Strength of interference screw fixation of meniscus prosthesis matches native meniscus attachments.

PURPOSE: Meniscal surgery is one of the most common orthopaedic surgical interventions. Total meniscus replacements have been proposed as a solution for patients with irreparable meniscal injuries. Reliable fixation is crucial for the success and functionality of such implants. The aim of this study was to characterise an interference screw fixation system developed for a novel fibre-matrix-reinforced synthetic total meniscus replacement in an ovine cadaveric model. METHODS: Textile straps were tested in tension to failure (n = 15) and in cyclic tension (70-220 N) for 1000 cycles (n = 5). The textile strap-interference screw fixation system was tested in 4.5 mm-diameter single anterior and double posterior tunnels in North of England Mule ovine tibias aged > 2 years using titanium alloy (Ti6Al4Va) and polyether-ether-ketone (PEEK) screws (n ≥ 5). Straps were preconditioned, dynamically loaded for 1000 cycles in tension (70-220 N), the fixation slippage under cyclic loading was measured, and then pulled to failure. RESULTS: Strap stiffness was at least 12 times that recorded for human meniscal roots. Strap creep strain at the maximum load (220 N) was 0.005 following 1000 cycles. For all tunnels, pull-out failure resulted from textile strap slippage or bone fracture rather than strap rupture, which demonstrated that the textile strap was comparatively stronger than the interference screw fixation system. Pull-out load (anterior 544 ± 119 N; posterior 889 ± 157 N) was comparable to human meniscal root strength. Fixation slippage was within the acceptable range for anterior cruciate ligament graft reconstruction (anterior 1.9 ± 0.7 mm; posterior 1.9 ± 0.5 mm). CONCLUSION: These findings show that the textile attachment-interference screw fixation system provides reliable fixation for a novel ovine meniscus implant, supporting progression to in vivo testing. This research provides a baseline for future development of novel human meniscus replacements, in relation to attachment design and fixation methods. The data suggest that surgical techniques familiar from ligament reconstruction may be used for the fixation of clinical meniscal prostheses.

Rat cardiovascular telemetry: Marginal distribution applied to positive control drugs.

Cardiovascular effects are considered frequent during drug safety testing. This investigation aimed to characterize the pharmacological response of the conscious telemetered rat in vivo model to known cardiovascular active agents. These effects were analyzed using statistical analysis and cloud representation with marginal distribution curves for the contractility index and heart rate as to assess the effect relationship between cardiac variables. Arterial blood pressure, left ventricular pressure, electrocardiogram and body temperature were monitored. The application of data cloud with marginal distribution curves to heart rate and contractility index provided an interesting tactic during the interpretation of drug-induced changes particularly during selective time resolution (i.e. marginal distribution curves restricted to Tmax). Taken together, the present data suggests that marginal distribution curves can be a valuable interpretation strategy when using the rat cardiovascular telemetry model to detect drug-induced cardiovascular effects. Marginal distribution curves could also be considered during the interpretation of other inter-dependent parameters in safety pharmacology studies.

Combinatorial scaffold morphologies for zonal articular cartilage engineering.

Articular cartilage lesions are a particular challenge for regenerative medicine strategies as cartilage function stems from a complex depth-dependent organization. Tissue engineering scaffolds that vary in morphology and function offer a template for zone-specific cartilage extracellular matrix (ECM) production and mechanical properties. We fabricated multi-zone cartilage scaffolds by the electrostatic deposition of polymer microfibres onto particulate-templated scaffolds produced with 0.03 or 1.0mm(3) porogens. The scaffolds allowed ample space for chondrocyte ECM production within the bulk while also mimicking the structural organization and functional interface of cartilage's superficial zone. Addition of aligned fibre membranes enhanced the mechanical and surface properties of particulate-templated scaffolds. Zonal analysis of scaffolds demonstrated region-specific variations in chondrocyte number, sulfated GAG-rich ECM, and chondrocytic gene expression. Specifically, smaller porogens (0.03mm(3)) yielded significantly higher sGAG accumulation and aggrecan gene expression. Our results demonstrate that bilayered scaffolds mimic some key structural characteristics of native cartilage, support in vitro cartilage formation, and have superior features to homogeneous particulate-templated scaffolds. We propose that these scaffolds offer promise for regenerative medicine strategies to repair articular cartilage lesions.

[Etiological hypothesis on five cases of elastofibroma dorsi]. / Ipotesi eziologica su cinque casi di elastofibroma dorsi.

Elastofibroma dorsi is a rare benign lesion of the soft tissue of the thoracic wall, usually located in the subscapular region. It occurs mostly in elderly women patients. This lesion usually arises in right region but it can also be bilateral. Even if the pathogenesis is still unknown, it is considered that "rubbing" of the scapula against the thorax wall could determine growth of the elastofibroma. The differential diagnosis from sarcoma is required but the typical localization and the MRI suggest the diagnosis which should be confirm with the histological exam. The Authors present their experience on five patients, with a median age of 64, affected by elastofibroma dorsi. In two cases, a builder and an obstetrician, the lesion was bilateral; in the other three cases, two teachers and a notary, the lesion are right-sided. A thorax computed tomography (CT) revealed a lesion with heterogeneous density, and the magnetic resonance imaging (MRI) , shows intralesional areas of medium and high intensity signals in the tissue with low intensity in both T12 and T2-sequences. The patient underwent surgery and diagnosis was confirmed by the histological exam. Prevalence of the right localization reported in literature, the correlation between the job of the patients and the lesion localization, more evident in the women, confirmed, according to the other Authors, the etiological hypothesis which considers the lesion as a proliferative response of the connective tissue to the repeated mechanical stress which excessive elastic fibrollogenesis probably due to genetic predisposition.

A late complication of transobturator tape: abscess and myositis.

The aim of the present study was to investigate a late complication of transobturator tape (TOT) implant: abscess and myositis. The case report included a 53 years-old vaginal multipara, subject to transobturator tape procedure in 2004, who came to the observation of the Department of Obstetrics and Gynecology (University of Catania, Italy) with a late vaginal polypropylene mesh erosion. She reported growing pain at her left leg, walking difficulty, fever and persistent stress urinary incontinence (SUI). She also described a shooting pain originating from the left inguinal ligament radiating down her left leg. Obturator internus and adducent muscles of the left thigh were involved. Ultrasounds and magnetic resonance imaging (MRI) clearly revealed the course of the mesh tape through the obturator muscles with myositis and abscess. The patient was treated by removing the polypropylene tape through the vaginal erosion. Her symptomatology improved within 3 weeks after the tape removal. Although developed to minimize surgical morbidity, the TOT procedure is not risk-free. Like for all the synthetic sling materials, the risk of erosion and resulting ascending infection from contamination exists. Because of the rarity of this complication, the Authors performed an assessment of this condition. Erosion may predispose the patient to secondary complications: abscess and myositis with great difficulty in deambulation. Imaging diagnosis is very effective. Ultrasound imaging is a useful method to investigate the whole pelvic floor condition. Moreover, MRI is a precise diagnostic procedure. This case not only proved the failure of the TOT for the treatment of stress incontinence, but also all the associated concerns. The study emphasizes the observation that abscess and symptomatic myositis may result into late disabling complications, although starting from a mini-invasive procedure.

Magnetic resonance findings in scuba diving-related spinal cord decompression sickness.

Scuba diving is associated with risk of severe decompression sickness (DCS type II), which results from rapid reduction of the environmental pressure sufficient to cause the formation into tissue or blood of inert gas bubbles previously loaded within tissues as a soluble phase. DCS type II constitutes a unique subset of ischemic insults to the central nervous system (CNS) with primarily involvement of the spinal cord. Ten patients with diving-related barotrauma underwent neurologic examination. Two of them presented progressive sensory and motor loss in the extremities at admission and were presumed affected by spinal cord DCS. Magnetic resonance imaging (MRI) demonstrated abnormalities in the white-matter tracts of the spinal cord in these patients, in each case corresponding to an area of the cord believed to be clinically involved. After a course of therapeutic recompressions, one patient was able to stand and walk a short distance, and MRI revealed a decreased extension of areas of spinal cord abnormalities. MRI has proved to be reliable in the detection of pathologic changes of spinal cord decompression sickness that were previously undetectable by other neuroimaging methods and also has proved to be useful in the follow-up during therapeutic hyperbaric recompressions.