ABSTRACT
Impact injury to a joint is a known risk factor for the subsequent development of secondary osteoarthritis. An in vitro model, employing a drop-tower loading machine, was used to examine the effect of an impact load on isolated articular cartilage explants from human and bovine femoral heads. Two different types of impact experiment were performed. In the first, 4 mm diameter explants were loaded using a plane-ended impactor. In the second, a modified impactor was developed that had a central 4 mm diameter plane-ended indentor which was used to load the centre of 8 mm diameter explants. This enabled the unloaded outer ring of each explant to be compared with the loaded central core. The modulus values measured using the impactor were found to be higher, compared with the indentor in both species. Scanning electron microscopy showed that cartilage surrounding the loaded central region of the 8 mm explants protected the indented tissue, and these explants showed less damage than the 4 mm samples that were fully impacted. In addition, human cartilage was found to be less damaged than bovine, possibly as a consequence of the different structure as well as of a greater thickness. Both the source of the tissue and the nature of the impact affected the type of damage observed.
Subject(s)
Cartilage, Articular/injuries , Cartilage, Articular/physiopathology , Physical Stimulation/adverse effects , Wounds, Nonpenetrating/pathology , Wounds, Nonpenetrating/physiopathology , Aged , Animals , Biophysics/methods , Cartilage, Articular/pathology , Cattle , Elasticity , Hardness , Humans , In Vitro Techniques , Species Specificity , Stress, Mechanical , Wounds, Nonpenetrating/etiologyABSTRACT
Expansion of native corn starch produces a high surface area mesoporous material capable of acting as a novel stationary phase for separating various mixtures of compounds.
Subject(s)
Chromatography, Gas/instrumentation , Silicon Dioxide/chemistry , Starch/chemistry , Adsorption , Particle Size , Surface PropertiesABSTRACT
Articular cartilage biopsies were subjected to a single impact load and the metabolic response of the chondrocytes investigated using radiolabelled precursors for protein ([3H]leucine) and glycosaminoglycan ([35S]sulfate). The severity of the impact was controlled by using different masses and drop heights in a purpose built drop tower. Loss of matrix components was studied by prelabelling prior to loading, the possible repair response by pulse labelling at defined intervals after loading. There was an increase in the loss of both labels from the tissue with increasing severity of impact though the patterns of loss were different. Only 25%-40% of the sulfate was lost over a two week period and the loss increased with the severity of impact. This contrasted with 60% of the leucine being lost over the same period independently of loading. In addition to the loss of synthetic activity caused by cell death, there was a suppression of incorporation immediately following loading. This eventually recovered and increased above control values but the recovery time appeared to depend on the severity of the impact. These results provide preliminary evidence for a repair response.
Subject(s)
Cartilage, Articular/metabolism , Extracellular Matrix/metabolism , Animals , Cattle , Cell Survival , In Vitro Techniques , Leucine/metabolism , Stress, Mechanical , Sulfates/metabolismABSTRACT
An impact load was applied to full-depth circular samples of articular cartilage in vitro and the effects of impact energy and velocity on matrix integrity and chondrocyte viability were studied. Following a severe impact, calculated to correspond to the energy density over the cartilage surface that might be expected in a man jumping off a 1-m-high wall, the tissue was grossly disrupted. It became elliptical, fissured, and flattened. Cartilage samples remaining attached to the underlying bone showed less damage at similar drop masses and heights. Chondrocyte viability was found to decrease linearly with increasing impact energy. Cartilage biopsies maintained in culture for up to 15 days following impact gained mass over the first 3 days which they did not subsequently lose. The gain in mass increased with the severity of impact and was due to an increased hydration of the tissue. Scanning electron microscopy and light microscopy showed fissures penetrating the tissue but which were never found to pass through the full depth. They were commonly oriented at about 45 degrees to the plane of the surface and gave the appearance of being deflected parallel to the surface on reaching the transition zone. This produced a "delaminating" effect where the surface zone was separating from the deep zone.
Subject(s)
Cartilage, Articular/injuries , Cartilage, Articular/physiology , Animals , Biomechanical Phenomena , Biophysical Phenomena , Biophysics , Cartilage, Articular/cytology , Cattle , Cell Survival , Humans , In Vitro Techniques , Male , Microscopy, Electron, Scanning , Stress, MechanicalABSTRACT
The practice of depositing units of autologous blood to prepare for elective surgery is steadily increasing. This article outlines the advantages and limitations of autologous blood donations. Secondary analysis from a study of functional recovery following total knee replacement compares functional outcomes of people who predeposited autologous units with those who did not. Clinical implications and suggestions are made for managing the patient's physiologic status during the donation process, as well as hemodynamic status during the postoperative transfusion period.
