Ncm at 12 weeks of healing, whereas RTQ values for the Ti-SLA implants were 42.1 Ncm, 75.0 Ncm, and 73.1 Ncm at corresponding time intervals. There is no statistical difference in RTQ values between Ti-SLA and zirconia implants at 8 weeks.Within the limits of the present study it was concluded that acid-etching of zirconia implants enhances bone apposition resulting in RTQ values which were equivalent to that of Ti-SLA.
Background. Protocols using chemical reagents for scaffold decellularization can cause changes in the properties of the matrix, depending on the type of tissue and the chemical reagent. Technologies using physical techniques may be possible alternatives for the production grafts with potential superior matrix characteristics. Material and Methods. We tested four different technologies for scaffold decellularization. Group 1: high hydrostatic pressure (HHP), 1 GPa; Group 2: pressure shift freezing (PSF); Group 3: pulsed electric fields (PEF); Group 4: control group: detergent (SDS). The degree of decellularization was assessed by histological analysis and the measurement of residual DNA. Results. Tissue treated with PSF showed a decellularization with a penetration depth (PD) of 1.5 mm and residual DNA content of . HHD treatment caused a PD of 0.2 mm with a residual DNA content of . PD in PEF was 0.5 mm, and the residual DNA content was . In the SDS group, PD was found to be 5 mm, and the DNA content was determined at . Conclusion. PSF showed promising results as a possible technique for scaffold decellularization. The penetration depth of PSF has to be optimized, and the mechanical as well as the biological characteristics of decellularized grafts have to be evaluated.
Acute kidney injury following cardiac surgery depicts a severe clinical problem that is strongly associated with adverse short- and long-term outcome. We analyzed two common genetic polymorphisms that have previously been linked to renal failure and inflammation, and have been supposed to be associated with cardiac surgery associated-acute kidney injury (CSA-AKI).A total of 1415 consecutive patients who underwent elective cardiac surgery with CPB at our institution were prospectively enrolled. Patients were genotyped for Apolipoprotein E (ApoE E2,E3,E4) (rs429358 and rs7412) and TNF-α-308 G > A (rs1800629).Demographic characteristics and procedural data revealed no significant differences between genotypes. No association between ApoE (E2,E3,E4) and TNF-α-308 G > A genotypes and the RIFLE criteria could be detected. Several multiple linear regression analyses for postoperative creatinine increase revealed highly significant associations for aortic cross clamp time (p < 0.001), CPB-time (p < 0.001), norepinephrine (p < 0.001), left ventricular function (p = 0.004) and blood transfusion (p < 0.001). No associations were found for ApoE (E2,E3,E4) and TNF-α-308 G > A genotypes or baseline creatinine. When the sample size is 1415, the multiple linear regression test of R(2 )= 0 for seven covariates assuming normal distribution will have at least 99% power with significance level 0.05 to detect an R(2) of 0.108 or 0.107 as observed in the data.ApoE (E2,E3,E4) polymorphism and the TNF-α-308 G > A polymorphism are not associated with renal injury after CPB.
